class Checkout
{

    const AMAZON_PAY_BUTTON_ID = 'AmazonPayButton';
    const AMAZON_CHECKOUT_JS_SLUG = 'amazon-checkout';
    const WCEXAAP_CHECKOUT_JS_SLUG = 'wcexaap-checkout';

    /**
     * AmazonPay module instance
     *
     * @var AmazonPay
     */
    private $module;

    /**
     * Sets `$module` member var
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @param AmazonPay $module
     */
    public function __construct(AmazonPay $module) {
        $this->module = $module;
    }

    /**
     * Returns variables that the Amazon checkout JS depends on
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @return array
     */
    protected function getCheckoutInjectionVariables() {
        $opts = $this->module->getActingOpts();
        return [
            'amzjsurl' => $opts['amzjsurl'],
            'sandbox' => $opts['sandbox'],
            'merchantId' => $opts['merchant_id'],
            'ledgerCurrency' => $opts['ledgerCurrency'],
            'checkoutLanguage' => $opts['checkoutLanguage'],
            'publicKeyId' => $opts['public_key_id'],
        ];
    }

    /**
     * Enqueues Amazon checkout JS
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @param string $checkoutEndpoint
     * @param string $placement
     * @param string $productType
     * @return void
     */
    public function load($checkoutEndpoint, $placement, $productType = 'PayAndShip') {
        $semantic = new Semantic();
        $semantic->loadToastCss();
        $semantic->loadTransitionCss();
        $semantic->loadSemanticJS();

        wp_enqueue_script(
            self::AMAZON_CHECKOUT_JS_SLUG,
            $this->module->getActingOpts()['amzjsurl'] . '/checkout.js',
            [],
            WCEXAAP_VERSION,
            false
        );

        wp_enqueue_script(
            self::WCEXAAP_CHECKOUT_JS_SLUG,
            WCEXAAP_PLUGIN_URL . '/dist/checkout.js',
            [self::AMAZON_CHECKOUT_JS_SLUG],
            WCEXAAP_VERSION,
            true
        );

        wp_localize_script(
            self::WCEXAAP_CHECKOUT_JS_SLUG,
            AmazonPay::L10N,
            array_merge(
                $this->module->getScriptInjectionVariables(),
                $this->getCheckoutInjectionVariables(),
                [
                    'checkoutEndpoint' => $checkoutEndpoint,
                    'productType' => $productType,
                    'placement' => $placement,
                ]
            )
        );
    }

    /**
     * Returns AmazonPay button div
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @return string
     */
    public static function getAmazonPayButton() {
        return '<div id="' . self::AMAZON_PAY_BUTTON_ID . '"></div>';
    }
}