/**
 * Timer App - Frontend
 *
 * Die Timer selbst leben auf dem Server. Der Browser zaehlt zwischen zwei
 * Server-Abgleichen nur lokal weiter, damit die Anzeige fluessig laeuft.
 * Gerechnet wird lokal ausschliesslich fuer die Anzeige - der verbindliche
 * Betrag entsteht beim Beenden auf dem Server.
 */

const state = {
    timers: [],          // {id, customerName, isRunning, baseMs, syncedAt}
    rate: { rateAmount: 10, rateInterval: 10 },
    tickHandle: null,
    syncHandle: null,
    history: { offset: 0, limit: 50, reachedEnd: false }
};

const SYNC_INTERVAL_MS = 15000;   // Abgleich mit dem Server
const TICK_INTERVAL_MS = 250;     // Anzeige-Aktualisierung

let oidcConfigured = false;       // ob Authentik erreichbar ist
let loggedInUser = null;          // {username, displayName, email} nach SSO-Login

// ---------------------------------------------------------------------------
// Hilfsfunktionen
// ---------------------------------------------------------------------------

function formatTime(ms) {
    const total = Math.floor(Math.max(0, ms) / 1000);
    const p = n => String(n).padStart(2, '0');
    return `${p(Math.floor(total / 3600))}:${p(Math.floor((total % 3600) / 60))}:${p(total % 60)}`;
}

function formatEuro(value) {
    return '€' + Number(value || 0).toLocaleString('de-DE', {
        minimumFractionDigits: Number.isInteger(Number(value)) ? 0 : 2,
        maximumFractionDigits: 2
    });
}

function calcAmount(ms) {
    if (!ms || ms <= 0) return 0;
    const minutes = Math.ceil(ms / 60000);
    const units = Math.ceil(minutes / state.rate.rateInterval);
    return Math.round(units * state.rate.rateAmount * 100) / 100;
}

/** Aktuelle Zeit eines Timers - lokal fortgeschrieben seit dem letzten Sync. */
function currentMs(timer) {
    if (!timer.isRunning) return timer.baseMs;
    return timer.baseMs + (Date.now() - timer.syncedAt);
}

function escapeHtml(str) {
    const div = document.createElement('div');
    div.textContent = str == null ? '' : String(str);
    return div.innerHTML;
}

let toastTimeout = null;
function toast(message, kind = 'info') {
    const el = document.getElementById('toast');
    el.textContent = message;
    el.className = 'toast show ' + kind;
    clearTimeout(toastTimeout);
    toastTimeout = setTimeout(() => { el.className = 'toast'; }, 4000);
}

async function api(url, options = {}) {
    const response = await fetch(url, {
        headers: { 'Content-Type': 'application/json' },
        ...options
    });
    if (response.status === 401) {
        stopLoops();
        showLogin();
        throw new Error('Nicht angemeldet');
    }
    if (!response.ok) {
        let msg = 'Serverfehler';
        try { msg = (await response.json()).error || msg; } catch (e) { /* egal */ }
        throw new Error(msg);
    }
    return response.status === 204 ? null : response.json();
}

// ---------------------------------------------------------------------------
// Ansichten
// ---------------------------------------------------------------------------

function switchView(id) {
    document.querySelectorAll('.view').forEach(v => v.classList.remove('active'));
    document.getElementById(id).classList.add('active');
}

function showLogin() {
    document.getElementById('header').style.display = 'none';
    switchView('loginView');
    applyLoginMode();
}

// Anmeldung ausschliesslich ueber Authentik. Ist Authentik nicht erreichbar,
// wird der Hinweis unter dem Button eingeblendet.
function applyLoginMode() {
    const err = document.getElementById('loginError');
    if (err) err.classList.toggle('show', !oidcConfigured);
}

function showTimer() {
    switchView('timerView');
}

async function showHistory() {
    switchView('historyView');
    state.history.offset = 0;
    state.history.reachedEnd = false;
    await loadHistory(true);
}

async function showSettings() {
    switchView('settingsView');
    await loadSettings();
}

// ---------------------------------------------------------------------------
// Anmeldung
// ---------------------------------------------------------------------------

async function checkAuth() {
    try {
        const data = await api('/api/auth/status');
        oidcConfigured = !!data.oidcConfigured;
        loggedInUser = data.user || null;
        if (data.authenticated) {
            await enterApp();
        } else {
            showLogin();
        }
    } catch (e) {
        showLogin();
    }
}

async function enterApp() {
    document.getElementById('header').style.display = 'flex';
    renderCurrentUser();
    showTimer();
    await syncTimers();
    startLoops();
}

// Zeigt den angemeldeten Authentik-Nutzer oben rechts im Header.
function renderCurrentUser() {
    const el = document.getElementById('currentUser');
    if (!el) return;
    const u = loggedInUser;
    el.textContent = u ? (u.displayName || u.username || '') : '';
    el.title = u && u.email ? u.email : 'Angemeldet';
}

async function logout() {
    const running = state.timers.filter(t => t.isRunning).length;
    if (running > 0 && !confirm(
        `${running} Timer ${running === 1 ? 'läuft' : 'laufen'} noch.\n\n` +
        `Sie laufen serverseitig weiter und sind nach dem nächsten Anmelden wieder da. Trotzdem abmelden?`
    )) return;

    stopLoops();
    state.timers = [];
    // GET-Navigation: beendet lokale Sitzung und – bei Authentik-Login – auch die SSO-Sitzung
    window.location.href = '/auth/logout';
}

// ---------------------------------------------------------------------------
// Timer-Synchronisation
// ---------------------------------------------------------------------------

async function syncTimers() {
    const data = await api('/api/timers');
    state.rate = data.rate;
    const now = Date.now();

    state.timers = data.timers.map(t => ({
        id: t.id,
        customerName: t.customerName,
        isRunning: t.isRunning,
        baseMs: t.elapsedMs,
        syncedAt: now,
        createdAt: t.createdAt
    }));

    renderTimers();
}

function startLoops() {
    stopLoops();
    state.tickHandle = setInterval(tick, TICK_INTERVAL_MS);
    state.syncHandle = setInterval(() => { syncTimers().catch(() => {}); }, SYNC_INTERVAL_MS);
}

function stopLoops() {
    clearInterval(state.tickHandle);
    clearInterval(state.syncHandle);
    state.tickHandle = null;
    state.syncHandle = null;
}

// Nach Ruhezustand/Tabwechsel sofort abgleichen statt bis zum naechsten Sync warten
document.addEventListener('visibilitychange', () => {
    if (!document.hidden && state.syncHandle) syncTimers().catch(() => {});
});

/** Aktualisiert nur die Zahlen - baut das DOM nicht neu (sonst springt der Fokus). */
function tick() {
    for (const timer of state.timers) {
        const ms = currentMs(timer);
        const timeEl = document.getElementById(`time-${timer.id}`);
        const amountEl = document.getElementById(`amount-${timer.id}`);
        if (timeEl) timeEl.textContent = formatTime(ms);
        if (amountEl) amountEl.textContent = formatEuro(calcAmount(ms));
    }
}

// ---------------------------------------------------------------------------
// Timer-Darstellung
// ---------------------------------------------------------------------------

function renderTimers() {
    const list = document.getElementById('timerList');
    const empty = document.getElementById('timerEmpty');

    document.getElementById('rateHint').textContent =
        `Tarif: ${formatEuro(state.rate.rateAmount)} pro angefangene ${state.rate.rateInterval} Minuten`;

    if (state.timers.length === 0) {
        list.innerHTML = '';
        empty.style.display = 'block';
        return;
    }
    empty.style.display = 'none';

    list.innerHTML = state.timers.map(timer => {
        const ms = currentMs(timer);
        const since = new Date(timer.createdAt).toLocaleTimeString('de-DE',
            { hour: '2-digit', minute: '2-digit' });

        return `
            <div class="timer-card ${timer.isRunning ? 'running' : 'paused'}" data-id="${timer.id}">
                <div class="timer-card-head">
                    <input class="timer-name" type="text" value="${escapeHtml(timer.customerName)}"
                           placeholder="Name / Platz (optional)" maxlength="80"
                           onchange="renameTimer(${timer.id}, this.value)">
                    <span class="timer-badge">${timer.isRunning ? '● läuft' : '❚❚ pausiert'}</span>
                </div>

                <div class="timer-card-time" id="time-${timer.id}">${formatTime(ms)}</div>
                <div class="timer-card-amount" id="amount-${timer.id}">${formatEuro(calcAmount(ms))}</div>
                <div class="timer-card-since">gestartet um ${since} Uhr</div>

                <div class="timer-card-actions">
                    ${timer.isRunning
                        ? `<button class="btn btn-stop btn-sm" onclick="pauseTimer(${timer.id})">❚❚ Pause</button>`
                        : `<button class="btn btn-start btn-sm" onclick="resumeTimer(${timer.id})">▶ Weiter</button>`}
                    <button class="btn btn-sm" onclick="stopTimer(${timer.id})">✓ Beenden</button>
                    <button class="btn btn-danger btn-sm" onclick="discardTimer(${timer.id})">✕ Verwerfen</button>
                </div>
            </div>`;
    }).join('');
}

// ---------------------------------------------------------------------------
// Timer-Aktionen
// ---------------------------------------------------------------------------

async function addTimer() {
    const field = document.getElementById('newTimerName');
    const name = field.value.trim();
    try {
        await api('/api/timers', { method: 'POST', body: JSON.stringify({ customerName: name }) });
        field.value = '';
        await syncTimers();
        toast(name ? `Timer für „${name}" gestartet` : 'Timer gestartet', 'success');
    } catch (e) {
        toast('Timer konnte nicht gestartet werden: ' + e.message, 'error');
    }
}

async function renameTimer(id, value) {
    try {
        await api(`/api/timers/${id}`, {
            method: 'PATCH',
            body: JSON.stringify({ customerName: value.trim() })
        });
        const timer = state.timers.find(t => t.id === id);
        if (timer) timer.customerName = value.trim();
    } catch (e) {
        toast('Name konnte nicht gespeichert werden: ' + e.message, 'error');
    }
}

async function pauseTimer(id) {
    try {
        await api(`/api/timers/${id}/pause`, { method: 'POST' });
        await syncTimers();
    } catch (e) {
        toast('Pause fehlgeschlagen: ' + e.message, 'error');
    }
}

async function resumeTimer(id) {
    try {
        await api(`/api/timers/${id}/resume`, { method: 'POST' });
        await syncTimers();
    } catch (e) {
        toast('Fortsetzen fehlgeschlagen: ' + e.message, 'error');
    }
}

async function stopTimer(id) {
    const timer = state.timers.find(t => t.id === id);
    if (!timer) return;

    const ms = currentMs(timer);
    const label = timer.customerName ? `„${timer.customerName}"` : 'Timer';
    if (!confirm(`${label} beenden?\n\nZeit: ${formatTime(ms)}\nBetrag: ${formatEuro(calcAmount(ms))}\n\nDer Eintrag wird in der Historie gespeichert.`)) return;

    try {
        const result = await api(`/api/timers/${id}/stop`, { method: 'POST' });
        await syncTimers();
        if (result.saved) {
            toast(`Gespeichert: ${formatTime(result.duration)} – ${formatEuro(result.amount)}`, 'success');
        } else {
            toast(result.reason || 'Nichts gespeichert.', 'info');
        }
    } catch (e) {
        toast('Beenden fehlgeschlagen: ' + e.message, 'error');
    }
}

async function discardTimer(id) {
    const timer = state.timers.find(t => t.id === id);
    if (!timer) return;
    const label = timer.customerName ? `„${timer.customerName}"` : 'Timer';
    if (!confirm(`${label} verwerfen?\n\nDie erfasste Zeit (${formatTime(currentMs(timer))}) wird NICHT gespeichert.`)) return;

    try {
        await api(`/api/timers/${id}`, { method: 'DELETE' });
        await syncTimers();
        toast('Timer verworfen - nichts gespeichert.', 'info');
    } catch (e) {
        toast('Verwerfen fehlgeschlagen: ' + e.message, 'error');
    }
}

document.getElementById('newTimerForm').addEventListener('submit', (e) => {
    e.preventDefault();
    addTimer();
});

// ---------------------------------------------------------------------------
// Historie
// ---------------------------------------------------------------------------

function historyQuery() {
    const params = new URLSearchParams();
    const from = document.getElementById('filterFrom').value;
    const to = document.getElementById('filterTo').value;
    const q = document.getElementById('filterName').value.trim();
    if (from) params.set('from', from);
    if (to) params.set('to', to);
    if (q) params.set('q', q);
    return params;
}

async function loadHistory(reset = false) {
    if (reset) {
        state.history.offset = 0;
        state.history.reachedEnd = false;
    }

    const params = historyQuery();
    params.set('limit', state.history.limit);
    params.set('offset', state.history.offset);

    try {
        const data = await api('/api/sessions?' + params.toString());
        renderHistory(data, reset);
    } catch (e) {
        document.getElementById('historyList').innerHTML =
            `<div class="empty-state"><div class="empty-state-icon">⚠️</div><p>Fehler beim Laden: ${escapeHtml(e.message)}</p></div>`;
    }
}

function renderHistory(data, reset) {
    const listEl = document.getElementById('historyList');
    const statsEl = document.getElementById('historyStats');
    const moreBtn = document.getElementById('historyMore');

    statsEl.innerHTML = `
        <div class="stat-card"><h3>Einträge</h3><p>${data.totals.count}</p></div>
        <div class="stat-card"><h3>Gesamtzeit</h3><p>${formatTime(data.totals.duration)}</p></div>
        <div class="stat-card"><h3>Gesamtbetrag</h3><p>${formatEuro(data.totals.amount)}</p></div>
    `;

    if (data.totals.count === 0) {
        listEl.innerHTML = '<div class="empty-state"><div class="empty-state-icon">📭</div><p>Keine Einträge für diesen Zeitraum</p></div>';
        moreBtn.style.display = 'none';
        return;
    }

    const rows = data.sessions.map(s => {
        const date = new Date(s.created_at * 1000).toLocaleString('de-DE', {
            day: '2-digit', month: '2-digit', year: 'numeric',
            hour: '2-digit', minute: '2-digit'
        });
        const name = s.customer_name
            ? `<span class="history-item-name">${escapeHtml(s.customer_name)}</span>`
            : '<span class="history-item-name muted">ohne Namen</span>';

        return `
            <div class="history-item">
                <div class="history-item-info">
                    ${name}
                    <div class="history-item-date">${date} Uhr</div>
                    <div class="history-item-duration">${formatTime(s.duration)}</div>
                </div>
                <div class="history-item-right">
                    <div class="history-item-amount">${formatEuro(s.amount)}</div>
                    <button class="btn btn-danger btn-sm" onclick="deleteSession(${s.id})" title="Eintrag löschen">🗑</button>
                </div>
            </div>`;
    }).join('');

    if (reset) {
        listEl.innerHTML = rows;
    } else {
        listEl.insertAdjacentHTML('beforeend', rows);
    }

    const shown = state.history.offset + data.sessions.length;
    state.history.reachedEnd = shown >= data.totals.count;
    moreBtn.style.display = state.history.reachedEnd ? 'none' : 'inline-block';
    moreBtn.textContent = `Weitere laden (${shown} von ${data.totals.count})`;
}

async function loadMoreHistory() {
    state.history.offset += state.history.limit;
    await loadHistory(false);
}

async function deleteSession(id) {
    if (!confirm('Diesen Eintrag endgültig aus der Historie löschen?')) return;
    try {
        await api(`/api/sessions/${id}`, { method: 'DELETE' });
        await loadHistory(true);
        toast('Eintrag gelöscht', 'info');
    } catch (e) {
        toast('Löschen fehlgeschlagen: ' + e.message, 'error');
    }
}

function exportCsv() {
    const params = historyQuery();
    window.location.href = '/api/sessions/export.csv?' + params.toString();
}

function resetFilter() {
    document.getElementById('filterFrom').value = '';
    document.getElementById('filterTo').value = '';
    document.getElementById('filterName').value = '';
    loadHistory(true);
}

function filterToday() {
    const today = new Date().toISOString().slice(0, 10);
    document.getElementById('filterFrom').value = today;
    document.getElementById('filterTo').value = today;
    loadHistory(true);
}

function filterThisMonth() {
    const now = new Date();
    const first = new Date(now.getFullYear(), now.getMonth(), 1);
    const pad = n => String(n).padStart(2, '0');
    document.getElementById('filterFrom').value =
        `${first.getFullYear()}-${pad(first.getMonth() + 1)}-01`;
    document.getElementById('filterTo').value =
        `${now.getFullYear()}-${pad(now.getMonth() + 1)}-${pad(now.getDate())}`;
    loadHistory(true);
}

['filterFrom', 'filterTo'].forEach(id =>
    document.getElementById(id).addEventListener('change', () => loadHistory(true)));
document.getElementById('filterName').addEventListener('input', (() => {
    let handle = null;
    return () => { clearTimeout(handle); handle = setTimeout(() => loadHistory(true), 350); };
})());

// ---------------------------------------------------------------------------
// Einstellungen  (serverseitig - gelten fuer alle Geraete)
// ---------------------------------------------------------------------------

async function loadSettings() {
    try {
        const rate = await api('/api/settings');
        state.rate = rate;
        document.getElementById('rateAmount').value = rate.rateAmount;
        document.getElementById('rateInterval').value = rate.rateInterval;
        updateSettingsPreview();
    } catch (e) {
        toast('Einstellungen konnten nicht geladen werden: ' + e.message, 'error');
    }
}

async function saveSettings() {
    const rateAmount = parseFloat(document.getElementById('rateAmount').value);
    const rateInterval = parseInt(document.getElementById('rateInterval').value);

    try {
        const rate = await api('/api/settings', {
            method: 'PUT',
            body: JSON.stringify({ rateAmount, rateInterval })
        });
        state.rate = rate;
        renderTimers();
        toast('Einstellungen gespeichert - gilt für alle Geräte', 'success');
        showTimer();
    } catch (e) {
        toast('Speichern fehlgeschlagen: ' + e.message, 'error');
    }
}

async function resetSettings() {
    if (!confirm('Tarif auf Standard zurücksetzen (€10 pro 10 Minuten)?')) return;
    document.getElementById('rateAmount').value = 10;
    document.getElementById('rateInterval').value = 10;
    await saveSettings();
}

function updateSettingsPreview() {
    const amount = parseFloat(document.getElementById('rateAmount').value) || 0;
    const interval = parseInt(document.getElementById('rateInterval').value) || 1;

    document.getElementById('settingsPreview').textContent =
        `${formatEuro(amount)} pro angefangene ${interval} Minuten`;

    const examples = [Math.max(1, interval - 5), interval + 5, interval * 2, 60]
        .filter((v, i, a) => a.indexOf(v) === i)
        .map(mins => `${mins} Min = ${formatEuro(Math.ceil(mins / interval) * amount)}`);

    document.getElementById('previewExamples').innerHTML =
        `<strong>Beispiele:</strong><br>${examples.join(' | ')}`;
}

document.getElementById('settingsForm').addEventListener('submit', (e) => {
    e.preventDefault();
    saveSettings();
});
document.getElementById('rateAmount').addEventListener('input', updateSettingsPreview);
document.getElementById('rateInterval').addEventListener('input', updateSettingsPreview);

// ---------------------------------------------------------------------------

checkAuth();