<?php
/**
 * UCP 2026-04-08 MCP JSON-RPC server over WordPress REST.
 *
 * @package Agentmatica
 */

declare(strict_types=1);

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

final class Agentmatica_Ucp_Mcp_Server {
	private const DEFAULT_PROTOCOL_VERSION = '2024-11-05';

	public static function init(): void {
		add_action( 'rest_api_init', array( __CLASS__, 'register_routes' ) );
	}

	public static function register_routes(): void {
		register_rest_route(
			'agentmatica/v1',
			'/ucp/mcp',
			array(
				'methods'             => WP_REST_Server::ALLMETHODS,
				'callback'            => array( __CLASS__, 'handle_request' ),
				'permission_callback' => array( Agentmatica_Auth::class, 'verify_request_token' ),
			)
		);
	}

	/**
	 * @param WP_REST_Request $request Incoming REST request.
	 * @return WP_REST_Response|WP_Error
	 */
	public static function handle_request( WP_REST_Request $request ) {
		if ( 'GET' === $request->get_method() ) {
			return new WP_REST_Response(
				array(
					'jsonrpc' => '2.0',
					'error'   => array(
						'code'    => -32000,
						'message' => __( 'SSE transport is not supported. Use POST JSON-RPC.', 'agentmatica-mcp-connector' ),
					),
					'id'      => null,
				),
				405
			);
		}

		$payload = $request->get_json_params();
		if ( ! is_array( $payload ) ) {
			return self::json_rpc_error( null, -32700, __( 'Parse error', 'agentmatica-mcp-connector' ) );
		}

		if ( self::is_batch_request( $payload ) ) {
			$responses = array();
			foreach ( $payload as $message ) {
				if ( ! is_array( $message ) ) {
					$responses[] = self::build_json_rpc_error( null, -32600, __( 'Invalid Request', 'agentmatica-mcp-connector' ) );
					continue;
				}
				$responses[] = self::dispatch_message( $message );
			}

			return new WP_REST_Response( $responses, 200 );
		}

		return self::dispatch_message( $payload );
	}

	/**
	 * @param array<string, mixed> $message JSON-RPC message.
	 * @return WP_REST_Response
	 */
	private static function dispatch_message( array $message ): WP_REST_Response {
		$method = isset( $message['method'] ) ? (string) $message['method'] : '';
		$id     = array_key_exists( 'id', $message ) ? $message['id'] : null;
		$params = isset( $message['params'] ) && is_array( $message['params'] ) ? $message['params'] : array();

		if ( '' === $method ) {
			return self::json_rpc_error( $id, -32600, __( 'Invalid Request', 'agentmatica-mcp-connector' ) );
		}

		if ( 0 === strpos( $method, 'notifications/' ) ) {
			return new WP_REST_Response( null, 202 );
		}

		if ( null === $id ) {
			return self::json_rpc_error( null, -32600, __( 'Invalid Request', 'agentmatica-mcp-connector' ) );
		}

		try {
			switch ( $method ) {
				case 'initialize':
					return self::json_rpc_result( $id, self::handle_initialize( $params ) );
				case 'ping':
					return self::json_rpc_result( $id, new stdClass() );
				case 'tools/list':
					return self::json_rpc_result( $id, self::handle_tools_list() );
				case 'tools/call':
					return self::json_rpc_result( $id, self::handle_tools_call( $params ) );
				default:
					return self::json_rpc_error( $id, -32601, __( 'Method not found', 'agentmatica-mcp-connector' ) );
			}
		} catch ( Throwable $exception ) {
			return self::json_rpc_error(
				$id,
				-32603,
				__( 'Internal error', 'agentmatica-mcp-connector' ),
				array(
					'detail' => $exception->getMessage(),
				)
			);
		}
	}

	/**
	 * @param array<string, mixed> $params Initialize params.
	 * @return array<string, mixed>
	 */
	private static function handle_initialize( array $params ): array {
		$protocol_version = isset( $params['protocolVersion'] )
			? sanitize_text_field( (string) $params['protocolVersion'] )
			: self::DEFAULT_PROTOCOL_VERSION;

		return array(
			'protocolVersion' => $protocol_version,
			'capabilities'    => array(
				'tools' => new stdClass(),
			),
			'serverInfo'      => array(
				'name'    => 'Agentmatica WordPress UCP MCP',
				'version' => AGENTMATICA_VERSION,
			),
		);
	}

	/**
	 * @return array<string, mixed>
	 */
	private static function handle_tools_list(): array {
		$tools = array(
			self::build_tool_definition(
				'search_catalog',
				__( 'Search the store product catalog (UCP). Matches product titles, categories, SKU, and description; handles common singular/plural forms (e.g. shirt/shirts).', 'agentmatica-mcp-connector' ),
				self::catalog_input_schema()
			),
			self::build_tool_definition(
				'lookup_catalog',
				__( 'Lookup products or variants by identifier (UCP).', 'agentmatica-mcp-connector' ),
				self::lookup_input_schema()
			),
			self::build_tool_definition(
				'get_product',
				__( 'Get full product details (UCP).', 'agentmatica-mcp-connector' ),
				self::get_product_input_schema()
			),
			self::build_tool_definition(
				'agentmatica_site_info',
				__( 'Site name, URL, tagline, and language.', 'agentmatica-mcp-connector' ),
				array(
					'type'       => 'object',
					'properties' => new stdClass(),
				)
			),
			self::build_tool_definition(
				'agentmatica_pages_list',
				__( 'List published WordPress pages.', 'agentmatica-mcp-connector' ),
				self::content_list_schema()
			),
			self::build_tool_definition(
				'agentmatica_posts_list',
				__( 'List published WordPress posts.', 'agentmatica-mcp-connector' ),
				self::content_list_schema()
			),
			self::build_tool_definition(
				'agentmatica_content_get',
				__( 'Fetch a single published page or post.', 'agentmatica-mcp-connector' ),
				array(
					'type'       => 'object',
					'properties' => array(
						'type' => array(
							'type' => 'string',
							'enum' => array( 'page', 'post' ),
						),
						'id'   => array( 'type' => 'integer' ),
						'slug' => array( 'type' => 'string' ),
					),
					'required'   => array( 'type' ),
				)
			),
		);

		if ( class_exists( 'WooCommerce' ) ) {
			$tools[] = self::build_tool_definition(
				'export_catalog_snapshot',
				__( 'Internal Agentmatica catalog snapshot for inventory-map generation. Not for visitor chat.', 'agentmatica-mcp-connector' ),
				array(
					'type'       => 'object',
					'properties' => array(
						'page'      => array(
							'type'    => 'integer',
							'minimum' => 1,
						),
						'page_size' => array(
							'type'    => 'integer',
							'minimum' => 1,
							'maximum' => 200,
						),
					),
				)
			);
			$tools[] = self::build_tool_definition(
				'create_cart',
				__( 'Create or update a guest cart session (UCP).', 'agentmatica-mcp-connector' ),
				self::cart_input_schema()
			);
			$tools[] = self::build_tool_definition(
				'update_cart',
				__( 'Update a guest cart session (UCP).', 'agentmatica-mcp-connector' ),
				self::cart_input_schema()
			);
			$tools[] = self::build_tool_definition(
				'get_cart',
				__( 'Get cart session state (UCP).', 'agentmatica-mcp-connector' ),
				array(
					'type'       => 'object',
					'properties' => array(
						'id' => array( 'type' => 'string' ),
					),
				)
			);
			$tools[] = self::build_tool_definition(
				'create_checkout',
				__( 'Create checkout from cart (UCP).', 'agentmatica-mcp-connector' ),
				self::checkout_input_schema()
			);
			$tools   = array_merge( $tools, self::woocommerce_support_tools() );
		}

		return array( 'tools' => $tools );
	}

	/**
	 * @param array<string, mixed> $params Tool call params.
	 * @return array<string, mixed>
	 */
	private static function handle_tools_call( array $params ): array {
		Agentmatica_Ability_Delegation::set_mcp_authenticated( true );

		try {
			return self::handle_tools_call_inner( $params );
		} finally {
			Agentmatica_Ability_Delegation::set_mcp_authenticated( false );
		}
	}

	/**
	 * @param array<string, mixed> $params Tool call params.
	 * @return array<string, mixed>
	 */
	private static function handle_tools_call_inner( array $params ): array {
		$tool_name = isset( $params['name'] ) ? sanitize_text_field( (string) $params['name'] ) : '';
		$arguments = isset( $params['arguments'] ) && is_array( $params['arguments'] ) ? $params['arguments'] : array();

		if ( '' === $tool_name ) {
			throw new InvalidArgumentException( 'Tool name is required.' );
		}

		switch ( $tool_name ) {
			case 'search_catalog':
				$structured = Agentmatica_Ucp_Catalog::search_catalog( $arguments );
				break;
			case 'lookup_catalog':
				$structured = Agentmatica_Ucp_Catalog::lookup_catalog( $arguments );
				break;
			case 'get_product':
				$structured = Agentmatica_Ucp_Catalog::get_product( $arguments );
				break;
			case 'export_catalog_snapshot':
				$structured = Agentmatica_Ucp_Catalog::export_catalog_snapshot( $arguments );
				break;
			case 'create_cart':
				$structured = Agentmatica_Ucp_Cart::create_cart( $arguments );
				break;
			case 'update_cart':
				$structured = Agentmatica_Ucp_Cart::update_cart( $arguments );
				break;
			case 'get_cart':
				$structured = Agentmatica_Ucp_Cart::get_cart( $arguments );
				break;
			case 'create_checkout':
				$structured = Agentmatica_Ucp_Cart::create_checkout( $arguments );
				break;
			case 'agentmatica_site_info':
				$structured = Agentmatica_Abilities::execute( Agentmatica_Content_Module::SITE_INFO, array() );
				break;
			case 'agentmatica_pages_list':
				$structured = Agentmatica_Abilities::execute(
					Agentmatica_Content_Module::PAGES_LIST,
					self::content_tool_parameters( $arguments )
				);
				break;
			case 'agentmatica_posts_list':
				$structured = Agentmatica_Abilities::execute(
					Agentmatica_Content_Module::POSTS_LIST,
					self::content_tool_parameters( $arguments )
				);
				break;
			case 'agentmatica_content_get':
				$structured = Agentmatica_Abilities::execute(
					Agentmatica_Content_Module::CONTENT_GET,
					self::content_tool_parameters( $arguments )
				);
				break;
			case 'customer_verify':
				$structured = Agentmatica_WooCommerce_Orders::customer_verify( $arguments );
				break;
			case 'orders_list':
				$structured = Agentmatica_WooCommerce_Orders::orders_list( $arguments );
				break;
			case 'order_get':
				$structured = Agentmatica_WooCommerce_Orders::order_get( $arguments );
				break;
			case 'verify_customer_token':
				$structured = Agentmatica_WooCommerce_Module::verify_customer_token( $arguments );
				break;
			case 'cancel_woo_order':
				$structured = Agentmatica_WooCommerce_Order_Mutations::cancel_order( $arguments );
				break;
			case 'update_woo_order_address':
				$structured = Agentmatica_WooCommerce_Order_Mutations::update_shipping_address( $arguments );
				break;
			case 'request_woo_return':
				$structured = Agentmatica_WooCommerce_Order_Mutations::request_return( $arguments );
				break;
			default:
				throw new InvalidArgumentException(
					esc_html(
						sprintf(
							/* translators: %s: tool name */
							__( 'Unknown tool: %s', 'agentmatica-mcp-connector' ),
							sanitize_text_field( $tool_name )
						)
					)
				);
		}

		return self::wrap_tool_result( $structured );
	}

	/**
	 * @return list<array<string, mixed>>
	 */
	private static function woocommerce_support_tools(): array {
		$session_schema = array(
			'type'       => 'object',
			'properties' => array(
				'session_key' => array( 'type' => 'string' ),
			),
			'required'   => array( 'session_key' ),
		);

		$tools = array(
			self::build_tool_definition(
				'customer_verify',
				__( 'Verify order number + billing email and bind this chat session.', 'agentmatica-mcp-connector' ),
				array(
					'type'       => 'object',
					'properties' => array(
						'session_key'  => array( 'type' => 'string' ),
						'order_number' => array( 'type' => 'string' ),
						'email'        => array( 'type' => 'string' ),
					),
					'required'   => array( 'session_key', 'order_number', 'email' ),
				)
			),
			self::build_tool_definition(
				'orders_list',
				__( 'List recent orders for a verified chat session.', 'agentmatica-mcp-connector' ),
				$session_schema
			),
			self::build_tool_definition(
				'order_get',
				__( 'Get order details for a verified chat session.', 'agentmatica-mcp-connector' ),
				array(
					'type'       => 'object',
					'properties' => array(
						'session_key'  => array( 'type' => 'string' ),
						'order_number' => array( 'type' => 'string' ),
					),
					'required'   => array( 'session_key', 'order_number' ),
				)
			),
			self::build_tool_definition(
				'verify_customer_token',
				__( 'Validate a short-lived logged-in customer token.', 'agentmatica-mcp-connector' ),
				array(
					'type'       => 'object',
					'properties' => array(
						'session_key'    => array( 'type' => 'string' ),
						'customer_token' => array( 'type' => 'string' ),
					),
					'required'   => array( 'session_key', 'customer_token' ),
				)
			),
		);

		if ( Agentmatica_Support_Settings::is_write_actions_enabled() ) {
			$tools[] = self::build_tool_definition(
				'cancel_woo_order',
				__( 'Cancel an unfulfilled order for a logged-in verified customer.', 'agentmatica-mcp-connector' ),
				array(
					'type'       => 'object',
					'properties' => array(
						'session_key'        => array( 'type' => 'string' ),
						'order_number'       => array( 'type' => 'string' ),
						'reason'             => array( 'type' => 'string' ),
						'confirmed'          => array( 'type' => 'boolean' ),
						'cancel_refund_mode' => array(
							'type' => 'string',
							'enum' => array( 'none', 'original' ),
						),
					),
					'required'   => array( 'session_key', 'order_number' ),
				)
			);

			$tools[] = self::build_tool_definition(
				'update_woo_order_address',
				__( 'Update shipping address on an unfulfilled order.', 'agentmatica-mcp-connector' ),
				array(
					'type'       => 'object',
					'properties' => array(
						'session_key'              => array( 'type' => 'string' ),
						'order_number'             => array( 'type' => 'string' ),
						'first_name'               => array( 'type' => 'string' ),
						'last_name'                => array( 'type' => 'string' ),
						'address1'                 => array( 'type' => 'string' ),
						'address2'                 => array( 'type' => 'string' ),
						'city'                     => array( 'type' => 'string' ),
						'zip'                      => array( 'type' => 'string' ),
						'province'                 => array( 'type' => 'string' ),
						'state'                    => array( 'type' => 'string' ),
						'country'                  => array( 'type' => 'string' ),
						'country_code'             => array( 'type' => 'string' ),
						'confirmed'                => array( 'type' => 'boolean' ),
						'address_same_region_only' => array( 'type' => 'boolean' ),
					),
					'required'   => array( 'session_key', 'order_number', 'address1', 'city', 'zip' ),
				)
			);

			$tools[] = self::build_tool_definition(
				'request_woo_return',
				__( 'Submit a return request for merchant review.', 'agentmatica-mcp-connector' ),
				array(
					'type'       => 'object',
					'properties' => array(
						'session_key'  => array( 'type' => 'string' ),
						'order_number' => array( 'type' => 'string' ),
						'reason'       => array( 'type' => 'string' ),
						'confirmed'    => array( 'type' => 'boolean' ),
					),
					'required'   => array( 'session_key', 'order_number' ),
				)
			);
		}

		return $tools;
	}

	/**
	 * @param array<string, mixed> $arguments Tool arguments.
	 * @return array<string, mixed>
	 */
	private static function content_tool_parameters( array $arguments ): array {
		unset( $arguments['meta'] );
		return $arguments;
	}

	/**
	 * @return array<string, mixed>
	 */
	private static function catalog_input_schema(): array {
		return array(
			'type'       => 'object',
			'properties' => array(
				'meta'    => array( 'type' => 'object' ),
				'catalog' => array(
					'type'       => 'object',
					'properties' => array(
						'query'      => array( 'type' => 'string' ),
						'pagination' => array(
							'type'       => 'object',
							'properties' => array(
								'limit' => array( 'type' => 'integer' ),
							),
						),
					),
				),
			),
		);
	}

	/**
	 * @return array<string, mixed>
	 */
	private static function lookup_input_schema(): array {
		return array(
			'type'       => 'object',
			'properties' => array(
				'meta'    => array( 'type' => 'object' ),
				'catalog' => array(
					'type'       => 'object',
					'properties' => array(
						'ids' => array(
							'type'  => 'array',
							'items' => array( 'type' => 'string' ),
						),
					),
					'required'   => array( 'ids' ),
				),
			),
		);
	}

	/**
	 * @return array<string, mixed>
	 */
	private static function get_product_input_schema(): array {
		return array(
			'type'       => 'object',
			'properties' => array(
				'meta'    => array( 'type' => 'object' ),
				'catalog' => array(
					'type'       => 'object',
					'properties' => array(
						'id' => array( 'type' => 'string' ),
					),
					'required'   => array( 'id' ),
				),
			),
		);
	}

	/**
	 * @return array<string, mixed>
	 */
	private static function cart_input_schema(): array {
		return array(
			'type'       => 'object',
			'properties' => array(
				'meta' => array( 'type' => 'object' ),
				'cart' => array(
					'type'       => 'object',
					'properties' => array(
						'context'    => array( 'type' => 'object' ),
						'line_items' => array( 'type' => 'array' ),
					),
				),
			),
		);
	}

	/**
	 * @return array<string, mixed>
	 */
	private static function checkout_input_schema(): array {
		return array(
			'type'       => 'object',
			'properties' => array(
				'meta'     => array( 'type' => 'object' ),
				'checkout' => array(
					'type'       => 'object',
					'properties' => array(
						'cart_id' => array( 'type' => 'string' ),
					),
				),
			),
		);
	}

	/**
	 * @return array<string, mixed>
	 */
	private static function content_list_schema(): array {
		return array(
			'type'       => 'object',
			'properties' => array(
				'search'   => array( 'type' => 'string' ),
				'per_page' => array( 'type' => 'integer' ),
				'page'     => array( 'type' => 'integer' ),
			),
		);
	}

	/**
	 * @param array<string, mixed> $structured Structured tool payload.
	 * @return array<string, mixed>
	 */
	private static function wrap_tool_result( array $structured ): array {
		return array(
			'content'           => array(
				array(
					'type' => 'text',
					'text' => wp_json_encode( $structured ),
				),
			),
			'structuredContent' => $structured,
		);
	}

	/**
	 * @param string               $name Tool name.
	 * @param string               $description Tool description.
	 * @param array<string, mixed> $input_schema JSON schema.
	 * @return array<string, mixed>
	 */
	private static function build_tool_definition(
		string $name,
		string $description,
		array $input_schema
	): array {
		return array(
			'name'        => $name,
			'description' => $description,
			'inputSchema' => $input_schema,
		);
	}

	/**
	 * @param mixed $payload Request body.
	 */
	private static function is_batch_request( $payload ): bool {
		if ( ! is_array( $payload ) || array() === $payload ) {
			return false;
		}

		return array_keys( $payload ) === range( 0, count( $payload ) - 1 );
	}

	/**
	 * @param mixed                $id Request id.
	 * @param array<string, mixed> $result JSON-RPC result.
	 */
	private static function json_rpc_result( $id, $result ): WP_REST_Response {
		return new WP_REST_Response(
			array(
				'jsonrpc' => '2.0',
				'id'      => $id,
				'result'  => $result,
			),
			200
		);
	}

	/**
	 * @param mixed              $id Request id.
	 * @param int                $code Error code.
	 * @param string             $message Error message.
	 * @param array<string,mixed> $data Optional error data.
	 */
	private static function json_rpc_error(
		$id,
		int $code,
		string $message,
		array $data = array()
	): WP_REST_Response {
		return new WP_REST_Response(
			self::build_json_rpc_error( $id, $code, $message, $data ),
			200
		);
	}

	/**
	 * @param mixed              $id Request id.
	 * @param int                $code Error code.
	 * @param string             $message Error message.
	 * @param array<string,mixed> $data Optional error data.
	 * @return array<string, mixed>
	 */
	private static function build_json_rpc_error(
		$id,
		int $code,
		string $message,
		array $data = array()
	): array {
		$error = array(
			'code'    => $code,
			'message' => $message,
		);

		if ( ! empty( $data ) ) {
			$error['data'] = $data;
		}

		return array(
			'jsonrpc' => '2.0',
			'id'      => $id,
			'error'   => $error,
		);
	}
}