<?php
/**
 * Generates and serves /llms.txt.
 *
 * @package AgentAisle
 */

defined( 'ABSPATH' ) || exit;

class AgentAisle_Llms {

	/**
	 * Hooks.
	 */
	public static function init() {
		add_action( 'init', array( __CLASS__, 'rewrite' ) );
		add_filter( 'query_vars', array( __CLASS__, 'query_vars' ) );
		add_action( 'template_redirect', array( __CLASS__, 'serve' ), 0 );
	}

	/**
	 * Activation: register rule and flush.
	 */
	public static function activate() {
		self::rewrite();
		flush_rewrite_rules();
	}

	/**
	 * Rewrite rule for /llms.txt.
	 */
	public static function rewrite() {
		add_rewrite_rule( '^llms\.txt$', 'index.php?agentaisle_llms=1', 'top' );
	}

	/**
	 * Register query var.
	 *
	 * @param array $vars Vars.
	 * @return array
	 */
	public static function query_vars( $vars ) {
		$vars[] = 'agentaisle_llms';
		return $vars;
	}

	/**
	 * Output llms.txt.
	 */
	public static function serve() {
		if ( ! get_query_var( 'agentaisle_llms' ) ) {
			return;
		}
		$settings = agentaisle_settings();
		if ( empty( $settings['llms_enabled'] ) ) {
			status_header( 404 );
			exit;
		}
		AgentAisle_Logger::maybe_log();
		status_header( 200 );
		header( 'Content-Type: text/plain; charset=utf-8' );
		header( 'X-Robots-Tag: noindex' );
		echo esc_html( self::content() );
		exit;
	}

	/**
	 * Current content: custom if saved, otherwise generated.
	 *
	 * @return string
	 */
	public static function content() {
		$custom = (string) agentaisle_settings()['llms_custom'];
		return '' !== trim( $custom ) ? $custom : self::generate();
	}

	/**
	 * Build llms.txt from the store.
	 *
	 * @return string
	 */
	public static function generate() {
		$name = wp_strip_all_tags( get_bloginfo( 'name' ) );
		$desc = wp_strip_all_tags( get_bloginfo( 'description' ) );
		$out  = "# {$name}\n\n";
		if ( $desc ) {
			$out .= "{$desc}\n\n";
		}

		$pages = array();
		if ( function_exists( 'wc_get_page_id' ) ) {
			foreach ( array( 'shop', 'terms' ) as $key ) {
				$id = wc_get_page_id( $key );
				if ( $id > 0 && 'publish' === get_post_status( $id ) ) {
					$pages[] = $id;
				}
			}
		}
		$privacy = (int) get_option( 'wp_page_for_privacy_policy' );
		if ( $privacy && 'publish' === get_post_status( $privacy ) ) {
			$pages[] = $privacy;
		}
		foreach ( self::find_policy_pages() as $id ) {
			$pages[] = $id;
		}
		$pages = array_unique( $pages );

		if ( $pages ) {
			$out .= "## Store information\n\n";
			foreach ( $pages as $id ) {
				$out .= '- [' . wp_strip_all_tags( get_the_title( $id ) ) . '](' . get_permalink( $id ) . ")\n";
			}
			$out .= "\n";
		}

		$cats = get_terms(
			array(
				'taxonomy'   => 'product_cat',
				'hide_empty' => true,
				'number'     => 30,
				'orderby'    => 'count',
				'order'      => 'DESC',
			)
		);
		if ( ! is_wp_error( $cats ) && $cats ) {
			$out .= "## Product categories\n\n";
			foreach ( $cats as $cat ) {
				$line = '- [' . wp_strip_all_tags( $cat->name ) . '](' . get_term_link( $cat ) . ')';
				if ( $cat->description ) {
					$line .= ': ' . wp_trim_words( wp_strip_all_tags( $cat->description ), 20 );
				}
				$out .= $line . "\n";
			}
			$out .= "\n";
		}

		if ( function_exists( 'wc_get_products' ) ) {
			$products = wc_get_products(
				array(
					'status'  => 'publish',
					'limit'   => 20,
					'orderby' => 'popularity',
				)
			);
			if ( $products ) {
				$out .= "## Popular products\n\n";
				foreach ( $products as $product ) {
					$out .= '- [' . wp_strip_all_tags( $product->get_name() ) . '](' . $product->get_permalink() . ")\n";
				}
				$out .= "\n";
			}
		}

		/**
		 * Filter the generated llms.txt content.
		 *
		 * @param string $out Content.
		 */
		return (string) apply_filters( 'agentaisle_llms_generated', $out );
	}

	/**
	 * Find published shipping, returns and contact pages by title.
	 *
	 * @return int[]
	 */
	private static function find_policy_pages() {
		$ids = array();
		foreach ( array( 'shipping', 'delivery', 'return', 'refund', 'contact', 'about' ) as $term ) {
			$found = get_posts(
				array(
					'post_type'      => 'page',
					'post_status'    => 'publish',
					's'              => $term,
					'search_columns' => array( 'post_title' ),
					'posts_per_page' => 1,
					'fields'         => 'ids',
				)
			);
			$ids   = array_merge( $ids, $found );
		}
		return $ids;
	}
}