Clear a user's active sessions following account suspension

[aur.git] / web / lib / acctfuncs.inc.php

<?php

/**
 * Determine if an HTTP request variable is set
 *
 * @param string $name The request variable to test for
 *
 * @return string Return the value of the request variable, otherwise blank
 */
function in_request($name) {
        if (isset($_REQUEST[$name])) {
                return $_REQUEST[$name];
        }
        return "";
}

/**
 * Format the PGP key fingerprint
 *
 * @param string $fingerprint An unformatted PGP key fingerprint
 *
 * @return string PGP fingerprint with spaces every 4 characters
 */
function html_format_pgp_fingerprint($fingerprint) {
        if (strlen($fingerprint) != 40 || !ctype_xdigit($fingerprint)) {
                return $fingerprint;
        }

        return htmlspecialchars(substr($fingerprint, 0, 4) . " " .
                substr($fingerprint, 4, 4) . " " .
                substr($fingerprint, 8, 4) . " " .
                substr($fingerprint, 12, 4) . " " .
                substr($fingerprint, 16, 4) . "  " .
                substr($fingerprint, 20, 4) . " " .
                substr($fingerprint, 24, 4) . " " .
                substr($fingerprint, 28, 4) . " " .
                substr($fingerprint, 32, 4) . " " .
                substr($fingerprint, 36, 4) . " ", ENT_QUOTES);
}

/**
 * Loads the account editing form, with any values that are already saved
 *
 * @global array $SUPPORTED_LANGS Languages that are supported by the AUR
 * @param string $UTYPE User type of the account accessing the form
 * @param string $A Form to use, either UpdateAccount or NewAccount
 * @param string $U The username to display
 * @param string $T The account type of the displayed user
 * @param string $S Whether the displayed user has a suspended account
 * @param string $E The e-mail address of the displayed user
 * @param string $P The password value of the displayed user
 * @param string $C The confirmed password value of the displayed user
 * @param string $R The real name of the displayed user
 * @param string $L The language preference of the displayed user
 * @param string $I The IRC nickname of the displayed user
 * @param string $K The PGP key fingerprint of the displayed user
 * @param string $UID The user ID of the displayed user
 *
 * @return void
 */
function display_account_form($UTYPE,$A,$U="",$T="",$S="",
                        $E="",$P="",$C="",$R="",$L="",$I="",$K="",$UID=0) {
        global $SUPPORTED_LANGS;

        include("account_edit_form.php");
        return;
} # function display_account_form()

/**
 * Process information given to new/edit account form
 *
 * @global array $SUPPORTED_LANGS Languages that are supported by the AUR
 * @param string $UTYPE The account type of the user modifying the account
 * @param string $TYPE Either "edit" for editing or "new" for registering an account
 * @param string $A Form to use, either UpdateAccount or NewAccount
 * @param string $U The username for the account
 * @param string $T The account type for the user
 * @param string $S Whether or not the account is suspended
 * @param string $E The e-mail address for the user
 * @param string $P The password for the user
 * @param string $C The confirmed password for the user
 * @param string $R The real name of the user
 * @param string $L The language preference of the user
 * @param string $I The IRC nickname of the user
 * @param string $K The PGP fingerprint of the user
 * @param string $UID The user ID of the modified account
 * @param \PDO $dbh An already established database connection
 *
 * @return string|void Return void if successful, otherwise return error
 */
function process_account_form($UTYPE,$TYPE,$A,$U="",$T="",$S="",$E="",
                        $P="",$C="",$R="",$L="",$I="",$K="",$UID=0,$dbh=NULL) {

        # error check and process request for a new/modified account
        global $SUPPORTED_LANGS;

        if (!$dbh) {
                $dbh = db_connect();
        }

        if(isset($_COOKIE['AURSID'])) {
                $editor_user = uid_from_sid($_COOKIE['AURSID'], $dbh);
        }
        else {
                $editor_user = null;
        }

        $error = "";
        if (empty($E) || empty($U)) {
                $error = __("Missing a required field.");
        }

        if ($TYPE == "new") {
                # they need password fields for this type of action
                #
                if (empty($P) || empty($C)) {
                        $error = __("Missing a required field.");
                }
        } else {
                if (!$UID) {
                        $error = __("Missing User ID");
                }
        }

  if (!$error && !valid_username($U) && !user_is_privileged($editor_user, $dbh))
        $error = __("The username is invalid.") . "<ul>\n"
                        ."<li>" . __("It must be between %s and %s characters long",
                        USERNAME_MIN_LEN,  USERNAME_MAX_LEN )
                        . "</li>"
                        . "<li>" . __("Start and end with a letter or number") . "</li>"
                        . "<li>" . __("Can contain only one period, underscore or hyphen.")
                        . "</li>\n</ul>";

        if (!$error && $P && $C && ($P != $C)) {
                $error = __("Password fields do not match.");
        }
        if (!$error && $P != '' && !good_passwd($P))
                $error = __("Your password must be at least %s characters.",PASSWD_MIN_LEN);

        if (!$error && !valid_email($E)) {
                $error = __("The email address is invalid.");
        }

        if (!$error && $K != '' && !valid_pgp_fingerprint($K)) {
                $error = __("The PGP key fingerprint is invalid.");
        }

        if (($UTYPE == "User" && $T > 1) || ($UTYPE == "Trusted User" && $T > 2)) {
                $error = __("Cannot increase account permissions.");
        }
        if (!$error && !array_key_exists($L, $SUPPORTED_LANGS)) {
                $error = __("Language is not currently supported.");
        }
        if (!$error) {
                # check to see if this username is available
                # NOTE: a race condition exists here if we care...
                #
                $q = "SELECT COUNT(*) AS CNT FROM Users ";
                $q.= "WHERE Username = " . $dbh->quote($U);
                if ($TYPE == "edit") {
                        $q.= " AND ID != ".intval($UID);
                }
                $result = $dbh->query($q);
                $row = $result->fetch(PDO::FETCH_NUM);

                if ($row[0]) {
                        $error = __("The username, %s%s%s, is already in use.",
                                "<strong>", htmlspecialchars($U,ENT_QUOTES), "</strong>");
                }
        }
        if (!$error) {
                # check to see if this email address is available
                # NOTE: a race condition exists here if we care...
                #
                $q = "SELECT COUNT(*) AS CNT FROM Users ";
                $q.= "WHERE Email = " . $dbh->quote($E);
                if ($TYPE == "edit") {
                        $q.= " AND ID != ".intval($UID);
                }
                $result = $dbh->query($q);
                $row = $result->fetch(PDO::FETCH_NUM);

                if ($row[0]) {
                        $error = __("The address, %s%s%s, is already in use.",
                                        "<strong>", htmlspecialchars($E,ENT_QUOTES), "</strong>");
                }
        }
        if ($error) {
                print "<span class='error'>".$error."</span><br/>\n";
                display_account_form($UTYPE, $A, $U, $T, $S, $E, "", "",
                                $R, $L, $I, $K, $UID);
        } else {
                if ($TYPE == "new") {
                        # no errors, go ahead and create the unprivileged user
                        $salt = generate_salt();
                        $P = salted_hash($P, $salt);
                        $U = $dbh->quote($U);
                        $E = $dbh->quote($E);
                        $P = $dbh->quote($P);
                        $salt = $dbh->quote($salt);
                        $R = $dbh->quote($R);
                        $L = $dbh->quote($L);
                        $I = $dbh->quote($I);
                        $K = $dbh->quote(str_replace(" ", "", $K));
                        $q = "INSERT INTO Users (AccountTypeID, Suspended, ";
                        $q.= "Username, Email, Passwd, Salt, RealName, ";
                        $q.= "LangPreference, IRCNick, PGPKey) VALUES (1, 0, ";
                        $q.= "$U, $E, $P, $salt, $R, $L, $I, $K)";
                        $result = $dbh->exec($q);
                        if (!$result) {
                                print __("Error trying to create account, %s%s%s.",
                                                "<strong>", htmlspecialchars($U,ENT_QUOTES), "</strong>");
                        } else {
                                # account created/modified, tell them so.
                                #
                                print __("The account, %s%s%s, has been successfully created.",
                                                "<strong>", htmlspecialchars($U,ENT_QUOTES), "</strong>");
                                print "<p>\n";
                                print __("Click on the Login link above to use your account.");
                                print "</p>\n";
                        }

                } else {
                        # no errors, go ahead and modify the user account

                        $q = "UPDATE Users SET ";
                        $q.= "Username = " . $dbh->quote($U);
                        if ($T) {
                                $q.= ", AccountTypeID = ".intval($T);
                        }
                        if ($S) {
                                /* Ensure suspended users can't keep an active session */
                                delete_user_sessions($UID, $dbh);
                                $q.= ", Suspended = 1";
                        } else {
                                $q.= ", Suspended = 0";
                        }
                        $q.= ", Email = " . $dbh->quote($E);
                        if ($P) {
                                $salt = generate_salt();
                                $hash = salted_hash($P, $salt);
                                $q .= ", Passwd = '$hash', Salt = '$salt'";
                        }
                        $q.= ", RealName = " . $dbh->quote($R);
                        $q.= ", LangPreference = " . $dbh->quote($L);
                        $q.= ", IRCNick = " . $dbh->quote($I);
                        $q.= ", PGPKey = " . $dbh->quote(str_replace(" ", "", $K));
                        $q.= " WHERE ID = ".intval($UID);
                        $result = $dbh->exec($q);
                        if (!$result) {
                                print __("Error trying to modify account, %s%s%s.",
                                                "<strong>", htmlspecialchars($U,ENT_QUOTES), "</strong>");
                        } else {
                                print __("The account, %s%s%s, has been successfully modified.",
                                                "<strong>", htmlspecialchars($U,ENT_QUOTES), "</strong>");
                        }
                }
        }
        return;
}

/**
 * Include the search accounts form
 *
 * @return void
 */
function search_accounts_form() {
        include("search_accounts_form.php");
        return;
}

/**
 * Display the search results page
 *
 * @param string $UTYPE User type of the account accessing the form
 * @param string $O The offset for the results page
 * @param string $SB The column to sort the results page by
 * @param string $U The username search criteria
 * @param string $T The account type search criteria
 * @param string $S Whether the account is suspended search criteria
 * @param string $E The e-mail address search criteria
 * @param string $R The real name search criteria
 * @param string $I The IRC nickname search criteria
 * @param string $K The PGP key fingerprint search criteria
 * @param \PDO $dbh An already established database connection
 *
 * @return void
 */
function search_results_page($UTYPE,$O=0,$SB="",$U="",$T="",
                $S="",$E="",$R="",$I="",$K="",$dbh=NULL) {

        $HITS_PER_PAGE = 50;
        if ($O) {
                $OFFSET = intval($O);
        } else {
                $OFFSET = 0;
        }
        if ($OFFSET < 0) {
                $OFFSET = 0;
        }
        $search_vars = array();

        if (!$dbh) {
                $dbh = db_connect();
        }

        $q = "SELECT Users.*, AccountTypes.AccountType ";
        $q.= "FROM Users, AccountTypes ";
        $q.= "WHERE AccountTypes.ID = Users.AccountTypeID ";
        if ($T == "u") {
                $q.= "AND AccountTypes.ID = 1 ";
                $search_vars[] = "T";
        } elseif ($T == "t") {
                $q.= "AND AccountTypes.ID = 2 ";
                $search_vars[] = "T";
        } elseif ($T == "d") {
                $q.= "AND AccountTypes.ID = 3 ";
                $search_vars[] = "T";
        }
        if ($S) {
                $q.= "AND Users.Suspended = 1 ";
                $search_vars[] = "S";
        }
        if ($U) {
                $U = "%" . addcslashes($U, '%_') . "%";
                $q.= "AND Username LIKE " . $dbh->quote($U) . " ";
                $search_vars[] = "U";
        }
        if ($E) {
                $E = "%" . addcslashes($E, '%_') . "%";
                $q.= "AND Email LIKE " . $dbh->quote($E) . " ";
                $search_vars[] = "E";
        }
        if ($R) {
                $R = "%" . addcslashes($R, '%_') . "%";
                $q.= "AND RealName LIKE " . $dbh->quote($R) . " ";
                $search_vars[] = "R";
        }
        if ($I) {
                $I = "%" . addcslashes($I, '%_') . "%";
                $q.= "AND IRCNick LIKE " . $dbh->quote($I) . " ";
                $search_vars[] = "I";
        }
        if ($K) {
                $K = "%" . addcslashes(str_replace(" ", "", $K), '%_') . "%";
                $q.= "AND PGPKey LIKE " . $dbh->quote($K) . " ";
                $search_vars[] = "K";
        }
        switch ($SB) {
                case 't':
                        $q.= "ORDER BY AccountTypeID, Username ";
                        break;
                case 'r':
                        $q.= "ORDER BY RealName, AccountTypeID ";
                        break;
                case 'i':
                        $q.= "ORDER BY IRCNick, AccountTypeID ";
                        break;
                case 'v':
                        $q.= "ORDER BY LastVoted, Username ";
                        break;
                default:
                        $q.= "ORDER BY Username, AccountTypeID ";
                        break;
        }
        $search_vars[] = "SB";
        $q.= "LIMIT " . $HITS_PER_PAGE . " OFFSET " . $OFFSET;

        if (!$dbh) {
                $dbh = db_connect();
        }

        $result = $dbh->query($q);

        while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
                $userinfo[] = $row;
        }

        include("account_search_results.php");
        return;
}

/**
 * Attempt to login and generate a session
 *
 * @global int $MAX_SESSIONS_PER_USER Maximum sessions a single user may have open
 * @global int $PERSISTENT_COOKIE_TIMEOUT Time until cookie expires
 * @param \PDO $dbh An already established database connection
 *
 * @return array Session ID for user, error message if applicable
 */
function try_login($dbh=NULL) {
        global $MAX_SESSIONS_PER_USER, $PERSISTENT_COOKIE_TIMEOUT;

        $login_error = "";
        $new_sid = "";
        $userID = null;

        if ( isset($_REQUEST['user']) || isset($_REQUEST['passwd']) ) {
                if (!$dbh) {
                        $dbh = db_connect();
                }
                $userID = valid_user($_REQUEST['user'], $dbh);

                if ( user_suspended($userID, $dbh) ) {
                        $login_error = "Account Suspended.";
                }
                elseif ( $userID && isset($_REQUEST['passwd'])
                  && valid_passwd($userID, $_REQUEST['passwd'], $dbh) ) {

                        $logged_in = 0;
                        $num_tries = 0;

                        # Account looks good.  Generate a SID and store it.

                        while (!$logged_in && $num_tries < 5) {
                                if ($MAX_SESSIONS_PER_USER) {
                                        # Delete all user sessions except the
                                        # last ($MAX_SESSIONS_PER_USER - 1).
                                        $q = "DELETE s.* FROM Sessions s ";
                                        $q.= "LEFT JOIN (SELECT SessionID FROM Sessions ";
                                        $q.= "WHERE UsersId = " . $userID . " ";
                                        $q.= "ORDER BY LastUpdateTS DESC ";
                                        $q.= "LIMIT " . ($MAX_SESSIONS_PER_USER - 1) . ") q ";
                                        $q.= "ON s.SessionID = q.SessionID ";
                                        $q.= "WHERE s.UsersId = " . $userID . " ";
                                        $q.= "AND q.SessionID IS NULL;";
                                        $dbh->query($q);
                                }

                                $new_sid = new_sid();
                                $q = "INSERT INTO Sessions (UsersID, SessionID, LastUpdateTS)"
                                  ." VALUES (" . $userID . ", '" . $new_sid . "', UNIX_TIMESTAMP())";
                                $result = $dbh->exec($q);

                                # Query will fail if $new_sid is not unique
                                if ($result) {
                                        $logged_in = 1;
                                        break;
                                }

                                $num_tries++;
                        }

                        if ($logged_in) {
                                $q = "UPDATE Users SET LastLogin = UNIX_TIMESTAMP() ";
                                $q.= "WHERE ID = '$userID'";
                                $dbh->exec($q);

                                # set our SID cookie
                                if (isset($_POST['remember_me']) &&
                                        $_POST['remember_me'] == "on") {
                                        # Set cookies for 30 days.
                                        $cookie_time = time() + $PERSISTENT_COOKIE_TIMEOUT;

                                        # Set session for 30 days.
                                        $q = "UPDATE Sessions SET LastUpdateTS = $cookie_time ";
                                        $q.= "WHERE SessionID = '$new_sid'";
                                        $dbh->exec($q);
                                }
                                else
                                        $cookie_time = 0;

                                setcookie("AURSID", $new_sid, $cookie_time, "/", null, !empty($_SERVER['HTTPS']), true);
                                header("Location: " . get_uri('/'));
                                $login_error = "";

                        }
                        else {
                                $login_error = "Error trying to generate session id.";
                        }
                }
                else {
                        $login_error = __("Bad username or password.");
                }
        }
        return array('SID' => $new_sid, 'error' => $login_error);
}

/**
 * Validate a username against a collection of rules
 *
 * The username must be longer or equal to USERNAME_MIN_LEN. It must be shorter
 * or equal to USERNAME_MAX_LEN. It must start and end with either a letter or
 * a number. It can contain one period, hypen, or underscore. Returns boolean
 * of whether name is valid.
 *
 * @param string $user Username to validate
 *
 * @return bool True if username meets criteria, otherwise false
 */
function valid_username($user) {
        if (!empty($user)) {

                #Is username at not too short or too long?
                if ( strlen($user) >= USERNAME_MIN_LEN &&
                  strlen($user) <= USERNAME_MAX_LEN ) {

                        $user = strtolower($user);
                        # Does username:
                        # start and end with a letter or number
                        # contain only letters and numbers,
                        #  and at most has one dash, period, or underscore
                        if ( preg_match("/^[a-z0-9]+[.\-_]?[a-z0-9]+$/", $user) ) {
                                return true;
                        }
                }
        }

        return false;
}

/**
 * Determine if a username exists in the database
 *
 * @param string $user Username to check in the database
 * @param \PDO $dbh An already established database connection
 *
 * @return string|void Return user ID if in database, otherwise void
 */
function valid_user($user, $dbh=NULL) {
        /*      if ( $user = valid_username($user) ) { */

        if(!$dbh) {
                $dbh = db_connect();
        }

        if ( $user ) {
                $q = "SELECT ID FROM Users ";
                $q.= "WHERE Username = " . $dbh->quote($user);

                $result = $dbh->query($q);
                # Is the username in the database?
                if ($result) {
                        $row = $result->fetch(PDO::FETCH_NUM);
                        return $row[0];
                }
        }
        return;
}

/**
 * Determine if a user already has a proposal open about themselves
 *
 * @param string $user Username to checkout for open proposal
 * @param \PDO $dbh An already established database connection
 *
 * @return bool True if there is an open proposal about the user, otherwise false
 */
function open_user_proposals($user, $dbh=NULL) {
        if(!$dbh) {
                $dbh = db_connect();
        }
        $q = "SELECT * FROM TU_VoteInfo WHERE User = " . $dbh->quote($user) . " ";
        $q.= "AND End > UNIX_TIMESTAMP()";
        $result = $dbh->query($q);
        if ($result->fetchColumn()) {
                return true;
        }
        else {
                return false;
        }
}

/**
 * Add a new Trusted User proposal to the database
 *
 * @param string $agenda The agenda of the vote
 * @param string $user The use the vote is about
 * @param int $votelength The length of time for the vote to last
 * @param string $submitteruid The user ID of the individual who submitted the proposal
 * @param \PDO $dbh An already established database connection
 *
 * @return void
 */
function add_tu_proposal($agenda, $user, $votelength, $submitteruid, $dbh=NULL) {
        if(!$dbh) {
                $dbh = db_connect();
        }

        $q = "INSERT INTO TU_VoteInfo (Agenda, User, Submitted, End, SubmitterID) VALUES ";
        $q.= "(" . $dbh->quote($agenda) . ", " . $dbh->quote($user) . ", ";
        $q.= "UNIX_TIMESTAMP(), UNIX_TIMESTAMP() + " . $dbh->quote($votelength);
        $q.= ", " . $submitteruid . ")";
        $result = $dbh->exec($q);
}

/**
 * Add a reset key to the database for a specified user
 *
 * @param string $resetkey A password reset key to be stored in database
 * @param string $uid The user ID to store the reset key for
 * @param \PDO $dbh An already established database connection
 *
 * @return void
 */
function create_resetkey($resetkey, $uid, $dbh=NULL) {
        if(!$dbh) {
                $dbh = db_connect();
        }
        $q = "UPDATE Users ";
        $q.= "SET ResetKey = '" . $resetkey . "' ";
        $q.= "WHERE ID = " . $uid;
        $dbh->exec($q);
}

/**
 * Change a user's password in the database if reset key and e-mail are correct
 *
 * @param string $hash New MD5 hash of a user's password
 * @param string $salt New salt for the user's password
 * @param string $resetkey Code e-mailed to a user to reset a password
 * @param string $email E-mail address of the user resetting their password
 * @param \PDO $dbh An already established database connection
 *
 * @return string|void Redirect page if successful, otherwise return error message
 */
function password_reset($hash, $salt, $resetkey, $email, $dbh=NULL) {
        if(!$dbh) {
                $dbh = db_connect();
        }
        $q = "UPDATE Users ";
        $q.= "SET Passwd = '$hash', ";
        $q.= "Salt = '$salt', ";
        $q.= "ResetKey = '' ";
        $q.= "WHERE ResetKey != '' ";
        $q.= "AND ResetKey = " . $dbh->quote($resetkey) . " ";
        $q.= "AND Email = " . $dbh->quote($email);
        $result = $dbh->exec($q);

        if (!$result) {
                $error = __('Invalid e-mail and reset key combination.');
                return $error;
        } else {
                header('Location: ' . get_uri('/passreset/') . '?step=complete');
                exit();
        }
}

/**
 * Determine if the password is longer than the minimum length
 *
 * @param string $passwd The password to check
 *
 * @return bool True if longer than minimum length, otherwise false
 */
function good_passwd($passwd) {
        if ( strlen($passwd) >= PASSWD_MIN_LEN ) {
                return true;
        }
        return false;
}

/**
 * Determine if the password is correct and salt it if it hasn't been already
 *
 * @param string $userID The user ID to check the password against
 * @param string $passwd The password the visitor sent
 * @param \PDO $dbh An already established database connection
 *
 * @return bool True if password was correct and properly salted, otherwise false
 */
function valid_passwd($userID, $passwd, $dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }
        if ( strlen($passwd) > 0 ) {
                # get salt for this user
                $salt = get_salt($userID);
                if ($salt) {
                        # use salt
                        $q = "SELECT ID FROM Users ";
                        $q.= "WHERE ID = " . $userID . " ";
                        $q.= "AND Passwd = " . $dbh->quote(salted_hash($passwd, $salt));
                        $result = $dbh->query($q);
                        if ($result) {
                                $row = $result->fetch(PDO::FETCH_NUM);
                                if ($row[0]) {
                                        return true;
                                }
                        }
                } else {
                        # check without salt
                        $q = "SELECT ID FROM Users ";
                        $q.= "WHERE ID = " . $userID . " ";
                        $q.= "AND Passwd = " . $dbh->quote(md5($passwd));
                        $result = $dbh->query($q);
                        if ($result) {
                                $row = $result->fetch(PDO::FETCH_NUM);
                                if ($row[0]) {
                                        # password correct, but salt it first
                                        if (!save_salt($userID, $passwd)) {
                                                trigger_error("Unable to salt user's password;" .
                                                        " ID " . $userID, E_USER_WARNING);
                                                return false;
                                        }
                                        return true;
                                }
                        }
                }
        }
        return false;
}

/**
 * Determine if the PGP key fingerprint is valid (must be 40 hexadecimal digits)
 *
 * @param string $fingerprint PGP fingerprint to check if valid
 *
 * @return bool True if the fingerprint is 40 hexadecimal digits, otherwise false
 */
function valid_pgp_fingerprint($fingerprint) {
        $fingerprint = str_replace(" ", "", $fingerprint);
        return (strlen($fingerprint) == 40 && ctype_xdigit($fingerprint));
}

/**
 * Determine if the user account has been suspended
 *
 * @param string $id The ID of user to check if suspended
 * @param \PDO $dbh An already established database connection
 *
 * @return bool True if the user is suspended, otherwise false
 */
function user_suspended($id, $dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }
        if (!$id) {
                return false;
        }
        $q = "SELECT Suspended FROM Users WHERE ID = " . $id;
        $result = $dbh->query($q);
        if ($result) {
                $row = $result->fetch(PDO::FETCH_NUM);
                if ($row[0]) {
                        return true;
                }
        }
        return false;
}

/**
 * Delete a specified user account from the database
 *
 * @param int $id The user ID of the account to be deleted
 * @param \PDO $dbh An already established database connection
 *
 * @return void
 */
function user_delete($id, $dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }
        $q = "DELETE FROM Users WHERE ID = " . $id;
        $dbh->query($q);
        return;
}

/**
 * Determine if a user is either a Trusted User or Developer
 *
 * @param string $id The ID of the user to check if privileged
 * @param \PDO $dbh An already established database connection
 *
 * @return int|string Return  0 if un-privileged, "2" if Trusted User, "3" if Developer
 */
function user_is_privileged($id, $dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }
        $q = "SELECT AccountTypeID FROM Users WHERE ID = " . $id;
        $result = $dbh->query($q);
        if ($result) {
                $row = $result->fetch(PDO::FETCH_NUM);
                if($row[0] > 1) {
                        return $row[0];
                }
        }
        return 0;

}

/**
 * Remove the session from the database on logout
 *
 * @param string $sid User's session ID
 * @param \PDO $dbh An already established database connection
 *
 * @return void
 */
function delete_session_id($sid, $dbh=NULL) {
        if(!$dbh) {
                $dbh = db_connect();
        }

        $q = "DELETE FROM Sessions WHERE SessionID = " . $dbh->quote($sid);
        $dbh->query($q);
}

/**
 * Remove all sessions belonging to a particular user
 *
 * @param int $uid ID of user to remove all sessions for
 * @param \PDO $dbh An already established database connection
 *
 * @return void
 */
function delete_user_sessions($uid, $dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }

        $q = "DELETE FROM Sessions WHERE UsersID = " . intval($uid);
        $dbh->exec($q);
}

/**
 * Remove sessions from the database that have exceed the timeout
 *
 * @global int $LOGIN_TIMEOUT Time until session expires
 * @param \PDO $dbh An already established database connection
 *
 * @return void
 */
function clear_expired_sessions($dbh=NULL) {
        global $LOGIN_TIMEOUT;

        if(!$dbh) {
                $dbh = db_connect();
        }

        $q = "DELETE FROM Sessions WHERE LastUpdateTS < (UNIX_TIMESTAMP() - $LOGIN_TIMEOUT)";
        $dbh->query($q);

        return;
}

/**
 * Get account details for a specific user
 *
 * @param string $uid The User ID of account to get information for
 * @param string $username The username of the account to get for
 * @param \PDO $dbh An already established database connection
 *
 * @return array Account details for the specified user
 */
function account_details($uid, $username, $dbh=NULL) {
        if(!$dbh) {
                $dbh = db_connect();
        }
        $q = "SELECT Users.*, AccountTypes.AccountType ";
        $q.= "FROM Users, AccountTypes ";
        $q.= "WHERE AccountTypes.ID = Users.AccountTypeID ";
        if (!empty($uid)) {
                $q.= "AND Users.ID = ".intval($uid);
        } else {
                $q.= "AND Users.Username = " . $dbh->quote($username);
        }
        $result = $dbh->query($q);

        if ($result) {
                $row = $result->fetch(PDO::FETCH_ASSOC);
        }

        return $row;
}

/**
 * Determine if a user has already voted on a specific proposal
 *
 * @param string $voteid The ID of the Trusted User proposal
 * @param string $uid The ID to check if the user already voted
 * @param \PDO $dbh An already established database connection
 *
 * @return bool True if the user has already voted, otherwise false
 */
function tu_voted($voteid, $uid, $dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }

        $q = "SELECT COUNT(*) FROM TU_Votes ";
        $q.= "WHERE VoteID = " . intval($voteid) . " AND UserID = " . intval($uid);
        $result = $dbh->query($q);
        if ($result->fetchColumn() > 0) {
                return true;
        }
        else {
                return false;
        }
}

/**
 * Get all current Trusted User proposals from the database
 *
 * @param string $order Ascending or descending order for the proposal listing
 * @param \PDO $dbh An already established database connection
 *
 * @return array The details for all current Trusted User proposals
 */
function current_proposal_list($order, $dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }

        $q = "SELECT * FROM TU_VoteInfo WHERE End > " . time() . " ORDER BY Submitted " . $order;
        $result = $dbh->query($q);

        $details = array();
        while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
                $details[] = $row;
        }

        return $details;
}

/**
 * Get a subset of all past Trusted User proposals from the database
 *
 * @param string $order Ascending or descending order for the proposal listing
 * @param string $lim The number of proposals to list with the offset
 * @param \PDO $dbh An already established database connection
 *
 * @return array The details for the subset of past Trusted User proposals
 */
function past_proposal_list($order, $lim, $dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }

        $q = "SELECT * FROM TU_VoteInfo WHERE End < " . time() . " ORDER BY Submitted " . $order . $lim;
        $result = $dbh->query($q);

        $details = array();
        while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
                $details[] = $row;
        }

        return $details;
}

/**
 * Determine the total number of Trusted User proposals
 *
 * @param \PDO $dbh An already established database connection
 *
 * @return string The total number of Trusted User proposals
 */
function proposal_count($dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }

        $q = "SELECT COUNT(*) FROM TU_VoteInfo";
        $result = $dbh->query($q);
        $row = $result->fetch(PDO::FETCH_NUM);

        return $row[0];
}

/**
 * Get all details related to a specific vote from the database
 *
 * @param string $voteid The ID of the Trusted User proposal
 * @param \PDO $dbh An already established database connection
 *
 * @return array All stored details for a specific vote
 */
function vote_details($voteid, $dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }

        $q = "SELECT * FROM TU_VoteInfo ";
        $q.= "WHERE ID = " . intval($voteid);

        $result = $dbh->query($q);
        $row = $result->fetch(PDO::FETCH_ASSOC);

        return $row;
}

/**
 * Get an alphabetical list of users who voted for a proposal with HTML links
 *
 * @param string $voteid The ID of the Trusted User proposal
 * @param \PDO $dbh An already established database connection
 *
 * @return array All users who voted for a specific proposal
 */
function voter_list($voteid, $dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }

        $whovoted = array();

        $q = "SELECT tv.UserID,U.Username ";
        $q.= "FROM TU_Votes tv, Users U ";
        $q.= "WHERE tv.VoteID = " . intval($voteid);
        $q.= " AND tv.UserID = U.ID ";
        $q.= "ORDER BY Username";

        $result = $dbh->query($q);
        if ($result) {
                while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
                        $whovoted[] = $row['Username'];
                }
        }
        return $whovoted;
}

/**
 * Cast a vote for a specific user proposal
 *
 * @param string $voteid The ID of the proposal being voted on
 * @param string $uid The user ID of the individual voting
 * @param string $vote Vote position, either "Yes", "No", or "Abstain"
 * @param int $newtotal The total number of votes after the user has voted
 * @param \PDO $dbh An already established database connection
 *
 * @return void
 */
function cast_proposal_vote($voteid, $uid, $vote, $newtotal, $dbh=NULL) {
        if (!$dbh) {
                $dbh = db_connect();
        }

        $q = "UPDATE TU_VoteInfo SET " . $vote . " = (" . $newtotal . ") WHERE ID = " . $voteid;
        $result = $dbh->exec($q);

        $q = "INSERT INTO TU_Votes (VoteID, UserID) VALUES (" . intval($voteid) . ", " . intval($uid) . ")";
        $result = $dbh->exec($q);
}

/**
 * Verify a user has the proper permissions to edit an account
 *
 * @param string $atype Account type of the editing user
 * @param array $acctinfo User account information for edited account
 * @param int $uid User ID of the editing user
 *
 * @return bool True if permission to edit the account, otherwise false
 */
function can_edit_account($atype, $acctinfo, $uid) {
        /* Developers can edit any account */
        if ($atype == 'Developer') {
                return true;
        }

        /* Trusted Users can edit all accounts except Developer accounts */
        if ($atype == 'Trusted User' &&
                $acctinfo['AccountType'] != 'Developer') {
                        return true;
        }

        /* Users can edit only their own account */
        if ($acctinfo['ID'] == $uid) {
                return true;
        }

        return false;
}