Add a new endpoint template-loader to resolve the correct template by type

projects/plugins/jetpack/_inc/lib/core-api/wpcom-endpoints/class-wpcom-rest-api-v2-endpoint-template-loader.php

@@ -0,0 +1,119 @@
+<?php
+/**
+ * REST API endpoint for resolving template.
+ *
+ * @package automattic/jetpack
+ */
+
+/**
+ * Returns the correct template for the site's page based on the template type
+ */
+class WPCOM_REST_API_V2_Endpoint_Template_Loader extends WP_REST_Controller {
+	/**
+	 * Constructor.
+	 */
+	public function __construct() {
+		$this->namespace = 'wpcom/v2';
+		$this->rest_base = 'template-loader';
+
+		add_action( 'rest_api_init', array( $this, 'register_routes' ) );
+	}
+
+	/**
+	 * Called automatically on `rest_api_init()`.
+	 */
+	public function register_routes() {
+		register_rest_route(
+			$this->namespace,
+			sprintf(
+				'/%s/(?P<template_type>\w+)',
+				$this->rest_base
+			),
+			array(
+				'methods'             => WP_REST_Server::READABLE,
+				'callback'            => array( $this, 'get_item' ),
+				'permission_callback' => array( $this, 'permissions_check' ),
+				'args'                => array(
+					'template_type' => array(
+						'description'       => __( 'The type of the template.', 'jetpack' ),
+						'type'              => 'string',
+						'required'          => true,
+						'validate_callback' => array( $this, 'validate_template_type' ),
+					),
+				),
+			)
+		);
+	}
+
+	/**
+	 * Checks if the user has permissions to make the request.
+	 *
+	 * @return true|WP_Error True if the request has read access, WP_Error object otherwise.
+	 */
+	public function permissions_check() {
+		// Verify if the current user has edit_theme_options capability.
+		// This capability is required to edit/view/delete templates.
+		if ( ! current_user_can( 'edit_theme_options' ) ) {
+			return new WP_Error(
+				'rest_cannot_manage_templates',
+				__( 'Sorry, you are not allowed to access the templates on this site.', 'jetpack' ),
+				array(
+					'status' => rest_authorization_required_code(),
+				)
+			);
+		}
+
+		return true;
+	}
+
+	/**
+	 * Validate the template type.
+	 *
+	 * @param string $template_type The template type.
+	 * @return boolean True if the template type is valid.
+	 */
+	public function validate_template_type( $template_type ) {
+		$template_types = array_keys( get_default_block_template_types() );
+		if ( ! in_array( $template_type, $template_types, true ) ) {
+			return new WP_Error(
+				'rest_invalid_param',
+				sprintf(
+					/* translators: %s: The template type. */
+					__( 'The template type %s are not allowed.', 'jetpack' ),
+					$template_type
+				),
+				array( 'status' => 400 )
+			);
+		}
+
+		return true;
+	}
+
+	/**
+	 * Retrieves the template by specified type.
+	 *
+	 * @param WP_REST_Request $request Full details about the request.
+	 * @return WP_REST_Response|WP_Error Response object on success, or WP_Error object on failure.
+	 */
+	public function get_item( $request ) {
+		$template_type = $request['template_type'];
+
+		// A list of template candidates, in descending order of priority.
+		$templates      = apply_filters( "{$template_type}_template_hierarchy", array( "{$template_type}.php" ) );
+		$template       = locate_template( $templates );
+		$block_template = resolve_block_template( $template_type, $templates, $template );
+
+		if ( empty( $block_template ) ) {
+			return new WP_Error( 'not_found', 'Template not found', array( 'status' => 404 ) );
+		}
+
+		return rest_ensure_response(
+			array(
+				'type' => $block_template->type,
+				'id'   => $block_template->id,
+			)
+		);
+	}
+}
+
+wpcom_rest_api_v2_load_plugin( 'WPCOM_REST_API_V2_Endpoint_Template_Loader' );

projects/plugins/jetpack/changelog/add-wpcom-v2-template-loader-endpoint

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+Significance: minor
+Type: other
+
+Add a new endpoint, template-loader, to resolve the correct template by its type