<?php
/**
 * REST routes kept from 1.x for one major version.
 *
 * @package KarmaDocs
 */

namespace KarmaDocs\Rest;

defined( 'ABSPATH' ) || exit;

/**
 * 2.0 kept the `karma-docs/v1` namespace, so almost every 1.x route still
 * exists. Routes that were replaced keep working here in their 1.x shape until
 * 3.0, answered from the new endpoints, with headers that tell clients to move:
 *
 *     Deprecation: @<unix time>            (RFC 9745)
 *     Sunset: <HTTP date>                  (RFC 8594)
 *     Link: <new route>; rel="successor-version"
 *
 * Each use fires `kdocs_deprecated_route` so sites can log who still calls them.
 */
class Legacy {

	/**
	 * When the 1.x routes were deprecated (2.0).
	 */
	const DEPRECATED = '2026-11-20';

	/**
	 * When they go away (3.0, at the earliest).
	 */
	const SUNSET = '2027-12-31';

	/**
	 * Hooks.
	 */
	public function register() {
		add_action( 'kdocs_rest_routes', array( $this, 'routes' ), 99 );
		add_filter( 'rest_post_dispatch', array( __CLASS__, 'headers' ), 10, 3 );
	}

	/**
	 * Deprecated route => replacement.
	 *
	 * @return array<string,string>
	 */
	public static function aliases() {
		/**
		 * Filters the deprecated routes and their replacements.
		 *
		 * @param array<string,string> $aliases Old route => new route (both with the namespace).
		 */
		return (array) apply_filters(
			'kdocs_rest_aliases',
			array(
				'/' . Routes::NS . '/analytics' => '/' . Routes::NS . '/analytics/overview',
			)
		);
	}

	/**
	 * Registers the 1.x routes whose replacements exist (Pro analytics).
	 *
	 * @param string $ns Namespace.
	 */
	public function routes( $ns ) {
		if ( ! class_exists( '\KarmaDocs\Pro\Analytics' ) || ! \KarmaDocs\Features::is_pro() ) {
			return;
		}
		register_rest_route(
			$ns,
			'/analytics',
			array(
				'methods'             => 'GET',
				'callback'            => array( $this, 'analytics' ),
				'permission_callback' => array( Routes::class, 'can_analytics' ),
				'args'                => array(
					'days' => array(
						'type'    => 'integer',
						'default' => 30,
						'minimum' => 1,
						'maximum' => 365,
					),
					'kb'   => array(
						'type'    => 'integer',
						'default' => 0,
					),
				),
			)
		);
	}

	/**
	 * Internal GET on a current route.
	 *
	 * @param string $route Route below the namespace.
	 * @param array  $query Query.
	 * @return array
	 */
	private static function fetch( $route, array $query ) {
		$request = new \WP_REST_Request( 'GET', '/' . Routes::NS . $route );
		$request->set_query_params( $query );
		$response = rest_do_request( $request );
		return $response->is_error() ? array() : (array) $response->get_data();
	}

	/**
	 * GET /analytics (1.x): totals, daily views, top articles and searches.
	 *
	 * @param \WP_REST_Request $request Request.
	 * @return \WP_REST_Response
	 */
	public function analytics( $request ) {
		$query    = array(
			'days' => (int) $request['days'],
			'kb'   => (int) $request['kb'],
		);
		$overview = self::fetch( '/analytics/overview', $query );
		$search   = self::fetch( '/analytics/search', $query );
		$kpis     = array_column( (array) ( $overview['kpis'] ?? array() ), null, 'id' );
		$series   = (array) ( $overview['series'] ?? array() );
		$yes      = (int) array_sum( array_column( $series, 'helpful_yes' ) );
		$no       = (int) array_sum( array_column( $series, 'helpful_no' ) );
		$totals   = (array) ( $search['totals'] ?? array() );

		$response = rest_ensure_response(
			array(
				'range'       => array(
					'from' => $overview['range']['from'] ?? '',
					'days' => (int) $request['days'],
				),
				'totals'      => array(
					'views'       => (int) ( $kpis['views']['value'] ?? 0 ),
					'viewsChange' => $kpis['views']['change'] ?? null,
					'searches'    => (int) ( $totals['searches'] ?? 0 ),
					'failed'      => (int) ( $totals['zero_results'] ?? 0 ),
					'yes'         => $yes,
					'no'          => $no,
					'score'       => ( $yes + $no ) ? (int) round( $yes / ( $yes + $no ) * 100 ) : null,
				),
				'series'      => array_map(
					static fn( $day ) => array(
						'date'  => $day['date'],
						'views' => (int) $day['views'],
					),
					$series
				),
				'topArticles' => array_map(
					static fn( $row ) => array(
						'id'       => (int) $row['id'],
						'title'    => $row['title'],
						'views'    => (int) $row['views'],
						'score'    => $row['helpful'] ?? null,
						'link'     => $row['link'],
						'editLink' => $row['editLink'],
					),
					(array) ( $overview['top'] ?? array() )
				),
				'topSearches' => array_map(
					static fn( $row ) => array(
						'term'    => $row['term'],
						'count'   => (int) $row['searches'],
						// 1.x stored the result count of each search; 2.0 keeps zero / non-zero.
						'results' => (int) $row['zero_results'] >= (int) $row['searches'] ? 0 : null,
					),
					(array) ( $search['terms'] ?? array() )
				),
				'failed'      => array_map(
					static fn( $row ) => array(
						'term'  => $row['term'],
						'count' => (int) ( $row['searches'] ?? $row['zero_results'] ?? 0 ),
					),
					(array) ( $search['zero'] ?? array() )
				),
			)
		);
		return self::headers( $response, rest_get_server(), $request );
	}

	/**
	 * Deprecation headers on 1.x routes.
	 *
	 * @param \WP_HTTP_Response $response Response.
	 * @param \WP_REST_Server   $server   Server.
	 * @param \WP_REST_Request  $request  Request.
	 * @return \WP_HTTP_Response
	 */
	public static function headers( $response, $server, $request ) {
		$aliases = self::aliases();
		$route   = (string) $request->get_route();
		if ( ! isset( $aliases[ $route ] ) || ! $response instanceof \WP_HTTP_Response ) {
			return $response;
		}
		if ( $response->get_headers()['Deprecation'] ?? false ) {
			return $response; // Already marked by the route itself.
		}
		$response->header( 'Deprecation', '@' . strtotime( self::DEPRECATED . ' 00:00:00 UTC' ) );
		$response->header( 'Sunset', gmdate( 'D, d M Y H:i:s', strtotime( self::SUNSET . ' 00:00:00 UTC' ) ) . ' GMT' );
		$response->header( 'Link', '<' . esc_url_raw( rest_url( ltrim( $aliases[ $route ], '/' ) ) ) . '>; rel="successor-version"' );
		/**
		 * Fires when a deprecated 1.x route is used.
		 *
		 * @param string $route       Deprecated route.
		 * @param string $replacement Replacement route.
		 */
		do_action( 'kdocs_deprecated_route', $route, $aliases[ $route ] );
		return $response;
	}
}