<?php
namespace Zadex\WooCommerce;

defined('ABSPATH') || exit;

use Zadex\Frontend\PostData;
use Zadex\Frontend\Renderer;
use Zadex\Theme\TemplatePost;

/**
 * The product a product widget renders.
 *
 * Order: the renderer's context post (single-product templates render with the product in the loop), the global
 * `$product`, the preview product of the theme template being edited (`previewPostId`: saved "Preview with" or the
 * latest product), and in the editor / REST previews the latest product so the widget never renders empty there.
 *
 * `with()` makes a product "the current one" for WooCommerce template functions (global `$post` + `$product`,
 * `setup_postdata`) and restores the previous globals afterwards.
 */
final class Product
{
    /** @return \WC_Product|null */
    public static function current(?Renderer $renderer = null): ?object
    {
        $context_id = $renderer ? (int) $renderer->context()->post_id : (function_exists('get_the_ID') ? (int) get_the_ID() : 0);
        $found = self::get($context_id);
        if ($found) {
            return $found;
        }
        $global = $GLOBALS['product'] ?? null;
        if (self::is_product($global)) {
            return $global;
        }
        if ($context_id > 0 && TemplatePost::is_template($context_id)) {
            $found = self::get(TemplatePost::preview_post($context_id));
            if ($found) {
                return $found;
            }
        }
        return self::previewing() ? self::latest() : null;
    }

    /** @return \WC_Product|null */
    public static function get(int $id): ?object
    {
        if ($id <= 0 || !function_exists('wc_get_product')) {
            return null;
        }
        $product = wc_get_product($id);
        return self::is_product($product) ? $product : null;
    }

    public static function is_product($value): bool
    {
        return is_object($value) && method_exists($value, 'get_id') && method_exists($value, 'get_type');
    }

    /** Editor requests: REST previews (POST /render) and the canvas page. */
    public static function previewing(): bool
    {
        return (defined('REST_REQUEST') && REST_REQUEST) || \Zadex\Editor\EditorLoader::mode() !== '';
    }

    /** @return \WC_Product|null */
    public static function latest(): ?object
    {
        if (!function_exists('get_posts')) {
            return null;
        }
        $ids = get_posts(['post_type' => 'product', 'post_status' => 'publish', 'numberposts' => 1, 'orderby' => 'date', 'order' => 'DESC', 'fields' => 'ids']);
        return $ids ? self::get((int) $ids[0]) : null;
    }

    /**
     * Runs $fn with $product as the global product / post and returns its output (echo or return value).
     *
     * @param \WC_Product $product
     */
    public static function with(object $product, callable $fn): string
    {
        $prev_product = $GLOBALS['product'] ?? null;
        $prev_product_id = self::is_product($prev_product) ? (int) $prev_product->get_id() : 0;
        $target = function_exists('get_post') ? get_post($product->get_id()) : null;
        // The product's post becomes the current post (PostData) and WooCommerce sets its global product itself.
        $returned = null;
        $echoed = (string) PostData::with($target, static function () use ($product, $target, $fn, &$returned): string {
            if ($target && function_exists('wc_setup_product_data')) {
                wc_setup_product_data($target);
            }
            ob_start();
            try {
                $returned = $fn($product);
            } finally {
                $echoed = (string) ob_get_clean();
            }
            return $echoed;
        });
        // Back to the product that was current before (or none): WooCommerce's own setup again.
        if (function_exists('wc_setup_product_data')) {
            wc_setup_product_data($prev_product_id > 0 ? $prev_product_id : 0);
        }
        return $echoed . (is_string($returned) ? $returned : '');
    }

    /** Editor-only placeholder shown when no product can be found. */
    public static function placeholder(string $attrs): string
    {
        if (!self::previewing()) {
            return '';
        }
        return '<div ' . $attrs . '><p class="zx-woo-placeholder">' . esc_html__('No product to preview. Publish a product or choose one in "Preview with".', 'zadex') . '</p></div>';
    }

    /** Adds WooCommerce's `woocommerce` class to a widget root so its base styles apply outside shop pages. */
    public static function woo_attrs(string $attrs): string
    {
        return preg_replace('/\bclass="/', 'class="woocommerce ', $attrs, 1) ?? $attrs;
    }
}