<?php
/**
 * Article / BlogPosting schema generator.
 *
 * Builds schema.org Article markup for singular blog posts and other
 * article-like post types so AI models and search engines can understand
 * editorial content — not just products.
 *
 * @package AICommerce\Schema
 */

declare(strict_types=1);

namespace AICommerce\Schema;

/**
 * Generates Article/BlogPosting schema for posts.
 */
class ArticleSchema {

	/**
	 * Generate Article schema for a post.
	 *
	 * @param \WP_Post $post The post object.
	 *
	 * @return array<string, mixed> Article schema, or empty array if not applicable.
	 */
	public function generate( \WP_Post $post ): array {
		$permalink = get_permalink( $post );
		if ( ! $permalink ) {
			return array();
		}

		/**
		 * Filters the schema.org Article type for a post.
		 *
		 * @param string   $type The Article type (default 'BlogPosting').
		 * @param \WP_Post $post The post.
		 */
		$type = (string) apply_filters( 'aicommerce_article_type', 'BlogPosting', $post );

		$article = array(
			'@context'         => 'https://schema.org',
			'@type'            => $type,
			'mainEntityOfPage' => array(
				'@type' => 'WebPage',
				'@id'   => $permalink,
			),
			'headline'         => $this->headline( $post ),
			'url'              => $permalink,
			'datePublished'    => $this->date( $post->post_date_gmt ),
			'dateModified'     => $this->date( $post->post_modified_gmt ),
		);

		$description = $this->description( $post );
		if ( '' !== $description ) {
			$article['description'] = $description;
		}

		$image = $this->image( $post );
		if ( ! empty( $image ) ) {
			$article['image'] = $image;
		}

		$author = $this->author( $post );
		if ( ! empty( $author ) ) {
			$article['author'] = $author;
		}

		$publisher = $this->publisher();
		if ( ! empty( $publisher ) ) {
			$article['publisher'] = $publisher;
		}

		$sections = $this->sections( $post );
		if ( ! empty( $sections ) ) {
			$article['articleSection'] = $sections;
		}

		$keywords = $this->keywords( $post );
		if ( '' !== $keywords ) {
			$article['keywords'] = $keywords;
		}

		$language = get_bloginfo( 'language' );
		if ( ! empty( $language ) ) {
			$article['inLanguage'] = $language;
		}

		/**
		 * Filters the Article schema for a post.
		 *
		 * @param array<string, mixed> $article The Article schema.
		 * @param \WP_Post             $post    The post.
		 */
		return (array) apply_filters( 'aicommerce_article_schema', $article, $post );
	}

	/**
	 * Build the headline (Google recommends <= 110 characters).
	 *
	 * @param \WP_Post $post The post.
	 *
	 * @return string
	 */
	private function headline( \WP_Post $post ): string {
		$title = wp_strip_all_tags( get_the_title( $post ) );
		if ( mb_strlen( $title ) > 110 ) {
			$title = mb_substr( $title, 0, 107 ) . '...';
		}
		return $title;
	}

	/**
	 * Build a plain-text description from the excerpt or content.
	 *
	 * @param \WP_Post $post The post.
	 *
	 * @return string
	 */
	private function description( \WP_Post $post ): string {
		$text = has_excerpt( $post ) ? get_the_excerpt( $post ) : $post->post_content;
		$text = wp_strip_all_tags( (string) $text );
		$text = trim( preg_replace( '/\s+/', ' ', $text ) ?? '' );

		if ( mb_strlen( $text ) > 300 ) {
			$text = mb_substr( $text, 0, 297 ) . '...';
		}

		return $text;
	}

	/**
	 * Build the image array from the featured image.
	 *
	 * @param \WP_Post $post The post.
	 *
	 * @return array<int, string>
	 */
	private function image( \WP_Post $post ): array {
		$thumb_id = get_post_thumbnail_id( $post );
		if ( ! $thumb_id ) {
			return array();
		}

		$url = wp_get_attachment_image_url( $thumb_id, 'full' );

		return $url ? array( $url ) : array();
	}

	/**
	 * Build the author (Person) node.
	 *
	 * @param \WP_Post $post The post.
	 *
	 * @return array<string, mixed>
	 */
	private function author( \WP_Post $post ): array {
		$author_id = (int) $post->post_author;
		if ( $author_id <= 0 ) {
			return array();
		}

		$name = get_the_author_meta( 'display_name', $author_id );
		if ( '' === (string) $name ) {
			return array();
		}

		$author = array(
			'@type' => 'Person',
			'name'  => $name,
		);

		$url = get_author_posts_url( $author_id );
		if ( $url ) {
			$author['url'] = $url;
		}

		return $author;
	}

	/**
	 * Build the publisher (Organization) node.
	 *
	 * @return array<string, mixed>
	 */
	private function publisher(): array {
		$publisher = array(
			'@type' => 'Organization',
			'name'  => get_bloginfo( 'name' ),
			'url'   => home_url( '/' ),
		);

		$logo_id = get_theme_mod( 'custom_logo' );
		if ( $logo_id ) {
			$logo_url = wp_get_attachment_image_url( $logo_id, 'full' );
			if ( $logo_url ) {
				$publisher['logo'] = array(
					'@type' => 'ImageObject',
					'url'   => $logo_url,
				);
			}
		}

		return $publisher;
	}

	/**
	 * Build the list of category names (articleSection).
	 *
	 * @param \WP_Post $post The post.
	 *
	 * @return array<int, string>
	 */
	private function sections( \WP_Post $post ): array {
		$terms = get_the_terms( $post, 'category' );
		if ( ! is_array( $terms ) ) {
			return array();
		}

		return array_values(
			array_map(
				static fn( \WP_Term $term ): string => $term->name,
				$terms
			)
		);
	}

	/**
	 * Build a comma-separated keyword string from tags.
	 *
	 * @param \WP_Post $post The post.
	 *
	 * @return string
	 */
	private function keywords( \WP_Post $post ): string {
		$terms = get_the_terms( $post, 'post_tag' );
		if ( ! is_array( $terms ) ) {
			return '';
		}

		$names = array_map(
			static fn( \WP_Term $term ): string => $term->name,
			$terms
		);

		return implode( ', ', $names );
	}

	/**
	 * Convert a GMT date string to ISO 8601.
	 *
	 * @param string $gmt_date The GMT date (Y-m-d H:i:s).
	 *
	 * @return string
	 */
	private function date( string $gmt_date ): string {
		if ( '' === $gmt_date || '0000-00-00 00:00:00' === $gmt_date ) {
			return '';
		}

		$timestamp = strtotime( $gmt_date . ' UTC' );

		return $timestamp ? gmdate( 'c', $timestamp ) : '';
	}
}