const $ = (id) => document.getElementById(id);
const money = (v) => new Intl.NumberFormat('pl-PL', { style: 'currency', currency: 'PLN', maximumFractionDigits: 0 }).format(v || 0);
const num = (id) => Number($(id).value || 0);

let lineChart, pieChart, barChart, detailChart;
let socket;
let debounceTimer;
let lastRequest = null;
window.lastSimulationData = null;

function todayIso() {
  const d = new Date();
  return d.toISOString().slice(0, 10);
}

function updateTermLabel() {
  const months = Math.max(1, Number($('termMonths').value || 1));
  const years = Math.max(1, Math.round(months / 12));
  $('yearsSlider').value = Math.min(50, years);
  $('yearsSliderLabel').textContent = `${months} mies. ≈ ${(months / 12).toFixed(1)} lat`;
}

function setMonthsFromYearsSlider() {
  const years = Number($('yearsSlider').value || 1);
  $('termMonths').value = years * 12;
  $('yearsSliderLabel').textContent = `${years} lat = ${years * 12} mies.`;
  recalc();
}

function defaultProtection() {
  return {
    commission: Number($('protectionCommission')?.value || 0),
    until: Number($('protectionMonths')?.value || 0) || ''
  };
}

function sumRows(rows, selector) {
  return (rows || []).reduce((acc, row) => acc + Number(selector(row) || 0), 0);
}

function comparisonMetrics(data) {
  const schedule = data?.schedule || [];
  const baseline = data?.baseline_schedule || [];
  const simulatedCosts = sumRows(schedule, r => r.interest_part + r.overpayment_fee);
  const nominalCosts = sumRows(baseline, r => r.interest_part);
  const simulatedPayments = sumRows(schedule, r => r.payment + r.overpayment + r.overpayment_fee);
  const nominalPayments = sumRows(baseline, r => r.payment);
  return {
    simulatedCosts,
    nominalCosts,
    simulatedPayments,
    nominalPayments,
    costDiff: nominalCosts - simulatedCosts,
    paymentDiff: nominalPayments - simulatedPayments
  };
}

function updateProtectionHint() {
  const defaults = defaultProtection();
  const hasProtection = defaults.commission > 0 || defaults.until !== '';
  const rows = [...document.querySelectorAll('#overpayments .dynamic-row')];
  const hasMismatch = rows.some(row => {
    const commission = Number(row.querySelector('[data-field="commission"]')?.value || 0);
    const until = Number(row.querySelector('[data-field="commissionUntil"]')?.value || 0) || '';
    return commission !== defaults.commission || until !== defaults.until;
  });
  const shouldWarn = hasProtection && rows.length > 0 && hasMismatch;
  $('applyProtection')?.classList.toggle('protection-warning', shouldWarn);
  $('protectionBox')?.classList.toggle('protection-warning-box', shouldWarn);
}

function applyProtectionToOverpayments() {
  const defaults = defaultProtection();
  document.querySelectorAll('#overpayments .dynamic-row').forEach(row => {
    const commissionInput = row.querySelector('[data-field="commission"]');
    const untilInput = row.querySelector('[data-field="commissionUntil"]');
    if (commissionInput) commissionInput.value = defaults.commission || 0;
    if (untilInput) untilInput.value = defaults.until || '';
  });
  updateProtectionHint();
  recalc();
}

function setTheme(theme) {
  document.body.dataset.theme = theme;
  localStorage.setItem('mortgage-theme', theme);
  const btn = $('themeToggle');
  if (btn) btn.textContent = theme === 'dark' ? '☀️ Jasny' : '🌙 Ciemny';
}

function initTheme() {
  const saved = localStorage.getItem('mortgage-theme') || 'dark';
  setTheme(saved);
  $('themeToggle').onclick = () => setTheme(document.body.dataset.theme === 'dark' ? 'light' : 'dark');
}

function connectWs() {
  const proto = location.protocol === 'https:' ? 'wss' : 'ws';
  socket = new WebSocket(`${proto}://${location.host}/ws/simulate`);
  socket.onopen = () => recalc();
  socket.onmessage = (event) => {
    const data = JSON.parse(event.data);
    if (data.error) return console.error(data.error);
    render(data);
  };
  socket.onclose = () => setTimeout(connectWs, 1200);
}

function buildRequest() {
  const rateChanges = [...document.querySelectorAll('#rateChanges .dynamic-row')].map(row => ({
    month: Number(row.querySelector('[data-field="month"]').value || 1),
    annual_rate: Number(row.querySelector('[data-field="rate"]').value || 0)
  })).filter(x => x.month > 0 && x.annual_rate >= 0);

  const overpayments = [...document.querySelectorAll('#overpayments .dynamic-row')].map(row => ({
    month: Number(row.querySelector('[data-field="month"]').value || 1),
    amount: Number(row.querySelector('[data-field="amount"]').value || 0),
    repeat: row.querySelector('[data-field="repeat"]').value,
    until_month: Number(row.querySelector('[data-field="until"]').value || 0) || null,
    commission_percent: Number(row.querySelector('[data-field="commission"]').value || 0),
    commission_until_month: Number(row.querySelector('[data-field="commissionUntil"]').value || 0) || null
  })).filter(x => x.month > 0 && x.amount > 0);

  const historicalMonths = [...document.querySelectorAll('#historicalMonths .dynamic-row')].map(row => {
    const rateRaw = row.querySelector('[data-field="rate"]').value;
    return {
      month: Number(row.querySelector('[data-field="month"]').value || 1),
      annual_rate: rateRaw === '' ? null : Number(rateRaw),
      grace_type: row.querySelector('[data-field="grace"]').value,
      overpayment: Number(row.querySelector('[data-field="overpayment"]').value || 0),
      overpayment_commission_percent: Number(row.querySelector('[data-field="commission"]').value || 0),
      note: row.querySelector('[data-field="note"]').value || ''
    };
  }).filter(x => x.month > 0);

  const termMonths = Math.max(1, Math.round(num('termMonths') || 1));

  return {
    principal: num('principal'),
    years: Math.max(1, Math.ceil(termMonths / 12)),
    term_months: termMonths,
    margin: num('margin'),
    base_rate: num('baseRate'),
    installment_type: $('installmentType').value,
    overpayment_effect: $('overpaymentEffect').value,
    loan_start_date: $('loanStartDate').value || todayIso(),
    due_day: num('dueDay') || 5,
    move_due_date_to_business_day: $('moveDueDate').checked,
    overpayment_protection_months: Number($('protectionMonths').value || 0) || null,
    overpayment_protection_commission_percent: Number($('protectionCommission').value || 0),
    rate_changes: rateChanges,
    overpayments: overpayments,
    historical_months: historicalMonths
  };
}

function recalc() {
  updateProtectionHint();
  clearTimeout(debounceTimer);
  debounceTimer = setTimeout(() => {
    lastRequest = buildRequest();
    if (socket?.readyState === WebSocket.OPEN) socket.send(JSON.stringify(lastRequest));
  }, 120);
}

function addRateRow(month = 13, rate = 7.0) {
  const div = document.createElement('div');
  div.className = 'dynamic-row rate-row';
  div.innerHTML = `
    <div><label class="form-label">Od miesiąca</label><input data-field="month" type="number" min="1" class="form-control form-control-sm" value="${month}"></div>
    <div><label class="form-label">Oproc. roczne %</label><input data-field="rate" type="number" step="0.01" class="form-control form-control-sm" value="${rate}"></div>
    <button class="btn btn-sm btn-outline-danger" type="button">Usuń</button>`;
  div.querySelector('button').onclick = () => { div.remove(); recalc(); };
  div.querySelectorAll('input').forEach(x => x.addEventListener('input', recalc));
  $('rateChanges').appendChild(div);
  recalc();
}

function syncOverpaymentAmountSlider(row, source) {
  const amountInput = row.querySelector('[data-field="amount"]');
  const slider = row.querySelector('[data-field="amountSlider"]');
  const label = row.querySelector('[data-field="amountSliderLabel"]');
  if (!amountInput || !slider || !label) return;
  const max = Number(slider.max);
  const min = Number(slider.min);
  if (source === 'slider') amountInput.value = slider.value;
  if (source === 'input') {
    const amount = Number(amountInput.value || 0);
    slider.value = Math.min(max, Math.max(min, amount));
  }
  label.textContent = money(Number(amountInput.value || 0));
}

function addOverpaymentRow(month = 12, amount = 10000, repeat = 'once', until = '', commission = null, commissionUntil = null) {
  const defaults = defaultProtection();
  if (commission === null || commission === undefined || commission === '') commission = defaults.commission;
  if (commissionUntil === null || commissionUntil === undefined || commissionUntil === '') commissionUntil = defaults.until;
  const div = document.createElement('div');
  div.className = 'dynamic-row overpay';
  div.innerHTML = `
    <div><label class="form-label">Miesiąc</label><input data-field="month" type="number" min="1" class="form-control form-control-sm" value="${month}"></div>
    <div class="overpay-amount"><label class="form-label">Kwota</label><input data-field="amount" type="number" min="1" class="form-control form-control-sm" value="${amount}"></div>
    <div><label class="form-label">Prowizja %</label><input data-field="commission" type="number" min="0" step="0.01" class="form-control form-control-sm" value="${commission}"></div>
    <div><label class="form-label">Prowizja do mies.</label><input data-field="commissionUntil" type="number" min="1" class="form-control form-control-sm" value="${commissionUntil || ''}" placeholder="bez limitu"></div>
    <div><label class="form-label">Powtarzaj</label><select data-field="repeat" class="form-select form-select-sm"><option value="once">raz</option><option value="monthly">co miesiąc</option><option value="yearly">co rok</option></select></div>
    <div><label class="form-label">Nadpłaty do mies.</label><input data-field="until" type="number" min="1" class="form-control form-control-sm" value="${until || ''}"></div>
    <button class="btn btn-sm btn-outline-danger" type="button">Usuń</button>
    <div class="overpay-slider mt-1"><div class="d-flex justify-content-between align-items-center"><label class="form-label mb-0">Suwak kwoty</label><span data-field="amountSliderLabel" class="small text-muted">${money(amount)}</span></div><input data-field="amountSlider" type="range" min="0" max="50000" step="100" class="form-range" value="${Math.min(50000, Number(amount || 0))}"></div>`;
  div.querySelector('[data-field="repeat"]').value = repeat;
  div.querySelector('button').onclick = () => { div.remove(); recalc(); };
  div.querySelector('[data-field="amountSlider"]').addEventListener('input', () => { syncOverpaymentAmountSlider(div, 'slider'); recalc(); });
  div.querySelector('[data-field="amount"]').addEventListener('input', () => { syncOverpaymentAmountSlider(div, 'input'); recalc(); });
  div.querySelectorAll('input:not([data-field="amount"]):not([data-field="amountSlider"]),select').forEach(x => x.addEventListener('input', recalc));
  $('overpayments').appendChild(div);
  syncOverpaymentAmountSlider(div, 'input');
  recalc();
}

function addHistoricalRow(month = 1, rate = '', grace = 'none', overpayment = 0, commission = 0, note = '') {
  const div = document.createElement('div');
  div.className = 'dynamic-row historical';
  div.innerHTML = `
    <div><label class="form-label">Miesiąc</label><input data-field="month" type="number" min="1" class="form-control form-control-sm" value="${month}"></div>
    <div><label class="form-label">Oproc. %</label><input data-field="rate" type="number" step="0.01" class="form-control form-control-sm" value="${rate ?? ''}" placeholder="auto"></div>
    <div><label class="form-label">Karencja</label><select data-field="grace" class="form-select form-select-sm"><option value="none">brak</option><option value="interest_only">tylko odsetki</option><option value="full">pełna</option></select></div>
    <div><label class="form-label">Nadpłata</label><input data-field="overpayment" type="number" min="0" class="form-control form-control-sm" value="${overpayment || 0}"></div>
    <div><label class="form-label">Prow. %</label><input data-field="commission" type="number" min="0" step="0.01" class="form-control form-control-sm" value="${commission || 0}"></div>
    <div><label class="form-label">Opis</label><input data-field="note" type="text" class="form-control form-control-sm" value="${String(note || '').replaceAll('"', '&quot;')}"></div>
    <button class="btn btn-sm btn-outline-danger" type="button">Usuń</button>`;
  div.querySelector('[data-field="grace"]').value = grace || 'none';
  div.querySelector('button').onclick = () => { div.remove(); recalc(); };
  div.querySelectorAll('input,select').forEach(x => x.addEventListener('input', recalc));
  $('historicalMonths').appendChild(div);
  recalc();
}

function render(data) {
  window.lastSimulationData = data;
  const s = data.summary;
  $('summaryCards').innerHTML = [
    ['Odsetki', money(s.total_interest)],
    ['Oszczędność netto', money(s.interest_saved)],
    ['Nadpłaty', money(s.total_overpayment)],
    ['Prowizje', money(s.total_overpayment_fees)],
    ['Okres', `${s.months} mies. / ${Math.ceil(s.months / 12)} lat`],
    ['Data spłaty', s.payoff_date || '-'],
    ['Skrócenie', `${s.months_saved} mies.`],
    ['Średnia rata', money(s.average_payment)]
  ].map(([label, value]) => `<div class="col-6 col-md-4 col-xxl-3"><div class="card border-0 shadow-sm stat-card"><div class="card-body py-3"><div class="stat-label">${label}</div><div class="stat-value">${value}</div></div></div></div>`).join('');

  const c = comparisonMetrics(data);
  $('resultText').textContent = `Dzięki nadpłatom ${money(s.total_overpayment)} oszczędność netto wynosi około ${money(s.interest_saved)} po uwzględnieniu prowizji ${money(s.total_overpayment_fees)}. Kredyt kończy się ${s.payoff_date || '—'} po ${s.months} miesiącach zamiast ${s.baseline_months}. Porównanie kosztów: nominalnie ${money(c.nominalCosts)}, po symulacji ${money(c.simulatedCosts)}, różnica ${money(c.costDiff)}. Porównanie łącznych płatności: nominalnie ${money(c.nominalPayments)}, po symulacji ${money(c.simulatedPayments)}, różnica ${money(c.paymentDiff)}.`;

  $('scheduleTable').innerHTML = data.schedule.slice(0, 240).map(r => `<tr><td>${r.month}</td><td>${r.due_date}</td><td>${r.days}</td><td>${r.rate.toFixed(2)}%</td><td>${money(r.payment)}</td><td>${money(r.principal_part)}</td><td>${money(r.interest_part)}</td><td>${money(r.overpayment)}</td><td>${money(r.overpayment_fee)}</td><td>${money(r.cumulative_cost)}</td><td>${money(r.remaining)}</td></tr>`).join('');

  renderCharts(data);
}

function renderCharts(data) {
  if (!data) return;
  const maxMonths = Math.max(data.schedule.length, (data.baseline_schedule || []).length);
  const labels = Array.from({ length: maxMonths }, (_, i) => i + 1);
  const balance = labels.map(m => data.schedule[m - 1]?.remaining ?? null);
  const payment = labels.map(m => data.schedule[m - 1]?.payment ?? null);
  const baselineBalance = labels.map(m => data.baseline_schedule?.[m - 1]?.remaining ?? null);
  const baselinePayment = labels.map(m => data.baseline_schedule?.[m - 1]?.payment ?? null);
  const principal = data.schedule.map(r => r.principal_part);
  const interest = data.schedule.map(r => r.interest_part);
  const cumulativeCost = data.schedule.map(r => r.cumulative_cost);
  const overpayments = data.schedule.map(r => r.overpayment);
  const yearly = new Map();
  const yearlyBaseline = new Map();
  data.schedule.forEach(r => {
    const year = Math.ceil(r.month / 12);
    yearly.set(year, (yearly.get(year) || 0) + r.interest_part + r.overpayment_fee);
  });
  (data.baseline_schedule || []).forEach(r => {
    const year = Math.ceil(r.month / 12);
    yearlyBaseline.set(year, (yearlyBaseline.get(year) || 0) + r.interest_part);
  });
  const yearLabels = Array.from(new Set([...yearly.keys(), ...yearlyBaseline.keys()])).sort((a, b) => a - b);

  lineChart?.destroy();
  lineChart = new Chart($('lineChart'), {
    type: 'line',
    data: { labels, datasets: [
      { label: 'Saldo po modyfikacjach', data: balance, yAxisID: 'y' },
      { label: 'Saldo nominalne', data: baselineBalance, yAxisID: 'y' },
      { label: 'Rata po modyfikacjach', data: payment, yAxisID: 'y1' },
      { label: 'Rata nominalna', data: baselinePayment, yAxisID: 'y1' }
    ] },
    options: { responsive: true, maintainAspectRatio: false, interaction: { mode: 'index', intersect: false }, scales: { y: { beginAtZero: true }, y1: { position: 'right', beginAtZero: true, grid: { drawOnChartArea: false } } } }
  });

  pieChart?.destroy();
  pieChart = new Chart($('pieChart'), {
    type: 'pie',
    data: { labels: ['Kapitał', 'Odsetki', 'Nadpłaty', 'Prowizje'], datasets: [{ data: [lastRequest.principal, data.summary.total_interest, data.summary.total_overpayment, data.summary.total_overpayment_fees] }] },
    options: { responsive: true, maintainAspectRatio: false }
  });


  barChart?.destroy();
  barChart = new Chart($('barChart'), {
    type: 'bar',
    data: { labels: yearLabels.map(x => `Rok ${x}`), datasets: [
      { label: 'Koszty nominalne', data: yearLabels.map(x => yearlyBaseline.get(x) || 0) },
      { label: 'Koszty po symulacji', data: yearLabels.map(x => yearly.get(x) || 0) }
    ] },
    options: { responsive: true, maintainAspectRatio: false, scales: { y: { beginAtZero: true } } }
  });

  detailChart?.destroy();
  detailChart = new Chart($('detailChart'), {
    data: {
      labels,
      datasets: [
        { type: 'bar', label: 'Kapitał w racie', data: principal, stack: 'rata', yAxisID: 'y' },
        { type: 'bar', label: 'Odsetki w racie', data: interest, stack: 'rata', yAxisID: 'y' },
        { type: 'bar', label: 'Nadpłata', data: overpayments, stack: 'rata', yAxisID: 'y' },
        { type: 'line', label: 'Koszt narastająco', data: cumulativeCost, yAxisID: 'y1' }
      ]
    },
    options: { responsive: true, maintainAspectRatio: false, interaction: { mode: 'index', intersect: false }, scales: { x: { stacked: true }, y: { stacked: true, beginAtZero: true }, y1: { position: 'right', beginAtZero: true, grid: { drawOnChartArea: false } } } }
  });
}

async function download(endpoint, filename) {
  const res = await fetch(endpoint, { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(buildRequest()) });
  const blob = await res.blob();
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = filename;
  a.click();
  URL.revokeObjectURL(url);
}

function exportJson() {
  const blob = new Blob([JSON.stringify(buildRequest(), null, 2)], { type: 'application/json' });
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = 'parametry-kredytu.json';
  a.click();
  URL.revokeObjectURL(url);
}

function clearRows() {
  $('rateChanges').innerHTML = '';
  $('overpayments').innerHTML = '';
  $('historicalMonths').innerHTML = '';
}

function applyRequest(data) {
  $('principal').value = data.principal ?? 600000;
  const loadedMonths = data.term_months ?? ((data.years ?? 25) * 12);
  $('termMonths').value = loadedMonths;
  updateTermLabel();
  $('margin').value = data.margin ?? 2;
  $('baseRate').value = data.base_rate ?? 5.75;
  $('installmentType').value = data.installment_type ?? 'equal';
  $('overpaymentEffect').value = data.overpayment_effect ?? 'shorten';
  $('loanStartDate').value = data.loan_start_date ?? todayIso();
  $('dueDay').value = data.due_day ?? 5;
  $('moveDueDate').checked = data.move_due_date_to_business_day ?? true;
  $('protectionMonths').value = data.overpayment_protection_months ?? '';
  $('protectionCommission').value = data.overpayment_protection_commission_percent ?? 0;
  clearRows();
  (data.rate_changes || []).forEach(x => addRateRow(x.month, x.annual_rate));
  (data.overpayments || []).forEach(x => addOverpaymentRow(x.month, x.amount, x.repeat, x.until_month || '', x.commission_percent || 0, x.commission_until_month || ''));
  (data.historical_months || []).forEach(x => addHistoricalRow(x.month, x.annual_rate ?? '', x.grace_type || 'none', x.overpayment || 0, x.overpayment_commission_percent || 0, x.note || ''));
  recalc();
}

function importJsonFile(file) {
  const reader = new FileReader();
  reader.onload = () => {
    try {
      applyRequest(JSON.parse(reader.result));
    } catch (e) {
      alert(`Nie udało się wczytać JSON: ${e.message}`);
    }
  };
  reader.readAsText(file, 'utf-8');
}

async function loadNbp() {
  const btn = $('loadNbp');
  const old = btn.textContent;
  btn.textContent = 'Pobieram...';
  try {
    const res = await fetch('/api/rate/nbp');
    const data = await res.json();
    if (!res.ok || data.error) throw new Error(data.error || 'Błąd pobierania');
    $('baseRate').value = data.rate;
    recalc();
    btn.textContent = `NBP: ${data.rate}%`;
    setTimeout(() => btn.textContent = old, 2500);
  } catch (e) {
    alert(`Nie udało się pobrać stopy NBP: ${e.message}`);
    btn.textContent = old;
  }
}

['principal','baseRate','margin','installmentType','overpaymentEffect','loanStartDate','dueDay','moveDueDate'].forEach(id => $(id).addEventListener('input', recalc));
['protectionMonths','protectionCommission'].forEach(id => $(id).addEventListener('input', () => { updateProtectionHint(); recalc(); }));
$('termMonths').addEventListener('input', () => { updateTermLabel(); recalc(); });
$('yearsSlider').addEventListener('input', setMonthsFromYearsSlider);
$('addRate').onclick = () => addRateRow();
$('addOverpayment').onclick = () => addOverpaymentRow();
$('applyProtection').onclick = applyProtectionToOverpayments;
$('addHistorical').onclick = () => addHistoricalRow();
$('exportCsv').onclick = () => download('/api/export/csv', 'symulacja-kredytu.csv');
$('exportPdf').onclick = () => download('/api/export/pdf', 'symulacja-kredytu.pdf');
$('exportJson').onclick = exportJson;
$('importJson').onclick = () => $('jsonFile').click();
$('jsonFile').onchange = (e) => e.target.files?.[0] && importJsonFile(e.target.files[0]);
$('loadNbp').onclick = loadNbp;
$('loanStartDate').value = todayIso();
updateTermLabel();
initTheme();

addOverpaymentRow(24, 20000, 'once', '', 0);
addOverpaymentRow(36, 500, 'monthly', 120, 0);
connectWs();