' . esc_html( get_bloginfo( 'name' ) ) . '

<?php
namespace TDL_GMC_Lite;

use WC_Product;
use WC_Product_Variable;
use WC_Product_Variation;

if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

class Feed {
    private static $instance = null;
    private $stats = [];

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

    public function get_stats(): array {
        return $this->stats;
    }

    private function reset_stats(): void {
        $this->stats = [
            'candidates' => 0,
            'included'   => 0,
            'skipped'    => 0,
            'reasons'    => [],
        ];
    }

    private function mark_candidate(): void {
        $this->stats['candidates']++;
    }

    private function mark_included(): void {
        $this->stats['included']++;
    }

    private function mark_skipped( string $reason ): void {
        $this->stats['skipped']++;
        if ( ! isset( $this->stats['reasons'][ $reason ] ) ) {
            $this->stats['reasons'][ $reason ] = 0;
        }
        $this->stats['reasons'][ $reason ]++;
    }

    private function clean_xml_text( string $text ): string {
        $text = str_replace( [ '&nbsp;', "\xC2\xA0" ], ' ', $text );
        $text = html_entity_decode( $text, ENT_QUOTES | ENT_XML1, 'UTF-8' );
        return $text;
    }

    private function clean_title( string $title ): string {
        $title = $this->clean_xml_text( wp_strip_all_tags( $title, true ) );
        $title = (string) preg_replace( '/\s+/u', ' ', $title );
        return limit_text( trim( $title ), 150 );
    }

    public function output(): void {
        $this->reset_stats();
        add_filter( 'doing_it_wrong_trigger_error', '__return_false' );

        header( 'Content-Type: application/xml; charset=utf-8' );
        echo '<?xml version="1.0" encoding="UTF-8"?>' . "\n";
        echo '<rss xmlns:g="http://base.google.com/ns/1.0" version="2.0">' . "\n";
        echo "<channel>\n";
        echo '<title>' . esc_html( get_bloginfo( 'name' ) ) . ' – Google Merchant Feed</title>' . "\n";
        echo '<link>' . esc_url( home_url( '/' ) ) . "</link>\n";
        $description = trim( (string) get_option( 'tdl_gmc_feed_channel_description', '' ) );
        if ( $description === '' ) $description = 'WooCommerce product feed';
        echo '<description>' . esc_html( $description ) . "</description>\n";

        $this->loop_products();

        echo "</channel>\n</rss>";
        remove_filter( 'doing_it_wrong_trigger_error', '__return_false' );
    }

    private function loop_products(): void {
        $paged = 1;
        do {
            $query = new \WP_Query( [
                'post_type'      => 'product',
                'post_status'    => 'publish',
                'posts_per_page' => 500,
                'paged'          => $paged,
                'no_found_rows'  => true,
                'fields'         => 'ids',
            ] );
            if ( ! $query->have_posts() ) break;
            foreach ( $query->posts as $product_id ) {
                $product = wc_get_product( $product_id );
                if ( ! $product instanceof WC_Product ) continue;
                $this->emit_product( $product );
            }
            $paged++;
            wp_reset_postdata();
        } while ( true );
    }

    private function emit_product( WC_Product $product ): void {
        if ( $product instanceof WC_Product_Variable || $product->is_type( 'variable' ) ) {
            foreach ( $product->get_children() as $variation_id ) {
                $this->mark_candidate();
                $variation = wc_get_product( $variation_id );
                if ( ! $variation instanceof WC_Product_Variation ) {
                    $this->mark_skipped( 'invalid_variation' );
                    continue;
                }
                if ( method_exists( $variation, 'get_status' ) && $variation->get_status() !== 'publish' ) {
                    $this->mark_skipped( 'not_published' );
                    continue;
                }
                if ( ! $variation->is_purchasable() ) {
                    $this->mark_skipped( 'not_purchasable' );
                    continue;
                }
                $this->emit_item( $product, $variation );
            }
            return;
        }

        $this->mark_candidate();
        if ( ! $product->is_purchasable() ) {
            $this->mark_skipped( 'not_purchasable' );
            return;
        }
        $this->emit_item( $product, null );
    }

    private function emit_item( WC_Product $product, ?WC_Product_Variation $variation ): void {
        if ( function_exists( 'TDL_GMC_Lite\\tdl_gmc_filter_result' ) ) {
            $filter = tdl_gmc_filter_result( $product, $variation );
            if ( empty( $filter['pass'] ) ) {
                $this->mark_skipped( ! empty( $filter['reason'] ) ? (string) $filter['reason'] : 'custom_filter' );
                return;
            }
        } elseif ( function_exists( 'TDL_GMC_Lite\\tdl_gmc_passes_filters' ) && ! tdl_gmc_passes_filters( $product, $variation ) ) {
            $this->mark_skipped( 'custom_filter' );
            return;
        }

        $subject = $variation ?: $product;
        $title = $this->resolve_title( $product, $variation );
        $description = $this->compose_description( $product, $variation );
        $price = $this->price_str( $subject );
        if ( $title === '' ) {
            $this->mark_skipped( 'missing_title' );
            return;
        }
        if ( $price === '' ) {
            $this->mark_skipped( 'missing_price' );
            return;
        }

        $image = $this->image_url( $product, $variation );
        // Google Merchant requires a main image for every product. Do not emit an item
        // that Google would reject immediately.
        if ( $image === '' ) {
            $this->mark_skipped( 'missing_image' );
            return;
        }

        [ $identifier_exists, $gtin, $mpn, $brand ] = identifier_block( $product, $variation );
        [ $unit_measure, $unit_base ] = derive_unit_measures( $product, $variation );

        echo "  <item>\n";
        echo '    <g:id>' . esc_html( $this->compose_item_id( $product, $variation ) ) . "</g:id>\n";
        echo '    <title>' . esc_html( $title ) . "</title>\n";
        echo '    <description>' . esc_html( $description ) . "</description>\n";
        echo '    <link>' . esc_url( product_variant_url( $product, $variation ) ) . "</link>\n";
        echo '    <g:image_link>' . esc_url( $image ) . "</g:image_link>\n";
        foreach ( $this->additional_images( $product, $variation ) as $img ) {
            echo '    <g:additional_image_link>' . esc_url( $img ) . "</g:additional_image_link>\n";
        }
        echo '    <g:availability>' . esc_html( $this->availability( $product, $variation ) ) . "</g:availability>\n";
        echo "    <g:condition>new</g:condition>\n";
        echo '    <g:price>' . esc_html( $price ) . "</g:price>\n";
        if ( $brand !== '' ) echo '    <g:brand>' . esc_html( limit_text( $brand, 70 ) ) . "</g:brand>\n";
        if ( $gtin !== '' ) echo '    <g:gtin>' . esc_html( $gtin ) . "</g:gtin>\n";
        if ( $mpn !== '' ) echo '    <g:mpn>' . esc_html( $mpn ) . "</g:mpn>\n";
        echo '    <g:identifier_exists>' . esc_html( $identifier_exists ) . "</g:identifier_exists>\n";
        if ( $variation instanceof WC_Product_Variation ) {
            $group_id = $product->get_sku() ?: 'GID-' . $product->get_id();
            echo '    <g:item_group_id>' . esc_html( $group_id ) . "</g:item_group_id>\n";
        }
        $product_type = $this->product_breadcrumb( $product );
        if ( $product_type !== '' ) echo '    <g:product_type>' . esc_html( $product_type ) . "</g:product_type>\n";
        $gpc = map_google_category( $product );
        if ( $gpc !== '' ) echo '    <g:google_product_category>' . esc_html( $gpc ) . "</g:google_product_category>\n";
        if ( $unit_measure !== '' ) echo '    <g:unit_pricing_measure>' . esc_html( $unit_measure ) . "</g:unit_pricing_measure>\n";
        if ( $unit_base !== '' ) echo '    <g:unit_pricing_base_measure>' . esc_html( $unit_base ) . "</g:unit_pricing_base_measure>\n";

        echo "  </item>\n";
        $this->mark_included();
    }

    private function resolve_title( WC_Product $product, ?WC_Product_Variation $variation ): string {
        if ( $variation instanceof WC_Product_Variation ) {
            $manual_variation = trim( (string) get_post_meta( $variation->get_id(), '_google_title_variation', true ) );
            if ( $manual_variation !== '' ) return $this->clean_title( $manual_variation );
        }

        $manual_product = trim( (string) get_post_meta( $product->get_id(), '_google_title', true ) );
        if ( $manual_product !== '' ) {
            $title = $this->clean_title( $manual_product );
            return $variation ? $this->title_with_variation_attributes( $title, $variation ) : $title;
        }

        $title = $this->clean_title( (string) ( $variation ?: $product )->get_name() );
        return $variation ? $this->title_with_variation_attributes( $title, $variation ) : $title;
    }

    private function title_with_variation_attributes( string $title, WC_Product_Variation $variation ): string {
        $attrs = method_exists( $variation, 'get_variation_attributes' ) ? $variation->get_variation_attributes() : $variation->get_attributes();
        if ( ! is_array( $attrs ) || ! $attrs ) return $title;

        $missing = [];
        $title_norm = strtolower( remove_accents( $title ) );
        foreach ( $attrs as $key => $value ) {
            if ( $value === '' || $value === null ) continue;
            $taxonomy = (string) preg_replace( '/^attribute_/', '', (string) $key );
            $label = (string) $value;
            if ( taxonomy_exists( $taxonomy ) ) {
                $term = get_term_by( 'slug', (string) $value, $taxonomy );
                if ( $term && ! is_wp_error( $term ) && isset( $term->name ) ) $label = (string) $term->name;
            }
            $label = $this->clean_title( rawurldecode( $label ) );
            if ( $label === '' ) continue;
            $label_norm = strtolower( remove_accents( $label ) );
            if ( strpos( $title_norm, $label_norm ) === false ) $missing[] = $label;
        }
        $missing = array_values( array_unique( $missing ) );
        if ( ! $missing ) return $title;
        return limit_text( $title . ' - ' . implode( ' / ', $missing ), 150 );
    }

    private function compose_item_id( WC_Product $product, ?WC_Product_Variation $variation ): string {
        $sku = trim( (string) ( $variation ?: $product )->get_sku() );
        if ( $sku !== '' ) return $sku;
        return $variation ? $product->get_id() . '-' . $variation->get_id() : (string) $product->get_id();
    }

    private function compose_description( WC_Product $product, ?WC_Product_Variation $variation ): string {
        $candidates = [];
        if ( $variation instanceof WC_Product_Variation ) $candidates[] = (string) $variation->get_description();
        $candidates[] = (string) $product->get_short_description();
        $candidates[] = (string) $product->get_description();
        $candidates[] = (string) $product->get_name();

        foreach ( $candidates as $desc ) {
            if ( trim( $desc ) === '' ) continue;
            $desc = $this->clean_xml_text( $desc );
            $desc = (string) preg_replace( '/<\s*(br|\/p|\/div|\/li|\/h[1-6])\b[^>]*>/iu', ' ', $desc );
            $desc = wp_strip_all_tags( $desc );
            $desc = trim( (string) preg_replace( '/\s+/u', ' ', $desc ) );
            if ( $desc !== '' ) return limit_text( $desc, 5000 );
        }
        return '';
    }

    private function image_url( WC_Product $product, ?WC_Product_Variation $variation ): string {
        $image_ids = [];
        if ( $variation instanceof WC_Product_Variation && $variation->get_image_id() ) {
            $image_ids[] = (int) $variation->get_image_id();
        }
        if ( $product->get_image_id() ) {
            $image_ids[] = (int) $product->get_image_id();
        }
        foreach ( (array) $product->get_gallery_image_ids() as $gallery_id ) {
            $image_ids[] = (int) $gallery_id;
        }

        $url = '';
        foreach ( array_values( array_unique( array_filter( $image_ids ) ) ) as $image_id ) {
            $src = wp_get_attachment_image_src( $image_id, 'full' );
            if ( is_array( $src ) && ! empty( $src[0] ) ) {
                $url = (string) $src[0];
                break;
            }
        }

        return trim( (string) apply_filters( 'tdl_gmc_image_url', $url, $product, $variation ) );
    }

    private function additional_images( WC_Product $product, ?WC_Product_Variation $variation ): array {
        $urls = [];
        $main = $this->image_url( $product, $variation );
        foreach ( (array) $product->get_gallery_image_ids() as $image_id ) {
            $src = wp_get_attachment_image_src( $image_id, 'full' );
            if ( is_array( $src ) && ! empty( $src[0] ) && $src[0] !== $main ) $urls[] = (string) $src[0];
            if ( count( $urls ) >= 10 ) break;
        }
        return array_values( array_unique( $urls ) );
    }

    private function price_str( WC_Product $product ): string {
        $price = wc_get_price_including_tax( $product );
        if ( ! is_numeric( $price ) ) $price = $product->get_price();
        if ( ! is_numeric( $price ) ) return '';
        return wc_format_decimal( $price, wc_get_price_decimals() ) . ' ' . get_woocommerce_currency();
    }

    private function availability( WC_Product $product, ?WC_Product_Variation $variation ): string {
        $subject = $variation ?: $product;
        if ( method_exists( $subject, 'is_on_backorder' ) && $subject->is_on_backorder( 1 ) ) return 'backorder';
        if ( $subject->is_in_stock() ) return 'in_stock';
        return 'out_of_stock';
    }

    private function product_breadcrumb( WC_Product $product ): string {
        $terms = get_the_terms( $product->get_id(), 'product_cat' );
        if ( ! is_array( $terms ) || ! $terms ) return '';
        $deepest = null;
        $max_depth = -1;
        foreach ( $terms as $term ) {
            $depth = count( (array) get_ancestors( $term->term_id, 'product_cat' ) );
            if ( $depth > $max_depth ) {
                $max_depth = $depth;
                $deepest = $term;
            }
        }
        if ( ! $deepest ) return '';
        $ids = array_reverse( (array) get_ancestors( $deepest->term_id, 'product_cat' ) );
        $ids[] = $deepest->term_id;
        $names = [];
        foreach ( $ids as $id ) {
            $term = get_term( $id, 'product_cat' );
            if ( $term && ! is_wp_error( $term ) && isset( $term->name ) ) $names[] = (string) $term->name;
        }
        return implode( ' > ', $names );
    }

}