<?php
/**
 * Bulk Converter Class
 *
 * @package AHS_Image_To_WebP
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

class AHSITW_Bulk_Converter {

	/**
	 * Batch size for processing.
	 */
	const BATCH_SIZE = 10;

	/**
	 * Constructor.
	 */
	public function __construct() {
		add_action( 'wp_ajax_ahsitw_bulk_convert', array( $this, 'ajax_bulk_convert' ) );
	}

	/**
	 * AJAX handler for bulk conversion.
	 */
	public function ajax_bulk_convert() {
		// Security check: Nonce verification.
		check_ajax_referer( 'ahsitw_bulk_convert', 'nonce' );

		// Security check: Capability check.
		if ( ! current_user_can( 'manage_options' ) ) {
			wp_send_json_error( array( 'message' => __( 'Insufficient permissions.', 'ahs-image-to-webp-converter' ) ) );
		}

		$batch = isset( $_POST['batch'] ) ? absint( $_POST['batch'] ) : 0;
		$result = $this->process_batch( $batch );

		wp_send_json_success( $result );
	}

	/**
	 * Process a single batch of images.
	 *
	 * @param int $batch Current batch number.
	 * @return array
	 */
	private function process_batch( $batch ) {
		// Note: We always grab the next set of images that haven't been converted.
		$images = $this->get_unconverted_image_ids( 0, self::BATCH_SIZE );
		
		$results = array( 
			'converted' => 0, 
			'failed'    => 0, 
			'skipped'   => 0, 
			'logs'      => array() 
		);
		
		if ( empty( $images ) ) {
			$results['total']    = $this->get_total_unconverted_count();
			$results['has_more'] = false;
			return $results;
		}

		$converter = new AHSITW_Converter();
		
		foreach ( $images as $image_id ) {
			// Limit check before processing each image.
			if ( ! AHSITW_Limiter::can_convert() ) {
				$results['logs'][] = array(
					'message' => __( 'Conversion limit reached. Please upgrade to continue.', 'ahs-image-to-webp-converter' ),
					'type'    => 'error'
				);
				break;
			}

			// Use the centralized method to convert and update the attachment.
			if ( $converter->update_attachment_to_webp( $image_id ) ) {
				$results['converted']++;
				AHSITW_Limiter::increment();
			} else {
				$results['failed']++;
			}
		}

		$total = $this->get_total_unconverted_count();
		$results['total']    = $total;
		$results['has_more'] = $total > 0;
		
		return $results;
	}

	/**
	 * Get IDs of images that haven't been converted to WebP.
	 *
	 * @param int $offset (unused now for efficiency)
	 * @param int $limit
	 * @return array
	 */
	private function get_unconverted_image_ids( $offset, $limit ) {
		$args = array( 
			'post_type'      => 'attachment', 
			'post_mime_type' => array( 'image/jpeg', 'image/png' ), 
			'post_status'    => 'inherit', 
			'posts_per_page' => $limit,
			'fields'         => 'ids',
			'meta_query'     => array(
				array(
					'key'     => '_AHSITW_converted',
					'compare' => 'NOT EXISTS',
				),
			),
			'no_found_rows'  => true,
		);

		$query = new WP_Query( $args );
		return $query->posts;
	}

	/**
	 * Get total count of unconverted images (cached).
	 *
	 * @return int
	 */
	public function get_total_unconverted_count() {
		$args = array( 
			'post_type'      => 'attachment', 
			'post_mime_type' => array( 'image/jpeg', 'image/png' ), 
			'post_status'    => 'inherit', 
			'posts_per_page' => 1, 
			'fields'         => 'ids',
			'meta_query'     => array(
				array(
					'key'     => '_AHSITW_converted',
					'compare' => 'NOT EXISTS',
				),
			),
			'no_found_rows'  => false, // We need the total count.
		);
		
		$query = new WP_Query( $args );
		return absint( $query->found_posts );
	}

	/**
	 * Static helper to get total count.
	 *
	 * @return int
	 */
	public static function get_convertible_count() {
		$instance = new self();
		return $instance->get_total_unconverted_count();
	}
}