<?php
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Adds the "Sync Variation Images" button to the Variations tab and handles
 * the AJAX call that copies each term's image + gallery onto matching variations.
 */
class WCVG_Sync {

	private static $instance = null;

	public static function instance() {
		if ( null === self::$instance ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	private function __construct() {
		add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_assets' ) );
		add_action( 'wp_ajax_wcvg_sync_variations', array( $this, 'ajax_sync_variations' ) );
	}

	public function enqueue_assets( $hook ) {
		global $post;

		if ( 'post.php' !== $hook && 'post-new.php' !== $hook ) {
			return;
		}
		if ( ! $post || 'product' !== $post->post_type ) {
			return;
		}

		wp_enqueue_script( 'wcvg-sync', WCVG_PLUGIN_URL . 'assets/js/wcvg-sync.js', array( 'jquery' ), WCVG_VERSION, true );
		wp_localize_script(
			'wcvg-sync',
			'WCVG_Sync',
			array(
				'ajaxUrl'    => admin_url( 'admin-ajax.php' ),
				'nonce'      => wp_create_nonce( 'wcvg_sync_nonce' ),
				'productId'  => $post->ID,
				'label'      => __( 'Sync Variation Images', 'addonn-attribute-image-gallery-woocommerce' ),
				'working'    => __( 'Syncing...', 'addonn-attribute-image-gallery-woocommerce' ),
				'noAttr'     => __( 'Set a primary attribute first under WooCommerce > Variation Gallery.', 'addonn-attribute-image-gallery-woocommerce' ),
				'hasPrimary' => (bool) WCVG_Settings::get_primary_attribute(),
			)
		);
	}

	public function ajax_sync_variations() {
		check_ajax_referer( 'wcvg_sync_nonce', 'nonce' );

		if ( ! current_user_can( 'edit_products' ) ) {
			wp_send_json_error( array( 'message' => __( 'Permission denied.', 'addonn-attribute-image-gallery-woocommerce' ) ) );
		}

		$product_id = isset( $_POST['product_id'] ) ? absint( $_POST['product_id'] ) : 0;
		$taxonomy   = WCVG_Settings::get_primary_attribute();

		if ( ! $product_id || ! $taxonomy ) {
			wp_send_json_error( array( 'message' => __( 'Missing product or primary attribute.', 'addonn-attribute-image-gallery-woocommerce' ) ) );
		}

		$product = wc_get_product( $product_id );
		if ( ! $product || ! $product->is_type( 'variable' ) ) {
			wp_send_json_error( array( 'message' => __( 'Not a variable product.', 'addonn-attribute-image-gallery-woocommerce' ) ) );
		}

		$updated = 0;
		$skipped = 0;
		$map     = WCVG_Product_Fields::get_product_map( $product_id );

		foreach ( $product->get_children() as $variation_id ) {
			$variation = wc_get_product( $variation_id );
			if ( ! $variation ) {
				continue;
			}

			$variation_attributes = $variation->get_attributes();
			$term_slug             = isset( $variation_attributes[ $taxonomy ] ) ? $variation_attributes[ $taxonomy ] : '';

			if ( ! $term_slug ) {
				$skipped++;
				continue;
			}

			$term = get_term_by( 'slug', $term_slug, $taxonomy );
			if ( ! $term || is_wp_error( $term ) || ! isset( $map[ $term->term_id ] ) ) {
				$skipped++;
				continue;
			}

			$image_id    = isset( $map[ $term->term_id ]['image_id'] ) ? (int) $map[ $term->term_id ]['image_id'] : 0;
			$gallery_ids = isset( $map[ $term->term_id ]['gallery_ids'] ) ? array_filter( array_map( 'absint', (array) $map[ $term->term_id ]['gallery_ids'] ) ) : array();

			if ( $image_id ) {
				$variation->set_image_id( $image_id );
			}

			// The frontend gallery swap (class-wcvg-frontend.php) rebuilds the
			// whole slider from this single meta value, replacing the native
			// gallery entirely rather than appending to it. It previously held
			// only the secondary gallery images, never the main "Select image"
			// set above — so the main photo was set as the variation's native
			// WooCommerce thumbnail (used by cart/listing pages) but silently
			// dropped from the swapped-in slider itself, which then opened on
			// the first secondary image instead of the intended main photo.
			// Storing the main image first, followed by the gallery images
			// (skipping it again if it was also added to the gallery by
			// mistake), keeps the two in sync.
			$full_gallery_ids = array();
			if ( $image_id ) {
				$full_gallery_ids[] = $image_id;
			}
			foreach ( $gallery_ids as $gallery_image_id ) {
				if ( ! in_array( $gallery_image_id, $full_gallery_ids, true ) ) {
					$full_gallery_ids[] = $gallery_image_id;
				}
			}

			$variation->update_meta_data( '_wcvg_gallery_ids', implode( ',', $full_gallery_ids ) );
			$variation->save();
			$updated++;
		}

		wp_send_json_success(
			array(
				'updated' => $updated,
				'skipped' => $skipped,
				'message' => sprintf(
					/* translators: 1: updated count 2: skipped count */
					__( '%1$d variation(s) updated, %2$d skipped (no image set for that value on this product).', 'addonn-attribute-image-gallery-woocommerce' ),
					$updated,
					$skipped
				),
			)
		);
	}
}