Mailchimp Campaign Metaboxes

class Mailchimp_Campaigns_Metaboxes {

	public function __construct() {

		if ( is_admin() ) {
			add_action( 'load-post.php',     array( $this, 'init_metabox' ) );
			add_action( 'load-post-new.php', array( $this, 'init_metabox' ) );
		}

	}

	public function init_metabox() {

		add_action( 'add_meta_boxes',        array( $this, 'add_metabox' )         );
		add_action( 'save_post',             array( $this, 'save_metabox' ), 10, 2 );

	}

	public function add_metabox() {

		add_meta_box(
			'campaign_settings',
			__( 'Mailchimp Campaign Settings', 'mailchimp-campaigns' ),
			array( $this, 'render_metabox' ),
			'dd_mailchimp',
			'advanced',
			'default'
		);

	}

	public function render_metabox( $post ) {

		// Retrieve an existing value from the database.
		$chimp_send_on = get_post_meta( $post->ID, 'chimp_send_on', true );
		$chimp_send_at = get_post_meta( $post->ID, 'chimp_send_at', true );
		$chimp_mailing_list = get_post_meta( $post->ID, 'chimp_mailing_list', true );
		$chimp_from_name = get_post_meta( $post->ID, 'chimp_from_name', true );
		$chimp_reply_to = get_post_meta( $post->ID, 'chimp_reply_to', true );
		$chimp_subject = get_post_meta( $post->ID, 'chimp_subject', true );

		// Set default values.
		if( empty( $chimp_send_on ) ) $chimp_send_on = '';
		if( empty( $chimp_send_at ) ) $chimp_send_at = '';
		if( empty( $chimp_mailing_list ) ) $chimp_mailing_list = '';
		if( empty( $chimp_from_name ) ) $chimp_from_name = '';
		if( empty( $chimp_reply_to ) ) $chimp_reply_to = '';
		if( empty( $chimp_subject ) ) $chimp_subject = '';

		// Form fields.
		echo '<table class="form-table">';

		echo '	<tr>';
		echo '		<th><label for="chimp_send_on" class="chimp_send_on_label">' . __( 'Campaign Send Date', 'mailchimp-campaigns' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="date" id="chimp_send_on" name="chimp_send_on" class="chimp_send_on_field" placeholder="' . esc_attr__( '', 'mailchimp-campaigns' ) . '" value="' . esc_attr( $chimp_send_on ) . '">';
		echo '			<p class="description">' . __( 'When do you want to send this', 'mailchimp-campaigns' ) . '</p>';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="chimp_send_at" class="chimp_send_at_label">' . __( 'Time to Send', 'mailchimp-campaigns' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="time" id="chimp_send_at" name="chimp_send_at" class="chimp_send_at_field" placeholder="' . esc_attr__( '', 'mailchimp-campaigns' ) . '" value="' . esc_attr( $chimp_send_at ) . '">';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="chimp_mailing_list" class="chimp_mailing_list_label">' . __( 'Mailing List', 'mailchimp-campaigns' ) . '</label></th>';
		echo '		<td>';
		echo '			<select id="chimp_mailing_list" name="chimp_mailing_list" class="chimp_mailing_list_field">';
		echo '			<option value="chimp_listv" ' . selected( $chimp_mailing_list, 'chimp_listv', false ) . '> ' . __( 'list 1', 'mailchimp-campaigns' ) . '</option>';
		echo '			<option value="chimp_list2" ' . selected( $chimp_mailing_list, 'chimp_list2', false ) . '> ' . __( 'List 2', 'mailchimp-campaigns' ) . '</option>';
		echo '			</select>';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="chimp_from_name" class="chimp_from_name_label">' . __( 'Campaign From', 'mailchimp-campaigns' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="text" id="chimp_from_name" name="chimp_from_name" class="chimp_from_name_field" placeholder="' . esc_attr__( '', 'mailchimp-campaigns' ) . '" value="' . esc_attr( $chimp_from_name ) . '">';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="chimp_reply_to" class="chimp_reply_to_label">' . __( 'Reply to E-Mail', 'mailchimp-campaigns' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="email" id="chimp_reply_to" name="chimp_reply_to" class="chimp_reply_to_field" placeholder="' . esc_attr__( '', 'mailchimp-campaigns' ) . '" value="' . esc_attr( $chimp_reply_to ) . '">';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="chimp_subject" class="chimp_subject_label">' . __( 'Subject Line', 'mailchimp-campaigns' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="text" id="chimp_subject" name="chimp_subject" class="chimp_subject_field" placeholder="' . esc_attr__( '', 'mailchimp-campaigns' ) . '" value="' . esc_attr( $chimp_subject ) . '">';
		echo '		</td>';
		echo '	</tr>';

		echo '</table>';

	}

	public function save_metabox( $post_id, $post ) {

		// Sanitize user input.
		$chimp_new_send_on = isset( $_POST[ 'chimp_send_on' ] ) ? sanitize_text_field( $_POST[ 'chimp_send_on' ] ) : '';
		$chimp_new_send_at = isset( $_POST[ 'chimp_send_at' ] ) ? sanitize_text_field( $_POST[ 'chimp_send_at' ] ) : '';
		$chimp_new_mailing_list = isset( $_POST[ 'chimp_mailing_list' ] ) ? $_POST[ 'chimp_mailing_list' ] : '';
		$chimp_new_from_name = isset( $_POST[ 'chimp_from_name' ] ) ? sanitize_text_field( $_POST[ 'chimp_from_name' ] ) : '';
		$chimp_new_reply_to = isset( $_POST[ 'chimp_reply_to' ] ) ? sanitize_email( $_POST[ 'chimp_reply_to' ] ) : '';
		$chimp_new_subject = isset( $_POST[ 'chimp_subject' ] ) ? sanitize_text_field( $_POST[ 'chimp_subject' ] ) : '';

		// Update the meta field in the database.
		update_post_meta( $post_id, 'chimp_send_on', $chimp_new_send_on );
		update_post_meta( $post_id, 'chimp_send_at', $chimp_new_send_at );
		update_post_meta( $post_id, 'chimp_mailing_list', $chimp_new_mailing_list );
		update_post_meta( $post_id, 'chimp_from_name', $chimp_new_from_name );
		update_post_meta( $post_id, 'chimp_reply_to', $chimp_new_reply_to );
		update_post_meta( $post_id, 'chimp_subject', $chimp_new_subject );

	}

}

new Mailchimp_Campaigns_Metaboxes;