Make thin branches setting to checkbox

[minetest_ltool.git] / init.lua

ltool = {}

ltool.VERSION = {}
ltool.VERSION.MAJOR = 1
ltool.VERSION.MINOR = 4
ltool.VERSION.PATCH = 2
ltool.VERSION.STRING = ltool.VERSION.MAJOR .. "." .. ltool.VERSION.MINOR .. "." .. ltool.VERSION.PATCH

ltool.playerinfos = {}
ltool.default_edit_fields = {
        axiom="",
        rules_a="",
        rules_b="",
        rules_c="",
        rules_d="",
        trunk="mapgen_tree",
        leaves="mapgen_leaves",
        leaves2="mapgen_jungleleaves",
        leaves2_chance="0",
        fruit="mapgen_apple",
        fruit_chance="0",
        angle="45",
        iterations="2",
        random_level="0",
        trunk_type="single",
        thin_branches="true",
        name = "",
}

local mod_select_item = minetest.get_modpath("select_item") ~= nil

local sapling_base_name = "L-System Tree Sapling"
local sapling_format_string = "L-System Tree Sapling (%s)"

local place_tree = function(pos)
        -- Place tree
        local meta = minetest.get_meta(pos)
        local treedef = minetest.deserialize(meta:get_string("treedef"))
        minetest.remove_node(pos)
        minetest.spawn_tree(pos, treedef)
end

--[[ This registers the sapling for planting the trees ]]
minetest.register_node("ltool:sapling", {
        description = sapling_base_name,
        _doc_items_longdesc = "This artificial sapling does not come from nature and contains the genome of a genetically engineered L-system tree. Every sapling of this kind is unique. Who knows what might grow from it when you plant it?",
        _doc_items_usagehelp = "Place the sapling on any floor and wait 5 seconds for the tree to appear. If you have the “lplant” privilege, you can grow it instantly by rightclicking it. If you hold down the sneak key while placing it, you will keep a copy of the sapling in your inventory. To create your own saplings, you need to have the “lplant” privilege and pick a tree from the L-System Tree Utility (accessed with the server command “treeform”).",
        drawtype = "plantlike",
        tiles = { "ltool_sapling.png" },
        inventory_image = "ltool_sapling.png",
        selection_box = {
                type = "fixed",
                fixed = { -10/32, -0.5, -10/32, 10/32, 12/32, 10/32 },
        },
        wield_image = "ltool_sapling.png",
        paramtype = "light",
        paramtype2= "wallmounted",
        walkable = false,
        groups = { dig_immediate = 3, not_in_creative_inventory=1, },
        drop = "",
        sunlight_propagates = true,
        is_ground_content = false,
        after_place_node = function(pos, placer, itemstack, pointed_thing)
                -- Transfer metadata and start timer
                local nodemeta = minetest.get_meta(pos)
                local itemmeta = itemstack:get_meta()
                local itemtreedef = itemmeta:get_string("treedef")

                -- Legacy support for saplings with legacy metadata
                if itemtreedef == nil or itemtreedef == "" then
                        itemtreedef = itemstack:get_metadata()
                        if itemtreedef == nil or itemtreedef == "" then
                                return nil
                        end
                end
                nodemeta:set_string("treedef", itemtreedef)
                local timer = minetest.get_node_timer(pos)
                timer:start(5)
                if placer:get_player_control().sneak == true then
                        return true
                else
                        return nil
                end
        end,
        -- Insta-grow when sapling got rightclicked
        on_rightclick = function(pos, node, clicker, itemstack, pointed_thing)
                if minetest.get_player_privs(clicker:get_player_name()).lplant then
                        place_tree(pos)
                end
        end,
        -- Grow after timer elapsed
        on_timer = place_tree,
        can_dig = function(pos, player)
                return minetest.get_player_privs(player:get_player_name()).lplant
        end,
})

minetest.register_craftitem("ltool:tool", {
        description = "L-System Tree Utility",
        _doc_items_longdesc = "This gadget allows the aspiring genetic engineer to invent and change L-system trees, create L-system tree saplings and look at the inventions from other players. L-system trees are trees and tree-like strucures which are built by a set of (possibly recursive) production rules.",
        _doc_items_usagehelp = "Punch to open the L-System editor. A tabbed form will open. To edit and create trees, you need the “ledit” privilege, to make saplings, you need “lplant”. Detailed usage help can be found in that menu. You can also access the same editor with the server command “treeform”.",
        inventory_image = "ltool_tool.png",
        wield_image = "ltool_tool.png",
        on_use = function(itemstack, user, pointed_thing)
                ltool.show_treeform(user:get_player_name())
        end,
})

--[[ Register privileges ]]
minetest.register_privilege("ledit", {
        description = "Can add, edit, rename and delete own L-system tree definitions of the ltool mod",
        give_to_singleplayer = false,
})
minetest.register_privilege("lplant", {
        description = "Can place L-system trees and get L-system tree samplings of the ltool mod",
        give_to_singleplayer = false,
})

--[[ Load previously saved data from file or initialize an empty tree table ]]
do
        local filepath = minetest.get_worldpath().."/ltool.mt"
        local file = io.open(filepath, "r")
        if(file) then
                local string = file:read()
                io.close(file)
                if(string ~= nil) then
                        local savetable = minetest.deserialize(string)
                        if(savetable ~= nil) then
                                ltool.trees = savetable.trees
                                ltool.next_tree_id = savetable.next_tree_id
                                ltool.number_of_trees = savetable.number_of_trees
                                minetest.log("action", "[ltool] Tree data loaded from "..filepath..".")
                        else
                                minetest.log("error", "[ltool] Failed to load tree data from "..filepath..".")
                        end
                else
                        minetest.log("error", "[ltool] Failed to load tree data from "..filepath..".")
                end
        else
                --[[ table of all trees ]]
                ltool.trees = {}
                --[[ helper variables to ensure unique IDs ]]
                ltool.number_of_trees = 0
                ltool.next_tree_id = 1
        end
end

--[[ Adds a tree to the tree table.
        name: The tree’s name.
        author: The author’s / owners’ name
        treedef: The full tree definition, see lua_api.txt

        returns the tree ID of the new tree
]]
function ltool.add_tree(name, author, treedef)
        local id = ltool.next_tree_id
        ltool.trees[id] = {name = name, author = author, treedef = treedef}
        ltool.next_tree_id = ltool.next_tree_id + 1
        ltool.number_of_trees = ltool.number_of_trees + 1
        return id
end

--[[ Removes a tree from the database
        tree_id: ID of the tree to be removed

        returns nil
]]
function ltool.remove_tree(tree_id)
        ltool.trees[tree_id] = nil
        ltool.number_of_trees = ltool.number_of_trees - 1
        for k,v in pairs(ltool.playerinfos) do
                if(v.dbsel ~= nil) then
                        if(v.dbsel > ltool.number_of_trees) then
                                v.dbsel = ltool.number_of_trees
                        end
                        if(v.dbsel < 1) then
                                v.dbsel = 1
                        end
                end
        end
end

--[[ Renames a tree in the database
        tree_id: ID of the tree to be renamed
        new_name: The name of the tree

        returns nil
]]
function ltool.rename_tree(tree_id, new_name)
        ltool.trees[tree_id].name = new_name
end

--[[ Copies a tree in the database
        tree_id: ID of the tree to be copied

        returns: the ID of the copy on success;
                 false on failure (tree does not exist)
]]
function ltool.copy_tree(tree_id)
        local tree = ltool.trees[tree_id]
        if(tree == nil) then
                return false
        end
        return ltool.add_tree(tree.name, tree.author, tree.treedef)
end

--[[ Gives a L-system tree sapling to a player
        treedef: L-system tree definition table of tree the sapling will grow
        seed: Seed of the tree (optional; can be nil)
        playername: name of the player to which
        ignore_priv: if true, player’s lplant privilige is not checked (optional argument; default: false)
        treename: Descriptive name of the tree for the item description (optional, is ignored if nil or empty string)

        returns:
                true on success
                false, 1 if privilege is not sufficient
                false, 2 if player’s inventory is full
]]
function ltool.give_sapling(treedef, seed, player_name, ignore_priv, treename)
        local privs = minetest.get_player_privs(player_name)
        if(ignore_priv == nil) then ignore_priv = false end
        if(ignore_priv == false and privs.lplant ~= true) then
                return false, 1
        end

        local sapling = ItemStack("ltool:sapling")
        local player = minetest.get_player_by_name(player_name)
        treedef.seed = seed
        local smeta = sapling:get_meta()
        smeta:set_string("treedef", minetest.serialize(treedef))
        if treename and treename ~= "" then
                smeta:set_string("description", string.format(sapling_format_string, treename))
        end
        treedef.seed = nil
        local leftover = player:get_inventory():add_item("main", sapling)
        if(not leftover:is_empty()) then
                return false, 2
        else
                return true
        end
end

--[[ Plants a tree as the specified position
        tree_id: ID of tree to be planted
        pos: Position of tree, in format {x=?, y=?, z=?}
        seed: Optional seed for randomness, equal seed makes equal trees

        returns false on failure, nil otherwise
]]
function ltool.plant_tree(tree_id, pos, seed)
        local tree = ltool.trees[tree_id]
        if(tree==nil) then
                return false
        end
        local treedef
        if seed ~= nil then
                treedef = table.copy(tree.treedef)
                treedef.seed = seed
        else
                treedef = tree.treedef
        end
        minetest.spawn_tree(pos, treedef)
end

--[[ Tries to return a tree data structure for a given tree_id

        tree_id: ID of tee to be returned

        returns false on failure, a tree otherwise
]]
function ltool.get_tree(tree_id)
        local tree = ltool.trees[tree_id]
        if(tree==nil) then
                return false
        end
        return tree
end


ltool.seed = os.time()


--[=[ Here come the functions to build the main formspec.
They do not build the entire formspec ]=]

ltool.formspec_size = "size[12,9]"

--[[ This is a part of the main formspec: Tab header ]]
function ltool.formspec_header(index)
        return "tabheader[0,0;ltool_tab;Edit,Database,Plant,Help;"..tostring(index)..";true;false]"
end

--[[ This creates the edit tab of the formspec
        fields: A template used to fill the default values of the formspec. ]]
function ltool.tab_edit(fields, has_ledit_priv, has_lplant_priv)
        if(fields==nil) then
                fields = ltool.default_edit_fields
        end
        local s = function(input)
                local ret
                if(input==nil) then
                        ret = ""
                else
                        ret = minetest.formspec_escape(tostring(input))
                end
                return ret
        end

        -- Show save/clear buttons depending on privs
        local leditbuttons
        if has_ledit_priv then
                leditbuttons = "button[0,8.7;4,0;edit_save;Save tree to database]"..
                "button[4,8.7;4,0;edit_clear;Reset fields]"
                if has_lplant_priv then
                        leditbuttons = leditbuttons .. "button[8,8.7;4,0;edit_sapling;Generate sapling]"
                end
        else
                leditbuttons = "label[0,8.3;Read-only mode. You need the “ledit” privilege to save trees to the database.]"
        end

        local nlength = "3"
        local fields_select_item = ""
        if mod_select_item then
                nlength = "2.6"
                fields_select_item = ""..
                "button[2.4,5.7;0.5,0;edit_trunk;>]"..
                "button[5.4,5.7;0.5,0;edit_leaves;>]"..
                "button[8.4,5.7;0.5,0;edit_leaves2;>]"..
                "button[11.4,5.7;0.5,0;edit_fruit;>]"..
                "tooltip[edit_trunk;Select node]"..
                "tooltip[edit_leaves;Select node]"..
                "tooltip[edit_leaves2;Select node]"..
                "tooltip[edit_fruit;Select node]"
        end

        local trunk_type_mapping_reverse = {
                ["single"] = 1,
                ["double"] = 2,
                ["crossed"] = 3,
        }
        local trunk_type_idx
        if fields.trunk_type then
                trunk_type_idx = trunk_type_mapping_reverse[fields.trunk_type]
        else
                trunk_type_idx = 1
        end

        return ""..
        "field[0.2,1;11,0;axiom;Axiom;"..s(fields.axiom).."]"..
        "button[11,0.7;1,0;edit_axiom;+]"..
        "tooltip[edit_axiom;Opens larger text field for Axiom]"..
        "field[0.2,2;11,0;rules_a;Rules set A;"..s(fields.rules_a).."]"..
        "button[11,1.7;1,0;edit_rules_a;+]"..
        "tooltip[edit_rules_a;Opens larger text field for Rules set A]"..
        "field[0.2,3;11,0;rules_b;Rules set B;"..s(fields.rules_b).."]"..
        "button[11,2.7;1,0;edit_rules_b;+]"..
        "tooltip[edit_rules_b;Opens larger text field for Rules set B]"..
        "field[0.2,4;11,0;rules_c;Rules set C;"..s(fields.rules_c).."]"..
        "button[11,3.7;1,0;edit_rules_c;+]"..
        "tooltip[edit_rules_c;Opens larger text field for Rules set C]"..
        "field[0.2,5;11,0;rules_d;Rules set D;"..s(fields.rules_d).."]"..
        "button[11,4.7;1,0;edit_rules_d;+]"..
        "tooltip[edit_rules_d;Opens larger text field for Rules set D]"..

        "field[0.2,6;"..nlength..",0;trunk;Trunk node;"..s(fields.trunk).."]"..
        "field[3.2,6;"..nlength..",0;leaves;Leaves node;"..s(fields.leaves).."]"..
        "field[6.2,6;"..nlength..",0;leaves2;Secondary leaves node;"..s(fields.leaves2).."]"..
        "field[9.2,6;"..nlength..",0;fruit;Fruit node;"..s(fields.fruit).."]"..
        fields_select_item..

        "dropdown[-0.075,6.35;3;trunk_type;single,double,crossed;"..trunk_type_mapping_reverse[fields.trunk_type].."]"..
        "tooltip[trunk_type;Tree trunk type. Possible values:\n- \"single\": trunk of size 1×1\n- \"double\": trunk of size 2×2\n- \"crossed\": trunk in cross shape (3×3).]"..
        "checkbox[2.9,6.2;thin_branches;Thin branches;"..s(fields.thin_branches).."]"..
        "tooltip[thin_branches;If enabled\\, all branches are just 1 node wide\\, otherwise, branches can be larger.]"..
        "field[6.2,7;3,0;leaves2_chance;Secondary leaves chance (%);"..s(fields.leaves2_chance).."]"..
        "tooltip[leaves2_chance;Chance (in percent) to replace a leaves node by a secondary leaves node]"..
        "field[9.2,7;3,0;fruit_chance;Fruit chance (%);"..s(fields.fruit_chance).."]"..
        "tooltip[fruit_chance;Chance (in percent) to replace a leaves node by a fruit node.]"..

        "field[0.2,8;3,0;iterations;Iterations;"..s(fields.iterations).."]"..
        "tooltip[iterations;Maximum number of iterations, usually between 2 and 5.]"..
        "field[3.2,8;3,0;random_level;Randomness level;"..s(fields.random_level).."]"..
        "tooltip[random_level;Factor to lower number of iterations, usually between 0 and 3.]"..
        "field[6.2,8;3,0;angle;Angle (°);"..s(fields.angle).."]"..
        "field[9.2,8;3,0;name;Name;"..s(fields.name).."]"..
        "tooltip[name;Descriptive name for this tree, only used for convenience.]"..
        leditbuttons
end

--[[ This creates the database tab of the formspec.
        index: Selected index of the textlist
        playername: To whom the formspec is shown
]]
function ltool.tab_database(index, playername)
        local treestr, tree_ids = ltool.build_tree_textlist(index, playername)
        if(treestr ~= nil) then
                local indexstr
                if(index == nil) then
                        indexstr = ""
                else
                        indexstr = tostring(index)
                end
                ltool.playerinfos[playername].treeform.database.textlist = tree_ids

                local leditbuttons, lplantbuttons
                if minetest.get_player_privs(playername).ledit then
                        leditbuttons = "button[3,7.5;3,1;database_rename;Rename tree]"..
                        "button[6,7.5;3,1;database_delete;Delete tree]"
                else
                        leditbuttons = "label[0.2,7.2;Read-only mode. You need the “ledit” privilege to edit trees.]"
                end
                if minetest.get_player_privs(playername).lplant then
                        lplantbuttons = "button[0,8.5;3,1;sapling;Generate sapling]"
                else
                        lplantbuttons = ""
                end

                return ""..
                "textlist[0,0;11,7;treelist;"..treestr..";"..tostring(index)..";false]"..
                lplantbuttons..
                leditbuttons..
                "button[3,8.5;3,1;database_copy;Copy tree to editor]"..
                "button[6,8.5;3,1;database_update;Reload database]"
        else
                return "label[0,0;The tree database is empty.]"..
                "button[6.5,8.5;3,1;database_update;Reload database]"
        end
end

--[[ This creates the "Plant" tab part of the main formspec ]]
function ltool.tab_plant(tree, fields, has_lplant_priv)
        if(tree ~= nil) then
                local seltree = "label[0,-0.2;Selected tree: "..minetest.formspec_escape(tree.name).."]"
                if not has_lplant_priv then
                        return seltree..
                        "label[0,0.3;Planting of trees is not allowed. You need to have the “lplant” privilege.]"
                end
                if(fields==nil) then
                        fields = {}
                end
                local s = function(i)
                        if(i==nil) then return ""
                        else return tostring(minetest.formspec_escape(i))
                        end
                end
                local seed
                if(fields.seed == nil) then
                        seed = tostring(ltool.seed)
                else
                        seed = fields.seed
                end
                local dropdownindex
                if(fields.plantmode == "Absolute coordinates") then
                        dropdownindex = 1
                elseif(fields.plantmode == "Relative coordinates") then
                        dropdownindex = 2
                elseif(fields.plantmode == "Distance in viewing direction") then
                        dropdownindex = 3
                else
                        dropdownindex = 1
                end

                return ""..
                seltree..
                "dropdown[-0.1,0.5;5;plantmode;Absolute coordinates,Relative coordinates,Distance in viewing direction;"..dropdownindex.."]"..
--[[ NOTE: This tooltip does not work for the dropdown list in 0.4.10,
but it is added anyways in case this gets fixed in later Minetest versions. ]]
                "tooltip[plantmode;"..
                "- \"Absolute coordinates\": Fields \"x\", \"y\" and \"z\" specify the absolute world coordinates where to plant the tree\n"..
                "- \"Relative coordinates\": Fields \"x\", \"y\" and \"z\" specify the relative position from your position\n"..
                "- \"Distance in viewing direction\": Plant tree relative from your position in the direction you look to, at the specified distance"..
                "]"..
                "field[0.2,-2;6,10;x;x;"..s(fields.x).."]"..
                "tooltip[x;Field is only used by absolute and relative coordinates.]"..
                "field[0.2,-1;6,10;y;y;"..s(fields.y).."]"..
                "tooltip[y;Field is only used by absolute and relative coordinates.]"..
                "field[0.2,0;6,10;z;z;"..s(fields.z).."]"..
                "tooltip[z;Field is only used by absolute and relative coordinates.]"..
                "field[0.2,1;6,10;distance;Distance;"..s(fields.distance).."]"..
                "tooltip[distance;This field is used to specify the distance (in node lengths) from your position\nin the viewing direction. It is ignored if you use coordinates.]"..
                "field[0.2,2;6,10;seed;Randomness seed;"..seed.."]"..
                "tooltip[seed;A number used for the random number generators. Identical randomness seeds will produce identical trees. This field is optional.]"..
                "button[3.5,8;3,1;plant_plant;Plant tree]"..
                "tooltip[plant_plant;Immediately place the tree at the specified position]"..
                "button[6.5,8;3,1;sapling;Generate sapling]"..
                "tooltip[sapling;This gives you an item which you can place manually in the world later]"
        else
                local notreestr = "No tree in database selected or database is empty."
                if has_lplant_priv then
                        return "label[0,0;"..notreestr.."]"
                else
                        return "label[0,0;"..notreestr.."\nYou are not allowed to plant trees anyway as you don't have the “lplant” privilege.]"
                end
        end
end


--[[ This creates the cheat sheet tab ]]
function ltool.tab_cheat_sheet()
        return ""..
        "tablecolumns[text;text]"..
        "tableoptions[background=#000000;highlight=#000000;border=false]"..
        "table[-0.15,0.75;12,8;cheat_sheet;"..
        "Symbol,Action,"..
        "G,Move forward one unit with the pen up,"..
        "F,Move forward one unit with the pen down drawing trunks and branches,"..
        "f,Move forward one unit with the pen down drawing leaves,"..
        "T,Move forward one unit with the pen down drawing trunks,"..
        "R,Move forward one unit with the pen down placing fruit,"..
        "A,Replace with rules set A,"..
        "B,Replace with rules set B,"..
        "C,Replace with rules set C,"..
        "D,Replace with rules set D,"..
        "a,Replace with rules set A\\, chance 90%,"..
        "b,Replace with rules set B\\, chance 80%,"..
        "c,Replace with rules set C\\, chance 70%,"..
        "d,Replace with rules set D\\, chance 60%,"..
        "+,Yaw the turtle right by angle parameter,"..
        "-,Yaw the turtle left by angle parameter,"..
        "&,Pitch the turtle down by angle parameter,"..
        "^,Pitch the turtle up by angle parameter,"..
        "/,Roll the turtle to the right by angle parameter,"..
        "*,Roll the turtle to the left by angle parameter,"..
        "\\[,Save in stack current state info,"..
        "\\],Recover from stack state info]"
end

function ltool.tab_help_intro()
        return ""..
        "tablecolumns[text]"..
        "tableoptions[background=#000000;highlight=#000000;border=false]"..
        "table[-0.15,0.75;12,7;help_intro;"..
        string.format("You are using the L-System Tree Utility, version %s.,", ltool.VERSION.STRING)..
        ","..
        "The purpose of this utility is to aid with the creation of L-system trees.,"..
        "You can create\\, save\\, manage and plant L-system trees.,"..
        "All trees are saved into <world path>/ltool.mt on server shutdown.,"..
        "It assumes you already understand the concept of L-systems\\;,"..
        "this utility is mainly aimed towards modders and nerds.,"..
        ","..
        "The usual workflow goes like this:,"..
        ","..
        "1. Create a new tree in the \"Edit\" tab and save it,"..
        "2. Select it in the database,"..
        "3. Plant it,"..
        ","..
        "To help you get started\\, you can create an example tree for the \"Edit\" tab,"..
        "by pressing this button:]"..
        "button[4,8;4,1;create_template;Create template]"
end

function ltool.tab_help_edit()
        return ""..
        "tablecolumns[text]"..
        "tableoptions[background=#000000;highlight=#000000;border=false]"..
        "table[-0.15,0.75;12,8;help_edit;"..
        "To create a L-system tree\\, switch to the \"Edit\" tab.,"..
        "When you are done\\, hit \"Save tree to database\". The tree will be stored in,"..
        "the database. The \"Reset fields\" button resets the input fields to defaults.,"..
        "To understand the meaning of the fields\\, read the introduction to L-systems.,"..
        "All trees must have an unique name. You are notified in case there is a name,"..
        "clash. If the name clash is with one of your own trees\\, you can choose to,"..
        "replace it.]"
end

function ltool.tab_help_database()
        return ""..
        "tablecolumns[text]"..
        "tableoptions[background=#000000;highlight=#000000;border=false]"..
        "table[-0.15,0.75;12,8;help_database;"..
        "The database contains a list of all created trees among all players.,"..
        "Each tree has an \"owner\". This kind of ownership is limited:,"..
        "The owner may rename\\, change and delete their own trees\\,,"..
        "everyone else is prevented from doing that. But all trees can be,"..
        "copied freely by everyone\\;,"..
        "To do so\\, simply hit \"Copy tree to editor\"\\, change the name and hit,"..
        "\"Save tree to database\". If you like someone else's tree definition\\,,"..
        "it is recommended to make a copy for yourself\\, since the original owner,"..
        "can at any time choose to delete or edit the tree. The trees which you \"own\","..
        "are written in a yellow font\\, all other trees in a white font.,"..
        "In order to plant a tree\\, you have to select a tree in the database first.]"
end

function ltool.tab_help_plant()
        return ""..
        "tablecolumns[text]"..
        "tableoptions[background=#000000;highlight=#000000;border=false]"..
        "table[-0.15,0.75;12,8;help_plant;"..
        "To plant a tree from a previously created tree definition\\, first select,"..
        "it in the database\\, then open the \"Plant\" tab.,"..
        "In this tab\\, you can directly place the tree or request a sapling.,"..
        "If you choose to directly place the tree\\, you can either specify absolute,"..
        "or relative coordinates or specify that the tree should be planted in your,"..
        "viewing direction. Absolute coordinates are the world coordinates as specified,"..
        "by the \"x\"\\, \"y\"\\, and \"z\" fields. Relative coordinates are relative,"..
        "to your position and use the same fields. When you choose to plant the tree,"..
        "based on your viewing direction\\, the tree will be planted at a distance,"..
        "specified by the field \"distance\" away from you in the direction you look to.,"..
        "When using coordinates\\, the \"distance\" field is ignored\\, when using,"..
        "direction\\, the coordinate fields are ignored.,"..
        ","..
        "You can also use the “lplant” server command to plant trees.,"..
        ","..
        "If you got a sapling\\, you can place it practically anywhere you like to.,"..
        "After placing it\\, the sapling will be replaced by the L-system tree after,"..
        "5 seconds\\, unless it was destroyed in the meantime.,"..
        "All requested saplings are independent from the moment they are created.,"..
        "The sapling will still work\\, even if the original tree definiton has been,"..
        "deleted.]"
end

function ltool.tab_help(index)
        local formspec = "tabheader[0.1,1;ltool_help_tab;Introduction,Creating Trees,Managing Trees,Planting Trees,Cheat Sheet;"..tostring(index)..";true;false]"
        if(index==1) then
                formspec = formspec .. ltool.tab_help_intro()
        elseif(index==2) then
                formspec = formspec .. ltool.tab_help_edit()
        elseif(index==3) then
                formspec = formspec .. ltool.tab_help_database()
        elseif(index==4) then
                formspec = formspec .. ltool.tab_help_plant()
        elseif(index==5) then
                formspec = formspec .. ltool.tab_cheat_sheet()
        end

        return formspec
end

function ltool.formspec_editplus(fragment)
        local formspec = ""..
        "size[12,8]"..
        "textarea[0.2,0.5;12,3;"..fragment.."]"..
        "label[0,3.625;Draw:]"..
        "button[2,3.5;1,1;editplus_c_G;G]"..
        "tooltip[editplus_c_G;Move forward one unit with the pen up]"..
        "button[3,3.5;1,1;editplus_c_F;F]"..
        "tooltip[editplus_c_F;Move forward one unit with the pen down drawing trunks and branches]"..
        "button[4,3.5;1,1;editplus_c_f;f]"..
        "tooltip[editplus_c_f;Move forward one unit with the pen down drawing leaves]"..
        "button[5,3.5;1,1;editplus_c_T;T]"..
        "tooltip[editplus_c_T;Move forward one unit with the pen down drawing trunks]"..
        "button[6,3.5;1,1;editplus_c_R;R]"..
        "tooltip[editplus_c_R;Move forward one unit with the pen down placing fruit]"..

        "label[0,4.625;Rules:]"..
        "button[2,4.5;1,1;editplus_c_A;A]"..
        "tooltip[editplus_c_A;Replace with rules set A]"..
        "button[3,4.5;1,1;editplus_c_B;B]"..
        "tooltip[editplus_c_B;Replace with rules set B]"..
        "button[4,4.5;1,1;editplus_c_C;C]"..
        "tooltip[editplus_c_C;Replace with rules set C]"..
        "button[5,4.5;1,1;editplus_c_D;D]"..
        "tooltip[editplus_c_D;Replace with rules set D]"..
        "button[6.5,4.5;1,1;editplus_c_a;a]"..
        "tooltip[editplus_c_a;Replace with rules set A, chance 90%]"..
        "button[7.5,4.5;1,1;editplus_c_b;b]"..
        "tooltip[editplus_c_b;Replace with rules set B, chance 80%]"..
        "button[8.5,4.5;1,1;editplus_c_c;c]"..
        "tooltip[editplus_c_c;Replace with rules set C, chance 70%]"..
        "button[9.5,4.5;1,1;editplus_c_d;d]"..
        "tooltip[editplus_c_d;Replace with rules set D, chance 60%]"..

        "label[0,5.625;Rotate:]"..
        "button[3,5.5;1,1;editplus_c_+;+]"..
        "tooltip[editplus_c_+;Yaw the turtle right by the value specified in \"Angle\"]"..
        "button[2,5.5;1,1;editplus_c_-;-]"..
        "tooltip[editplus_c_-;Yaw the turtle left by the value specified in \"Angle\"]"..
        "button[4.5,5.5;1,1;editplus_c_&;&]"..
        "tooltip[editplus_c_&;Pitch the turtle down by the value specified in \"Angle\"]"..
        "button[5.5,5.5;1,1;editplus_c_^;^]"..
        "tooltip[editplus_c_^;Pitch the turtle up by the value specified in \"Angle\"]"..
        "button[8,5.5;1,1;editplus_c_/;/]"..
        "tooltip[editplus_c_/;Roll the turtle to the right by the value specified in \"Angle\"]"..
        "button[7,5.5;1,1;editplus_c_*;*]"..
        "tooltip[editplus_c_*;Roll the turtle to the left by the value specified in \"Angle\"]"..

        "label[0,6.625;Stack:]"..
        "button[2,6.5;1,1;editplus_c_P;\\[]"..
        "tooltip[editplus_c_P;Save current state info into stack]"..
        "button[3,6.5;1,1;editplus_c_p;\\]]"..
        "tooltip[editplus_c_p;Recover from current stack state info]"..

        "button[2.5,7.5;3,1;editplus_save;Save]"..
        "button[5.5,7.5;3,1;editplus_cancel;Cancel]"

        return formspec
end

--[[ creates the content of a textlist which contains all trees.
        index: Selected entry
        playername: To which the main formspec is shown to. Used for highlighting owned trees

        returns (string to be used in the text list, table of tree IDs)
]]
function ltool.build_tree_textlist(index, playername)
        local string = ""
        local colorstring
        if(ltool.number_of_trees == 0) then
                return nil
        end
        local tree_ids = ltool.get_tree_ids()
        for i=1,#tree_ids do
                local tree_id = tree_ids[i]
                local tree = ltool.trees[tree_id]
                if(tree.author == playername) then
                        colorstring = "#FFFF00"
                else
                        colorstring = ""
                end
                string = string .. colorstring .. tostring(tree_id) .. ": " .. minetest.formspec_escape(tree.name)
                if(i~=#tree_ids) then
                        string = string .. ","
                end
        end
        return string, tree_ids
end

--[=[ Here come functions which show formspecs to players ]=]

--[[ Shows the main tree form to the given player, starting with the "Edit" tab ]]
function ltool.show_treeform(playername)
        local privs = minetest.get_player_privs(playername)
        local formspec = ltool.formspec_size..ltool.formspec_header(1)..ltool.tab_edit(ltool.playerinfos[playername].treeform.edit.fields, privs.ledit, privs.lplant)
        minetest.show_formspec(playername, "ltool:treeform_edit", formspec)
end

--[[ spawns a simple dialog formspec to a player ]]
function ltool.show_dialog(playername, formname, message)
        local formspec = "size[12,2;]label[0,0.2;"..message.."]"..
        "button[4.5,1.5;3,1;okay;OK]"
        minetest.show_formspec(playername, formname, formspec)

end


--[=[ End of formspec-relatec functions ]=]

--[[ This function does a lot of parameter checks and returns (tree, tree_name) on success.
        If ANY parameter check fails, the whole function fails.
        On failure, it returns (nil, <error message string>).]]
function ltool.evaluate_edit_fields(fields, ignore_name)
        local treedef = {}
        -- Validation helper: Checks for invalid characters for the fields “axiom” and the 4 rule sets
        local v = function(str)
                local match = string.match(str, "[^][abcdfABCDFGTR+-/*&^]")
                if(match==nil) then
                        return true
                else
                        return false
                end
        end
        -- Validation helper: Checks for balanced brackets
        local b = function(str)
                local brackets = 0
                for c=1, string.len(str) do
                        local char = string.sub(str, c, c)
                        if char == "[" then
                                brackets = brackets + 1
                        elseif char == "]" then
                                brackets = brackets - 1
                                if brackets < 0 then
                                        return false
                                end
                        end
                end
                return brackets == 0
        end

        if(v(fields.axiom) and v(fields.rules_a) and v(fields.rules_b) and v(fields.rules_c) and v(fields.rules_d)) then
                if(b(fields.axiom) and b(fields.rules_a) and b(fields.rules_b) and b(fields.rules_c) and b(fields.rules_d)) then
                        treedef.rules_a = fields.rules_a
                        treedef.rules_b = fields.rules_b
                        treedef.rules_c = fields.rules_c
                        treedef.rules_d = fields.rules_d
                        treedef.axiom = fields.axiom
                else
                        return nil, "The brackets are unbalanced! For each of the axiom and the rule sets, each opening bracket must be matched by a closing bracket."
                end
        else
                return nil, "The axiom or one of the rule sets contains at least one invalid character.\nSee the cheat sheet for a list of allowed characters."
        end
        treedef.trunk = fields.trunk
        treedef.leaves = fields.leaves
        treedef.leaves2 = fields.leaves2
        treedef.leaves2_chance = fields.leaves2_chance
        treedef.angle = tonumber(fields.angle)
        if(treedef.angle == nil) then
                return nil, "The field \"Angle\" must contain a number."
        end
        treedef.iterations = tonumber(fields.iterations)
        if(treedef.iterations == nil) then
                return nil, "The field \"Iterations\" must contain a natural number greater or equal to 0."
        elseif(treedef.iterations < 0) then
                return nil, "The field \"Iterations\" must contain a natural number greater or equal to 0."
        end
        treedef.random_level = tonumber(fields.random_level)
        if(treedef.random_level == nil) then
                return nil, "The field \"Randomness level\" must contain a number."
        end
        treedef.fruit = fields.fruit
        treedef.fruit_chance = tonumber(fields.fruit_chance)
        if(treedef.fruit_chance == nil) then
                return nil, "The field \"Fruit chance\" must contain a number."
        elseif(treedef.fruit_chance > 100 or treedef.fruit_chance < 0) then
                return nil, "Fruit chance must be between 0% and 100%."
        end
        if(fields.trunk_type == "single" or fields.trunk_type == "double" or fields.trunk_type == "crossed") then
                treedef.trunk_type = fields.trunk_type
        else
                return nil, "Trunk type must be \"single\", \"double\" or \"crossed\"."
        end
        treedef.thin_branches = fields.thin_branches
        if(fields.thin_branches == "true") then
                treedef.thin_branches = true
        elseif(fields.thin_branches == "false") then
                treedef.thin_branches = false
        else
                return nil, "Field \"Thin branches?\" must be \"true\" or \"false\"."
        end
        local name = fields.name
        if(ignore_name ~= true and name == "") then
                return nil, "Name is empty."
        end
        return treedef, name
end


--[=[ Here come several utility functions ]=]

--[[ converts a given tree to field names, as if they were given to a
minetest.register_on_plyer_receive_fields callback function ]]
function ltool.tree_to_fields(tree)
        local s = function(i)
                if(i==nil) then
                        return ""
                else
                        return tostring(i)
                end
        end
        local fields = {}
        fields.axiom = s(tree.treedef.axiom)
        fields.rules_a = s(tree.treedef.rules_a)
        fields.rules_b = s(tree.treedef.rules_b)
        fields.rules_c = s(tree.treedef.rules_c)
        fields.rules_d = s(tree.treedef.rules_d)
        fields.trunk = s(tree.treedef.trunk)
        fields.leaves = s(tree.treedef.leaves)
        fields.leaves2 = s(tree.treedef.leaves2)
        fields.leaves2_chance = s(tree.treedef.leaves2)
        fields.fruit = s(tree.treedef.fruit)
        fields.fruit_chance = s(tree.treedef.fruit_chance)
        fields.angle = s(tree.treedef.angle)
        fields.iterations = s(tree.treedef.iterations)
        fields.random_level = s(tree.treedef.random_level)
        fields.trunk_type = s(tree.treedef.trunk_type)
        fields.thin_branches = s(tree.treedef.thin_branches)
        fields.name = s(tree.name)
        return fields
end



-- returns a simple table of all the tree IDs
function ltool.get_tree_ids()
        local ids = {}
        for tree_id, _ in pairs(ltool.trees) do
                table.insert(ids, tree_id)
        end
        table.sort(ids)
        return ids
end

--[[ In a table of tree IDs (returned by ltool.get_tree_ids, parameter tree_ids), this function
searches for the first occourance of the value searched_tree_id and returns its index.
This is basically a reverse lookup utility. ]]
function ltool.get_tree_id_index(searched_tree_id, tree_ids)
        for i=1, #tree_ids do
                local table_tree_id = tree_ids[i]
                if(searched_tree_id == table_tree_id) then
                        return i
                end
        end
end

-- Returns the selected tree of the given player
function ltool.get_selected_tree(playername)
        local sel = ltool.playerinfos[playername].dbsel
        if(sel ~= nil) then
                local tree_id = ltool.playerinfos[playername].treeform.database.textlist[sel]
                if(tree_id ~= nil) then
                        return ltool.trees[tree_id]
                end
        end
        return nil
end

-- Returns the ID of the selected tree of the given player
function ltool.get_selected_tree_id(playername)
        local sel = ltool.playerinfos[playername].dbsel
        if(sel ~= nil) then
                return ltool.playerinfos[playername].treeform.database.textlist[sel]
        end
        return nil
end


ltool.treeform = ltool.formspec_size..ltool.formspec_header(1)..ltool.tab_edit()

minetest.register_chatcommand("treeform",
{
        params = "",
        description = "Open L-System Tree Utility.",
        privs = {},
        func = function(playername, param)
                ltool.show_treeform(playername)
        end
})

minetest.register_chatcommand("lplant",
{
        description = "Plant a L-system tree at the specified position",
        privs = { lplant = true },
        params = "<tree ID> <x> <y> <z> [<seed>]",
        func = function(playername, param)
                local p = {}
                local tree_id, x, y, z, seed = string.match(param, "^([^ ]+) +([%d.-]+)[, ] *([%d.-]+)[, ] *([%d.-]+) *([%d.-]*)")
                tree_id, p.x, p.y, p.z, seed = tonumber(tree_id), tonumber(x), tonumber(y), tonumber(z), tonumber(seed)
                if not tree_id or not p.x or not p.y or not p.z then
                        return false, "Invalid usage, see /help lplant."
                end
                local lm = tonumber(minetest.settings:get("map_generation_limit") or 31000)
                if p.x < -lm or p.x > lm or p.y < -lm or p.y > lm or p.z < -lm or p.z > lm then
                        return false, "Cannot plant tree out of map bounds!"
                end

                local success = ltool.plant_tree(tree_id, p, seed)
                if success == false then
                        return false, "Unknown tree ID!"
                else
                        return true
                end
        end
})

function ltool.dbsel_to_tree(dbsel, playername)
        return ltool.trees[ltool.playerinfos[playername].treeform.database.textlist[dbsel]]
end

function ltool.save_fields(playername,formname,fields)
        if not fields.thin_branches then
                fields.thin_branches = ltool.playerinfos[playername].treeform.edit.thin_branches
        end
        if(formname=="ltool:treeform_edit") then
                ltool.playerinfos[playername].treeform.edit.fields = fields
        elseif(formname=="ltool:treeform_database") then
                ltool.playerinfos[playername].treeform.database.fields = fields
        elseif(formname=="ltool:treeform_plant") then
                ltool.playerinfos[playername].treeform.plant.fields = fields
        end
end

local function handle_sapling_button_database_plant(seltree, seltree_id, privs, formname, fields, playername)
        if(seltree ~= nil) then
                if(privs.lplant ~= true) then
                        ltool.save_fields(playername, formname, fields)
                        local message = "You can't request saplings, you need to have the \"lplant\" privilege."
                        ltool.show_dialog(playername, "ltool:treeform_error_sapling", message)
                        return false
                end
                local seed = nil
                if(tonumber(fields.seed)~=nil) then
                        seed = tonumber(fields.seed)
                end
                if ltool.trees[seltree_id] then
                        local ret, ret2 = ltool.give_sapling(ltool.trees[seltree_id].treedef, seed, playername, true, ltool.trees[seltree_id].name)
                        if(ret==false and ret2==2) then
                                ltool.save_fields(playername, formname, fields)
                                ltool.show_dialog(playername, "ltool:treeform_error_sapling", "Error: The sapling could not be given to you. Probably your inventory is full.")
                        end
                end
        end
end

--[=[ Callback functions start here ]=]
function ltool.process_form(player,formname,fields)
        local playername = player:get_player_name()

        local seltree = ltool.get_selected_tree(playername)
        local seltree_id = ltool.get_selected_tree_id(playername)
        local privs = minetest.get_player_privs(playername)
        local s = function(input)
                local ret
                if(input==nil) then
                        ret = ""
                else
                        ret = minetest.formspec_escape(tostring(input))
                end
                return ret
        end
        -- Update thin_branches field
        if(formname == "ltool:treeform_edit") then
                if(not fields.thin_branches) then
                        fields.thin_branches = ltool.playerinfos[playername].treeform.edit.thin_branches
                        if(not fields.thin_branches) then
                                minetest.log("error", "[ltool] thin_branches field of "..playername.." is nil!")
                        end
                else
                        ltool.playerinfos[playername].treeform.edit.thin_branches = fields.thin_branches
                end
        end
        --[[ process clicks on the tab header ]]
        if(formname == "ltool:treeform_edit" or formname == "ltool:treeform_database" or formname == "ltool:treeform_plant" or formname == "ltool:treeform_help") then
                if fields.ltool_tab ~= nil then
                        ltool.save_fields(playername, formname, fields)
                        local tab = tonumber(fields.ltool_tab)
                        local formspec, subformname, contents
                        if(tab==1) then
                                contents = ltool.tab_edit(ltool.playerinfos[playername].treeform.edit.fields, privs.ledit, privs.lplant)
                                subformname = "edit"
                        elseif(tab==2) then
                                contents = ltool.tab_database(ltool.playerinfos[playername].dbsel, playername)
                                subformname = "database"
                        elseif(tab==3) then
                                if(ltool.number_of_trees > 0) then
                                        contents = ltool.tab_plant(seltree, ltool.playerinfos[playername].treeform.plant.fields, privs.lplant)
                                else
                                        contents = ltool.tab_plant(nil, nil, privs.lplant)
                                end
                                subformname = "plant"
                        elseif(tab==4) then
                                contents = ltool.tab_help(ltool.playerinfos[playername].treeform.help.tab)
                                subformname = "help"
                        end
                        formspec = ltool.formspec_size..ltool.formspec_header(tab)..contents
                        minetest.show_formspec(playername, "ltool:treeform_" .. subformname, formspec)
                        return
                end
        end
        --[[ "Plant" tab ]]
        if(formname == "ltool:treeform_plant") then
                if(fields.plant_plant) then
                        if(seltree ~= nil) then
                                if(privs.lplant ~= true) then
                                        ltool.save_fields(playername, formname, fields)
                                        local message = "You can't plant trees, you need to have the \"lplant\" privilege."
                                        ltool.show_dialog(playername, "ltool:treeform_error_lplant", message)
                                        return
                                end
                                minetest.log("action","[ltool] Planting tree")
                                local treedef = seltree.treedef

                                local x,y,z = tonumber(fields.x), tonumber(fields.y), tonumber(fields.z)
                                local distance = tonumber(fields.distance)
                                local tree_pos
                                local fail_coordinates = function()
                                        ltool.save_fields(playername, formname, fields)
                                        ltool.show_dialog(playername, "ltool:treeform_error_badplantfields", "Error: When using coordinates, you have to specifiy numbers in the fields \"x\", \"y\", \"z\".")
                                end
                                local fail_distance = function()
                                        ltool.save_fields(playername, formname, fields)
                                        ltool.show_dialog(playername, "ltool:treeform_error_badplantfields", "Error: When using viewing direction for planting trees,\nyou must specify how far away you want the tree to be placed in the field \"Distance\".")
                                end
                                if(fields.plantmode == "Absolute coordinates") then
                                        if(type(x)~="number" or type(y) ~= "number" or type(z) ~= "number") then
                                                fail_coordinates()
                                                return
                                        end
                                        tree_pos = {x=x, y=y, z=z}
                                elseif(fields.plantmode == "Relative coordinates") then
                                        if(type(x)~="number" or type(y) ~= "number" or type(z) ~= "number") then
                                                fail_coordinates()
                                                return
                                        end
                                        tree_pos = player:getpos()
                                        tree_pos.x = tree_pos.x + x
                                        tree_pos.y = tree_pos.y + y
                                        tree_pos.z = tree_pos.z + z
                                elseif(fields.plantmode == "Distance in viewing direction") then
                                        if(type(distance)~="number") then
                                                fail_distance()
                                                return
                                        end
                                        tree_pos = vector.round(vector.add(player:getpos(), vector.multiply(player:get_look_dir(), distance)))
                                else
                                        minetest.log("error", "[ltool] fields.plantmode = "..tostring(fields.plantmode))
                                end
        
                                if(tonumber(fields.seed)~=nil) then
                                        treedef.seed = tonumber(fields.seed)
                                end
        
                                ltool.plant_tree(seltree_id, tree_pos)
        
                                treedef.seed = nil
                        end
                elseif(fields.sapling) then
                        local ret = handle_sapling_button_database_plant(seltree, seltree_id, privs, formname, fields, playername)
                        if ret == false then
                                return
                        end
                end
        --[[ "Edit" tab ]]
        elseif(formname == "ltool:treeform_edit") then
                if(fields.edit_save or fields.edit_sapling) then
                        local param1, param2
                        param1, param2 = ltool.evaluate_edit_fields(fields, fields.edit_sapling ~= nil)
                        if(fields.edit_save and privs.ledit ~= true) then
                                ltool.save_fields(playername, formname, fields)
                                local message = "You can't save trees, you need to have the \"ledit\" privilege."
                                ltool.show_dialog(playername, "ltool:treeform_error_ledit", message)
                                return
                        end
                        if(fields.edit_sapling and privs.lplant ~= true) then
                                ltool.save_fields(playername, formname, fields)
                                local message = "You can't request saplings, you need to have the \"lplant\" privilege."
                                ltool.show_dialog(playername, "ltool:treeform_error_ledit", message)
                                return
                        end
                        local tree_ok = true
                        local treedef, name
                        if(param1 ~= nil) then
                                treedef = param1
                                name = param2
                                for k,v in pairs(ltool.trees) do
                                        if(fields.edit_save and v.name == name) then
                                                ltool.save_fields(playername, formname, fields)
                                                if(v.author == playername) then
                                                        local formspec = "size[6,2;]label[0,0.2;You already have a tree with this name.\nDo you want to replace it?]"..
                                                        "button[0,1.5;3,1;replace_yes;Yes]"..
                                                        "button[3,1.5;3,1;replace_no;No]"
                                                        minetest.show_formspec(playername, "ltool:treeform_replace", formspec)
                                                else
                                                        ltool.show_dialog(playername, "ltool:treeform_error_nameclash", "Error: This name is already taken by someone else.\nPlease choose a different name.")
                                                end
                                                return
                                        end
                                end
                        else
                                tree_ok = false
                        end
                        ltool.save_fields(playername, formname, fields)
                        if(tree_ok == true) then
                                if fields.edit_save then
                                        ltool.add_tree(name, playername, treedef)
                                elseif fields.edit_sapling then
                                        local ret, ret2 = ltool.give_sapling(treedef, tostring(ltool.seed), playername, true, fields.name)
                                        if(ret==false and ret2==2) then
                                                ltool.save_fields(playername, formname, fields)
                                                ltool.show_dialog(playername, "ltool:treeform_error_sapling", "Error: The sapling could not be given to you. Probably your inventory is full.")
                                        end
                                end
                        else
                                local message = "Error: The tree definition is invalid.\n"..
                                minetest.formspec_escape(param2)
                                ltool.show_dialog(playername, "ltool:treeform_error_badtreedef", message)
                        end
                end
                if(fields.edit_clear) then
                        local privs = minetest.get_player_privs(playername)
                        ltool.save_fields(playername, formname, ltool.default_edit_fields)
                        local formspec = ltool.formspec_size..ltool.formspec_header(1)..ltool.tab_edit(ltool.default_edit_fields, privs.ledit, privs.lplant)

                        --[[ hacky_spaces is part of a workaround, see comment on hacky_spaces in ltool.join.
                        This workaround will slightly change the formspec by adding 0-5 spaces
                        to the end, changing the number of spaces on each send. This forces
                        Minetest to re-send the formspec.
                        Spaces are completely harmless in a formspec.]]
                        -- BEGIN OF WORKAROUND
                        local hacky_spaces = ltool.playerinfos[playername].treeform.hacky_spaces
                        hacky_spaces = hacky_spaces .. " "
                        if string.len(hacky_spaces) > 5 then
                                hacky_spaces = ""
                        end
                        ltool.playerinfos[playername].treeform.hacky_spaces = hacky_spaces
                        local real_formspec = formspec .. hacky_spaces
                        -- END OF WORKAROUND

                        minetest.show_formspec(playername, "ltool:treeform_edit", real_formspec)
                end
                if(fields.edit_axiom or fields.edit_rules_a or fields.edit_rules_b or fields.edit_rules_c or fields.edit_rules_d) then
                        local fragment
                        if(fields.edit_axiom) then
                                fragment = "axiom;Axiom;"..s(fields.axiom)
                        elseif(fields.edit_rules_a) then
                                fragment = "rules_a;Rules set A;"..s(fields.rules_a)
                        elseif(fields.edit_rules_b) then
                                fragment = "rules_b;Rules set B;"..s(fields.rules_b)
                        elseif(fields.edit_rules_c) then
                                fragment = "rules_c;Rules set C;"..s(fields.rules_c)
                        elseif(fields.edit_rules_d) then
                                fragment = "rules_d;Rules set D;"..s(fields.rules_d)
                        end

                        ltool.save_fields(playername, formname, fields)
                        local formspec = ltool.formspec_editplus(fragment)
                        minetest.show_formspec(playername, "ltool:treeform_editplus", formspec)
                end
                if(mod_select_item and (fields.edit_trunk or fields.edit_leaves or fields.edit_leaves2 or fields.edit_fruit)) then
                        ltool.save_fields(playername, formname, fields)
                        -- Prepare sorting.
                        -- Move tree, leaves, apple/leafdecay nodes to the beginning
                        local compare_group, fruit
                        if fields.edit_trunk then
                                compare_group = "tree"
                        elseif fields.edit_leaves or fields.edit_leaves2 then
                                compare_group = "leaves"
                        elseif fields.edit_fruit or fields.edit_fruit then
                                compare_group = "leafdecay"
                                local alias = minetest.registered_aliases["mapgen_apple"]
                                if alias and minetest.registered_nodes[alias] then
                                        fruit = alias
                                end
                        end
                        select_item.show_dialog(playername, "ltool:node", function(itemstring)
                                if itemstring ~= "air" and minetest.registered_nodes[itemstring] ~= nil then
                                        return true
                                end
                        end,
                        function(i1, i2)
                                if fruit and i1 == fruit then
                                        return true
                                end
                                if fruit and i2 == fruit then
                                        return false
                                end
                                local i1t = minetest.get_item_group(i1, compare_group)
                                local i2t = minetest.get_item_group(i2, compare_group)
                                local i1d = minetest.registered_items[i1].description
                                local i2d = minetest.registered_items[i2].description
                                local i1nici = minetest.get_item_group(i1, "not_in_creative_inventory")
                                local i2nici = minetest.get_item_group(i2, "not_in_creative_inventory")
                                if (i1d == "" and i2d ~= "") then
                                        return false
                                elseif (i1d ~= "" and i2d == "") then
                                        return true
                                end
                                if (i1nici == 1 and i2nici == 0) then
                                        return false
                                elseif (i1nici == 0 and i2nici == 1) then
                                        return true
                                end
                                if i1t < i2t then
                                        return false
                                elseif i1t > i2t then
                                        return true
                                end
                                return i1 < i2
                        end)
                end
        --[[ Larger edit fields for axiom and rules fields ]]
        elseif(formname == "ltool:treeform_editplus") then
                local editfields = ltool.playerinfos[playername].treeform.edit.fields
                local function addchar(c)
                        local fragment
                        if(c=="P") then c = "[" end
                        if(c=="p") then c = "]" end
                        if(fields.axiom) then
                                fragment = "axiom;Axiom;"..s(fields.axiom..c)
                        elseif(fields.rules_a) then
                                fragment = "rules_a;Rules set A;"..s(fields.rules_a..c)
                        elseif(fields.rules_b) then
                                fragment = "rules_b;Rules set B;"..s(fields.rules_b..c)
                        elseif(fields.rules_c) then
                                fragment = "rules_c;Rules set C;"..s(fields.rules_c..c)
                        elseif(fields.rules_d) then
                                fragment = "rules_d;Rules set D;"..s(fields.rules_d..c)
                        end
                        local formspec = ltool.formspec_editplus(fragment)
                        minetest.show_formspec(playername, "ltool:treeform_editplus", formspec)
                end
                if(fields.editplus_save) then
                        local function o(writed, writer)
                                if(writer~=nil) then
                                        return writer
                                else
                                        return writed
                                end
                        end
                        editfields.axiom = o(editfields.axiom, fields.axiom)
                        editfields.rules_a = o(editfields.rules_a, fields.rules_a)
                        editfields.rules_b = o(editfields.rules_b, fields.rules_b)
                        editfields.rules_c = o(editfields.rules_c, fields.rules_c)
                        editfields.rules_d = o(editfields.rules_d, fields.rules_d)
                        local formspec = ltool.formspec_size..ltool.formspec_header(1)..ltool.tab_edit(editfields, privs.ledit, privs.lplant)
                        minetest.show_formspec(playername, "ltool:treeform_edit", formspec)
                elseif(fields.editplus_cancel or fields.quit) then
                        local formspec = ltool.formspec_size..ltool.formspec_header(1)..ltool.tab_edit(editfields, privs.ledit, privs.lplant)
                        minetest.show_formspec(playername, "ltool:treeform_edit", formspec)
                else
                        for id, field in pairs(fields) do
                                if(string.sub(id,1,11) == "editplus_c_") then
                                        local char = string.sub(id,12,12)
                                        addchar(char)
                                end
                        end
                end
        --[[ "Database" tab ]]
        elseif(formname == "ltool:treeform_database") then
                if(fields.treelist) then
                        local event = minetest.explode_textlist_event(fields.treelist)
                        if(event.type == "CHG") then
                                ltool.playerinfos[playername].dbsel = event.index
                                local formspec = ltool.formspec_size..ltool.formspec_header(2)..ltool.tab_database(event.index, playername)
                                minetest.show_formspec(playername, "ltool:treeform_database", formspec)
                        end
                elseif(fields.database_copy) then
                        if(seltree ~= nil) then
                                if(ltool.playerinfos[playername] ~= nil) then
                                        local formspec = ltool.formspec_size..ltool.formspec_header(1)..ltool.tab_edit(ltool.tree_to_fields(seltree), privs.ledit, privs.lplant)
                                        minetest.show_formspec(playername, "ltool:treeform_edit", formspec)
                                end
                        else
                                ltool.show_dialog(playername, "ltool:treeform_error_nodbsel", "Error: No tree is selected.")
                        end
                elseif(fields.database_update) then
                        local formspec = ltool.formspec_size..ltool.formspec_header(2)..ltool.tab_database(ltool.playerinfos[playername].dbsel, playername)
                        minetest.show_formspec(playername, "ltool:treeform_database", formspec)

                elseif(fields.database_delete) then
                        if(privs.ledit ~= true) then
                                ltool.save_fields(playername, formname, fields)
                                local message = "You can't delete trees, you need to have the \"ledit\" privilege."
                                ltool.show_dialog(playername, "ltool:treeform_error_ledit_db", message)
                                return
                        end
                        if(seltree ~= nil) then
                                if(playername == seltree.author) then
                                        local remove_id = ltool.get_selected_tree_id(playername)
                                        if(remove_id ~= nil) then
                                                ltool.remove_tree(remove_id)
                                                local formspec = ltool.formspec_size..ltool.formspec_header(2)..ltool.tab_database(ltool.playerinfos[playername].dbsel, playername)
                                                minetest.show_formspec(playername, "ltool:treeform_database", formspec)
                                        end
                                else
                                        ltool.show_dialog(playername, "ltool:treeform_error_delete", "Error: This tree is not your own. You may only delete your own trees.")
                                end
                        else
                                ltool.show_dialog(playername, "ltool:treeform_error_nodbsel", "Error: No tree is selected.")
                        end
                elseif(fields.database_rename) then
                        if(seltree ~= nil) then
                                if(privs.ledit ~= true) then
                                        ltool.save_fields(playername, formname, fields)
                                        local message = "You can't rename trees, you need to have the \"ledit\" privilege."
                                        ltool.show_dialog(playername, "ltool:treeform_error_ledit_db", message)
                                        return
                                end
                                if(playername == seltree.author) then
                                        local formspec = "field[newname;New name:;"..minetest.formspec_escape(seltree.name).."]"
                                        minetest.show_formspec(playername, "ltool:treeform_rename", formspec)
                                else
                                        ltool.show_dialog(playername, "ltool:treeform_error_rename_forbidden", "Error: This tree is not your own. You may only rename your own trees.")
                                end
                        else
                                ltool.show_dialog(playername, "ltool:treeform_error_nodbsel", "Error: No tree is selected.")
                        end
                elseif(fields.sapling) then
                        local ret = handle_sapling_button_database_plant(seltree, seltree_id, privs, formname, fields, playername)
                        if ret == false then
                                return
                        end
                end
        --[[ Process "Do you want to replace this tree?" dialog ]]
        elseif(formname == "ltool:treeform_replace") then
                local editfields = ltool.playerinfos[playername].treeform.edit.fields
                local newtreedef, newname = ltool.evaluate_edit_fields(editfields)
                if(privs.ledit ~= true) then
                        local message = "You can't overwrite trees, you need to have the \"ledit\" privilege."
                        minetest.show_dialog(playername, "ltool:treeform_error_ledit", message)
                        return
                end
                if(fields.replace_yes) then
                        for tree_id,tree in pairs(ltool.trees) do
                                if(tree.name == newname) then
                                        --[[ The old tree is deleted and a
                                        new one with a new ID is created ]]
                                        local new_tree_id = ltool.next_tree_id
                                        ltool.trees[new_tree_id] = {}
                                        ltool.trees[new_tree_id].treedef = newtreedef
                                        ltool.trees[new_tree_id].name = newname
                                        ltool.trees[new_tree_id].author = tree.author
                                        ltool.next_tree_id = ltool.next_tree_id + 1
                                        ltool.trees[tree_id] = nil
                                        ltool.playerinfos[playername].dbsel = ltool.number_of_trees
                                end
                        end
                end
                local formspec = ltool.formspec_size..ltool.formspec_header(1)..ltool.tab_edit(editfields, privs.ledit, privs.lplant)
                minetest.show_formspec(playername, "ltool:treeform_edit", formspec)
        elseif(formname == "ltool:treeform_help") then
                local tab = tonumber(fields.ltool_help_tab)
                if(tab ~= nil) then
                        ltool.playerinfos[playername].treeform.help.tab = tab
                        local formspec = ltool.formspec_size..ltool.formspec_header(4)..ltool.tab_help(tab)
                        minetest.show_formspec(playername, "ltool:treeform_help", formspec)
                end
                if(fields.create_template) then
                        local newfields = {
                                axiom="FFFFFAFFBF",
                                rules_a="[&&&FFFFF&&FFFF][&&&++++FFFFF&&FFFF][&&&----FFFFF&&FFFF]",
                                rules_b="[&&&++FFFFF&&FFFF][&&&--FFFFF&&FFFF][&&&------FFFFF&&FFFF]",
                                trunk="mapgen_tree",
                                leaves="mapgen_leaves",
                                leaves2_chance="0",
                                angle="30",
                                iterations="2",
                                random_level="0",
                                trunk_type="single",
                                thin_branches="true",
                                fruit_chance="10",
                                fruit="mapgen_apple",
                                name = "Example Tree "..ltool.next_tree_id
                        }
                        ltool.save_fields(playername, formname, newfields)
                        local formspec = ltool.formspec_size..ltool.formspec_header(1)..ltool.tab_edit(newfields, privs.ledit, privs.lplant)
                        minetest.show_formspec(playername, "ltool:treeform_edit", formspec)
                end
        --[[ Tree renaming dialog ]]
        elseif(formname == "ltool:treeform_rename") then
                if(privs.ledit ~= true) then
                        ltool.save_fields(playername, formname, fields)
                        local message = "You can't delete trees, you need to have the \"ledit\" privilege."
                        ltool.show_dialog(playername, "ltool:treeform_error_ledit_delete", message)
                        return
                end
                if(fields.newname ~= "" and fields.newname ~= nil) then
                        ltool.rename_tree(ltool.get_selected_tree_id(playername), fields.newname)
                        local formspec = ltool.formspec_size..ltool.formspec_header(2)..ltool.tab_database(ltool.playerinfos[playername].dbsel, playername)
                        minetest.show_formspec(playername, "ltool:treeform_database", formspec)
                else
                        ltool.show_dialog(playername, "ltool:treeform_error_bad_rename", "Error: This name is empty. The tree name must be non-empty.")
                end
        --[[ Here come various error messages to handle ]]
        elseif(formname == "ltool:treeform_error_badtreedef" or formname == "ltool:treeform_error_nameclash" or formname == "ltool:treeform_error_ledit") then
                local formspec = ltool.formspec_size..ltool.formspec_header(1)..ltool.tab_edit(ltool.playerinfos[playername].treeform.edit.fields, privs.ledit, privs.lplant)
                minetest.show_formspec(playername, "ltool:treeform_edit", formspec)
        elseif(formname == "ltool:treeform_error_badplantfields" or formname == "ltool:treeform_error_sapling" or formname == "ltool:treeform_error_lplant") then
                local formspec = ltool.formspec_size..ltool.formspec_header(3)..ltool.tab_plant(seltree, ltool.playerinfos[playername].treeform.plant.fields, privs.lplant)
                minetest.show_formspec(playername, "ltool:treeform_plant", formspec)
        elseif(formname == "ltool:treeform_error_delete" or formname == "ltool:treeform_error_rename_forbidden" or formname == "ltool:treeform_error_nodbsel" or formname == "ltool:treeform_error_ledit_db") then
                local formspec = ltool.formspec_size..ltool.formspec_header(2)..ltool.tab_database(ltool.playerinfos[playername].dbsel, playername)
                minetest.show_formspec(playername, "ltool:treeform_database", formspec)
        elseif(formname == "ltool:treeform_error_bad_rename") then
                local formspec = "field[newname;New name:;"..minetest.formspec_escape(seltree.name).."]"
                minetest.show_formspec(playername, "ltool:treeform_rename", formspec)
        else
                -- Action for Inventory++ button
                if fields.ltool and minetest.get_modpath("inventory_plus") then
                        ltool.show_treeform(playername)
                        return
                end
        end
end

if mod_select_item then
        select_item.register_on_select_item(function(playername, dialogname, itemstring)
                if dialogname == "ltool:node" then
                        if itemstring then
                                local f = ltool.playerinfos[playername].treeform.edit.fields
                                if f.edit_trunk then
                                        f.trunk = itemstring
                                elseif f.edit_leaves then
                                        f.leaves = itemstring
                                elseif f.edit_leaves2 then
                                        f.leaves2 = itemstring
                                elseif f.edit_fruit then
                                        f.fruit = itemstring
                                end
                        end
                        ltool.show_treeform(playername)
                        return false
                end
        end)
end

--[[ These 2 functions are basically just table initializions and cleanups ]]
function ltool.leave(player)
        ltool.playerinfos[player:get_player_name()] = nil
end

function ltool.join(player)
        local infotable = {}
        infotable.dbsel = nil
        infotable.treeform = {}
        infotable.treeform.database = {}
        --[[ This table stores a mapping of the textlist IDs in the database formspec and the tree IDs.
        It is updated each time ltool.tab_database is called. ]]
        infotable.treeform.database.textlist = {}
        --[[ the “fields” tables store the values of the input fields of a formspec. It is updated
        whenever the formspec is changed, i.e. on tab change ]]
        infotable.treeform.database.fields = {}
        infotable.treeform.plant = {}
        infotable.treeform.plant.fields = {}
        infotable.treeform.edit = {}
        infotable.treeform.edit.fields = ltool.default_edit_fields
        infotable.treeform.edit.thin_branches = "true"
        infotable.treeform.help = {}
        infotable.treeform.help.tab = 1
        --[[ Workaround for annoying bug in Minetest: When you call the identical formspec twice,
        Minetest does not send the second one. This is an issue when the player has changed the
        input fields in the meanwhile, resetting fields will fail sometimes.
        TODO: Remove workaround when not needed anymore. ]]
        -- BEGIN OF WORKAROUND
        infotable.treeform.hacky_spaces = ""
        -- END OF WORKAROUND

        ltool.playerinfos[player:get_player_name()] = infotable

        -- Add Inventory++ support
        if minetest.get_modpath("inventory_plus") then
                inventory_plus.register_button(player, "ltool", "L-System Tree Utility")
        end
end

function ltool.save_to_file()
        local savetable = {}
        savetable.trees = ltool.trees
        savetable.number_of_trees = ltool.number_of_trees
        savetable.next_tree_id = ltool.next_tree_id
        local savestring = minetest.serialize(savetable)
        local filepath = minetest.get_worldpath().."/ltool.mt"
        local file = io.open(filepath, "w")
        if(file) then
                file:write(savestring)
                io.close(file)
                minetest.log("action", "[ltool] Tree data saved to "..filepath..".")
        else
                minetest.log("error", "[ltool] Failed to write ltool data to "..filepath".")
        end
        
end

minetest.register_on_player_receive_fields(ltool.process_form)

minetest.register_on_leaveplayer(ltool.leave)

minetest.register_on_joinplayer(ltool.join)

minetest.register_on_shutdown(ltool.save_to_file)

local button_action = function(player)
        ltool.show_treeform(player:get_player_name())
end

if minetest.get_modpath("unified_inventory") ~= nil then
        unified_inventory.register_button("ltool", {
                type = "image",
                image = "ltool_sapling.png",
                tooltip = "L-System Tree Utility",
                action = button_action,
        })
end

if minetest.get_modpath("sfinv_buttons") ~= nil then
        sfinv_buttons.register_button("ltool", {
                title = "L-System Tree Utility",
                tooltip = "Invent your own trees and plant them",
                image = "ltool_sapling.png",
                action = button_action,
        })
end