Easy Instagram index.php

<?php
/*
Plugin Name: Easy Instagram
Plugin URI:
Description: Display one or more Instagram images by user id or tag
Version: 1.2.1
Author: VeloMedia
Author URI: http://www.velomedia.com
Licence:
*/
require_once 'include/Instagram-PHP-API/Instagram.php';
add_action( 'admin_menu', array( 'Easy_Instagram', 'admin_menu' ) );
add_action( 'wp_enqueue_scripts', array( 'Easy_Instagram', 'init_scripts_and_styles' ) );
add_action( 'admin_init', array( 'Easy_Instagram', 'admin_init' ) );
register_activation_hook( __FILE__, array( 'Easy_Instagram', 'plugin_activation' ) );
register_deactivation_hook( __FILE__, array( 'Easy_Instagram', 'plugin_deactivation' ) );
add_action( 'easy_instagram_clear_cache_event', array( 'Easy_Instagram', 'clear_expired_cache_action' ) );
add_shortcode( 'easy-instagram', array( 'Easy_Instagram', 'shortcode' ) );
//=============================================================================
define( 'EASY_INSTAGRAM_PLUGIN_PATH', dirname( __FILE__ ) );
class Easy_Instagram {
    static $cache_dir = 'cache/';
    static $minimum_cache_expire_minutes = 10;
    static $default_cache_expire_minutes = 30;
    static $max_images = 10;
    static function admin_menu() {
        add_submenu_page(
            'options-general.php',
            __( 'Easy Instagram', 'Easy_Instagram' ),
            __( 'Easy Instagram', 'Easy_Instagram' ),
            'manage_options',
            'easy-instagram',
            array( 'Easy_Instagram', 'admin_page' )
        );
    }
    //=========================================================================
    static function init_scripts_and_styles() {
        if ( ! is_admin() ) {
            wp_register_style( 'Easy_Instagram', plugins_url( 'css/style.css', __FILE__ ) );
            wp_enqueue_style( 'Easy_Instagram' );
        }
    }
    //=========================================================================
    static function admin_init() {
        wp_register_style( 'Easy_Instagram_Admin', plugins_url( 'css/admin.css', __FILE__ ) );
        wp_enqueue_style( 'Easy_Instagram_Admin' );
    }
    //=========================================================================
    static function set_instagram_settings( $client_id, $client_secret, $redirect_uri ) {
        update_option( 'easy_instagram_client_id', $client_id );
        update_option( 'easy_instagram_client_secret', $client_secret );
        update_option( 'easy_instagram_redirect_uri', $redirect_uri );
    }
    //=========================================================================
    static function get_instagram_settings() {
        $client_id = get_option( 'easy_instagram_client_id' );
        $client_secret = get_option( 'easy_instagram_client_secret' );
        $redirect_uri = get_option( 'easy_instagram_redirect_uri' );
        return array( $client_id, $client_secret, $redirect_uri );
    }
    //=========================================================================
    static function get_instagram_config() {
        list( $client_id, $client_secret, $redirect_uri ) = self::get_instagram_settings();
        return array(
            'client_id'     => $client_id,
            'client_secret' => $client_secret,
            'grant_type'    => 'authorization_code',
            'redirect_uri'  => $redirect_uri
        );
    }
    //=========================================================================
    static function admin_page() {
        if ( isset( $_POST['ei_general_settings'] ) &&
                check_admin_referer( 'ei_general_settings_nonce', 'ei_general_settings_nonce' ) ) {
            $errors = array();
            $instagram_client_id = isset( $_POST['ei_client_id'] )
                ? trim( $_POST['ei_client_id'] )
                : '';
            $instagram_client_secret = isset( $_POST['ei_client_secret'] )
                ? trim( $_POST['ei_client_secret'] )
                : '';
            $instagram_redirect_uri = isset( $_POST['ei_redirect_uri'] )
                ? trim( $_POST['ei_redirect_uri'] )
                : '';
            if ( empty( $instagram_client_id ) ) {
                $errors['client_id'] = __( 'Please enter your Instagram client id', 'Easy_Instagram' );
            }

            if ( empty( $instagram_client_secret ) ) {
                $errors['client_secret'] = __( 'Please enter your Instagram client secret', 'Easy_Instagram' );
            }
            if ( empty( $instagram_redirect_uri ) ) {
                $errors['redirect_uri'] = __( 'Please enter your Instagram redirect URI', 'Easy_Instagram' );
            }
            if ( empty( $errors ) ) {
                self::set_instagram_settings( $instagram_client_id, $instagram_client_secret, $instagram_redirect_uri );
            }
            $cache_expire_time = isset( $_POST['ei_cache_expire_time'] )
                ? (int) $_POST['ei_cache_expire_time']
                : 0;
            if ( $cache_expire_time < self::$minimum_cache_expire_minutes ) {
                $cache_expire_time = self::$minimum_cache_expire_minutes;
            }
            self::set_cache_refresh_minutes( $cache_expire_time );
        }
        else {
            list( $instagram_client_id, $instagram_client_secret, $instagram_redirect_uri )
                = self::get_instagram_settings();
        }
        if ( isset( $_POST['instagram-logout'] )
                && check_admin_referer( 'ei_user_logout_nonce', 'ei_user_logout_nonce' ) ) {
            self::set_access_token( '' );
            update_option( 'ei_access_token', '' );
        }
        $config = self::get_instagram_config();
        $instagram = new MC_Instagram_Connector( $config );
        $access_token = self::get_access_token();
        $cache_dir = self::get_cache_dir();
        $cache_expire_time = self::get_cache_refresh_minutes();
        if ( empty ( $access_token ) ) {
            if ( isset( $_GET['code'] ) ) {
                $access_token = $instagram->getAccessToken();
                if ( !empty( $access_token ) ) {
                    self::set_access_token( $access_token );
                }
                $instagram_user = $instagram->getCurrentUser();
                if ( !empty( $instagram_user ) ) {
                    self::set_instagram_user_data( $instagram_user->username, $instagram_user->id );
                }
            }
        }
?>
    <div id="icon-options-general" class="icon32"></div>
    <h2><?php _e( 'Easy Instagram', 'Easy_Instagram' ) ?></h2>
    <form method='POST' action='' class='easy-instagram-settings-form'>
        <table class='easy-instagram-settings'>
            <?php if ( !is_writable( $cache_dir ) ): ?>
                <tr class='warning'>
                    <td colspan='2'>
                        <?php printf( __( 'The directory %s is not writable !', 'Easy_Instagram' ), $cache_dir ); ?>
                    </td>
                </tr>
            <?php endif; ?>
            <tr>
                <td colspan='2'><h3><?php _e( 'General Settings', 'Easy_Instagram' ); ?></h3></td>
            </tr>
            <tr>
                <td class='labels'>
                    <label for='ei-client-id'><?php _e( 'Application Client ID', 'Easy_Instagram' ); ?></label>
                </td>
                <td>
                    <input type='text' name='ei_client_id' id='ei-client-id' value='<?php echo esc_html( $instagram_client_id ); ?>' />
                    <br />
                    <?php if ( isset( $errors['client_id'] ) ): ?>
                        <div class='form-error'><?php echo $errors['client_id']; ?></div>
                    <?php endif; ?>
                    <span class='info'><?php _e( 'This is the ID of your Instagram application', 'Easy_Instagram' ); ?></span>
                </td>
            </tr>
            <tr>
                <td class='labels'>
                    <label for='ei-client-secret'><?php _e( 'Application Client Secret', 'Easy_Instagram' ); ?></label>
                </td>
                <td>
                    <input type='text' name='ei_client_secret' id='ei-client-secret' value='<?php echo esc_html( $instagram_client_secret ); ?>' />
                    <br />
                    <?php if ( isset( $errors['client_secret'] ) ): ?>
                        <div class='form-error'><?php echo $errors['client_secret']; ?></div>
                    <?php endif; ?>
                    <span class='info'><?php _e( 'This is your Instagram application secret', 'Easy_Instagram' ); ?></span>
                </td>
            </tr>
            <tr>
                <td class='labels'>
                    <label for='ei-redirect-uri'><?php _e( 'Application Redirect URI', 'Easy_Instagram' ); ?></label>
                </td>
                <td>
                    <input type='text' name='ei_redirect_uri' id='ei-redirect-uri' value='<?php echo esc_html( $instagram_redirect_uri ); ?>' />
                    <br />
                    <?php if ( isset( $errors['redirect_uri'] ) ): ?>
                        <div class='form-error'><?php echo $errors['redirect_uri']; ?></div>
                    <?php endif; ?>
                    <span class='info'><?php _e( 'This is your Instagram application redirect URI', 'Easy_Instagram' ); ?></span>
                </td>
            </tr>
            <tr>
                <td class='labels'>
                    <label for='ei-cache-expire-time'><?php _e( 'Cache Expire Time (minutes)', 'Easy_Instagram' ); ?></label>
                </td>
                <td>
                    <input type='text' name='ei_cache_expire_time' id='ei-cache-expire-time' value='<?php echo esc_html( $cache_expire_time ); ?>' />
                    <br />
                    <span class='info'>
                        <?php printf( __( 'Minimum expire time: %d minute.',
                                            'Easy_Instagram' ),
                                        self::$minimum_cache_expire_minutes ); ?>
                    </span>
                </td>
            </tr>
            <tr>
                <td>
                    <input type='hidden' name='ei_general_settings' value='1' />
                    <?php wp_nonce_field( 'ei_general_settings_nonce', 'ei_general_settings_nonce' ); ?>
                </td>
                <td>
                    <input type='submit' value='<?php _e( "Save Settings" , "Easy_Instagram" ) ?>' name='submit' />
                </td>
            </tr>
        </table>
    </form>
    <form method='POST' action='' class='easy-instagram-settings-form'>
        <table class='easy-instagram-settings'>
        <?php if ( empty( $access_token ) ) : ?>
            <tr>
                <td colspan='2'><h3><?php _e( 'Instagram Account', 'Easy_Instagram' ); ?></h3></td>
            </tr>
            <tr>
                <td>
                    <?php if ( !empty( $instagram_client_id )
                        && !empty( $instagram_client_secret )
                        && ! empty( $instagram_redirect_uri ) ): ?>
                        <?php $authorization_url = $instagram->getAuthorizationUrl(); ?>
                        <a href="<?php echo $authorization_url;?>"><?php _e( 'Instagram Login' );?></a>
                    <?php else: ?>
                        <?php _e( 'Please configure the General Settings first', 'Easy_Instagram' ); ?>
                    <?php endif; ?>
                </td>
                <td>
                </td>
            </tr>
        <?php else: ?>
            <?php list( $username, $user_id ) = self::get_instagram_user_data(); ?>
                <tr>
                    <td colspan='2'><h3><?php _e( 'Instagram Account', 'Easy_Instagram' ); ?></h3></td>
                </tr>
                <tr>
                    <td class='labels'>
                        <label><?php _e( 'Instagram Username', 'Easy_Instagram' ); ?></label>
                    </td>
                    <td>
                        <?php echo $username; ?>
                    </td>
                </tr>
                <tr>
                    <td class='labels'>
                        <label><?php _e( 'Instagram User ID', 'Easy_Instagram' ); ?></label>
                    </td>
                    <td>
                        <?php echo $user_id; ?>
                    </td>
                </tr>
                <tr>
                    <td>
                        <?php wp_nonce_field( 'ei_user_logout_nonce', 'ei_user_logout_nonce' ); ?>
                    </td>
                    <td>
                        <input type='submit' name='instagram-logout' value="<?php _e( 'Instagram Logout' );?>" />
                    </td>
                </tr>
        <?php endif; ?>
        </table>
    </form>
<?php
    }
    //=========================================================================
    static function set_instagram_user_data( $username, $id ) {
        update_option( 'easy_instagram_username', $username );
        update_option( 'easy_instagram_user_id', $id );
    }
    //=========================================================================
    static function get_instagram_user_data() {
        $username = get_option( 'easy_instagram_username' );
        $user_id = get_option( 'easy_instagram_user_id' );
        return array( $username, $user_id );
    }
    //=========================================================================
    static function set_access_token( $access_token ) {
        update_option( 'easy_instagram_access_token', $access_token );
    }
    //=========================================================================
    static function get_access_token() {
        return get_option( 'easy_instagram_access_token' );
    }
    //=========================================================================
    static function get_live_user_data( $instagram, $user_id, $limit = 1 ) {
        if ( $limit > self::$max_images ) {
            $limit = self::$max_images;
        }
        $live_data = $instagram->getUserRecent( $user_id );
        $recent = json_decode( $live_data );
        if ( empty( $recent ) ) {
            $live_data = NULL;
        }
        else {
            $live_data = array_slice( $recent->data, 0, $limit );
        }
        return $live_data;
    }
    //=========================================================================
    static function get_live_tag_data( $instagram, $tag, $limit = 1 ) {
        if ( $limit > self::$max_images ) {
            $limit = self::$max_images;
        }
        $live_data = $instagram->getRecentTags( $tag );
        $recent = json_decode( $live_data );
        if ( empty( $recent ) || !isset( $recent->data ) ) {
            $live_data = NULL;
        }
        else {
            $live_data = array_slice( $recent->data, 0, $limit );
        }
        return $live_data;
    }
    //=========================================================================

    static function shortcode( $attributes ) {
        extract(
            shortcode_atts(
                array(
                    'tag'               => '',
                    'user_id'           => '',
                    'limit'             => 1,
                    'caption_hashtags'  => 'true'
                ),
                $attributes
            )
        );

        $caption_hashtags = strtolower( $caption_hashtags );
        return self::generate_content( $tag, $user_id, $limit, $caption_hashtags );
    }
    //=========================================================================

    static function generate_content( $tag, $user_id, $limit, $caption_hashtags ) {
        if ( empty( $tag ) && empty( $user_id ) ) {
            return '';
        }
        $access_token = self::get_access_token();
        if ( empty( $access_token ) ) {
            return '';
        }
        $out = '';
        $config = self::get_instagram_config();
        $instagram = new MC_Instagram_Connector( $config );
        $instagram->setAccessToken( $access_token );
        if ( ! empty( $user_id ) ) {
            list( $data, $expired ) = self::get_cached_data_for_id_or_tag( $user_id, $limit, 'id' );

            if ( $expired ) {
                $live_data = self::get_live_user_data( $instagram, $user_id, $limit );
                if ( ! empty( $live_data ) ) {
                    self::clear_cache( $user_id, 'id' );
                }
                else {
                    $live_data = NULL;
                }
            }
            elseif ( NULL == $data ) {
                $live_data = self::get_live_user_data( $instagram, $user_id, $limit );
            }

            $cache_index = 'id' . $user_id;
        }
        else {
            if ( ! empty( $tag ) ) {
                list( $data, $expired ) = self::get_cached_data_for_id_or_tag( $tag, $limit, 'tag' );
                if ( $expired ) {
                    $live_data = self::get_live_tag_data( $instagram, $tag, $limit );
                    if ( ! empty( $live_data ) ) {
                        self::clear_cache( $tag, 'tag' );
                    }
                    else {
                        $live_data = NULL;
                    }
                }
                elseif ( NULL == $data ) {
                    $live_data = self::get_live_tag_data( $instagram, $tag, $limit );
                }
                $cache_index = 'tag' . $tag;
            }
        }
        if ( isset( $live_data ) && !empty( $live_data ) ) {
            $hash = md5( $cache_index );
            $timestamp = time();
            $cache_data = array( 'cache_timestamp' => $timestamp );
            $cache_data['data'] = array();
            foreach ( $live_data as $elem ) {
                if ( isset( $elem->caption ) ) {
                    $caption_text = isset( $elem->caption->text ) ? trim( $elem->caption->text ) : '';
                    $caption_from = '';

                    if ( isset( $elem->caption->from ) ) {
                        if ( isset( $elem->caption->from->full_name ) ) {
                            $caption_from = $elem->caption->from->full_name;
                        }
                        if ( empty( $caption_from ) && isset( $elem->caption->from->username ) ) {
                            $caption_from = $elem->caption->from->username;
                        }
                    }
                    if ( empty( $caption_from ) ) {
                        if ( isset( $elem->user ) ) {
                            if ( isset( $elem->user->full_name ) ) {
                                $caption_from = $elem->user->full_name;
                            }
                            if ( empty( $caption_from ) && isset( $elem->user->username ) ) {
                                $caption_from = $elem->user->username;
                            }
                        }
                    }
                    $caption_created_time = isset( $elem->caption->created_time ) ? $elem->caption->created_time : time();
                }
                else {
                    $caption_text = '';
                    $caption_from = '';
                    $caption_created_time = time();
                }

                $cached_elem = array(
                    'link'                  => isset( $elem->link ) ? $elem->link : '#',
                    'caption_text'          => $caption_text,
                    'caption_from'          => $caption_from,
                    'created_time'          => $elem->created_time,
                    'caption_created_time'  => $caption_created_time
                );
                $images = $elem->images;
                if ( isset( $images->low_resolution ) ) {
                    $cached_elem['low_resolution'] = array(
                        'width'     => $images->low_resolution->width,
                        'height'    => $images->low_resolution->height
                    );
                    $local_url = self::save_remote_image(
                        $images->low_resolution->url,
                        'low_resolution'
                    );
                    if ( NULL == $local_url ) {
                        $cached_elem['low_resolution']['url'] = $images->low_resolution->url;
                    }
                    else {
                        $cached_elem['low_resolution']['url'] = $local_url;
                    }
                }
                if ( isset( $images->thumbnail ) ) {
                    $cached_elem['thumbnail'] = array(
                        'width'     => $images->thumbnail->width,
                        'height'    => $images->thumbnail->height
                    );

                    $local_url = self::save_remote_image(
                        $images->thumbnail->url,
                        'thumbnail'
                    );
                    if ( NULL == $local_url ) {
                        $cached_elem['thumbnail']['url'] = $images->thumbnail->url;
                    }
                    else {
                        $cached_elem['thumbnail']['url'] = $local_url;
                    }
                }
                if ( isset( $images->standard_resolution ) ) {
                    $cached_elem['standard_resolution'] = array(
                        'width'     => $images->standard_resolution->width,
                        'height'    => $images->standard_resolution->height
                    );

                    $local_url = self::save_remote_image(
                        $images->standard_resolution->url,
                        'standard_resolution'
                    );
                    if ( NULL == $local_url ) {
                        $cached_elem['standard_resolution']['url'] = $images->standard_resolution->url;
                    }
                    else {
                        $cached_elem['standard_resolution']['url'] = $local_url;
                    }
                }
                $cache_data['data'][] = $cached_elem;
            }
            self::cache_data( $cache_index, $cache_data );
            $instagram_elements = $cache_data['data'];
        }
        else {
            if ( ! empty( $data ) ) {
                $instagram_elements = $data['data'];
            }
        }
        if ( isset( $instagram_elements ) ) {
            $crt = 0;
            foreach ( $instagram_elements as $elem ) {
                $image_url = $elem['thumbnail']['url'];
                $width = $elem['thumbnail']['width'];
                $height = $elem['thumbnail']['height'];
                $out .= '<div class="easy-instagram-thumbnail-wrapper">';
                $out .= '<img src="' . $image_url . '" alt="" style="width:'
                    . $width. 'px; height: ' . $height . 'px;" class="easy-instagram-thumbnail" />';
                $out .= '<div class="easy-instagram-thumbnail-author">by ' . $elem['caption_from'] . '</div>';
                $caption_text = $elem['caption_text'] ;
                if ( 'false' == $caption_hashtags ) {
                    $caption_text = preg_replace( '/#[^\\s]+/', '', $caption_text );
                    $caption_text = trim( $caption_text );
                }
                $out .= '<div class="easy-instagram-thumbnail-caption">' . $caption_text . '</div>';
                $elem_time = ( $elem['caption_created_time'] > $elem['created_time'] )
                            ? $elem['caption_created_time'] : $elem['created_time'];
                $out .= '<div class="easy-instagram-thumbnail-time">'
                    . self::relative_time( $elem_time )
                    . __( ' using Instagram', 'Easy_Instagram' )
                    . '</div>';
                $out .= '</div>';
                $crt++;
                if ( $crt >= $limit ) {
                    break;
                }
            }
        }
        return $out;
    }
    //=========================================================================
    static public function get_cache_dir() {
        return EASY_INSTAGRAM_PLUGIN_PATH . '/' . self::$cache_dir;
    }
    //=========================================================================
    static function cache_data( $id_or_tag, $data ) {
        $timestamp = time();
        $hash = md5( $id_or_tag );
        $path = self::get_cache_dir() . $hash . '.cache';
        $handle = fopen( $path, 'w' );
        if ( FALSE === $handle ) {
            return FALSE;
        }
        $serialized = serialize( $data );
        $would_block = TRUE;
        if ( flock( $handle, LOCK_EX, $would_block ) ) {
            fwrite( $handle, $serialized );
            fflush( $handle );
            flock( $handle, LOCK_UN ); // release the lock
        }
        else {
            error_log( 'Couldn\'t get the lock in cache_data.' );
        }
        fclose( $handle );
        return TRUE;
    }
    //=========================================================================
    // Returns the cached data and a flag telling if the data expired
    static function get_cached_data_for_id_or_tag( $id_or_tag, $limit, $type = 'id' ) {
        $now = time();
        $hash = md5( $type . $id_or_tag );
        $path = self::get_cache_dir() . $hash . '.cache';
        if ( !file_exists( $path ) ) {
            return array( NULL, FALSE );
        }
        $handle = fopen( $path, 'r' );
        if ( flock( $handle, LOCK_SH ) ) {
            $data = fgets( $handle );
            flock( $handle, LOCK_UN ); // release the lock
        }
        else {
            error_log( 'Couldn\'t get the lock in get_cached_data_for_id_or_tag.' );
        }
        if ( !empty( $data ) ) {
            $cached_data = unserialize( $data );
        }
        fclose( $handle );
        if ( !isset( $cached_data ) || !isset( $cached_data['data'] ) || !isset( $cached_data['cache_timestamp'] ) ) {
            return array( NULL, FALSE ); //No cached data found
        }
        // If limit is greater than the cached data size, force clear cache
        if ( $limit > count( $cached_data['data'] ) ) {
            return array( $cached_data, TRUE );
        }
        $cache_minutes = self::get_cache_refresh_minutes();
        $delta = ( $now - $cached_data['cache_timestamp'] ) / 60;
        if ( $delta > $cache_minutes ) {
            return array( $cached_data, TRUE );
        }
        else {
            return array( $cached_data, FALSE );
        }
    }
    //=========================================================================
    static function clear_cache( $id_or_tag, $type ) {
        $hash = md5( $type . $id_or_tag );
        $cache_dir = self::get_cache_dir();
        $path = $cache_dir . $hash . '.cache';
        if ( file_exists( $path ) ) {
            $handle = fopen( $path, 'r' );
            if ( flock( $handle, LOCK_EX ) ) {
                $data = fread( $handle, filesize( $path ) );
            }
            if ( !empty( $data ) ) {
                $cached_data = unserialize( $data );
            }
            fclose( $handle );
            unlink( $path );

            $file_types = array( 'thumbnail', 'low_resolution', 'standard_resolution' );
            if ( isset( $cached_data ) && isset( $cached_data['data'] ) ) {
                foreach ( $cached_data['data'] as $elem ) {
                    //Delete images
                    foreach ( $file_types as $file_type ) {
                        if ( isset( $elem[$file_type] ) && isset( $elem[$file_type]['url'] ) ) {
                            // Extract the file name from the file URL and look for the file in the cache directory
                            $file_path = $cache_dir . basename( $elem[$file_type]['url'] );
                            if ( file_exists( $file_path ) ) {
                                unlink( $file_path );
                            }
                        }
                    }
                }
            }
        }
    }
    //=========================================================================
    static function save_remote_image( $remote_image_url, $id ) {
        $filename = '';
        if ( preg_match( '/([^\/\.\?\&]+)\.([^\.\?\/]+)(\?[^\.\/]*)?$/', $remote_image_url, $matches ) ) {
            $filename .= $matches[1] . '_' . $id . '.' . $matches[2];
        }
        else {
            return NULL;
        }
        $path = self::get_cache_dir() . $filename;
        $content = file_get_contents( $remote_image_url );
        if ( FALSE == $content ) {
            return NULL;
        }

        if ( FALSE == file_put_contents( $path, $content ) ) {
            return NULL;
        }
        return plugins_url( self::$cache_dir . $filename, __FILE__ );
    }
    //=========================================================================
    static function get_cache_refresh_minutes() {
        return get_option( 'easy_instagram_cache_expire_time', self::$default_cache_expire_minutes );
    }
    //=========================================================================
    static function set_cache_refresh_minutes( $minutes = 0 ) {
        if ( 0 == $minutes ) {
            $minutes = self::$default_cache_expire_minutes;
        }
        update_option( 'easy_instagram_cache_expire_time', (int) $minutes );
    }
    //=========================================================================
    static function relative_time( $timestamp ) {
        $difference = time() - $timestamp;
        $periods = array( "sec", "min", "hour", "day", "week", "month", "years", "decade" );
        $lengths = array( "60", "60", "24", "7", "4.35", "12", "10" );
        if ($difference > 0) { // this was in the past
            $ending = "ago";
        } else { // this was in the future
            $difference = -$difference;
            $ending = "to go";
        }
        for( $j = 0; $difference >= $lengths[$j]; $j++ ) {
            $difference /= $lengths[$j];
        }
        $difference = round( $difference );
        if($difference != 1) {
            $periods[$j] .= "s";
        }

        $text = "$difference $periods[$j] $ending";
        return $text;
    }
    //=====================================================================
    static function plugin_activation() {
        wp_schedule_event(
            current_time( 'timestamp' ),
            'daily',
            'easy_instagram_clear_cache_event'
        );
    }

    //=====================================================================

    static function clear_expired_cache_action() {
        $valid_files = array();
        $cache_dir = self::get_cache_dir();
        $files = scandir( $cache_dir );
        if ( ! empty( $files ) ) {
            foreach ( $files as $file ) {
                if ( preg_match( '/\.cache$/', $file ) ) {
                    $ret = self::remove_cache_file( $file );
                    if ( ! empty( $ret ) ) {
                        $valid_files = array_merge( $valid_files, $ret );
                    }
                }
            }
            // Remove all the files from the cache folder not in the valid files array (or valid files is empty)
            foreach ( $files as $file ) {
                if ( ( '.' != $file ) && ( '..' != $file ) ) {
                    if ( ! in_array( $file, $valid_files ) ) {
                        $file_path = $cache_dir . '/' . $file;
                        if ( file_exists( $file_path ) ) {
                            unlink( $file_path );
                        }
                    }
                }
            }
        }
    }
    //=====================================================================
    static function remove_cache_file( $filename ) {
        $cache_dir = self::get_cache_dir() ;
        $path = $cache_dir . $filename;

        $handle = fopen( $path, 'r' );
        if ( flock( $handle, LOCK_EX ) ) {
            $data = fread( $handle, filesize( $path ) );
        }
        if ( !empty( $data ) ) {
            $cached_data = unserialize( $data );
        }
        fclose( $handle );
        $now = time();
        $delta = ( $now - $cached_data['cache_timestamp'] ) / 60;
        $file_types = array( 'thumbnail', 'low_resolution', 'standard_resolution' );
        $valid_files = array();
        if ( ! isset( $cached_data ) ) {
            return $valid_files;
        }
        if ( $delta > 24 * 60 ) {
            if ( !empty( $cached_data['data'] ) ) {
                foreach ( $cached_data['data'] as $elem ) {
                    //Delete images
                    foreach ( $file_types as $file_type ) {
                        if ( isset( $elem[$file_type] ) && isset( $elem[$file_type]['url'] ) ) {
                            // Extract the file name from the file URL and look for the file in the cache directory
                            $file_path = $cache_dir . basename( $elem[$file_type]['url'] );
                            if ( file_exists( $file_path ) ) {
                                unlink( $file_path );
                            }
                        }
                    }
                }
            }

            unlink( $path );
        }
        else {
            if ( ! empty( $cached_data['data'] ) ) {
                foreach ( $cached_data['data'] as $elem ) {
                    foreach ( $file_types as $file_type ) {
                        if ( isset( $elem[$file_type]['url'] ) ) {
                            $filename = basename( $elem[$file_type]['url'] );
                            $file_path = $cache_dir . $filename;
                            if ( file_exists( $file_path ) ) {
                                $valid_files[] = $filename;
                            }
                        }
                    }
                }
                $valid_files[] = $path;
            }
            $valid_files[] = $filename; //Keep the cache file as valid
        }

        return $valid_files;
    }
    //=====================================================================

    static function plugin_deactivation() {
        wp_clear_scheduled_hook( 'easy_instagram_clear_cache_event' );
    }
}
/*
 * Easy Instagram Widget
 */
class Easy_Instagram_Widget extends WP_Widget {
    public function __construct() {
        parent::__construct(
            'easy_instagram_widget_base',
            'Easy Instagram',
            array(
                'description' => 'Display one or more images from Instagram based on a tag or Instagram user id',
                'class' => 'easy-instagram-widget'
            )
        );
    }
    //==========================================================================
    public function form( $instance ) {
        if ( isset( $instance['type'] ) ) {
            $type = $instance['type'];
        }
        else {
            $type = 'tag';
        }

        if ( isset( $instance['value'] ) ) {
            $value = $instance['value'];
        }
        else {
            $value = '';
        }
        if ( isset( $instance['limit'] ) ) {
            $limit = $instance['limit'];
        }
        else {
            $limit = 1;
        }
        if ( $limit > Easy_Instagram::$max_images ) {
            $limit = Easy_Instagram::$max_images;
        }
        if ( isset( $instance['caption_hashtags'] ) ) {
            $caption_hashtags = $instance['caption_hashtags'];
        }
        else {
            $caption_hashtags = 'true';
        }
?>
        <p>
        <label for="<?php echo $this->get_field_id( 'type' ); ?>"><?php _e( 'Type:' ); ?></label>
        <select class="widefat" id="<?php echo $this->get_field_id( 'type' ); ?>" name="<?php echo $this->get_field_name( 'type' ); ?>">
            <?php $selected = ( 'tag' == $type ) ? 'selected="selected"' : ''; ?>
            <option value="tag" <?php echo $selected;?>><?php _e( 'Tag' ); ?></option>

            <?php $selected = ( 'user_id' == $type ) ? 'selected="selected"' : ''; ?>
            <option value="user_id" <?php echo $selected;?>><?php _e( 'User ID' ); ?></option>
        </select>
        </p>

        <p>
        <label for="<?php echo $this->get_field_id( 'value' ); ?>"><?php _e( 'Value:' ); ?></label>
        <input type='text' class="widefat" id="<?php echo $this->get_field_id( 'value' ); ?>" name="<?php echo $this->get_field_name( 'value' ); ?>" value="<?php _e( $value ); ?> " />
        </p>

        <p>
        <label for="<?php echo $this->get_field_id( 'limit' ); ?>"><?php _e( 'Images:' ); ?></label>
        <select class="widefat" id="<?php echo $this->get_field_id( 'limit' ); ?>" name="<?php echo $this->get_field_name( 'limit' ); ?>">
        <?php for ( $i=1; $i<= Easy_instagram::$max_images; $i++ ): ?>

        <?php printf(
            '<option value="%s"%s>%s</option>',
                $i,
                selected( $limit, $i, false ),
                $i );
        ?>

        <?php endfor; ?>
        </select>
        </p>
        <p>
        <label for="<?php echo $this->get_field_id( 'caption_hashtags' ); ?>"><?php _e( 'Show Caption Hashtags:' ); ?></label>
        <select class="widefat" id="<?php echo $this->get_field_id( 'caption_hashtags' ); ?>" name="<?php echo $this->get_field_name( 'caption_hashtags' ); ?>">
            <?php $selected = ( 'true' == $caption_hashtags ) ? 'selected="selected"' : ''; ?>
            <option value="true" <?php echo $selected;?>><?php _e( 'Yes' ); ?></option>

            <?php $selected = ( 'false' == $caption_hashtags ) ? 'selected="selected"' : ''; ?>
            <option value="false" <?php echo $selected;?>><?php _e( 'No' ); ?></option>
        </select>
        </p>
<?php

    }
    //==========================================================================
    public function update( $new_instance, $old_instance ) {
        $instance = array();
        $instance['type']               = strip_tags( $new_instance['type'] );
        $instance['value']              = trim( strip_tags( $new_instance['value'] ) );
        $instance['limit']              = strip_tags( $new_instance['limit'] );
        $instance['caption_hashtags']   = $new_instance['caption_hashtags'];
        return $instance;
    }
    //==========================================================================

    public function widget( $args, $instance ) {
        extract( $args );
        echo $before_widget;

        $tag = '';
        $user_id = '';
        $limit = 1;
        $caption_hashtags = 'true';

        if ( 'tag' == $instance['type'] ) {
            $tag = trim( $instance['value'] );
            $user_id = '';
        }
        else {
            $tag = '';
            $user_id = $instance['value'];
        }

        if ( isset( $instance['limit'] ) ) {
            $limit = (int) $instance['limit'];
            if ( $limit > Easy_Instagram::$max_images ) {
                $limit = Easy_Instagram::$max_images;
            }
        }

        if ( isset( $instance['caption_hashtags'] ) ) {
            $caption_hashtags = $instance['caption_hashtags'];
        }
        $content = Easy_Instagram::generate_content( $tag, $user_id, $limit, $caption_hashtags );

        echo $content;

        echo $after_widget;
    }
    //==========================================================================
}
add_action( 'widgets_init', create_function( '', 'register_widget( "Easy_Instagram_Widget" );' ) );