<?php

namespace AdPresso\Core\Rest;

use AdPresso\Constants;
use AdPresso\Entities\Ad;
use AdPresso\Entities\Entity;
use AdPresso\Entities\Group;
use AdPresso\Entities\Placement;
use WP_Error;
use WP_REST_Request;
use WP_REST_Response;
use WP_REST_Server;

defined( 'ABSPATH' ) || exit;

/**
 * Abstract REST Controller for AdPresso Entities.
 *
 * Handles the registration of standard CRUD routes for a given entity type.
 * Child classes must define the entity type and implement the callback methods.
 */
abstract class AbstractEntityController {

	/**
	 * The namespace for the REST API routes.
	 * @var string
	 */
	protected string $namespace = 'adpresso/v1';

	/**
	 * The base of this controller's route.
	 * Must be defined by the child class (e.g., 'ads', 'groups').
	 * @var string
	 */
	protected string $rest_base;

	/**
	 * The WordPress post type this controller manages.
	 * Must be defined by the child class.
	 * @var string
	 */
	protected string $post_type;

	/**
	 * The registry for all query handlers.
	 * @var Handlers\QueryHandlerRegistry
	 */
	protected Handlers\QueryHandlerRegistry $query_handler_registry;

	/**
	 * Constructor.
	 * Initializes the query handler registry and registers default handlers.
	 */
	public function __construct() {
		$this->query_handler_registry = Handlers\QueryHandlerRegistry::get_instance();
		$this->register_default_handlers();
		add_action( 'rest_api_init', [ $this, 'register_routes' ] );

		/**
		 * Allows themes and plugins to register their own custom query handlers.
		 *
		 * @param Handlers\QueryHandlerRegistry $registry The registry instance.
		 */
		apply_filters( 'adpresso_register_query_handlers', $this->query_handler_registry );
	}

	/**
	 * Registers the default handlers for core filtering and sorting capabilities.
	 */
	private function register_default_handlers(): void {
		$this->query_handler_registry->register( new Handlers\PostStatusQueryHandler() );
		$this->query_handler_registry->register( new Handlers\AuthorQueryHandler() );
		$this->query_handler_registry->register( new Handlers\IdQueryHandler() );
		$this->query_handler_registry->register( new Handlers\TitleQueryHandler() );
		$this->query_handler_registry->register( new Handlers\ConditionsQueryHandler() );
		$this->query_handler_registry->register( new Handlers\UsedInQueryHandler() );
		$this->query_handler_registry->register( new Handlers\DateQueryHandler() );

		// A generic handler for simple meta-queries based on a mapping.
		$this->query_handler_registry->register( new Handlers\MetaQueryHandler( [
			'ads'        => [ 'type' => Constants::META_PREFIX . 'ad_type' ],
			'placements' => [ 'type' => Constants::META_PREFIX . 'placement_type' ],
			'groups'     => [ 'output_type' => Constants::META_PREFIX . 'output' ],
		] ) );

		// Sort Handler ---
		$sort_map = apply_filters( 'adpresso_rest_sortable_columns_map', [
			'id'            => 'ID',
			'title'         => 'title',
			'status'        => 'status',
			'date'          => 'date',
			'date_modified' => 'modified',
			'author'        => 'author',
			'conditions'    => [ 'meta_key' => Constants::META_PREFIX . 'conditions_tree' ],
			'preview'       => [ 'meta_key' => Constants::META_PREFIX . 'image_id', 'orderby' => 'meta_value_num' ],
			'target_url'    => [ 'meta_key' => Constants::META_PREFIX . 'target_url' ],
			'refresh'       => [
				'meta_key' => Constants::META_PREFIX . 'refresh',
				'orderby'  => 'meta_value_num',
			],
		] );
		$this->query_handler_registry->register( new Handlers\SortQueryHandler( $sort_map ) );
	}

	/**
	 * Registers all REST API routes for this controller.
	 * This method is called by the main plugin's hook system.
	 */
	public function register_routes(): void {
		// Route for the collection (e.g., GET /wp-json/adpresso/v1/ads)
		register_rest_route( $this->namespace, '/' . $this->rest_base, [
			[
				'methods'             => WP_REST_Server::READABLE,
				'callback'            => [ $this, 'get_items' ],
				'permission_callback' => [ $this, 'get_items_permissions_check' ],
				'args'                => $this->get_collection_params(),
			],
			[
				'methods'             => WP_REST_Server::CREATABLE,
				'callback'            => [ $this, 'create_item' ],
				'permission_callback' => [ $this, 'create_item_permissions_check' ],
				'args'                => $this->get_endpoint_args_for_item_schema( WP_REST_Server::CREATABLE ),
			],
		] );

		// Route for a single item (e.g., GET /wp-json/adpresso/v1/ads/123)
		register_rest_route( $this->namespace, '/' . $this->rest_base . '/(?P<id>[\d]+)', [
			[
				'methods'             => WP_REST_Server::READABLE,
				'callback'            => [ $this, 'get_item' ],
				'permission_callback' => [ $this, 'get_item_permissions_check' ],
				'args'                => [
					'context' => $this->get_context_param(),
				],
			],
			[
				'methods'             => WP_REST_Server::EDITABLE,
				'callback'            => [ $this, 'update_item' ],
				'permission_callback' => [ $this, 'update_item_permissions_check' ],
				'args'                => $this->get_endpoint_args_for_item_schema( WP_REST_Server::EDITABLE ),
			],
			[
				'methods'             => WP_REST_Server::DELETABLE,
				'callback'            => [ $this, 'delete_item' ],
				'permission_callback' => [ $this, 'delete_item_permissions_check' ],
				'args'                => [
					'force' => [ 'type' => 'boolean', 'default' => false ],
				],
			],
		] );

		register_rest_route( $this->namespace, '/schema/(?P<entity_type>[\w-]+)', [
			[
				'methods'             => WP_REST_Server::READABLE,
				'callback'            => [ $this, 'get_item_schema_data' ],
				'permission_callback' => [ $this, 'create_item_permissions_check' ],
				'args'                => [
					'entity_type' => [ 'required' => true, 'type' => 'string' ],
				],
			],
		] );
	}

	// Methods to be implemented by child classes ---
	abstract public function get_items( WP_REST_Request $request ): WP_REST_Response|WP_Error;

	abstract public function get_item( WP_REST_Request $request ): WP_REST_Response|WP_Error;

	abstract public function create_item( WP_REST_Request $request ): WP_REST_Response|WP_Error;

	abstract public function update_item( WP_REST_Request $request ): WP_REST_Response|WP_Error;

	abstract public function delete_item( WP_REST_Request $request ): WP_REST_Response|WP_Error;

	abstract public function get_items_permissions_check( WP_REST_Request $request ): bool|WP_Error;

	abstract public function get_item_permissions_check( WP_REST_Request $request ): bool|WP_Error;

	abstract public function create_item_permissions_check( WP_REST_Request $request ): bool|WP_Error;

	abstract public function update_item_permissions_check( WP_REST_Request $request ): bool|WP_Error;

	abstract public function delete_item_permissions_check( WP_REST_Request $request ): bool|WP_Error;

	abstract protected function get_collection_params(): array;

	abstract protected function get_endpoint_args_for_item_schema( string $method ): array;

	/**
	 * Get the context parameters.
	 *
	 * @param array $args
	 *
	 * @return array
	 */
	protected function get_context_param( array $args = [] ): array {
		return array_merge( [
			'description' => 'Scope under which the request is made; determines fields returned.',
			'type'        => 'string',
			'enum'        => [ 'view', 'edit' ],
			'default'     => 'view',
		], $args );
	}

	/**
	 * Builds the WP_Query arguments from the REST request parameters
	 * by delegating to the registered Query Handlers.
	 *
	 * @param WP_REST_Request $request The request object.
	 *
	 * @return array The arguments for WP_Query.
	 */
	protected function build_query_args( WP_REST_Request $request ): array {
		$params      = $request->get_params();
		$entity_type = $this->rest_base; // e.g., 'ads', 'groups'

		$args = [
			'post_type'      => $this->post_type,
			'post_status'    => 'any',
			'posts_per_page' => $params['per_page'],
			'paged'          => $params['page'],
			'order'          => ( strtolower( $params['order'] ) === 'asc' ) ? 'ASC' : 'DESC',
		];

		// Apply Sorting
		$orderby_key  = $params['orderby'];
		$sort_handler = $this->query_handler_registry->find( 'orderby', $entity_type );
		if ( $sort_handler ) {
			$args = $sort_handler->apply( $args, $orderby_key, $entity_type );
		} else {
			$args['orderby'] = 'date'; // Default fallback
		}

		// Apply Search Term
		if ( ! empty( $params['s'] ) ) {
			$args['s'] = $params['s'];
		}

		// Apply Filters
		$filters         = $params['filters'] ?? [];
		$args['filters'] = $filters;
		foreach ( $filters as $filter_key => $filter_value ) {
			if ( empty( $filter_value ) ) {
				continue;
			}

			$filter_handler = $this->query_handler_registry->find( (string) $filter_key, $entity_type );
			if ( $filter_handler ) {
				$args = $filter_handler->apply( $args, $filter_value, $entity_type );
			}
		}

		return $args;
	}

	/**
	 * Returns the UI schema and default values for creating a new item.
	 *
	 * @param WP_REST_Request $request
	 *
	 * @return WP_REST_Response|WP_Error
	 */
	public function get_item_schema_data( WP_REST_Request $request ): WP_REST_Response|WP_Error {
		$entity_type_slug = $request->get_param( 'entity_type' );

		$entity = $this->create_empty_entity( $entity_type_slug );

		if ( ! $entity ) {
			return new WP_Error( 'rest_invalid_entity_type', 'invalid entity type' );
		}

		$response_data = $entity->prepare_for_rest_response();

		// Override ID to signal that it's a new entity.
		$response_data['id']     = 0;
		$response_data['title']  = '';
		$response_data['status'] = 'publish';

		// We need to ensure that 'meta_data' is not empty.
		// We return default metadata for virtual entities.
		$response_data['meta_data'] = $entity->get_default_meta_data();

		return new WP_REST_Response( $response_data, 200 );
	}

	/**
	 * Helper to create an empty entity instance based on slug.
	 *
	 * @param string $slug
	 *
	 * @return Entity|null
	 */
	private function create_empty_entity( string $slug ): ?Entity {
		return match ( $slug ) {
			'ads' => new Ad( null ),
			'groups' => new Group( null ),
			'placements' => new Placement( null ),
			default => null,
		};
	}
}