<?php
/**
 * Plugin Name: Easy Add Thumbnail
 * Plugin URI: http://wordpress.org/extend/plugins/easy-add-thumbnail/
 * Description: Checks if you defined the featured image, and if not it sets the featured image to the first uploaded image into that post. So easy like that...
 * Author: Samuel Aguilera
 * Version: 1.1.3
 * Author URI: http://www.samuelaguilera.com
 * Requires at least: 4.7
 *
 * @package Easy Add Thumbnail
 */

/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License version 3 as published by
the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

if ( function_exists( 'add_theme_support' ) ) {

	add_theme_support( 'post-thumbnails' ); // This should be in your theme. But we add this here because this way we can have featured images before switching to a theme that supports them.

	/**
	 * Main function.
	 *
	 * @param object $post Post Object.
	 */
	function easy_add_thumbnail( $post ) {

		$already_has_thumb = has_post_thumbnail();
		$post_type         = get_post_type( $post->ID );
		$exclude_types     = array( '' );
		$exclude_types     = apply_filters( 'eat_exclude_types', $exclude_types );

		// Do nothing if the post has already a featured image set.
		if ( $already_has_thumb ) {
			return;
		}

		// Do the job if the post is not from an excluded type.
		if ( ! in_array( $post_type, $exclude_types, true ) ) {

			// Get first attached image.
			$attached_image = get_children( "order=ASC&post_parent=$post->ID&post_type=attachment&post_mime_type=image&numberposts=1" );

			if ( $attached_image ) {

				$attachment_values = array_values( $attached_image );
				// Add attachment ID.
				add_post_meta( $post->ID, '_thumbnail_id', $attachment_values[0]->ID, true );

			}
		}

	}

	// Set featured image before post is displayed on the site front-end (for old posts published before enabling this plugin).
	add_action( 'the_post', 'easy_add_thumbnail' );

	// Hooks added to set the thumbnail when publishing too.
	add_action( 'new_to_publish', 'easy_add_thumbnail' );
	add_action( 'draft_to_publish', 'easy_add_thumbnail' );
	add_action( 'pending_to_publish', 'easy_add_thumbnail' );
	add_action( 'future_to_publish', 'easy_add_thumbnail' );

}