<?php
/**
 * The sizes WordPress makes (1.9.0, D-500 gap 2). Settings chooses which registered sizes WordPress makes for new uploads.
 * Tools makes, for the pictures already in the library, the sizes they are missing and those whose dimensions no longer
 * match the registered size (after a theme change). Nothing is overwritten or deleted: an out-of-date size's file stays
 * where it is and is kept in the attachment's backup sizes, so pages that use it keep working. Sizes that no theme or plugin
 * registers any more are counted, not removed.
 *
 * @package AffStackDevImageManager
 */

namespace AffStackDev\ImageManager;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/** WordPress's image sizes. */
final class Image_Sizes {
	public const OPTION = 'afsd_im_sizes_check';

	/**
	 * The sizes WordPress is about to make, without those Settings leaves out.
	 *
	 * @param mixed $sizes Size name => definition.
	 * @return mixed
	 */
	public static function chosen( $sizes ) {
		$skip = (array) ( Settings::get()['skip_sizes'] ?? array() );
		return is_array( $sizes ) && $skip ? array_diff_key( $sizes, array_flip( $skip ) ) : $sizes;
	}

	/**
	 * The registered sizes: name => width, height, crop.
	 *
	 * @return array
	 */
	public static function registered(): array {
		return function_exists( 'wp_get_registered_image_subsizes' ) ? (array) wp_get_registered_image_subsizes() : array();
	}

	/**
	 * The saved check, or an empty array.
	 *
	 * @return array
	 */
	public static function state(): array {
		$s = get_option( self::OPTION, array() );
		return is_array( $s ) ? $s : array();
	}

	/**
	 * The sizes one picture should have now that differ from what it has: missing ones are left to WordPress, out-of-date
	 * ones are named.
	 *
	 * @param array $meta  The attachment metadata.
	 * @param array $sizes The registered sizes WordPress makes.
	 * @return array Out-of-date size names.
	 */
	private static function outdated( array $meta, array $sizes ): array {
		$out = array();
		$w   = (int) ( $meta['width'] ?? 0 );
		$h   = (int) ( $meta['height'] ?? 0 );
		foreach ( (array) ( $meta['sizes'] ?? array() ) as $name => $have ) {
			if ( ! isset( $sizes[ $name ] ) || ! is_array( $have ) || ! $w || ! $h ) {
				continue;
			}
			$d    = $sizes[ $name ];
			$want = image_resize_dimensions( $w, $h, (int) $d['width'], (int) $d['height'], $d['crop'] );
			if ( is_array( $want ) && ( (int) ( $have['width'] ?? 0 ) !== (int) $want[4] || (int) ( $have['height'] ?? 0 ) !== (int) $want[5] ) ) {
				$out[] = (string) $name;
			}
		}
		return $out;
	}

	/**
	 * Start a check, or continue the saved one, for about eight seconds: each picture gets its missing sizes, and its
	 * out-of-date sizes again (the old files kept as backup sizes).
	 *
	 * @param bool $start Start a new check.
	 * @return array The saved check.
	 * @throws \RuntimeException When the check may not run now.
	 */
	public static function step( bool $start ): array {
		$lock = Reviewed_Store::enter();
		try {
			if ( ! current_user_can( 'manage_options' ) || ! current_user_can( 'upload_files' ) ) {
				throw new \RuntimeException( 'sizes_access' );
			}
			$token = Repository::acquire( 'image_sizes', 300 );
			if ( ! $token ) {
				throw new \RuntimeException( 'sizes_busy' );
			}
			try {
				require_once ABSPATH . 'wp-admin/includes/image.php';
				global $wpdb;
				$s = self::state();
				if ( $start ) {
					$s = array(
						'v'            => 1,
						'started'      => time(),
						'updated'      => time(),
						'cursor'       => 0,
						'checked'      => 0,
						'pictures'     => 0,
						'made'         => 0,
						'remade'       => 0,
						'failed'       => array(),
						'unregistered' => array(),
						'status'       => 'more',
					);
				} elseif ( ! $s || 'more' !== ( $s['status'] ?? '' ) ) {
					throw new \RuntimeException( 'sizes_stale' );
				}
				$sizes = self::chosen( self::registered() );
				$all   = self::registered();
				$until = microtime( true ) + 8;
				while ( 'more' === $s['status'] && microtime( true ) < $until ) {
					// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching -- one bounded batch of a check the administrator starts; it must read the current rows.
					$ids = $wpdb->get_col( $wpdb->prepare( "SELECT ID FROM %i WHERE post_type = 'attachment' AND post_status = 'inherit' AND post_mime_type LIKE %s AND ID > %d ORDER BY ID ASC LIMIT 20", $wpdb->posts, 'image/%', (int) $s['cursor'] ) );
					if ( ! $ids ) {
						$s['status'] = 'done';
						break;
					}
					foreach ( array_map( 'intval', $ids ) as $id ) {
						$s['cursor'] = $id;
						++$s['checked'];
						$meta = wp_get_attachment_metadata( $id );
						if ( ! is_array( $meta ) || ( empty( $meta['sizes'] ) && empty( $meta['width'] ) ) ) {
							continue;
						}
						foreach ( array_keys( (array) ( $meta['sizes'] ?? array() ) ) as $name ) {
							if ( ! isset( $all[ $name ] ) ) {
								$entry                      = $s['unregistered'][ $name ] ?? array( 0, 0 );
								$s['unregistered'][ $name ] = array( $entry[0] + 1, $entry[1] + (int) ( $meta['sizes'][ $name ]['filesize'] ?? 0 ) );
							}
						}
						$old     = self::outdated( $meta, $sizes );
						$missing = function_exists( 'wp_get_missing_image_subsizes' ) ? array_keys( (array) wp_get_missing_image_subsizes( $id ) ) : array();
						if ( ! $old && ! $missing ) {
							continue;
						}
						if ( ! current_user_can( 'edit_post', $id ) || ! is_file( (string) wp_get_original_image_path( $id ) ) ) {
							$s['failed'][] = $id;
							continue;
						}
						if ( $old ) {
							$backup = get_post_meta( $id, '_wp_attachment_backup_sizes', true );
							$backup = is_array( $backup ) ? $backup : array();
							foreach ( $old as $name ) {
								$backup[ $name . '-afsd-' . time() ] = $meta['sizes'][ $name ];
								unset( $meta['sizes'][ $name ] );
							}
							Reviewed_Store::update_post_meta( $id, '_wp_attachment_backup_sizes', $backup );
							Reviewed_Store::wp_update_attachment_metadata( $id, $meta );
						}
						$done = wp_update_image_subsizes( $id );
						if ( is_wp_error( $done ) ) {
							$s['failed'][] = $id;
							continue;
						}
						++$s['pictures'];
						$s['made']   += count( $missing );
						$s['remade'] += count( $old );
					}
					if ( ! Repository::owns( $token, 'image_sizes' ) ) {
						throw new \RuntimeException( 'sizes_busy' );
					}
				}
				$s['failed']  = array_slice( array_values( array_unique( array_map( 'intval', $s['failed'] ) ) ), 0, 500 );
				$s['updated'] = time();
				if ( ! Reviewed_Store::update_option( self::OPTION, $s, false ) && self::state() !== $s ) {
					throw new \RuntimeException( 'sizes_storage' );
				}
				return $s;
			} finally {
				Repository::release( $token, 'image_sizes' );
			}
		} finally {
			Reviewed_Store::leave( $lock );
		}
	}

	/**
	 * Words for the check's error codes.
	 *
	 * @param string $code The code.
	 * @return string
	 */
	public static function human_error( string $code ): string {
		$messages = array(
			'sizes_access'  => __( 'Only an administrator who may upload files can make sizes.', 'affstackdev-image-manager' ),
			'sizes_busy'    => __( 'Sizes are being made already. Try again in a few minutes.', 'affstackdev-image-manager' ),
			'sizes_storage' => __( 'The progress could not be saved.', 'affstackdev-image-manager' ),
			'sizes_stale'   => __( 'There is nothing to continue. Start again.', 'affstackdev-image-manager' ),
		);
		return $messages[ $code ] ?? '';
	}
}