Automattic / jetpack

json-endpoints/class.wpcom-json-api-autosave-post-v1-1-endpoint.php

<?php
class WPCOM_JSON_API_Autosave_Post_v1_1_Endpoint extends WPCOM_JSON_API_Post_v1_1_Endpoint {
	function __construct( $args ) {
		parent::__construct( $args );
	}

	// /sites/%s/posts/%d/autosave -> $blog_id, $post_id
	function callback( $path = '', $blog_id = 0, $post_id = 0 ) {

		$blog_id = $this->api->switch_to_blog_and_validate_user( $this->api->get_blog_id( $blog_id ) );

Consider using a different name than the parameter $blog_id. This often makes code more readable.

		if ( is_wp_error( $blog_id ) ) {
			return $blog_id;
		}

		$args = $this->query_args();

		$input = $this->input( false );

		if ( ! is_array( $input ) || ! $input ) {
			return new WP_Error( 'invalid_input', 'Invalid request input', 400 );
		}

		$post = get_post( $post_id );

		if ( ! $post || is_wp_error( $post ) ) {
			return new WP_Error( 'unknown_post', 'Unknown post', 404 );
		}

		if ( ! current_user_can( 'edit_post', $post->ID ) ) {
			return new WP_Error( 'unauthorized', 'User cannot edit post', 403 );
		}

		$post_data = array (
			'post_ID'      => $post_id,
			'post_title'   => $input['title'],
			'post_content' => $input['content'],
			'post_excerpt' => $input['excerpt'],
		);

		$preview_url = add_query_arg( 'preview', 'true', get_permalink( $post->ID ) );

		if ( ! wp_check_post_lock( $post->ID ) &&
			 get_current_user_id() == $post->post_author &&
			 ( 'auto-draft' == $post->post_status || 'draft' == $post->post_status )
		) {
			// Drafts and auto-drafts are just overwritten by autosave for the same user if the post is not locked
			$auto_ID = edit_post( wp_slash( $post_data ) );
		} else {
			// Non drafts or other users drafts are not overwritten. The autosave is stored in a special post revision for each user.
			$auto_ID = wp_create_post_autosave( wp_slash( $post_data ) );
			$nonce = wp_create_nonce( 'post_preview_' . $post->ID );
			$preview_url = add_query_arg( array( 'preview_id' => $auto_ID, 'preview_nonce' => $nonce ), $preview_url );
		}

		$updated_post = get_post( $auto_ID );

		if ( $updated_post && $updated_post->ID && $updated_post->post_modified ) {
			return array(
				'ID'          => $auto_ID,
				'post_ID'     => $post->ID,
				'modified'    => $this->format_date( $updated_post->post_modified ),
				'preview_URL' => $preview_url
			);
		} else {
			return new WP_Error( 'autosave_error', __( 'Autosave encountered an unexpected error', 'jetpack' ), 500 );
		}
	}
}