Custom Post Type Metabox Class

cpt-metabox.php

<?php
/**
 * Custom Post Type Meta Box.
 *
 * @package Heartland
 */

/**
 * Meta box class.
 */
class Heartland_Core_Meta_Box {
	/**
	 * Meta box data.
	 *
	 * @var array
	 */
	protected $meta_box;

	/**
	 * Create meta box based on given data.
	 *
	 * @param array $meta_box Meta box data.
	 */
	public function __construct( $meta_box ) {
		$this->meta_box = $meta_box;
		add_action( 'admin_menu', array( $this, 'add' ) );
		add_action( 'save_post', array( $this, 'save' ) );
		add_action( 'admin_menu', array( $this, 'metahide' ) );
	}

	/**
	 * Hides the custom meta box from locations.
	 */
	public function metahide() {
		if ( empty( $this->meta_box['posts'] ) ) {
			return;
		}

		remove_meta_box( 'postcustom', $this->meta_box['posts'], 'normal' );
	}

	/**
	 * Add meta box for multiple post types.
	 */
	public function add() {
		if ( empty( $this->meta_box['posts'] ) ) {
			return;
		}

		foreach ( $this->meta_box['posts'] as $page ) {
			add_meta_box( $this->meta_box['id'], $this->meta_box['title'], array( $this, 'show' ), $page, $this->meta_box['context'], $this->meta_box['priority'] );
		}
	}

	/**
	 * Callback function to show fields in meta box.
	 */
	public function show() {
		global $post;

		/**
		 * Use nonce for verification.
		 */
		echo '<input type="hidden" name="heartland_core_prefix_meta_box_nonce" value="' . esc_attr( wp_create_nonce( basename( __FILE__ ) ) ), '" />';

		echo '<table class="form-table">';

		foreach ( $this->meta_box['fields'] as $field ) {
			/**
			 * Get current post meta data.
			 */
			$meta       = get_post_meta( $post->ID, $field['id'], true );
			$field_name = 'heartland_core_' . $field['id'];

			?>

			<tr>
				<th style="width:20%">
					<label for="<?php echo esc_attr( $field_name ); ?>"><?php echo esc_html( $field['name'] ); ?></label>
				</th>
				<td>

			<?php

			switch ( $field['type'] ) {
				case 'thumbnail':
					$default_url      = \Elementor\Utils::get_placeholder_image_src();
					$featured_img_url = $default_url;

					if ( $meta ) {
						$featured_img_url = wp_get_attachment_url( $meta, 'medium' );
					}

					?>
					<div class="editor-post-featured-image__preview" style="display: inline-block; max-width: 160px;">
						<img data-default-url="<?php echo esc_url( $default_url ); ?>" id="<?php echo esc_attr( $field_name ); ?>_image" src="<?php echo esc_url( $featured_img_url ); ?>" class="editor-post-featured-image__preview-image" />
					</div>

					<input type="hidden" name="<?php echo esc_attr( $field_name ); ?>" id="<?php echo esc_attr( $field_name ); ?>" value="<?php echo esc_attr( $meta ); ?>" />
					<button type="button" id="<?php echo esc_attr( $field_name ); ?>_select" class="button heartland-core-upload-button"><?php esc_html_e( 'Select Image', 'heartland' ); ?></button>
					<button type="button" id="<?php echo esc_attr( $field_name ); ?>_remove" class="button heartland-core-remove-button"><?php esc_html_e( 'Remove Image', 'heartland' ); ?></button>
					<br>

					<script>
						document.getElementById('<?php echo esc_attr( $field_name ); ?>_select').addEventListener('click', function() {
							var custom_uploader = wp.media({
								title: 'Select Image',
								button: {
									text: 'Use this image',
								},
								multiple: false,
							}).on('select', function() {
								var attachment = custom_uploader.state().get('selection').first().toJSON();
								document.getElementById('<?php echo esc_attr( $field_name ); ?>').value = attachment.id;
								document.getElementById('<?php echo esc_attr( $field_name ); ?>_image').src = attachment.url;
							}).open();
						});

						document.getElementById('<?php echo esc_attr( $field_name ); ?>_remove').addEventListener('click', function() {
							document.getElementById('<?php echo esc_attr( $field_name ); ?>').value = '';

							const image = document.getElementById('<?php echo esc_attr( $field_name ); ?>_image');
							image.src = image.getAttribute('data-default-url');
						});
					</script>

					<?php
					echo esc_html( $field['desc'] );

					break;
				case 'text':
					?>
					<input type="text" name="<?php echo esc_attr( $field_name ); ?>" id="<?php echo esc_attr( $field_name ); ?>" value="<?php echo esc_attr( $meta ? $meta : $field['std'] ); ?>" size="30" style="width:97%" />
					<br>
					<?php
					echo esc_html( $field['desc'] );

					break;
				case 'textarea':
					?>

					<textarea name="<?php echo esc_attr( $field_name ); ?>" id="<?php echo esc_attr( $field_name ); ?>" cols="60" rows="4" style="width:97%"><?php echo esc_html( $meta ? $meta : $field['std'] ); ?></textarea>
					<br>
					<?php
					echo esc_html( $field['desc'] );

					break;
				case 'select':
					?>
					<select name="<?php echo esc_attr( $field_name ); ?>" id="<?php echo esc_attr( $field_name ); ?>">
					<?php
					foreach ( $field['options'] as $option ) {
						?>
						<option value="<?php echo esc_attr( $option['value'] ); ?>"<?php selected( $meta, $option['value'] ); ?>><?php echo esc_html( $option['name'] ); ?></option>
						<?php
					}
					?>
					</select>
					<br>
					<?php
					echo esc_html( $field['desc'] );

					break;
				case 'radio':
					foreach ( $field['options'] as $option ) {
						?>
						<input type="radio" name="<?php echo esc_attr( $field_name ); ?>" value="<?php echo esc_attr( $option['value'] ); ?>"<?php checked( $meta, $option['value'] ); ?> />
						<?php
						echo esc_html( $option['name'] );
					}
					echo '<br>' . esc_html( $field['desc'] );

					break;

				case 'checkbox':
					foreach ( $field['options'] as $option ) {
						?>
						<input type="checkbox" name="<?php echo esc_attr( $field_name ); ?>" value="<?php echo esc_attr( $option['value'] ); ?>"<?php checked( $meta, $option['value'] ); ?> />
						<?php
						echo esc_html( $option['name'] );
					}
					echo '<br>' . esc_html( $field['desc'] );

					break;
			}

			echo '<td></tr>';
		}

		echo '</table>';
	}

	/**
	 * Save data from meta box
	 *
	 * @param int $post_id Post ID.
	 */
	public function save( $post_id ) {
		/**
		 * Verify nonce.
		 */
		$nonce_safe = isset( $_POST['heartland_core_prefix_meta_box_nonce'] ) ? sanitize_text_field( wp_unslash( $_POST['heartland_core_prefix_meta_box_nonce'] ) ) : false;

		if ( ! isset( $_POST['heartland_core_prefix_meta_box_nonce'] ) || ! wp_verify_nonce( $nonce_safe, basename( __FILE__ ) ) ) {
				return $post_id;
		}

		/**
		 * Check autosave.
		 */
		if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
			return $post_id;
		}

		/**
		 * Check permissions.
		 */
		if ( ! empty( $_POST['post_type'] ) && 'page' === $_POST['post_type'] ) {
			if ( ! current_user_can( 'edit_page', $post_id ) ) {
				return $post_id;
			}
		} elseif ( ! current_user_can( 'edit_post', $post_id ) ) {
			return $post_id;
		}

		foreach ( $this->meta_box['fields'] as $field ) {
			$old        = get_post_meta( $post_id, $field['id'], true );
			$field_name = 'heartland_core_' . $field['id'];
			$new        = empty( $_POST[ $field_name ] ) ? '' : sanitize_text_field( wp_unslash( $_POST[ $field_name ] ) );

			if ( $new && $new !== $old ) {
				update_post_meta( $post_id, $field['id'], $new );
			} elseif ( '' === $new && $old ) {
				delete_post_meta( $post_id, $field['id'], $old );
			}
		}
	}
}