lib/flickrclient.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * Provides {@link flickr_client} class.
  19  *
  20  * @package     core
  21  * @copyright   2017 David Mudrák <david@moodle.com>
  22  * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23  */
  24
  25 defined('MOODLE_INTERNAL') || die();
  26
  27 require_once($CFG->libdir.'/oauthlib.php');
  28
  29 /**
  30  * Simple Flickr API client implementing the features needed by Moodle
  31  *
  32  * @copyright 2017 David Mudrak <david@moodle.com>
  33  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  34  */
  35 class flickr_client extends oauth_helper {
  36
  37     /**
  38      * Base URL for Flickr OAuth 1.0 API calls.
  39      */
  40     const OAUTH_ROOT = 'https://www.flickr.com/services/oauth';
  41
  42     /**
  43      * Base URL for Flickr REST API calls.
  44      */
  45     const REST_ROOT = 'https://api.flickr.com/services/rest';
  46
  47     /**
  48      * Base URL for Flickr Upload API call.
  49      */
  50     const UPLOAD_ROOT = 'https://up.flickr.com/services/upload/';
  51
  52     /**
  53      * Set up OAuth and initialize the client.
  54      *
  55      * The callback URL specified here will override the one specified in the
  56      * auth flow defined at Flickr Services.
  57      *
  58      * @param string $consumerkey
  59      * @param string $consumersecret
  60      * @param moodle_url|string $callbackurl
  61      */
  62     public function __construct($consumerkey, $consumersecret, $callbackurl = '') {
  63
  64         parent::__construct([
  65             'api_root' => self::OAUTH_ROOT,
  66             'oauth_consumer_key' => $consumerkey,
  67             'oauth_consumer_secret' => $consumersecret,
  68             'oauth_callback' => $callbackurl,
  69         ]);
  70     }
  71
  72     /**
  73      * Temporarily store the request token secret in the session.
  74      *
  75      * The request token secret is returned by the oauth request_token method.
  76      * It needs to be stored in the session before the user is redirected to
  77      * the Flickr to authorize the client. After redirecting back, this secret
  78      * is used for exchanging the request token with the access token.
  79      *
  80      * The identifiers help to avoid collisions between multiple calls to this
  81      * method from different plugins in the same session. They are used as the
  82      * session cache identifiers. Provide an associative array identifying the
  83      * particular method call. At least, the array must contain the 'caller'
  84      * with the caller's component name. Use additional items if needed.
  85      *
  86      * @param array $identifiers Identification of the call
  87      * @param string $secret
  88      */
  89     public function set_request_token_secret(array $identifiers, $secret) {
  90
  91         if (empty($identifiers) || empty($identifiers['caller'])) {
  92             throw new coding_exception('Invalid call identification');
  93         }
  94
  95         $cache = cache::make_from_params(cache_store::MODE_SESSION, 'core', 'flickrclient', $identifiers);
  96         $cache->set('request_token_secret', $secret);
  97     }
  98
  99     /**
 100      * Returns previously stored request token secret.
 101      *
 102      * See {@link self::set_request_token_secret()} for more details on the
 103      * $identifiers argument.
 104      *
 105      * @param array $identifiers Identification of the call
 106      * @return string|bool False on error, string secret otherwise.
 107      */
 108     public function get_request_token_secret(array $identifiers) {
 109
 110         if (empty($identifiers) || empty($identifiers['caller'])) {
 111             throw new coding_exception('Invalid call identification');
 112         }
 113
 114         $cache = cache::make_from_params(cache_store::MODE_SESSION, 'core', 'flickrclient', $identifiers);
 115
 116         return $cache->get('request_token_secret');
 117     }
 118
 119     /**
 120      * Call a Flickr API method.
 121      *
 122      * @param string $function API function name like 'flickr.photos.getSizes' or just 'photos.getSizes'
 123      * @param array $params Additional API call arguments.
 124      * @param string $method HTTP method to use (GET or POST).
 125      * @return object|bool Response as returned by the Flickr or false on invalid authentication
 126      */
 127     public function call($function, array $params = [], $method = 'GET') {
 128
 129         if (strpos($function, 'flickr.') !== 0) {
 130             $function = 'flickr.'.$function;
 131         }
 132
 133         $params['method'] = $function;
 134         $params['format'] = 'json';
 135         $params['nojsoncallback'] = 1;
 136
 137         $rawresponse = $this->request($method, self::REST_ROOT, $params);
 138         $response = json_decode($rawresponse);
 139
 140         if (!is_object($response) || !isset($response->stat)) {
 141             throw new moodle_exception('flickr_api_call_failed', 'core_error', '', $rawresponse);
 142         }
 143
 144         if ($response->stat === 'ok') {
 145             return $response;
 146
 147         } else if ($response->stat === 'fail' && $response->code == 98) {
 148             // Authentication failure, give the caller a chance to re-authenticate.
 149             return false;
 150
 151         } else {
 152             throw new moodle_exception('flickr_api_call_failed', 'core_error', '', $response);
 153         }
 154
 155         return $response;
 156     }
 157
 158     /**
 159      * Return the URL to fetch the given photo from.
 160      *
 161      * Flickr photos are distributed via farm servers staticflickr.com in
 162      * various sizes (resolutions). The method tries to find the source URL of
 163      * the photo in the highest possible resolution. Results are cached so that
 164      * we do not need to query the Flickr API over and over again.
 165      *
 166      * @param string $photoid Flickr photo identifier
 167      * @return string URL
 168      */
 169     public function get_photo_url($photoid) {
 170
 171         $cache = cache::make_from_params(cache_store::MODE_APPLICATION, 'core', 'flickrclient');
 172
 173         $url = $cache->get('photourl_'.$photoid);
 174
 175         if ($url === false) {
 176             $response = $this->call('photos.getSizes', ['photo_id' => $photoid]);
 177             // Sizes are returned from smallest to greatest.
 178             if (!empty($response->sizes->size) && is_array($response->sizes->size)) {
 179                 while ($bestsize = array_pop($response->sizes->size)) {
 180                     if (isset($bestsize->source)) {
 181                         $url = $bestsize->source;
 182                         break;
 183                     }
 184                 }
 185             }
 186         }
 187
 188         if ($url === false) {
 189             throw new repository_exception('cannotdownload', 'repository');
 190
 191         } else {
 192             $cache->set('photourl_'.$photoid, $url);
 193         }
 194
 195         return $url;
 196     }
 197
 198     /**
 199      * Upload a photo from Moodle file pool to Flickr.
 200      *
 201      * Optional meta information are title, description, tags, is_public,
 202      * is_friend, is_family, safety_level, content_type and hidden.
 203      * See {@link https://www.flickr.com/services/api/upload.api.html}.
 204      *
 205      * Upload can't be asynchronous because then the query would not return the
 206      * photo ID which we need to add the photo to a photoset (album)
 207      * eventually.
 208      *
 209      * @param stored_file $photo stored in Moodle file pool
 210      * @param array $meta optional meta information
 211      * @return int|bool photo id, false on authentication failure
 212      */
 213     public function upload(stored_file $photo, array $meta = []) {
 214
 215         $args = [
 216             'title' => isset($meta['title']) ? $meta['title'] : null,
 217             'description' => isset($meta['description']) ? $meta['description'] : null,
 218             'tags' => isset($meta['tags']) ? $meta['tags'] : null,
 219             'is_public' => isset($meta['is_public']) ? $meta['is_public'] : 0,
 220             'is_friend' => isset($meta['is_friend']) ? $meta['is_friend'] : 0,
 221             'is_family' => isset($meta['is_family']) ? $meta['is_family'] : 0,
 222             'safety_level' => isset($meta['safety_level']) ? $meta['safety_level'] : 1,
 223             'content_type' => isset($meta['content_type']) ? $meta['content_type'] : 1,
 224             'hidden' => isset($meta['hidden']) ? $meta['hidden'] : 2,
 225         ];
 226
 227         $this->sign_secret = $this->consumer_secret.'&'.$this->access_token_secret;
 228         $params = $this->prepare_oauth_parameters(self::UPLOAD_ROOT, ['oauth_token' => $this->access_token] + $args, 'POST');
 229
 230         $params['photo'] = $photo;
 231
 232         $response = $this->http->post(self::UPLOAD_ROOT, $params);
 233
 234         if ($response) {
 235             $xml = simplexml_load_string($response);
 236
 237             if ((string)$xml['stat'] === 'ok') {
 238                 return (int)$xml->photoid;
 239
 240             } else if ((string)$xml['stat'] === 'fail' && (int)$xml->err['code'] == 98) {
 241                 // Authentication failure.
 242                 return false;
 243
 244             } else {
 245                 throw new moodle_exception('flickr_upload_failed', 'core_error', '',
 246                     ['code' => (int)$xml->err['code'], 'message' => (string)$xml->err['msg']]);
 247             }
 248
 249         } else {
 250             throw new moodle_exception('flickr_upload_error', 'core_error', '', null, $response);
 251         }
 252     }
 253 }