<?php
/**
 * WebPage schema generator.
 *
 * Builds schema.org WebPage markup for singular pages (About, Contact, and
 * general content pages), detecting a more specific type where possible.
 *
 * @package AICommerce\Schema
 */

declare(strict_types=1);

namespace AICommerce\Schema;

/**
 * Generates WebPage schema for pages.
 */
class WebPageSchema {

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

		$schema = array(
			'@context'      => 'https://schema.org',
			'@type'         => $this->detect_type( $post ),
			'@id'           => $permalink,
			'url'           => $permalink,
			'name'          => wp_strip_all_tags( get_the_title( $post ) ),
			'isPartOf'      => array(
				'@type' => 'WebSite',
				'@id'   => home_url( '/' ),
				'name'  => get_bloginfo( 'name' ),
				'url'   => home_url( '/' ),
			),
			'datePublished' => $this->date( $post->post_date_gmt ),
			'dateModified'  => $this->date( $post->post_modified_gmt ),
		);

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

		$thumb_id = get_post_thumbnail_id( $post );
		if ( $thumb_id ) {
			$image_url = wp_get_attachment_image_url( $thumb_id, 'full' );
			if ( $image_url ) {
				$schema['primaryImageOfPage'] = array(
					'@type' => 'ImageObject',
					'url'   => $image_url,
				);
			}
		}

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

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

	/**
	 * Detect a more specific WebPage subtype from the page.
	 *
	 * @param \WP_Post $post The page.
	 *
	 * @return string A schema.org WebPage type.
	 */
	private function detect_type( \WP_Post $post ): string {
		$type  = 'WebPage';
		$slug  = $post->post_name;
		$title = strtolower( get_the_title( $post ) );

		$front_id = (int) get_option( 'page_on_front' );

		if ( $front_id && $front_id === $post->ID ) {
			$type = 'WebPage';
		} elseif ( $this->matches( $slug, $title, array( 'about', 'about-us', 'our-story', 'company' ) ) ) {
			$type = 'AboutPage';
		} elseif ( $this->matches( $slug, $title, array( 'contact', 'contact-us', 'get-in-touch' ) ) ) {
			$type = 'ContactPage';
		} elseif ( $this->matches( $slug, $title, array( 'faq', 'faqs', 'help', 'support' ) ) ) {
			$type = 'FAQPage';
		} elseif ( $this->matches( $slug, $title, array( 'checkout', 'cart' ) ) ) {
			$type = 'CheckoutPage';
		} elseif ( $this->matches( $slug, $title, array( 'privacy', 'terms', 'policy', 'legal' ) ) ) {
			$type = 'WebPage';
		}

		/**
		 * Filters the detected WebPage subtype.
		 *
		 * @param string   $type The detected type.
		 * @param \WP_Post $post The page.
		 */
		return (string) apply_filters( 'aicommerce_webpage_type', $type, $post );
	}

	/**
	 * Whether a slug or title matches any of the given keywords.
	 *
	 * @param string             $slug     The page slug.
	 * @param string             $title    The lowercased page title.
	 * @param array<int, string> $keywords Keywords to match.
	 *
	 * @return bool
	 */
	private function matches( string $slug, string $title, array $keywords ): bool {
		foreach ( $keywords as $keyword ) {
			if ( $slug === $keyword || str_contains( $title, $keyword ) ) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Build a plain-text description from the excerpt or content.
	 *
	 * @param \WP_Post $post The page.
	 *
	 * @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;
	}

	/**
	 * 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 ) : '';
	}
}