<?php
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Serves /llms.txt and /llms-full.txt as virtual endpoints.
 * No files are written to disk; output is cached in a transient
 * and refreshed whenever content changes.
 */
class ATBA_Llms_Txt {

	public function __construct() {
		add_action( 'init', array( __CLASS__, 'add_rewrite' ) );
		add_filter( 'query_vars', array( $this, 'query_vars' ) );
		add_action( 'template_redirect', array( $this, 'maybe_serve' ), 0 );
		add_action( 'save_post', array( $this, 'bust_cache' ) );
		add_action( 'deleted_post', array( $this, 'bust_cache' ) );
	}

	public static function add_rewrite() {
		add_rewrite_rule( '^llms\.txt$', 'index.php?atba_llms=index', 'top' );
		add_rewrite_rule( '^llms-full\.txt$', 'index.php?atba_llms=full', 'top' );
	}

	public function query_vars( $vars ) {
		$vars[] = 'atba_llms';
		return $vars;
	}

	public function bust_cache() {
		delete_transient( 'atba_llms_index' );
		delete_transient( 'atba_llms_full' );
	}

	public function maybe_serve() {
		$mode = get_query_var( 'atba_llms' );
		if ( ! $mode ) {
			return;
		}

		if ( ! get_option( 'atba_llms_enabled', 1 ) ) {
			status_header( 404 );
			exit;
		}

		$body = ( 'full' === $mode ) ? $this->build_full() : $this->build_index();

		status_header( 200 );
		header( 'Content-Type: text/plain; charset=utf-8' );
		header( 'X-Robots-Tag: noindex' );
		echo $body; // phpcs:ignore WordPress.Security.EscapeOutput -- plain text endpoint, content built internally.
		exit;
	}

	private function included_post_types() {
		$types = get_option( 'atba_post_types', array( 'post', 'page' ) );
		return apply_filters( 'atba_post_types', (array) $types );
	}

	private function build_index() {
		$cached = get_transient( 'atba_llms_index' );
		if ( false !== $cached ) {
			return $cached;
		}

		$out  = '# ' . get_bloginfo( 'name' ) . "\n\n";
		$desc = get_option( 'atba_site_summary', get_bloginfo( 'description' ) );
		if ( $desc ) {
			$out .= '> ' . wp_strip_all_tags( $desc ) . "\n\n";
		}

		foreach ( $this->included_post_types() as $type ) {
			$obj = get_post_type_object( $type );
			if ( ! $obj ) {
				continue;
			}
			$posts = get_posts(
				array(
					'post_type'      => $type,
					'post_status'    => 'publish',
					'posts_per_page' => (int) apply_filters( 'atba_index_limit', 200 ),
					'orderby'        => 'modified',
					'order'          => 'DESC',
				)
			);
			if ( ! $posts ) {
				continue;
			}
			$out .= '## ' . $obj->labels->name . "\n\n";
			foreach ( $posts as $p ) {
				$excerpt = $p->post_excerpt ? $p->post_excerpt : wp_trim_words( wp_strip_all_tags( $p->post_content ), 25, '' );
				$out    .= sprintf( "- [%s](%s): %s\n", $p->post_title, get_permalink( $p ), trim( $excerpt ) );
			}
			$out .= "\n";
		}

		$out .= "## Sitemaps\n\n- [XML Sitemap](" . home_url( '/sitemap.xml' ) . ")\n";

		set_transient( 'atba_llms_index', $out, DAY_IN_SECONDS );
		return $out;
	}

	private function build_full() {
		$cached = get_transient( 'atba_llms_full' );
		if ( false !== $cached ) {
			return $cached;
		}

		$out = '# ' . get_bloginfo( 'name' ) . " — full content\n\n";

		foreach ( $this->included_post_types() as $type ) {
			$posts = get_posts(
				array(
					'post_type'      => $type,
					'post_status'    => 'publish',
					'posts_per_page' => (int) apply_filters( 'atba_full_limit', 100 ),
					'orderby'        => 'modified',
					'order'          => 'DESC',
				)
			);
			foreach ( $posts as $p ) {
				$out .= '## ' . $p->post_title . "\n";
				$out .= 'URL: ' . get_permalink( $p ) . "\n";
				$out .= 'Updated: ' . get_the_modified_date( 'Y-m-d', $p ) . "\n\n";
				$out .= trim( wp_strip_all_tags( strip_shortcodes( $p->post_content ) ) ) . "\n\n---\n\n";
			}
		}

		set_transient( 'atba_llms_full', $out, DAY_IN_SECONDS );
		return $out;
	}
}