<?php
/**
 * WooCommerce API Resource class
 *
 * Provides shared functionality for resource-specific API classes
 *
 * @author      WooThemes
 * @category    API
 * @package     WooCommerce/API
 * @since       2.1
 */

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

class WC_API_Resource {

	/** @var WC_API_Server the API server */
	protected $server;

	/** @var string sub-classes override this to set a resource-specific base route */
	protected $base;

	/**
	 * Setup class
	 *
	 * @since 2.1
	 * @param WC_API_Server $server
	 * @return WC_API_Resource
	 */
	public function __construct( WC_API_Server $server ) {

		$this->server = $server;

		// automatically register routes for sub-classes
		add_filter( 'woocommerce_api_endpoints', array( $this, 'register_routes' ) );

		// remove fields from responses when requests specify certain fields
		// note these are hooked at a later priority so data added via filters (e.g. customer data to the order response)
		// still has the fields filtered properly
		foreach ( array( 'order', 'coupon', 'customer', 'product', 'report' ) as $resource ) {

			add_filter( "woocommerce_api_{$resource}_response", array( $this, 'maybe_add_meta' ), 15, 2 );
			add_filter( "woocommerce_api_{$resource}_response", array( $this, 'filter_response_fields' ), 20, 3 );
		}
	}

	/**
	 * Validate the request by checking:
	 *
	 * 1) the ID is a valid integer
	 * 2) the ID returns a valid post object and matches the provided post type
	 * 3) the current user has the proper permissions to read/edit/delete the post
	 *
	 * @since 2.1
	 * @param string|int $id the post ID
	 * @param string $type the post type, either `shop_order`, `shop_coupon`, or `product`
	 * @param string $context the context of the request, either `read`, `edit` or `delete`
	 * @return int|WP_Error valid post ID or WP_Error if any of the checks fails
	 */
	protected function validate_request( $id, $type, $context ) {

		if ( 'shop_order' === $type || 'shop_coupon' === $type )
			$resource_name = str_replace( 'shop_', '', $type );
		else
			$resource_name = $type;

		$id = absint( $id );

		// validate ID
		if ( empty( $id ) )
			return new WP_Error( "woocommerce_api_invalid_{$resource_name}_id", sprintf( __( 'Invalid %s ID', 'woocommerce' ), $type ), array( 'status' => 404 ) );

		// only custom post types have per-post type/permission checks
		if ( 'customer' !== $type ) {

			$post = get_post( $id, ARRAY_A );

			// TODO: redo this check, it's a bit janky
			$post_type = ( 'product_variation' === $post['post_type'] ) ? 'product' : $post['post_type'];

			// validate post type
			if ( $type !== $post_type )
				return new WP_Error( "woocommerce_api_invalid_{$resource_name}", sprintf( __( 'Invalid %s', 'woocommerce' ), $resource_name ), array( 'status' => 404 ) );

			// validate permissions
			switch ( $context ) {

				case 'read':
					if ( ! $this->is_readable( $post ) )
						return new WP_Error( "woocommerce_api_user_cannot_read_{$resource_name}", sprintf( __( 'You do not have permission to read this %s', 'woocommerce' ), $resource_name ), array( 'status' => 401 ) );
					break;

				case 'edit':
					if ( ! $this->is_editable( $post ) )
						return new WP_Error( "woocommerce_api_user_cannot_edit_{$resource_name}", sprintf( __( 'You do not have permission to edit this %s', 'woocommerce' ), $resource_name ), array( 'status' => 401 ) );
					break;

				case 'delete':
					if ( ! $this->is_deletable( $post ) )
						return new WP_Error( "woocommerce_api_user_cannot_delete_{$resource_name}", sprintf( __( 'You do not have permission to delete this %s', 'woocommerce' ), $resource_name ), array( 'status' => 401 ) );
					break;
			}
		}

		return $id;
	}

	/**
	 * Add common request arguments to argument list before WP_Query is run
	 *
	 * @since 2.1
	 * @param array $base_args required arguments for the query (e.g. `post_type`, etc)
	 * @param array $request_args arguments provided in the request
	 * @return array
	 */
	protected function merge_query_args( $base_args, $request_args ) {

		$args = array();

		// TODO: convert all dates from provided timezone into UTC
		// TODO: return all dates in provided timezone, else UTC
		// date
		if ( ! empty( $request_args['created_at_min'] ) || ! empty( $request_args['created_at_max'] ) || ! empty( $request_args['updated_at_min'] ) || ! empty( $request_args['updated_at_max'] ) ) {

			$args['date_query'] = array();

			// resources created after specified date
			if ( ! empty( $request_args['created_at_min'] ) )
				$args['date_query'][] = array( 'column' => 'post_date_gmt', 'after' => $request_args['created_at_min'], 'inclusive' => true );

			// resources created before specified date
			if ( ! empty( $request_args['created_at_max'] ) )
				$args['date_query'][] = array( 'column' => 'post_date_gmt', 'before' => $request_args['created_at_max'], 'inclusive' => true );

			// resources updated after specified date
			if ( ! empty( $request_args['updated_at_min'] ) )
				$args['date_query'][] = array( 'column' => 'post_modified_gmt', 'after' => $request_args['updated_at_min'], 'inclusive' => true );

			// resources updated before specified date
			if ( ! empty( $request_args['updated_at_max'] ) )
				$args['date_query'][] = array( 'column' => 'post_modified_gmt', 'before' => $request_args['updated_at_max'], 'inclusive' => true );
		}

		// search
		if ( ! empty( $request_args['q'] ) )
			$args['s'] = $request_args['q'];

		// resources per response
		if ( ! empty( $request_args['limit'] ) )
			$args['posts_per_page'] = $request_args['limit'];

		// resource offset
		if ( ! empty( $request_args['offset'] ) )
			$args['offset'] = $request_args['offset'];

		// resource page
		if ( empty( $request_args['page'] ) )
			$args['paged'] = 1;
		else
			$args['paged'] = absint( $request_args['page'] );

		return array_merge( $base_args, $args );
	}


	/**
	 * Add meta to resources when requested by the client. Meta is added as a top-level
	 * `<resource_name>_meta` attribute (e.g. `order_meta`) as a list of key/value pairs.
	 *
	 * @since 2.1
	 * @param array $data the resource data
	 * @param object $resource the resource object (e.g WC_Order)
	 * @return mixed
	 */
	public function maybe_add_meta( $data, $resource ) {

		if ( isset( $this->server->params['GET']['filter']['meta'] ) && 'true' === $this->server->params['GET']['filter']['meta'] ) {

			// TODO: implement
		}

		return $data;
	}

	/**
	 * Restrict the fields included in the response if the request specified certain only certain fields should be returned
	 *
	 * @TODO this should also work with sub-fields, like billing_address.country
	 *
	 * @since 2.1
	 * @param array $data the response data
	 * @param object $resource the object that provided the response data, e.g. WC_Coupon or WC_Order
	 * @param array|string the requested list of fields to include in the response
	 * @return mixed
	 */
	public function filter_response_fields( $data, $resource, $fields ) {

		if ( empty( $fields ) )
			return $data;

		$fields = explode( ',', $fields );

		foreach ( $data as $data_field => $data_value ) {

			if ( ! in_array( $data_field, $fields ) )
				unset( $data[ $data_field ] );
		}

		return $data;
	}

	/**
	 * Delete a given resource
	 *
	 * @since 2.1
	 * @param int $id the resource ID
	 * @param string $type the resource post type, or `customer`
	 * @param bool $force true to permanently delete resource, false to move to trash (not supported for `customer`)
	 * @return array|WP_Error
	 */
	protected function delete( $id, $type, $force = false ) {

		if ( 'shop_order' === $type || 'shop_coupon' === $type )
			$resource_name = str_replace( 'shop_', '', $type );
		else
			$resource_name = $type;

		if ( 'customer' === $type ) {

			$result = wp_delete_user( $id );

			if ( $result )
				return array( 'message' => __( 'Permanently deleted customer', 'woocommerce' ) );
			else
				return new WP_Error( 'woocommerce_api_cannot_delete_customer', __( 'The customer cannot be deleted', 'woocommerce' ), array( 'status' => 500 ) );

		} else {

			// delete order/coupon/product

			$result = ( $force ) ? wp_delete_post( $id, true ) : wp_trash_post( $id );

			if ( ! $result )
				return new WP_Error( "woocommerce_api_cannot_delete_{$resource_name}", sprintf( __( 'This %s cannot be deleted', 'woocommerce' ), $resource_name ), array( 'status' => 500 ) );

			if ( $force ) {
				return array( 'message' => sprintf( __( 'Permanently deleted %s', 'woocommerce' ), $resource_name ) );

			} else {

				$this->server->send_status( '202' );

				return array( 'message' => sprintf( __( 'Deleted %s', 'woocommerce' ), $resource_name ) );
			}
		}
	}


	/**
	 * Checks if the given post is readable by the current user
	 *
	 * @since 2.1
	 * @see WC_API_Resource::check_permission()
	 * @param WP_Post|int $post
	 * @return bool
	 */
	protected function is_readable( $post ) {

		return $this->check_permission( $post, 'read' );
	}

	/**
	 * Checks if the given post is editable by the current user
	 *
	 * @since 2.1
	 * @see WC_API_Resource::check_permission()
	 * @param WP_Post|int $post
	 * @return bool
	 */
	protected function is_editable( $post ) {

		return $this->check_permission( $post, 'edit' );

	}

	/**
	 * Checks if the given post is deletable by the current user
	 *
	 * @since 2.1
	 * @see WC_API_Resource::check_permission()
	 * @param WP_Post|int $post
	 * @return bool
	 */
	protected function is_deletable( $post ) {

		return $this->check_permission( $post, 'delete' );
	}

	/**
	 * Checks the permissions for the current user given a post and context
	 *
	 * @since 2.1
	 * @param WP_Post|int $post
	 * @param string $context the type of permission to check, either `read`, `write`, or `delete`
	 * @return bool true if the current user has the permissions to perform the context on the post
	 */
	private function check_permission( $post, $context ) {

		if ( ! is_a( $post, 'WP_Post' ) )
			$post = get_post( $post, ARRAY_A );

		if ( is_null( $post ) )
			return false;

		$post_type = get_post_type_object( $post['post_type'] );

		if ( 'read' === $context )
			return current_user_can( $post_type->cap->read_post, $post['ID'] );

		elseif ( 'edit' === $context )
			return current_user_can( $post_type->cap->edit_post, $post['ID'] );

		elseif ( 'delete' === $context )
			return current_user_can( $post_type->cap->delete_post, $post['ID'] );

		else
			return false;
	}

}