<?php
/**
 * AEO Ranking REST API
 * 
 * Phase 2: REST API endpoints for real-time analysis
 * Subscription-ready architecture with proper permissions and caching.
 * 
 * @package AI_Answer_Toolkit
 * @since 2.0.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * AI_Answer_Toolkit_REST_API Class.
 * 
 * Provides REST endpoints for real-time AEO analysis.
 */
class AI_Answer_Toolkit_REST_API {

	/**
	 * API namespace.
	 */
	const NAMESPACE = 'aeo/v1';

	/**
	 * Cache group for transients.
	 */
	const CACHE_GROUP = 'aitk_analysis';

	/**
	 * Initialize REST API.
	 */
	public static function init() {
		add_action( 'rest_api_init', array( __CLASS__, 'register_routes' ) );
	}

	/**
	 * Register REST API routes.
	 */
	public static function register_routes() {
		// Analyze endpoint - unified analysis for all components
		register_rest_route(
			self::NAMESPACE,
			'/analyze/(?P<post_id>\d+)',
			array(
				'methods'             => 'POST',
				'callback'            => array( __CLASS__, 'analyze_content' ),
				'permission_callback' => array( __CLASS__, 'check_edit_permission' ),
				'args'                => array(
					'post_id' => array(
						'required'          => true,
						'type'              => 'integer',
						'validate_callback' => function( $param ) {
							return is_numeric( $param ) && $param > 0;
						},
					),
					'content' => array(
						'required'          => false,
						'type'              => 'string',
						'sanitize_callback' => 'wp_kses_post',
					),
				),
			)
		);

		// Score endpoint - get only score data
		register_rest_route(
			self::NAMESPACE,
			'/score/(?P<post_id>\d+)',
			array(
				'methods'             => 'GET',
				'callback'            => array( __CLASS__, 'get_score' ),
				'permission_callback' => array( __CLASS__, 'check_read_permission' ),
				'args'                => array(
					'post_id' => array(
						'required'          => true,
						'type'              => 'integer',
						'validate_callback' => function( $param ) {
							return is_numeric( $param ) && $param > 0;
						},
					),
				),
			)
		);

		// Tips endpoint - get only improvement tips
		register_rest_route(
			self::NAMESPACE,
			'/tips/(?P<post_id>\d+)',
			array(
				'methods'             => 'GET',
				'callback'            => array( __CLASS__, 'get_tips' ),
				'permission_callback' => array( __CLASS__, 'check_read_permission' ),
				'args'                => array(
					'post_id' => array(
						'required'          => true,
						'type'              => 'integer',
						'validate_callback' => function( $param ) {
							return is_numeric( $param ) && $param > 0;
						},
					),
				),
			)
		);

		// Visibility endpoint - get only visibility checks
		register_rest_route(
			self::NAMESPACE,
			'/visibility/(?P<post_id>\d+)',
			array(
				'methods'             => 'GET',
				'callback'            => array( __CLASS__, 'get_visibility' ),
				'permission_callback' => array( __CLASS__, 'check_read_permission' ),
				'args'                => array(
					'post_id' => array(
						'required'          => true,
						'type'              => 'integer',
						'validate_callback' => function( $param ) {
							return is_numeric( $param ) && $param > 0;
						},
					),
				),
			)
		);
	}

	/**
	 * Check if user can edit the post.
	 * 
	 * @param WP_REST_Request $request Request object.
	 * @return bool True if user can edit.
	 */
	public static function check_edit_permission( $request ) {
		$post_id = $request->get_param( 'post_id' );
		
		if ( ! $post_id ) {
			return false;
		}

		return current_user_can( 'edit_post', $post_id );
	}

	/**
	 * Check if user can read the post.
	 * 
	 * @param WP_REST_Request $request Request object.
	 * @return bool True if user can read.
	 */
	public static function check_read_permission( $request ) {
		$post_id = $request->get_param( 'post_id' );
		
		if ( ! $post_id ) {
			return false;
		}

		return current_user_can( 'read_post', $post_id );
	}

	/**
	 * Analyze content endpoint - unified analysis.
	 * 
	 * @param WP_REST_Request $request Request object.
	 * @return WP_REST_Response|WP_Error Response object.
	 */
	public static function analyze_content( $request ) {
		$post_id = $request->get_param( 'post_id' );
		$content = $request->get_param( 'content' );

		// Rate limiting check
		if ( ! self::check_rate_limit( $post_id ) ) {
			return new WP_Error(
				'rate_limit_exceeded',
				__( 'Rate limit exceeded. Please wait before requesting another analysis.', 'ai-answer-toolkit' ),
				array( 'status' => 429 )
			);
		}

		// Get post
		$post = get_post( $post_id );
		if ( ! $post ) {
			return new WP_Error(
				'post_not_found',
				__( 'Post not found.', 'ai-answer-toolkit' ),
				array( 'status' => 404 )
			);
		}

		// Check cache
		$cache_key = self::get_cache_key( $post_id, $content );
		$cached = get_transient( $cache_key );
		if ( $cached !== false ) {
			return rest_ensure_response( array(
				'cached' => true,
				'data'   => $cached,
			) );
		}

		// Temporarily update content if provided
		$original_content = $post->post_content;
		if ( $content ) {
			$post->post_content = $content;
			$GLOBALS['post'] = $post;
		}

		// Calculate all components
		$response = array(
			'score'      => self::calculate_score_data( $post_id ),
			'tips'       => self::calculate_tips_data( $post_id ),
			'visibility' => self::calculate_visibility_data( $post_id ),
			'guidance'   => self::calculate_guidance_data( $post_id ),
			'timestamp'  => current_time( 'timestamp' ),
		);

		// Apply subscription filter (for future gating)
		$response = apply_filters( 'aitk_rest_analyze_response', $response, $post_id );

		// Restore original content
		if ( $content ) {
			$post->post_content = $original_content;
			$GLOBALS['post'] = $post;
		}

		// Cache response
		set_transient( $cache_key, $response, 5 ); // 5 seconds cache

		// Update rate limit
		self::update_rate_limit( $post_id );

		return rest_ensure_response( array(
			'cached' => false,
			'data'   => $response,
		) );
	}

	/**
	 * Get score endpoint.
	 * 
	 * @param WP_REST_Request $request Request object.
	 * @return WP_REST_Response|WP_Error Response object.
	 */
	public static function get_score( $request ) {
		$post_id = $request->get_param( 'post_id' );

		$score_data = self::calculate_score_data( $post_id );
		
		return rest_ensure_response( array(
			'data' => $score_data,
		) );
	}

	/**
	 * Get tips endpoint.
	 * 
	 * @param WP_REST_Request $request Request object.
	 * @return WP_REST_Response|WP_Error Response object.
	 */
	public static function get_tips( $request ) {
		$post_id = $request->get_param( 'post_id' );

		$tips_data = self::calculate_tips_data( $post_id );
		
		return rest_ensure_response( array(
			'data' => $tips_data,
		) );
	}

	/**
	 * Get visibility endpoint.
	 * 
	 * @param WP_REST_Request $request Request object.
	 * @return WP_REST_Response|WP_Error Response object.
	 */
	public static function get_visibility( $request ) {
		$post_id = $request->get_param( 'post_id' );

		$visibility_data = self::calculate_visibility_data( $post_id );
		
		return rest_ensure_response( array(
			'data' => $visibility_data,
		) );
	}

	/**
	 * Calculate score data.
	 * 
	 * @param int $post_id Post ID.
	 * @return array Score data.
	 */
	private static function calculate_score_data( $post_id ) {
		$score_data = AI_Answer_Toolkit_Score::calculate_score( $post_id );
		
		return array(
			'unified_score' => $score_data['score'],
			'label'         => $score_data['label'],
			'color'         => $score_data['color'],
			'status'        => $score_data['status'],
			'breakdown'     => $score_data['breakdown'],
		);
	}

	/**
	 * Calculate tips data.
	 * 
	 * @param int $post_id Post ID.
	 * @return array Tips data.
	 */
	private static function calculate_tips_data( $post_id ) {
		$tips = AI_Answer_Toolkit_AI_Suggestions::get_improvement_hints( $post_id );
		
		// Apply subscription filter (for future gating)
		$tips = apply_filters( 'aitk_rest_tips_response', $tips, $post_id );
		
		return $tips;
	}

	/**
	 * Calculate visibility data.
	 * 
	 * @param int $post_id Post ID.
	 * @return array Visibility data.
	 */
	private static function calculate_visibility_data( $post_id ) {
		$visibility_data = AI_Answer_Toolkit_Visibility::analyze_visibility( $post_id );
		
		return array(
			'score'    => $visibility_data['score'],
			'checks'   => $visibility_data['checks'],
			'warnings' => $visibility_data['warnings'],
		);
	}

	/**
	 * Calculate guidance data.
	 * 
	 * @param int $post_id Post ID.
	 * @return array Guidance data.
	 */
	private static function calculate_guidance_data( $post_id ) {
		$guidance = AI_Answer_Toolkit_Content_Guidance::analyze_content( $post_id );
		
		return $guidance;
	}

	/**
	 * Get cache key for analysis.
	 * 
	 * @param int    $post_id Post ID.
	 * @param string $content Content hash.
	 * @return string Cache key.
	 */
	private static function get_cache_key( $post_id, $content = '' ) {
		$content_hash = md5( $content );
		return self::CACHE_GROUP . '_' . $post_id . '_' . $content_hash;
	}

	/**
	 * Check rate limit for post analysis.
	 * 
	 * @param int $post_id Post ID.
	 * @return bool True if within rate limit.
	 */
	private static function check_rate_limit( $post_id ) {
		$rate_key = 'aitk_rate_limit_' . $post_id . '_' . get_current_user_id();
		$requests = get_transient( $rate_key );
		
		// Allow 10 requests per minute
		$max_requests = apply_filters( 'aitk_rate_limit_max', 10 );
		
		if ( $requests !== false && $requests >= $max_requests ) {
			return false;
		}
		
		return true;
	}

	/**
	 * Update rate limit counter.
	 * 
	 * @param int $post_id Post ID.
	 */
	private static function update_rate_limit( $post_id ) {
		$rate_key = 'aitk_rate_limit_' . $post_id . '_' . get_current_user_id();
		$requests = get_transient( $rate_key );
		
		if ( $requests === false ) {
			set_transient( $rate_key, 1, 60 ); // 1 minute
		} else {
			set_transient( $rate_key, $requests + 1, 60 );
		}
	}

	/**
	 * Clear cache for a post.
	 * 
	 * @param int $post_id Post ID.
	 */
	public static function clear_cache( $post_id ) {
		global $wpdb;
		
		$pattern = '_transient_' . self::CACHE_GROUP . '_' . $post_id . '_%';
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
		$wpdb->query(
			$wpdb->prepare(
				"DELETE FROM {$wpdb->options} WHERE option_name LIKE %s",
				$pattern
			)
		);
	}
}