<?php
/**
 * LLMs.txt Handler.
 *
 * @package AgentShop
 */

namespace AgentShop\LlmsTxt;

defined( 'ABSPATH' ) || exit;

/**
 * Handler class.
 */
class Handler {

	/**
	 * Cache TTL (1 hour).
	 */
	const CACHE_TTL = 3600;

	/**
	 * Cache prefix.
	 */
	const CACHE_PREFIX = 'agentshop_llms_txt_';

	/**
	 * Constructor.
	 */
	public function __construct() {
		$this->register_rewrite_rules();

		add_filter( 'query_vars', array( $this, 'add_query_vars' ) );
		add_action( 'template_redirect', array( $this, 'handle_request' ) );
	}

	/**
	 * Register rewrite rules.
	 */
	public function register_rewrite_rules() {
		if ( ! agentshop()->is_connected() ) {
			return;
		}

		add_rewrite_rule( '^llms\.txt$', 'index.php?agentshop_llms_txt=standard', 'top' );
		add_rewrite_rule( '^\.well-known/llms\.txt$', 'index.php?agentshop_llms_txt=standard', 'top' );
		add_rewrite_rule( '^llms-full\.txt$', 'index.php?agentshop_llms_txt=full', 'top' );
	}

	/**
	 * Add query vars.
	 *
	 * @param array $vars Query vars.
	 * @return array
	 */
	public function add_query_vars( $vars ) {
		$vars[] = 'agentshop_llms_txt';
		return $vars;
	}

	/**
	 * Handle request.
	 */
	public function handle_request() {
		$version = get_query_var( 'agentshop_llms_txt' );

		if ( empty( $version ) ) {
			return;
		}

		if ( ! agentshop()->is_connected() ) {
			$this->send_error( 503, 'Service Unavailable' );
			return;
		}

		$content = $this->get_content( $version );

		if ( false === $content ) {
			$this->send_error( 500, 'Error generating llms.txt' );
			return;
		}

		$this->send_response( $content );
	}

	/**
	 * Get content (cached or fresh).
	 *
	 * @param string $version Version.
	 * @return string|false
	 */
	public function get_content( $version = 'standard' ) {
		$cache_key = self::CACHE_PREFIX . $version;
		$cached    = get_transient( $cache_key );

		if ( false !== $cached ) {
			return $cached;
		}

		$content = $this->fetch_content( $version );

		if ( false !== $content ) {
			set_transient( $cache_key, $content, self::CACHE_TTL );
		}

		return $content;
	}

	/**
	 * Fetch content from backend.
	 *
	 * @param string $version Version.
	 * @return string|false
	 */
	private function fetch_content( $version = 'standard' ) {
		$result = agentshop()->api->fetch_llms_txt( $version );

		if ( is_wp_error( $result ) ) {
			agentshop()->log( 'llms.txt fetch failed: ' . $result->get_error_message(), 'error' );
			return false;
		}

		$body = $result['data']['content'] ?? '';

		if ( empty( $body ) && isset( $result['data'] ) && is_string( $result['data'] ) ) {
			$body = $result['data'];
		}

		return $body ?: false;
	}

	/**
	 * Clear cache.
	 */
	public function clear_cache() {
		delete_transient( self::CACHE_PREFIX . 'standard' );
		delete_transient( self::CACHE_PREFIX . 'full' );
	}

	/**
	 * Send response.
	 *
	 * @param string $content Content.
	 */
	private function send_response( $content ) {
		status_header( 200 );
		header( 'Content-Type: text/plain; charset=utf-8' );
		header( 'Cache-Control: public, max-age=3600' );
		header( 'X-Robots-Tag: noindex' );
		header( 'X-Content-Type-Options: nosniff' );

		echo $content; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
		exit;
	}

	/**
	 * Send error.
	 *
	 * @param int    $code    Status code.
	 * @param string $message Message.
	 */
	private function send_error( $code, $message ) {
		status_header( $code );
		header( 'Content-Type: text/plain; charset=utf-8' );
		echo esc_html( $message );
		exit;
	}
}