<?php
/**
 * MailChimp API
 *
 * @class Opt_In_Mailchimp_Api
 **/
class Opt_In_Mailchimp_Api {
	
	private $_api_key;
	private $_data_center;
	private $_user;
	
	/* 
	The <dc> part of the URL corresponds to the data center for your account. For example, if the last part of your MailChimp API key is us6, all API endpoints for your account are available at https://us6.api.mailchimp.com/3.0/.
	*/
	private $_endpoint = 'https://<dc>.api.mailchimp.com/3.0/';
	
	/**
	 * Constructs class with required data
	 *
	 * Opt_In_Mailchimp_Api constructor.
	 * @param $api_key
	 */
	function __construct( $api_key, $data_center ) {
		$this->_api_key = $api_key;
		$this->_data_center = $data_center;
		$this->_endpoint = str_replace( '<dc>', $data_center, $this->_endpoint );
		$this->_user = wp_get_current_user()->display_name;
	}
	
	/**
	 * Sends request to the endpoint url with the provided $action
	 *
	 * @param string $verb
	 * @param string $action rest action
	 * @param array $args
	 * @return object|WP_Error
	 */
	private function _request( $verb = "GET", $action, $args = array() ){
		$url = trailingslashit( $this->_endpoint )  . $action;
		
		$_args = array(
			"method" => $verb,
			"headers" =>  array(
				'Authorization' => 'apikey '. $this->_api_key,
				'Content-Type' => 'application/json;charset=utf-8'
			)
		);

		if( "GET" === $verb ){
			$url .= ( "?" . http_build_query( $args ) );
		}else{
			$_args['body'] = json_encode( $args['body'] );
		}

		$res = wp_remote_request( $url, $_args );
		
		if ( !is_wp_error( $res ) && is_array( $res ) ) {
			if( $res['response']['code'] <= 204 )
				return json_decode(  wp_remote_retrieve_body( $res ) );

			$err = new WP_Error();
			$err->add($res['response']['code'], $res['response']['message'] );
			return  $err;
		}

		return $res;
	}

	/**
	 * Sends rest GET request
	 *
	 * @param $action
	 * @param array $args
	 * @return array|mixed|object|WP_Error
	 */
	private function _get( $action, $args = array() ){
		return $this->_request( "GET", $action, $args );
	}

	/**
	 * Sends rest POST request
	 *
	 * @param $action
	 * @param array $args
	 * @return array|mixed|object|WP_Error
	 */
	private function _post( $action, $args = array()  ){
		return $this->_request( "POST", $action, $args );
	}
	
	 /**
	 * Sends rest PUT request
	 *
	 * @param $action
	 * @param array $args
	 * @return array|mixed|object|WP_Error
	 */
	private function _put( $action, $args = array()  ){
		return $this->_request( "PUT", $action, $args );
	}
	
	/**
	 * Gets all the lists
	 *
	 * @param $count - current total lists to show
	 *
	 * @return array|mixed|object|WP_Error
	 */
	public function get_lists( $count = 0 ) {
		return $this->_get( 'lists', array(
			'user' => $this->_user . ':' . $this->_api_key,
			'count' => ( $count > 0 ) ? ( $count * 10 ) : 10
		) );
	}
	
	/**
	 * Gets all the groups under a list
	 * @param $list_id
	 *
	 * @return array|mixed|object|WP_Error
	 */
	public function get_interest_categories( $list_id, $total = 10 ) {
		return $this->_get( 'lists/' . $list_id . '/interest-categories' , array(
			'user' => $this->_user . ':' . $this->_api_key, 'count' => $total
		) );
	}
	
	/**
	 * Gets all the interests under a group list
	 * @param $list_id
	 * @param $category_id
	 *
	 * @return array|mixed|object|WP_Error
	 */
	public function get_interests( $list_id, $category_id, $total = 10 ) {
		return $this->_get( 'lists/' . $list_id . '/interest-categories/' . $category_id . '/interests' , array(
			'user' => $this->_user . ':' . $this->_api_key, 'count' => $total
		) );
	}
	
	/**
	 * Check member email address if already existing
	 * @param $list_id
	 * @param $email
	 *
	 * @return array|mixed|object|WP_Error
	 */
	public function check_email( $list_id, $email ) {
		$md5_email = md5( strtolower( $email ) );
		return $this->_get( 'lists/' . $list_id . '/members/' . $md5_email, array(
			'user' => $this->_user . ':' . $this->_api_key
		) );
	}
	
	/**
	 * Add custom field for list
	 * @param $list_id
	 * @param $field_data
	 *
	 * @return array|mixed|object|WP_Error
	 */
	public function add_custom_field( $list_id, $field_data ) {
		return $this->_post( 'lists/'. $list_id .'/merge-fields', array(
			"body" =>  $field_data
		) );
	}
	
	/**
	 * Add new subscriber
	 *
	 * @param $list_id
	 * @param $data
	 * @return array|mixed|object|WP_Error
	 */
	public function subscribe( $list_id, $data ){
		$res = $this->_post( 'lists/'. $list_id .'/members', array(
			"body" =>  $data
		) );
		
		$error = __("Something went wrong, please compare your Opt-in fields with MailChimp fields and add any missing fields.", Opt_In::TEXT_DOMAIN);
		
		if ( !is_wp_error( $res ) ) {
			return __("Successful subscription", Opt_In::TEXT_DOMAIN);
		} else {
			throw new Exception($error);
		}
	}
	
	/**
	 * Update subscription
	 *
	 * @param $list_id - the list id
	 * @param $email - the email
	 * @param $data - array
	 *
	 * @return array|mixed|object|WP_Error
	 */
	public function update_subscription( $list_id, $email, $data ) {
		$md5_email = md5( strtolower( $email ) );
		$resp = $this->_put( 'lists/' . $list_id . '/members/' . $md5_email, array(
			"body" =>  $data
		) );
		$error = __("This email address has already subscribed", Opt_In::TEXT_DOMAIN);
		
		if ( !is_wp_error( $res ) ) {
			return __("You have been added to the new group", Opt_In::TEXT_DOMAIN);
		} else {
			throw new Exception( $error );
		}
	}
	
}