embed-piwigo.php

<?php
/**
 * The Embed Piwigo plugin adds support for embedding photos from whitelisted Piwigo websites.
 *
 * @file
 * @package           piwigo-embed
 * @since             0.1.0
 *
 * @wordpress-plugin
 * Plugin Name:       Embed Piwigo
 * Plugin URI:        https://samwilson.id.au/plugins/embed-piwigo/
 * Description:       Embed photos from a whitelist of Piwigo websites.
 * Version:           1.0.1
 * Author:            Sam Wilson
 * Author URI:        https://samwilson.id.au
 * License:           GPL-2.0+
 * License URI:       http://www.gnu.org/licenses/gpl-2.0.txt
 * Text Domain:       embed-piwigo
 * Domain Path:       /languages
 */

// If this file is called directly, abort.
if ( ! defined( 'WPINC' ) ) {
	die;
}

// Load the URLs and register embed handlers for them all.
$base_urls = array_filter( explode( "\n", get_option( 'embed-piwigo-urls' ) ) );
foreach ( $base_urls as $i => $base_url ) {
	$trimmed_base_url = trim( $base_url, "\t\n\r\0\x0B/" );
	wp_embed_register_handler(
		"piwigo_$i",
		"|($trimmed_base_url)/picture[^0-9]*([0-9]+)|i",
		function ( $matches, $attr, $url, $rawattr ) {
			$base_url = $matches[1];
			$image_id = $matches[2];
			try {
				$info = embed_piwigo_get_image_info( $base_url, $image_id );
			} catch ( Exception $exception ) {
				// translators: a prefix to add to error messages.
				$msg = __( 'Error: %s', 'embed-piwigo' );
				return '<p class="embed-piwigo error">' . sprintf( $msg, $exception->getMessage() ) . '</p>';
			}
			$medium        = $info['derivatives']['medium'];
			$image_url     = $medium['url'];
			$title         = $info['name'];
			$date          = $info['date_creation']
				? date_i18n( get_option( 'date_format' ), strtotime( $info['date_creation'] ) )
				: false;
			$description   = $info['comment'];
			$link_format   = '<a href="%s"><img src="%s" alt="%s" /></a>';
			$img_link      = sprintf( $link_format, $url, $image_url, $title );
			$caption_attrs = [
				'caption' => embed_piwigo_format_caption( $title, $date, $description ),
				'width'   => $medium['width'],
				'align'   => 'aligncenter',
			];
			return img_caption_shortcode( $caption_attrs, $img_link );
		}
	);
}

// Add the "Piwigo site URLs" option to the end of the general options page.
add_action(
	'admin_init', function () {
		$option_group = 'writing';
		register_setting( $option_group, 'embed-piwigo-urls', [ 'type' => 'string' ] );
		add_settings_field(
			'embed-piwigo-urls',
			__( 'Piwigo site URLs', 'embed-piwigo' ),
			function ( $args ) {
				$val = get_option( 'embed-piwigo-urls' );
				echo '<textarea id="embed-piwigo-urls" name="embed-piwigo-urls" cols="80" rows="3">' . esc_html( $val ) . '</textarea>';
				// translators: help text for this plugin's configuration option.
				echo '<p class="description">' . esc_html( __( 'Base URLs of Piwigo sites, one per line.', 'embed-piwigo' ) ) . '</p>';
			},
			$option_group
		); }
);

/**
 * Format an HTML caption.
 *
 * @param string $title The photo title.
 * @param string $date The photo date (already formatted).
 * @param string $description The photo description.
 * @return string
 */
function embed_piwigo_format_caption( $title, $date, $description ) {
	$caption = '';
	// Format the caption depending on what metadata is present.
	if ( $title && $date && $description ) {
		$caption = sprintf( '<strong>%1$s (%2$s):</strong> %3$s', $title, $date, $description );
	} elseif ( $title && $date ) {
		$caption = sprintf( '<strong>%1$s (%2$s)</strong>', $title, $date );
	} elseif ( $date && $description ) {
		$caption = sprintf( '<strong>%1$s:</strong> %2$s', $date, $description );
	} elseif ( $title && $description ) {
		$caption = sprintf( '<strong>%1$s:</strong> %2$s', $title, $description );
	}
	return $caption;
}

/**
 * Get information from a Piwigo site about a single image.
 * This function takes care of caching, and will only request new information every hour at most (unless we're in debug mode).
 *
 * @param string $base_url The base URL for the Piwigo site.
 * @param int    $image_id The Piwigo ID of the image to get information for.
 * @return string[][][]
 * @throws Exception If no data could be retrieved.
 */
function embed_piwigo_get_image_info( $base_url, $image_id ) {
	$api_url        = "$base_url/ws.php?format=json&method=pwg.images.getInfo&image_id=$image_id";
	$transient_name = 'embed_piwigo_site_' . md5( $base_url ) . '_' . $image_id;
	$cached         = get_transient( $transient_name );
	if ( $cached && ! WP_DEBUG ) {
		return $cached;
	}
	$response = wp_remote_get( $api_url );
	if ( $response instanceof WP_Error ) {
		// translators: error message displayed when no response could be got from a Piwigo API call.
		$msg = __( 'Unable to retrieve photo %s', 'embed-piwigo' );
		throw new Exception( sprintf( $msg, $image_id ) );
	} else {
		$info = json_decode( $response['body'], true );
		if ( ! isset( $info['result'] ) && isset( $info['message'] ) ) {
			// translators: error message displayed when an error was received from a Piwigo API call.
			$msg = __( 'Unable to retrieve photo %1$s (Piwigo said: %2$s)', 'embed-piwigo' );
			throw new Exception( sprintf( $msg, $image_id, $info['message'] ) );
		}
		set_transient( $transient_name, $info['result'], 60 * 60 );
		return $info['result'];
	}
}