Opal-Estate-Pro/inc/message/functions.php

<?php
function opalestate_get_message_by_user( $args = [] ) {
	return [
		'items' => OpalEstate_User_Message::get_instance()->get_list( $args ),
		'total' => OpalEstate_User_Message::get_instance()->get_total( $args ),
	];
}

function opalestate_get_member_email_data( $post_id ) {
	$type = get_post_meta( $post_id, OPALESTATE_PROPERTY_PREFIX . 'author_type', true );

	$receiver_id = 0;
	switch ( $type ) {
		case 'agent':
			$agent_id = get_post_meta( $post_id, OPALESTATE_PROPERTY_PREFIX . 'agent', true );
			if ( ! $agent_id ) {
				$post        = get_post( $post_id );
				$user        = get_user_by( 'id', $post->post_author );
				$email       = $user->data->user_email;
				$name        = $user->data->display_name;
				$receiver_id = $post->post_author;
			} else {
				$user_id = get_post_meta( $agent_id, OPALESTATE_AGENT_PREFIX . 'user_id', true );
				if ( $user_id ) {
					$post        = get_post( $post_id );
					$user        = get_user_by( 'id', $user_id );
					$email       = $user->data->user_email;
					$name        = $user->data->display_name;
					$receiver_id = $post->post_author;
				} else {
					$post       = get_post( $agent_id );
					$name       = $post->post_title;
					$email      = get_post_meta( $agent_id, OPALESTATE_AGENT_PREFIX . 'email', true );
				}
			}

			break;

		case 'agency':
			$agency_id = get_post_meta( $post_id, OPALESTATE_PROPERTY_PREFIX . 'agency', true );

			if ( ! $agency_id ) {
				$post        = get_post( $post_id );
				$user        = get_user_by( 'id', $post->post_author );
				$email       = $user->data->user_email;
				$name        = $user->data->display_name;
				$receiver_id = $post->post_author;
			} else {
				$user_id = get_post_meta( $agency_id, OPALESTATE_AGENCY_PREFIX . 'user_id', true );
				if ( $user_id ) {
					$post        = get_post( $post_id );
					$user        = get_user_by( 'id', $user_id );
					$email       = $user->data->user_email;
					$name        = $user->data->display_name;
					$receiver_id = $post->post_author;
				} else {
					$post       = get_post( $agency_id );
					$name       = $post->post_title;
					$email      = get_post_meta( $agency_id, OPALESTATE_AGENCY_PREFIX . 'email', true );
				}
			}

			break;
		default:
			$post        = get_post( $post_id );
			$user        = get_user_by( 'id', $post->post_author );
			$email       = $user->data->user_email;
			$name        = $user->data->display_name;
			$receiver_id = $post->post_author;

			break;
	}

	return [
		'receiver_email' => $email,
		'receiver_name'  => $name,
		'receiver_id'    => $receiver_id,
	];
}