<?php
/**
 * Scanning service.
 *
 * @package AdbearImageCleaner
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Scanner class.
 */
class Adbear_Image_Cleaner_Scanner {

	/**
	 * Transient key for current scan results.
	 */
	const RESULTS_TRANSIENT_KEY = 'adbear_image_cleaner_scan_results';

	/**
	 * Constructor.
	 */
	public function __construct() {
		add_action( 'wp_ajax_adbear_scan_start', array( $this, 'ajax_scan_start' ) );
		add_action( 'wp_ajax_adbear_scan_batch', array( $this, 'ajax_scan_batch' ) );
		add_action( 'wp_ajax_adbear_get_unused_results', array( $this, 'ajax_get_unused_results' ) );
	}

	/**
	 * Reset previous scan cache.
	 *
	 * @return void
	 */
	public function ajax_scan_start() {
		$this->ensure_permissions();
		check_ajax_referer( 'adbear_scan_nonce', 'nonce' );

		set_transient( self::RESULTS_TRANSIENT_KEY, array(), DAY_IN_SECONDS );

		wp_send_json_success(
			array(
				'message' => __( 'Scan initialized.', 'adbear-image-cleaner' ),
			)
		);
	}

	/**
	 * Process one scan batch.
	 *
	 * @return void
	 */
	public function ajax_scan_batch() {
		$this->ensure_permissions();
		check_ajax_referer( 'adbear_scan_nonce', 'nonce' );

		$offset = isset( $_POST['offset'] ) ? absint( wp_unslash( $_POST['offset'] ) ) : 0;
		$limit  = isset( $_POST['limit'] ) ? absint( wp_unslash( $_POST['limit'] ) ) : 25;
		$limit  = max( 1, min( 100, $limit ) );

		$query = new WP_Query(
			array(
				'post_type'      => 'attachment',
				'post_status'    => 'inherit',
				'post_mime_type' => Adbear_Image_Cleaner_Helpers::get_supported_mimes(),
				'posts_per_page' => $limit,
				'offset'         => $offset,
				'orderby'        => 'ID',
				'order'          => 'ASC',
				'fields'         => 'ids',
				'no_found_rows'  => false,
			)
		);

		$batch_results = array();
		foreach ( $query->posts as $attachment_id ) {
			$batch_results[] = $this->analyze_attachment( (int) $attachment_id );
		}

		$results = get_transient( self::RESULTS_TRANSIENT_KEY );
		if ( ! is_array( $results ) ) {
			$results = array();
		}

		$results = array_merge( $results, $batch_results );
		set_transient( self::RESULTS_TRANSIENT_KEY, $results, DAY_IN_SECONDS );

		$processed = $offset + count( $query->posts );
		$total     = (int) $query->found_posts;
		$complete  = $processed >= $total;

		wp_send_json_success(
			array(
				'processed' => $processed,
				'total'     => $total,
				'complete'  => $complete,
			)
		);
	}

	/**
	 * Return current unused row set for live table refresh.
	 *
	 * @return void
	 */
	public function ajax_get_unused_results() {
		$this->ensure_permissions();
		check_ajax_referer( 'adbear_scan_nonce', 'nonce' );

		$rows = $this->get_unused_results();

		$rows = array_map(
			static function ( $row ) {
				$row['file_size_human'] = Adbear_Image_Cleaner_Helpers::format_bytes( isset( $row['file_size'] ) ? (int) $row['file_size'] : 0 );
				return $row;
			},
			$rows
		);

		wp_send_json_success(
			array(
				'rows' => $rows,
			)
		);
	}

	/**
	 * Return only unused/broken entries.
	 *
	 * @return array<int, array<string, mixed>>
	 */
	public function get_unused_results() {
		$results = get_transient( self::RESULTS_TRANSIENT_KEY );
		if ( ! is_array( $results ) ) {
			return array();
		}

		return array_values(
			array_filter(
				$results,
				static function ( $item ) {
					return isset( $item['status'] ) && in_array( $item['status'], Adbear_Image_Cleaner_Helpers::get_deletable_statuses(), true );
				}
			)
		);
	}

	/**
	 * Analyze one attachment usage status.
	 *
	 * @param int $attachment_id Attachment ID.
	 * @return array<string, mixed>
	 */
	private function analyze_attachment( $attachment_id ) {
		$url          = (string) wp_get_attachment_url( $attachment_id );
		$file_path    = (string) get_attached_file( $attachment_id );
		$file_name    = wp_basename( $file_path ? $file_path : $url );
		$upload_date  = get_the_date( 'Y-m-d H:i:s', $attachment_id );
		$file_exists  = $file_path && file_exists( $file_path );
		$file_size    = $file_exists ? filesize( $file_path ) : 0;
		$status       = 'unused';
		$status_label = __( 'Unused', 'adbear-image-cleaner' );

		if ( ! $file_exists ) {
			$status       = 'broken';
			$status_label = __( 'Broken file', 'adbear-image-cleaner' );
		} elseif (
			$this->is_used_in_content( $attachment_id, $url, $file_name ) ||
			$this->is_featured_image( $attachment_id ) ||
			$this->is_used_in_woocommerce( $attachment_id ) ||
			$this->is_used_in_acf_meta( $attachment_id, $url ) ||
			$this->is_used_in_postmeta( $attachment_id, $url, $file_name ) ||
			$this->is_used_in_options( $attachment_id, $url, $file_name ) ||
			$this->is_used_in_theme_mods( $attachment_id, $url, $file_name ) ||
			$this->is_site_identity_image( $attachment_id )
		) {
			$status       = 'in_use';
			$status_label = __( 'In use', 'adbear-image-cleaner' );
		}

		return array(
			'id'          => $attachment_id,
			'file_name'   => $file_name,
			'file_path'   => $file_path,
			'file_size'   => (int) $file_size,
			'upload_date' => $upload_date ? $upload_date : '',
			'status'      => $status,
			'status_text' => $status_label,
		);
	}

	/**
	 * Check if used in post content.
	 *
	 * @param int    $attachment_id Attachment ID.
	 * @param string $url Attachment URL.
	 * @param string $file_name File basename.
	 * @return bool
	 */
	private function is_used_in_content( $attachment_id, $url, $file_name ) {
		$identifiers   = $this->get_attachment_asset_identifiers( $attachment_id, $url, $file_name );
		$identifiers[] = 'wp-image-' . $attachment_id;
		$identifiers[] = '[gallery ids="' . $attachment_id;
		$identifiers   = array_values( array_unique( array_filter( $identifiers ) ) );

		foreach ( $identifiers as $identifier ) {
			$results = get_posts(
				array(
					'post_type'              => 'any',
					'post_status'            => 'any',
					's'                      => $identifier,
					'posts_per_page'         => 1,
					'fields'                 => 'ids',
					'update_post_meta_cache' => false,
					'update_post_term_cache' => false,
				)
			);

			if ( ! empty( $results ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Get possible image references that may appear in content.
	 *
	 * @param int    $attachment_id Attachment ID.
	 * @param string $url Attachment URL.
	 * @param string $file_name Original file name.
	 * @return string[]
	 */
	private function get_attachment_asset_identifiers( $attachment_id, $url, $file_name ) {
		$identifiers = array();

		if ( ! empty( $url ) ) {
			$identifiers[] = $url;

			$path = wp_parse_url( $url, PHP_URL_PATH );
			if ( is_string( $path ) && '' !== $path ) {
				$identifiers[] = $path;
			}
		}

		if ( ! empty( $file_name ) ) {
			$identifiers[] = $file_name;
		}

		$metadata = wp_get_attachment_metadata( $attachment_id );
		if ( is_array( $metadata ) ) {
			if ( isset( $metadata['file'] ) && is_string( $metadata['file'] ) ) {
				$identifiers[] = wp_basename( $metadata['file'] );
			}

			if ( isset( $metadata['sizes'] ) && is_array( $metadata['sizes'] ) ) {
				foreach ( $metadata['sizes'] as $size_data ) {
					if ( isset( $size_data['file'] ) && is_string( $size_data['file'] ) ) {
						$identifiers[] = $size_data['file'];
					}
				}
			}
		}

		return array_values( array_unique( array_filter( $identifiers ) ) );
	}

	/**
	 * Check featured image relation.
	 *
	 * @param int $attachment_id Attachment ID.
	 * @return bool
	 */
	private function is_featured_image( $attachment_id ) {
		$results = get_posts(
			array(
				'post_type'              => 'any',
				'post_status'            => 'any',
				'posts_per_page'         => 1,
				'fields'                 => 'ids',
				'meta_key'               => '_thumbnail_id',
				'meta_value'             => (string) $attachment_id,
				'update_post_meta_cache' => false,
				'update_post_term_cache' => false,
			)
		);

		return ! empty( $results );
	}

	/**
	 * Check WooCommerce product image usage.
	 *
	 * @param int $attachment_id Attachment ID.
	 * @return bool
	 */
	private function is_used_in_woocommerce( $attachment_id ) {
		$thumb_posts = get_posts(
			array(
				'post_type'              => 'product',
				'post_status'            => 'any',
				'posts_per_page'         => 1,
				'fields'                 => 'ids',
				'meta_key'               => '_thumbnail_id',
				'meta_value'             => (string) $attachment_id,
				'update_post_meta_cache' => false,
				'update_post_term_cache' => false,
			)
		);

		if ( ! empty( $thumb_posts ) ) {
			return true;
		}

		$gallery_posts = get_posts(
			array(
				'post_type'              => 'product',
				'post_status'            => 'any',
				'posts_per_page'         => 1,
				'fields'                 => 'ids',
				'meta_query'             => array(
					array(
						'key'     => '_product_image_gallery',
						'value'   => '"' . $attachment_id . '"',
						'compare' => 'LIKE',
					),
				),
				'update_post_meta_cache' => false,
				'update_post_term_cache' => false,
			)
		);

		if ( ! empty( $gallery_posts ) ) {
			return true;
		}

		$gallery_posts = get_posts(
			array(
				'post_type'              => 'product',
				'post_status'            => 'any',
				'posts_per_page'         => 1,
				'fields'                 => 'ids',
				'meta_query'             => array(
					array(
						'key'     => '_product_image_gallery',
						'value'   => (string) $attachment_id,
						'compare' => 'LIKE',
					),
				),
				'update_post_meta_cache' => false,
				'update_post_term_cache' => false,
			)
		);

		return ! empty( $gallery_posts );
	}

	/**
	 * Check attachment usage in ACF-like image meta values.
	 *
	 * @param int    $attachment_id Attachment ID.
	 * @param string $url Attachment URL.
	 * @return bool
	 */
	private function is_used_in_acf_meta( $attachment_id, $url ) {
		$id_string = (string) $attachment_id;
		$checks    = array( $id_string );
		$meta_keys = array(
			'image',
			'images',
			'gallery',
			'thumbnail',
			'hero_image',
			'banner_image',
			'logo',
			'icon',
			'media',
		);

		if ( ! empty( $url ) ) {
			$checks[] = $url;
		}

		foreach ( $meta_keys as $meta_key ) {
			foreach ( $checks as $check_value ) {
				$posts = get_posts(
					array(
						'post_type'              => 'any',
						'post_status'            => 'any',
						'posts_per_page'         => 1,
						'fields'                 => 'ids',
						'meta_query'             => array(
							array(
								'key'     => $meta_key,
								'value'   => $check_value,
								'compare' => 'LIKE',
							),
						),
						'update_post_meta_cache' => false,
						'update_post_term_cache' => false,
					)
				);

				if ( ! empty( $posts ) ) {
					return true;
				}
			}
		}

		return false;
	}

	/**
	 * Check usage in postmeta values (Elementor/builders/custom meta).
	 *
	 * @param int    $attachment_id Attachment ID.
	 * @param string $url Attachment URL.
	 * @param string $file_name Original file name.
	 * @return bool
	 */
	private function is_used_in_postmeta( $attachment_id, $url, $file_name ) {
		$asset_identifiers = $this->get_attachment_asset_identifiers( $attachment_id, $url, $file_name );
		$asset_identifiers[] = (string) $attachment_id;
		$asset_identifiers   = array_values( array_unique( array_filter( $asset_identifiers ) ) );
		$meta_keys           = array(
			'_thumbnail_id',
			'_product_image_gallery',
			'logo',
			'image',
			'images',
			'gallery',
			'hero_image',
			'banner_image',
			'icon',
			'media',
			'_elementor_data',
		);

		foreach ( $meta_keys as $meta_key ) {
			foreach ( $asset_identifiers as $identifier ) {
				$posts = get_posts(
					array(
						'post_type'              => 'any',
						'post_status'            => 'any',
						'posts_per_page'         => 1,
						'fields'                 => 'ids',
						'meta_query'             => array(
							array(
								'key'     => $meta_key,
								'value'   => $identifier,
								'compare' => 'LIKE',
							),
						),
						'update_post_meta_cache' => false,
						'update_post_term_cache' => false,
					)
				);

				if ( ! empty( $posts ) ) {
					return true;
				}
			}
		}

		return false;
	}

	/**
	 * Check usage in wp_options values.
	 *
	 * @param int    $attachment_id Attachment ID.
	 * @param string $url Attachment URL.
	 * @param string $file_name Original file name.
	 * @return bool
	 */
	private function is_used_in_options( $attachment_id, $url, $file_name ) {
		$asset_identifiers = $this->get_attachment_asset_identifiers( $attachment_id, $url, $file_name );
		$asset_identifiers[] = (string) $attachment_id;
		$asset_identifiers   = array_values( array_unique( array_filter( $asset_identifiers ) ) );

		$option_names = array(
			'theme_mods_' . get_option( 'stylesheet' ),
			'theme_mods_' . get_option( 'template' ),
			'custom_logo',
			'site_icon',
			'elementor_active_kit',
		);

		foreach ( $option_names as $option_name ) {
			$option_value = get_option( $option_name );
			if ( $this->array_contains_attachment_reference( $option_value, $asset_identifiers, $attachment_id ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Check known site identity image relations.
	 *
	 * @param int $attachment_id Attachment ID.
	 * @return bool
	 */
	private function is_site_identity_image( $attachment_id ) {
		$custom_logo_id = (int) get_theme_mod( 'custom_logo' );
		$site_icon_id   = (int) get_option( 'site_icon' );

		return ( $custom_logo_id > 0 && $custom_logo_id === $attachment_id ) ||
			( $site_icon_id > 0 && $site_icon_id === $attachment_id );
	}

	/**
	 * Check usage in Customizer theme mods.
	 *
	 * @param int    $attachment_id Attachment ID.
	 * @param string $url Attachment URL.
	 * @param string $file_name Original file name.
	 * @return bool
	 */
	private function is_used_in_theme_mods( $attachment_id, $url, $file_name ) {
		$theme_mods = get_theme_mods();
		if ( ! is_array( $theme_mods ) || empty( $theme_mods ) ) {
			return false;
		}

		$identifiers = $this->get_attachment_asset_identifiers( $attachment_id, $url, $file_name );
		$identifiers = array_values( array_unique( array_filter( $identifiers ) ) );

		return $this->array_contains_attachment_reference( $theme_mods, $identifiers, $attachment_id );
	}

	/**
	 * Recursively inspect array values for attachment references.
	 *
	 * @param mixed    $value Data tree.
	 * @param string[] $identifiers Known URL/path/file/id string identifiers.
	 * @param int      $attachment_id Attachment ID.
	 * @return bool
	 */
	private function array_contains_attachment_reference( $value, array $identifiers, $attachment_id ) {
		if ( is_array( $value ) ) {
			foreach ( $value as $nested ) {
				if ( $this->array_contains_attachment_reference( $nested, $identifiers, $attachment_id ) ) {
					return true;
				}
			}

			return false;
		}

		if ( is_numeric( $value ) && (int) $value === $attachment_id ) {
			return true;
		}

		if ( is_string( $value ) && '' !== $value ) {
			foreach ( $identifiers as $identifier ) {
				if ( '' !== $identifier && false !== strpos( $value, $identifier ) ) {
					return true;
				}
			}
		}

		return false;
	}

	/**
	 * Ensure user permissions.
	 *
	 * @return void
	 */
	private function ensure_permissions() {
		if ( ! current_user_can( 'manage_options' ) ) {
			wp_send_json_error(
				array(
					'message' => __( 'You are not allowed to perform this action.', 'adbear-image-cleaner' ),
				),
				403
			);
		}
	}
}