/* global usScheduler, Stripe */
(function () {
    'use strict';

    const { restUrl, nonce, stripeKey } = usScheduler;

    function apiFetch(path, options = {}) {
        return fetch(restUrl + path, {
            ...options,
            headers: {
                'Content-Type': 'application/json',
                'X-WP-Nonce': nonce,
                ...(options.headers || {}),
            },
        }).then(async (res) => {
            const data = await res.json();
            if (!res.ok) throw new Error(data.message || 'Request failed');
            return data;
        });
    }

    function escHtml(str) {
        return String(str)
            .replace(/&/g, '&')
            .replace(/</g, '&lt;')
            .replace(/>/g, '&gt;')
            .replace(/"/g, '&quot;');
    }

    function money(amount, currency) {
        return `${Number(amount).toFixed(2)} ${escHtml(currency || '')}`.trim();
    }

    // Render Stripe's Payment Element into mountEl and resolve once the card has
    // been confirmed. The server is told the result out-of-band via webhook, so a
    // successful confirm here just means "the charge is on its way".
    function confirmCard(intent, mountEl) {
        return new Promise((resolve, reject) => {
            if (typeof Stripe === 'undefined') {
                reject(new Error('Card payment is unavailable right now. Please try again later.'));
                return;
            }

            const stripe = Stripe(intent.publishable_key || stripeKey);
            const elements = stripe.elements({ clientSecret: intent.client_secret });
            const paymentEl = elements.create('payment');

            mountEl.innerHTML = `
                <div class="us-pay">
                    <h3>Payment</h3>
                    <p>Amount due: ${money(intent.amount, intent.currency)}</p>
                    <div id="us-card-element"></div>
                    <div id="us-card-error" role="alert" class="us-card-error" style="display:none;"></div>
                    <p><button type="button" id="us-pay-btn" class="us-book-btn">Pay now</button></p>
                </div>`;
            paymentEl.mount('#us-card-element');

            const payBtn = mountEl.querySelector('#us-pay-btn');
            const cardError = mountEl.querySelector('#us-card-error');

            payBtn.addEventListener('click', () => {
                payBtn.disabled = true;
                cardError.style.display = 'none';
                stripe.confirmPayment({ elements, redirect: 'if_required' })
                    .then((result) => {
                        if (result.error) {
                            cardError.textContent = result.error.message;
                            cardError.style.display = 'block';
                            payBtn.disabled = false;
                            return;
                        }
                        resolve(intent);
                    })
                    .catch((err) => {
                        cardError.textContent = err.message;
                        cardError.style.display = 'block';
                        payBtn.disabled = false;
                    });
            });
        });
    }

    // Public helper used by the booking and group-class flows. Given a freshly
    // created registration, drive its payment step and resolve with the intent
    // result (method card/etransfer/comp) so the caller can show a message.
    window.usPayment = {
        collect(type, registrationId, mountEl) {
            if (!registrationId) {
                return Promise.resolve(null);
            }

            return apiFetch('payments/intent', {
                method: 'POST',
                body: JSON.stringify({ registration_type: type, registration_id: registrationId }),
            }).then((intent) => {
                if (intent.method === 'card' && intent.client_secret) {
                    return confirmCard(intent, mountEl);
                }
                return intent;
            });
        },

        // Human-readable confirmation copy for a completed payment step.
        message(result) {
            if (!result) {
                return 'Your registration is confirmed.';
            }
            if (result.method === 'etransfer') {
                const where = result.etransfer_email
                    ? ` to ${escHtml(result.etransfer_email)}`
                    : '';
                return `Please send an e-transfer of ${money(result.amount, result.currency)}${where}. `
                    + 'Your spot is reserved and will be confirmed once payment is received.';
            }
            if (result.method === 'card') {
                return 'Thank you — your payment is processing. Your registration will be confirmed shortly.';
            }
            return 'Your registration is confirmed.';
        },
    };
}());