<?php
/**
 * @package AgentgateWebMCP
 */

namespace AgentgateWebMCP;

defined( 'ABSPATH' ) || exit;

class Endpoints {

	private const NS = 'webmcp/v1';

	private Tool_Resolver $resolver;

	public function __construct( Tool_Resolver $resolver ) {
		$this->resolver = $resolver;
		add_action( 'rest_api_init', [ $this, 'mount' ] );
	}

	public function mount(): void {
		register_rest_route( self::NS, '/tools', [
			'methods'             => \WP_REST_Server::READABLE,
			'callback'            => [ $this, 'handle_list' ],
			'permission_callback' => '__return_true',
		] );

		register_rest_route( self::NS, '/execute/(?P<ability>[a-zA-Z0-9_%\-]+)', [
			'methods'             => \WP_REST_Server::CREATABLE,
			'callback'            => [ $this, 'handle_run' ],
			'permission_callback' => '__return_true',
			'args'                => [
				'ability' => [
					'required'          => true,
					'sanitize_callback' => fn( $v ) => sanitize_text_field( rawurldecode( $v ) ),
				],
			],
		] );

		register_rest_route( self::NS, '/nonce', [
			'methods'             => \WP_REST_Server::READABLE,
			'callback'            => fn() => new \WP_REST_Response( [ 'nonce' => wp_create_nonce( 'webmcp_run' ) ] ),
			'permission_callback' => '__return_true',
		] );
	}

	public function handle_list( \WP_REST_Request $req ): \WP_REST_Response {
		$tools = $this->resolver->for_current_user();
		$hash  = $this->resolver->etag();

		$client_etag = $req->get_header( 'if_none_match' );
		if ( $client_etag && trim( $client_etag, '"' ) === $hash ) {
			return new \WP_REST_Response( null, 304 );
		}

		$resp = new \WP_REST_Response( [ 'tools' => $tools, 'nonce' => wp_create_nonce( 'webmcp_run' ) ] );
		$resp->header( 'Cache-Control', 'private, max-age=300' );
		$resp->header( 'Vary', 'Cookie' );
		$resp->header( 'ETag', '"' . $hash . '"' );
		return $resp;
	}

	public function handle_run( \WP_REST_Request $req ): \WP_REST_Response {
		$name = $req->get_param( 'ability' );
		$uid  = get_current_user_id();

		// Payload size guard.
		$max = (int) apply_filters( 'webmcp_max_payload', 102400 );
		if ( strlen( $req->get_body() ) > $max ) {
			return $this->err( 'webmcp_too_large', __( 'Payload exceeds maximum size.', 'agentgate-for-webmcp' ), 400 );
		}

		// Abilities API must be present.
		if ( ! function_exists( 'wp_has_ability' ) || ! wp_has_ability( $name ) ) {
			return $this->err( 'webmcp_missing', __( 'Tool not found.', 'agentgate-for-webmcp' ), 404 );
		}

		// Only allow hardcoded tools.
		if ( ! in_array( $name, Core::TOOLS, true ) ) {
			return $this->err( 'webmcp_missing', __( 'Tool not found.', 'agentgate-for-webmcp' ), 404 );
		}

		$ability = wp_get_ability( $name );
		$input   = $req->get_json_params() ?? [];

		// Ability-level permission gate.
		if ( true !== $ability->check_permissions( $input ) ) {
			return $this->err( 'webmcp_denied', __( 'Permission denied for this tool.', 'agentgate-for-webmcp' ), 403 );
		}

		// CSRF check for write operations by logged-in users.
		if ( is_user_logged_in() && ! $ability->get_meta_item( 'webmcp_readonly', false ) ) {
			$tok = $req->get_header( 'x_wp_nonce' );
			if ( ! $tok || ! wp_verify_nonce( $tok, 'webmcp_run' ) ) {
				return $this->err( 'webmcp_bad_token', __( 'Invalid or expired security token.', 'agentgate-for-webmcp' ), 403 );
			}
		}

		// Extensibility hook.
		$gate = apply_filters( 'webmcp_pre_run', true, $name, $input, $uid );
		if ( is_wp_error( $gate ) ) {
			return $this->err( $gate->get_error_code(), $gate->get_error_message(), 403 );
		}

		// Run the tool.
		try {
			$output = $ability->execute( $input );
		} catch ( \Throwable $ex ) {
			do_action( 'webmcp_after_run', $name, $uid, false );
			return $this->err( 'webmcp_error', __( 'Tool execution failed.', 'agentgate-for-webmcp' ), 500 );
		}

		if ( is_wp_error( $output ) ) {
			do_action( 'webmcp_after_run', $name, $uid, false );
			return $this->err( $output->get_error_code(), $output->get_error_message(), $output->get_error_data( 'status' ) ?? 500 );
		}

		do_action( 'webmcp_after_run', $name, $uid, true );
		return new \WP_REST_Response( [ 'result' => $output ] );
	}

	private function err( string $code, string $msg, int $status ): \WP_REST_Response {
		return new \WP_REST_Response( [ 'code' => $code, 'message' => $msg ], $status );
	}
}