// app.js — UI glue for the BabyMobile manager PWA.
import { BabyMobile, isSupported, MAX_TRACKS } from './ble.js';
import { decodeFileToMono, encodeWav, trimSamples, RATES, BITS } from './wav.js';

const $ = (id) => document.getElementById(id);
const dev = new BabyMobile();

// Slot metadata is kept locally because the firmware can't enumerate tracks
// over BLE. This remembers what *we* uploaded so the UI can show slot contents.
const SLOTS_KEY = 'babymobile.slots.v1';
let slots = loadSlots();

let pendingWav = null;     // { wav, durationSec, rate, bits, name }
let deviceTracks = null;   // last result of dev.listTracks(), or null
let currentFile = null;    // the picked File
let decoded = null;        // { samples, rate, srcRate } cached decode of currentFile

function loadSlots() {
  try { return JSON.parse(localStorage.getItem(SLOTS_KEY)) || {}; }
  catch { return {}; }
}
function saveSlots() {
  localStorage.setItem(SLOTS_KEY, JSON.stringify(slots));
}

function log(msg) {
  const el = $('log');
  const time = new Date().toLocaleTimeString();
  el.textContent += `[${time}] ${msg}\n`;
  el.scrollTop = el.scrollHeight;
}

function fmtBytes(n) {
  if (n < 1024) return `${n} B`;
  if (n < 1024 * 1024) return `${(n / 1024).toFixed(1)} KB`;
  return `${(n / 1024 / 1024).toFixed(2)} MB`;
}

// ---- connection state ----
dev.addEventListener('log', (e) => log(e.detail));
dev.addEventListener('connected', (e) => { setConnected(true, e.detail.name); refresh(); });
dev.addEventListener('disconnected', () => { setConnected(false); deviceTracks = null; renderSlots(); });

function setConnected(on, name) {
  $('status-dot').className = on ? 'dot on' : 'dot';
  $('status-text').textContent = on ? `Connected${name ? ' · ' + name : ''}` : 'Not connected';
  $('btn-connect').textContent = on ? 'Disconnect' : 'Scan & connect';
  document.querySelectorAll('[data-needs-conn]').forEach((el) => { el.disabled = !on; });
}

$('btn-connect').addEventListener('click', async () => {
  try {
    if (dev.connected) await dev.disconnect();
    else await dev.connect();
  } catch (err) {
    if (err && err.name === 'NotFoundError') log('Scan cancelled.');
    else log('Error: ' + (err && err.message ? err.message : err));
  }
});

// ---- file selection & conversion ----
const fileInput = $('file');
$('drop').addEventListener('click', () => fileInput.click());
$('drop').addEventListener('dragover', (e) => { e.preventDefault(); $('drop').classList.add('hover'); });
$('drop').addEventListener('dragleave', () => $('drop').classList.remove('hover'));
$('drop').addEventListener('drop', (e) => {
  e.preventDefault(); $('drop').classList.remove('hover');
  if (e.dataTransfer.files.length) handleFile(e.dataTransfer.files[0]);
});
fileInput.addEventListener('change', () => { if (fileInput.files.length) handleFile(fileInput.files[0]); });

// Decode the file (expensive) once per file/rate, then re-encode cheaply when
// the user tweaks bit-depth or trim.
async function handleFile(file) {
  stopPreview();
  currentFile = file;
  decoded = null;
  pendingWav = null;
  $('btn-upload').disabled = true;
  $('btn-preview').disabled = true;
  $('trim').hidden = true;
  $('convert-info').textContent = `Decoding "${file.name}"…`;
  try {
    const rate = parseInt($('rate').value, 10);
    decoded = await decodeFileToMono(file, rate);
    $('trim-start').value = '0';
    $('trim-end').value = '0';
    $('trim').hidden = false;
    reEncode();
  } catch (err) {
    $('convert-info').textContent = 'Could not decode this file: ' + (err.message || err) +
      '. Try a WAV/MP3/M4A the browser can decode.';
  }
}

function trimValues() {
  return {
    trimStart: Math.max(0, parseFloat($('trim-start').value) || 0),
    trimEnd: Math.max(0, parseFloat($('trim-end').value) || 0),
  };
}

// Re-encode the staged WAV from the cached decode (no re-decode).
function reEncode() {
  if (!decoded || !currentFile) return;
  const bits = parseInt($('bits').value, 10);
  const { trimStart, trimEnd } = trimValues();
  const fullDur = decoded.samples.length / decoded.rate;
  const { wav, durationSec } = encodeWav(decoded.samples, decoded.rate, bits, { trimStart, trimEnd });
  pendingWav = { wav, durationSec, rate: decoded.rate, bits, name: currentFile.name };

  const trimmed = (trimStart || trimEnd) ? ` (trimmed from ${fullDur.toFixed(1)}s)` : '';
  $('convert-info').innerHTML =
    `<b>${currentFile.name}</b> → ${bits}-bit ${decoded.rate / 1000} kHz mono<br>` +
    `${durationSec.toFixed(1)}s${trimmed} · ${fmtBytes(wav.byteLength)} (incl. 44-byte WAV header)`;
  $('btn-upload').disabled = !dev.connected || durationSec <= 0;
  $('btn-preview').disabled = durationSec <= 0;
}

// Changing the rate needs a fresh decode; bits/trim only need a re-encode.
$('rate').addEventListener('change', () => { if (currentFile) handleFile(currentFile); });
['bits', 'trim-start', 'trim-end'].forEach((id) => $(id).addEventListener('input', () => { stopPreview(); reEncode(); }));

// ---- local preview of the trimmed clip ----
let previewCtx = null;
let previewSrc = null;
function stopPreview() {
  if (previewSrc) { try { previewSrc.stop(); } catch {} previewSrc = null; }
  if (previewCtx) { try { previewCtx.close(); } catch {} previewCtx = null; }
  $('btn-preview').textContent = '▶ Preview';
}
$('btn-preview').addEventListener('click', () => {
  if (previewSrc) { stopPreview(); return; }
  if (!decoded) return;
  const { trimStart, trimEnd } = trimValues();
  const slice = trimSamples(decoded.samples, decoded.rate, trimStart, trimEnd);
  if (!slice.length) return;
  const AC = window.AudioContext || window.webkitAudioContext;
  previewCtx = new AC();
  const buf = previewCtx.createBuffer(1, slice.length, decoded.rate);
  buf.getChannelData(0).set(slice);
  previewSrc = previewCtx.createBufferSource();
  previewSrc.buffer = buf;
  previewSrc.connect(previewCtx.destination);
  previewSrc.onended = stopPreview;
  previewSrc.start();
  $('btn-preview').textContent = '⏹ Stop';
});

// ---- upload ----
$('btn-upload').addEventListener('click', async () => {
  if (!pendingWav) return;
  const track = parseInt($('upload-slot').value, 10);
  if (occupiedSlots().has(track)) {
    const name = slots[track]?.name;
    if (!confirm(`Slot ${track} already holds ${name ? `"${name}"` : 'a track'}. Overwrite it?`)) return;
  }
  stopPreview();
  $('btn-upload').disabled = true;
  const bar = $('upload-bar');
  bar.style.width = '0%';
  bar.parentElement.classList.add('active');
  try {
    const { ok, acked } = await dev.upload(track, pendingWav.wav, (sent, total) => {
      bar.style.width = `${Math.round((sent / total) * 100)}%`;
    });
    if (ok) {
      slots[track] = {
        name: pendingWav.name, bits: pendingWav.bits, rate: pendingWav.rate,
        durationSec: pendingWav.durationSec, bytes: pendingWav.wav.byteLength, at: Date.now(),
      };
      saveSlots();
      await refresh(); // pull the authoritative list back from the device
    }
  } catch (err) {
    log('Upload failed: ' + (err.message || err));
  } finally {
    bar.parentElement.classList.remove('active');
    $('btn-upload').disabled = !dev.connected;
  }
});

// ---- track list ----
$('btn-refresh').addEventListener('click', () => refresh());

async function refresh() {
  if (!dev.connected) return;
  try {
    deviceTracks = await dev.listTracks();
    log(`Device reports ${deviceTracks.length} track(s).`);
    renderSlots();
  } catch (err) {
    log('List failed: ' + (err.message || err));
  }
}

async function onDelete(idx, onDevice, name) {
  const label = name ? `"${name}"` : `the track in slot ${idx}`;
  if (onDevice) {
    if (!confirm(`Delete ${label} from the device? This can't be undone.`)) return;
    try {
      const r = await dev.deleteTrack(idx);
      if (r.success) {
        delete slots[idx]; saveSlots();
        log(`🗑 Deleted slot ${idx}.`);
        await refresh();
      } else {
        log(`Device could not delete slot ${idx}.`);
      }
    } catch (err) {
      log('Delete failed: ' + (err.message || err));
    }
  } else {
    if (!confirm(`Forget ${label} from this browser's list? (It only clears the local record.)`)) return;
    delete slots[idx]; saveSlots(); renderSlots();
  }
}

function renderSlots() {
  const list = $('slots');
  list.innerHTML = '';
  const onDevice = dev.connected && Array.isArray(deviceTracks);

  // When connected, the device list is the source of truth (annotated with local
  // names). Otherwise fall back to the local record of past uploads.
  const rows = onDevice
    ? deviceTracks.map((t) => ({ ...t, name: slots[t.idx]?.name }))
    : Object.keys(slots).map(Number).sort((a, b) => a - b).map((k) => ({
        idx: k, bits: slots[k].bits, rate: slots[k].rate,
        durationSec: slots[k].durationSec, name: slots[k].name,
      }));

  updateUploadSlotOptions(); // keep the upload picker's "next free" in sync

  if (!rows.length) {
    list.innerHTML = `<li class="empty">${onDevice ? 'No tracks on the device yet.' : 'Connect to list device tracks.'}</li>`;
    return;
  }

  for (const t of rows) {
    const li = document.createElement('li');
    const title = t.name || `Track ${t.idx}`;
    li.innerHTML =
      `<div class="slot-meta"><span class="slot-num">${t.idx}</span>` +
      `<div><b>${title}</b><small>${t.bits}-bit ${t.rate / 1000}kHz · ${(+t.durationSec).toFixed(1)}s</small></div></div>`;
    const actions = document.createElement('div');
    actions.className = 'slot-actions';
    const playBtn = btn('▶', 'Play', () => dev.play(t.idx).catch((e) => log('' + e)));
    const stopBtn = btn('⏹', 'Stop', () => dev.stop().catch((e) => log('' + e)));
    playBtn.dataset.needsConn = ''; stopBtn.dataset.needsConn = '';
    playBtn.disabled = stopBtn.disabled = !dev.connected;
    const delBtn = btn('🗑', onDevice ? 'Delete from device' : 'Forget (local only)',
      () => onDelete(t.idx, onDevice, t.name));
    actions.append(playBtn, stopBtn, delBtn);
    li.append(actions);
    list.append(li);
  }
}
function btn(label, title, fn) {
  const b = document.createElement('button');
  b.textContent = label; b.title = title; b.className = 'mini';
  b.addEventListener('click', fn);
  return b;
}

// ---- populate selectors ----
function fillSelect(sel, values, fmt, selected) {
  sel.innerHTML = '';
  for (const v of values) {
    const o = document.createElement('option');
    o.value = v; o.textContent = fmt(v);
    if (v === selected) o.selected = true;
    sel.append(o);
  }
}
fillSelect($('rate'), RATES, (v) => `${v / 1000} kHz`, 8000);
fillSelect($('bits'), BITS, (v) => `${v}-bit`, 8);
fillSelect($('play-slot'), Array.from({ length: MAX_TRACKS }, (_, i) => i), (v) => `Slot ${v}`, 0);

// Which slots currently hold a track: device truth when connected, else local memory.
function occupiedSlots() {
  if (dev.connected && Array.isArray(deviceTracks)) return new Set(deviceTracks.map((t) => t.idx));
  return new Set(Object.keys(slots).map(Number));
}
function nextFreeSlot() {
  const occ = occupiedSlots();
  for (let i = 0; i < MAX_TRACKS; i++) if (!occ.has(i)) return i;
  return MAX_TRACKS - 1; // all full → default to the last slot
}
// Rebuild the upload-slot picker, label occupied slots, and default to next free.
function updateUploadSlotOptions() {
  const occ = occupiedSlots();
  const sel = $('upload-slot');
  sel.innerHTML = '';
  for (let i = 0; i < MAX_TRACKS; i++) {
    const o = document.createElement('option');
    o.value = i;
    const name = slots[i]?.name;
    o.textContent = occ.has(i) ? `Slot ${i} — in use${name ? `: ${name}` : ''}` : `Slot ${i} — free`;
    sel.append(o);
  }
  sel.value = String(nextFreeSlot());
}
updateUploadSlotOptions();

// ---- support banner ----
if (!isSupported()) {
  $('unsupported').hidden = false;
  $('btn-connect').disabled = true;
}

renderSlots();
setConnected(false);

// ---- PWA service worker ----
if ('serviceWorker' in navigator) {
  navigator.serviceWorker.register('./sw.js').catch(() => {});
}