2. Construct

__construct()

public function __construct() {
	// Define gateway unique slug
	$this->unique_id = 'sample';

	// Add gateway options to Admin > Jobster Settings > Payment Gateways
	add_action( 'wpj_after_admin_paypal_settings_fields', function() {
		if ( class_exists( 'Redux' ) ) {
			Redux::setSection( 'jobster_settings', array(
				'id'         => 'sample-settings', // settings option name
				'title'      => __( 'Sample', 'wpjobster-sample' ), // gateway settings page title
				'desc'       => __( 'Sample Settings', 'wpjobster-sample' ), // gateway settings page description
				'subsection' => true, // subsection of Payment Gateways section
				'fields'     => wpj_get_gateway_default_fields(
					array(
						'gateway_id'           => $this->unique_id, // gateway id
						'gateway_name'         => 'Sample', // gateway name
						'gateway_version'      => WPJ_SAMPLE_VERSION, // gateway version
						'gateway_instructions' => array( // gateway instructions
							'Do you have any special instructions for your gateway?',
							'You can put them here.',
						),
						'license'              => true, // include license field
						'enable'               => true, // include enable field
						'enable_sandbox'       => true, // include enable sandbox field
						'exclude_payment_type' => array( 'withdraw' ), // exclude payment types from options; accepted values: job_purchase, 'topup', 'featured', 'withdraw', 'tips', 'subscription', 'custom_extra'
						'button_name'          => true, // include button name field
						'public_key'           => false, // include public key field
						'secret_key'           => false, // include secret key field
						'succes_page_url'      => true, // include transaction success page field
						'fail_page_url'        => true, // include transaction failure page field
						'new_fields'           => array( // extra fields (optional fields)
							array(
								'unique_id' => 'sample-settings-section',
								'type'      => 'section',
								'title'     => esc_html__( 'Keys', 'wpjobster-sample' ),
								'indent'    => true,
							),
							array(
								'unique_id' => 'wpjobster_sample_id',
								'type'      => 'text',
								'title'     => __( 'Sample ID', 'wpjobster-sample' ),
							),
							array(
								'unique_id' => 'wpjobster_sample_key',
								'type'      => 'text',
								'title'     => __( 'Sample Key', 'wpjobster-sample' )
							)
						)
					)
				)
			) );
		}
	});

	// Add gateway (button) to payment methods list - add button to checkout page
	add_filter( 'wpj_payment_gateways_filter', function ( $payment_gateways_list ) {
		$payment_gateways_list[$this->unique_id] = __( 'Sample', 'wpjobster-sample' );
		return $payment_gateways_list;
	}, 10, 1 );

	// Add gateway to payment process flow - send and receive the payment info
	add_action( 'wpjobster_taketo_' . $this->unique_id . '_gateway', array( $this, 'initializePayment' ), 10, 2 );
	add_action( 'wpjobster_processafter_' . $this->unique_id . '_gateway', array( $this, 'processPayment' ), 10, 2 );

	// Use this filter if your gateway works with a specific currency only
	add_filter( 'wpjobster_take_allowed_currency_' . $this->unique_id, array( $this, 'setGatewayCurrency' ) );

	// Set plugin compatibility - prevents the plugin from activating on other themes
	add_action( 'admin_notices', array( $this, 'checkCompatibility' ) );

	// Set plugin action link - show 'Settings' link to plugins page
	add_filter( 'plugin_action_links_' . plugin_basename( __FILE__ ), function ( $links ) {
		return function_exists( 'wpj_generate_settings_link' ) ? array_merge( array( wpj_generate_settings_link( $this->unique_id ) ), $links ) : $links;
	});

	// Set plugin textdomain
	add_action( 'plugins_loaded', function () {
		load_plugin_textdomain( 'wpjobster-sample', false, trailingslashit( dirname( plugin_basename( __FILE__ ) ) ) );
	}, 0 );

	// Gateway name translatable - allows the Gateway name to be translated into other languages
	add_filter( 'wpjobster_database_strings_filter', array( $this, 'translateGatewayName' ), 10, 1 );

	// Add gateway to all plugins list
	add_filter( 'wpj_gateways_plugins_folder_list_filter', array( $this, 'addToGatwaysList' ), 10, 1 );
}

$this->unique_id - This is the lowercase name of your gateway and it really needs to be unique.

setGatewayCurrency()

public function setGatewayCurrencies( $currency ) {
	$currency = 'EUR'; return $currency;
}

This function is filtering the currency for processing the payment.

If your gateway only accepts a certain currency this is the place where you can define it.

Feel free to play around with the conditions. For example, if your gateway accepts a limited range of currencies you can check if the selected currency is in the range, otherwise return a specific currency.

checkCompatibility()

public function checkCompatibility() {
	if ( ! function_exists( 'wpj_get_wpjobster_plugins_list' ) && ! defined( 'wpjobster_VERSION' ) )
		$error = sprintf( __( 'The current theme is not compatible with the %s gateway. Activate the WPJobster theme before installing this plugin.', 'wpjobster' ), $this->unique_id );

	if ( ! empty( $error ) && is_plugin_active( plugin_basename( __FILE__ ) ) ) {

		deactivate_plugins( plugin_basename( __FILE__ ), true ); ?>

		<div data-dismissible="compatibility-theme-notice" class="notice notice-error is-dismissible"><p><?php echo $error; ?></p></div>

		<?php if ( isset( $_GET['activate'] ) ) unset( $_GET['activate'] );

	}

	do_action( 'wpj_after_plugin_compatibility_errors', WPJ_SAMPLE_VERSION, 'Sample', plugin_basename( __FILE__ ), WPJ_SAMPLE_REQUIRED_THEME_VERSION );
}<br>

This function checks if the gateway is compatible with the theme activated on the site, and if not, it will display a message and will not allow the plugin to be activated until the WPJobster theme is activated.

translateGatewayName()

public function translateGatewayName( $strings ) {
	$strings['sample'] = _x( 'Sample', 'Sample gateway', 'wpjobster-sample' );
	return $strings;
}

This function will allow the name of the plugin to be translated when it is saved as a string in the database, when an order is paid.

addToGatwaysList()

public function addToGatwaysList( $plugins ) {
	$plugins[] = 'wpjobster-sample-gateway';
	return $plugins;
}

This function will add the gateway to a WPJobster array containing all the gateways and extensions we have.