// api.js — shared fetch helpers and utilities used by every page

const API = {
    async _fetch(url, options = {}) {
        const headers = { 'Content-Type': 'application/json' };
        const res = await fetch(url, { credentials: 'include', headers, ...options });

        if (res.status === 401) {
            localStorage.removeItem('user');
            window.location.href = '/login';
            return;
        }

        if (!res.ok) {
            const err = await res.json().catch(() => ({ detail: res.statusText }));
            throw new Error(err.detail || `Request failed (${res.status})`);
        }
        if (res.status === 204) return null;   // DELETE returns No Content
        return res.json();
    },

    // GET requests retry up to 3 times with exponential backoff on network errors or 5xx.
    // Mutating methods (POST/PUT/DELETE) are not retried — they are not idempotent.
    async _fetchWithRetry(url, options = {}) {
        const isReadOnly = !options.method || options.method === 'GET';
        const delays = [500, 1000, 2000];
        let lastErr;
        const attempts = isReadOnly ? 3 : 1;
        for (let i = 0; i < attempts; i++) {
            try {
                return await API._fetch(url, options);
            } catch (err) {
                lastErr = err;
                // Don't retry client errors (4xx) or if it's the last attempt
                const is5xx = err.message.match(/\(5\d\d\)/);
                if ((!isReadOnly || (!is5xx && !err.message.includes('Failed to fetch'))) || i === attempts - 1) throw err;
                await new Promise(r => setTimeout(r, delays[i]));
            }
        }
        throw lastErr;
    },

    get:  (url)       => API._fetchWithRetry(url),
    post: (url, data) => API._fetchWithRetry(url, { method: 'POST',   body: JSON.stringify(data) }),
    put:  (url, data) => API._fetchWithRetry(url, { method: 'PUT',    body: JSON.stringify(data) }),
    del:  (url)       => API._fetchWithRetry(url, { method: 'DELETE' }),
};

// ── Offline indicator ─────────────────────────────────────────────────────────

function _setOfflineBanner(offline) {
    let banner = document.getElementById('offline-banner');
    if (offline) {
        if (!banner) {
            banner = document.createElement('div');
            banner.id = 'offline-banner';
            banner.textContent = 'You are offline — changes cannot be saved';
            document.body.prepend(banner);
        }
    } else {
        if (banner) banner.remove();
    }
}

window.addEventListener('online',  () => _setOfflineBanner(false));
window.addEventListener('offline', () => _setOfflineBanner(true));
document.addEventListener('DOMContentLoaded', () => _setOfflineBanner(!navigator.onLine));

// Show a timed success or error message inside a .message element
function showMessage(el, text, type = 'success') {
    el.textContent = text;
    el.className = `message ${type} visible`;
    setTimeout(() => { el.className = 'message'; }, 4000);
}

// Set an input[type=date] to today's date in the user's configured timezone
function setToday(inputEl) {
    const tz = (typeof Auth !== 'undefined' && Auth.getUser()?.timezone)
        || Intl.DateTimeFormat().resolvedOptions().timeZone
        || 'UTC';
    // en-CA locale produces YYYY-MM-DD which is what date inputs expect
    inputEl.value = new Date().toLocaleDateString('en-CA', { timeZone: tz });
}

// Format YYYY-MM-DD → MM/DD/YYYY for display
function fmtDate(str) {
    if (!str) return '—';
    const [y, m, d] = str.split('-');
    return `${m}/${d}/${y}`;
}

// Format a number as a dollar amount
function fmtMoney(val) {
    if (val == null || val === '' || isNaN(Number(val))) return '—';
    return '$' + Number(val).toFixed(2);
}

// Format a small decimal (cost per egg) with 4 decimal places
function fmtMoneyFull(val) {
    if (val == null || val === '' || isNaN(Number(val))) return '—';
    return '$' + Number(val).toFixed(4);
}

// Escape HTML special characters to prevent XSS when rendering user content
function escHtml(str) {
    if (!str) return '';
    return str
        .replace(/&/g, '&amp;')
        .replace(/</g, '&lt;')
        .replace(/>/g, '&gt;')
        .replace(/"/g, '&quot;')
        .replace(/'/g, '&#39;');
}

// Highlight the nav link that matches the current page
function highlightNav() {
    const path = window.location.pathname.replace(/\.html$/, '').replace(/\/$/, '') || '/';
    document.querySelectorAll('.nav-links a').forEach(a => {
        const href = a.getAttribute('href').replace(/\/$/, '') || '/';
        if (href === path) a.classList.add('active');
    });
}

document.addEventListener('DOMContentLoaded', highlightNav);