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

/**
 * Injects each variation's gallery into the variation JSON WooCommerce sends
 * to the browser, pre-rendering the gallery slide HTML with WooCommerce's
 * own wc_get_gallery_image_html() so the markup matches whatever the
 * installed WooCommerce/theme version expects. The frontend script swaps
 * that HTML into the native `.woocommerce-product-gallery__wrapper` and
 * re-runs WooCommerce's own gallery init ($.fn.wc_product_gallery) — the
 * same mechanism WooCommerce itself uses — instead of hand-building a
 * competing gallery UI.
 */
class WCVG_Frontend {

	private static $instance = null;

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

	private function __construct() {
		add_filter( 'woocommerce_available_variation', array( $this, 'add_gallery_to_variation_data' ), 10, 3 );
		add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_assets' ) );
	}

	public function enqueue_assets() {
		if ( ! function_exists( 'is_product' ) || ! is_product() ) {
			return;
		}

		// Don't rely on the $product global here: wp_enqueue_scripts fires
		// before WooCommerce's main loop sets it up on many themes/builders
		// (including Elementor's Theme Builder single product templates),
		// so it can be empty even on a real product page. Look it up from
		// the queried post instead, which is reliable at this point.
		$post_id = get_queried_object_id();
		$product = $post_id ? wc_get_product( $post_id ) : false;

		if ( ! $product || ! $product->is_type( 'variable' ) ) {
			return;
		}

		wp_enqueue_script( 'wcvg-frontend', WCVG_PLUGIN_URL . 'assets/js/wcvg-frontend.js', array( 'jquery', 'wc-single-product' ), WCVG_VERSION, true );
	}

	public function add_gallery_to_variation_data( $data, $product, $variation ) {
		$gallery_raw = $variation->get_meta( '_wcvg_gallery_ids' );

		if ( ! $gallery_raw || ! function_exists( 'wc_get_gallery_image_html' ) ) {
			$data['wcvg_gallery_html']   = '';
			$data['wcvg_gallery_images'] = array();
			return $data;
		}

		$ids    = array_filter( array_map( 'absint', explode( ',', $gallery_raw ) ) );
		$html   = '';
		$images = array();

		foreach ( $ids as $index => $id ) {
			if ( ! wp_attachment_is_image( $id ) ) {
				continue;
			}
			// wc_get_gallery_image_html() is WooCommerce's own template
			// function (used to build the product's default gallery) — using
			// it here guarantees our markup, classes and data attributes
			// (data-large_image, data-large_image_width/height, etc.) match
			// exactly what the installed WooCommerce version and its zoom /
			// slider scripts expect, instead of us guessing at the structure
			// by hand and drifting out of sync on a future WooCommerce update.
			$html .= wc_get_gallery_image_html( $id, 0 === $index );

			// Themes that replace the native gallery entirely (WoodMart,
			// Woostify, and others) don't understand the markup above at
			// all — they never render a `.woocommerce-product-gallery`
			// element for us to swap HTML into in the first place. For
			// those, the frontend script needs the raw image data instead
			// so it can build each theme's own expected markup itself.
			// Kept as a plain array (not HTML) so it's safe/reusable
			// regardless of which theme-specific integration consumes it.
			$full  = wp_get_attachment_image_src( $id, 'full' );
			$large = wp_get_attachment_image_src( $id, 'woocommerce_single' );
			$thumb = wp_get_attachment_image_src( $id, 'woocommerce_gallery_thumbnail' );

			$images[] = array(
				'id'     => $id,
				'full'   => $full ? $full[0] : '',
				'full_w' => $full ? $full[1] : 0,
				'full_h' => $full ? $full[2] : 0,
				'src'    => $large ? $large[0] : ( $full ? $full[0] : '' ),
				'w'      => $large ? $large[1] : 0,
				'h'      => $large ? $large[2] : 0,
				'srcset' => wp_get_attachment_image_srcset( $id, 'woocommerce_single' ),
				'sizes'  => wp_get_attachment_image_sizes( $id, 'woocommerce_single' ),
				'thumb'  => $thumb ? $thumb[0] : ( $large ? $large[0] : '' ),
				'alt'    => get_post_meta( $id, '_wp_attachment_image_alt', true ),
			);
		}

		$data['wcvg_gallery_html']   = $html;
		$data['wcvg_gallery_images'] = $images;
		return $data;
	}
}