// =========================================================================
//  Live sync (PM_E-1 beta) — bidirectional mirror with a connected PM_K-1.
//
//  Rides the SAME Web-MIDI SysEx channel as the rest of the device link
//  (manufacturer 0x7D); see editor's _ensureMidi / _send / onDeviceMidi.
//  Opcodes (free 0x40 block, alongside 0x01 RTC / 0x02-03 version /
//  0x10 programs / 0x21-23 firmware / 0x7E-7F NAK-ACK):
//
//    0x40 HELLO  -> "begin mirroring; reply with your full state"   payload: <origin>
//    0x41 FULL   -> full snapshot (resync / heartbeat / on connect) payload: <origin>;<seq>;<running>;<sl>;<item>;<patch>
//    0x42 DELTA  -> one mutation event                              payload: <origin>;<seq>;<evt>
//    0x43 BYE    -> mirroring off                                   payload: <origin>
//    0x44 SLSYNC -> live set-list CONTENT merge (user lists only)   payload: <origin>;<seq>;<json>   (§8)
//    0x45 LOGSYNC-> practice-log entry merge (additive, by at+name) payload: <origin>;<seq>;<json>   (§9)
//
//  DELTA <evt> grammar (reuses the share-language tokens — see engine.js):
//    play | stop | bpm=<n> | vol=<pct> | sel=<sl>/<item>
//    beat=<lane>/<step>/<level>            level 0/1/2/3 = mute/normal/accent/ghost
//    lane=<lane>/<field>/<value>          field: sound|groups|sub|swing|gain|poly|enabled
//
//  Echo/loop guard: applying a remote change is wrapped in _applyingRemote so
//  it never re-broadcasts, and any message whose origin == our own is dropped.
//  The DEVICE is the convergence authority — its periodic 0x41 is ground truth,
//  so simultaneous edits reconcile within one heartbeat. The editor emits fine
//  deltas for transport/tempo/volume/selection/beat-taps and a coalesced 0x41
//  for structural lane/practice edits; it APPLIES every delta type either way.
//  Full protocol + firmware checklist: docs/livesync-protocol.md.
// =========================================================================
var _applyingRemote = false;            // true while applying a remote change (suppresses re-broadcast)
var _syncOn = false;                    // mirroring armed
var _loopback = /[?&]loopback=1/.test(location.search);   // no-hardware self-echo test mode

var LiveSync = {
  origin: "e" + Math.floor(Math.random() * 1e9).toString(36),   // this editor's id (drop our own echoes)
  seq: 0,
  peerSeq: 0,            // loopback only: stand-in counter for the simulated peer
  peerOrigin: null,      // last origin we heard from (for the status line)
  connected: false,      // a peer has answered (HELLO/FULL/DELTA seen)

  async connect() {
    var hasMidi = await _ensureMidi();
    if (!hasMidi && !_loopback) { alert("Live sync needs the Web MIDI API — use Chrome, Edge, or Firefox.\nConnect the PM_K-1 (CircuitPython firmware) and try again."); return false; }
    _syncOn = true;
    this.send(0x40, "");        // HELLO — ask the device for its full state
    this.broadcastFull();       // and push ours so the device mirrors us immediately
    this.broadcastSetlists();   // offer our user set-list library (content merge — §8)
    this.broadcastLogBatch();   // and our whole practice history (additive merge — §9)
    if (_loopback) { this.connected = true; this.peerOrigin = "loopback"; }
    updateSyncBtn();
    return true;
  },
  disconnect() {
    if (_syncOn) this.send(0x43, "");   // BYE
    _syncOn = false; this.connected = false; this.peerOrigin = null;
    updateSyncBtn();
  },

  // ---- transmit ----------------------------------------------------------
  send(op, evt) {
    var text = (op === 0x40 || op === 0x43) ? this.origin
                                            : this.origin + ";" + (this.seq++) + ";" + evt;
    var bytes = [0xF0, 0x7D, op];
    for (var i = 0; i < text.length; i++) { var c = text.charCodeAt(i); bytes.push(c > 0x7F ? 0x3F : c); }
    bytes.push(0xF7);
    try { _send(bytes); } catch (e) {}
    if (_loopback) {                    // simulate a perfect mirror: echo back as a "peer"
      var self = this, peer = (op === 0x40 || op === 0x43) ? "peer" : "peer;" + (this.peerSeq++) + ";" + evt;
      setTimeout(function () { self.applyRemote(op, peer); }, 0);
    }
  },
  broadcast(evt) { if (_syncOn && !_applyingRemote) this.send(0x42, evt); },
  broadcastFull() {
    if (!_syncOn) return;
    var patch; try { patch = currentPatch(); } catch (e) { return; }
    this.send(0x41, (state.running ? 1 : 0) + ";" + loadedSL + ";" + activeItem + ";" + patch);
  },
  // 0x44 SLSYNC — full manifest of OUR user set lists (titles + items + progs),
  // in the same JSON shape the 0x10 programs push uses. Built-ins/seeded lists
  // are excluded (both halves bake identical copies); merge is by title (§8).
  broadcastSetlists() {
    if (!_syncOn || _applyingRemote) return;
    var json; try { json = _userSetlistsJSON(); } catch (e) { return; }
    this.send(0x44, _ascii7(json));
  },
  // 0x45 LOGSYNC — practice-log entries, normalized to {at,name,dur,bpm} (§9).
  // entries omitted => whole log (on connect); else a single new session.
  broadcastLog(entry) {
    if (!_syncOn || _applyingRemote) return;
    this.send(0x45, _ascii7(JSON.stringify({ log: [entry] })));
  },
  broadcastLogBatch() {
    if (!_syncOn || _applyingRemote) return;
    var json; try { json = _logBatchJSON(); } catch (e) { return; }
    this.send(0x45, _ascii7(json));
  },

  // ---- receive -----------------------------------------------------------
  applyRemote(op, text) {
    var origin = text.split(";", 1)[0];
    if (origin === this.origin) return;             // our own echo — ignore
    this.peerOrigin = origin; this.connected = true;
    if (op === 0x40) { this.broadcastFull(); updateSyncBtn(); return; }   // peer said HELLO -> send our state
    if (op === 0x43) { this.connected = false; updateSyncBtn(); return; } // peer said BYE
    var parts = text.split(";");
    if (op === 0x41) {                              // FULL: origin;seq;running;sl;item;patch...
      var running = parts[2] === "1";
      var sl = parseInt(parts[3], 10), item = parseInt(parts[4], 10);
      var patch = parts.slice(5).join(";");         // patch is the tail (it contains ; and /)
      _applyRemote(function () { _applyFull(running, patch, sl, item); });
    } else if (op === 0x42) {                       // DELTA: origin;seq;evt
      var evt = parts.slice(2).join(";");
      _applyRemote(function () { _applyDelta(evt); });
    } else if (op === 0x44) {                        // SLSYNC: origin;seq;json (set-list content)
      var sj = parts.slice(2).join(";");
      _applyRemote(function () { _applySetlists(sj); });
    } else if (op === 0x45) {                        // LOGSYNC: origin;seq;json (practice entries)
      var lj = parts.slice(2).join(";");
      _applyRemote(function () { _applyLog(lj); });
    }
    updateSyncBtn();
  },
};

// Run fn with re-broadcast suppressed, then refresh the live patch-string field.
function _applyRemote(fn) {
  var prev = _applyingRemote; _applyingRemote = true;
  try { fn(); } catch (e) { console.warn("[sync] apply failed", e); }
  finally { _applyingRemote = prev; }
  if (typeof refreshPatchField === "function") refreshPatchField();
}

function _applyDelta(evt) {
  var eq = evt.indexOf("="), key = eq < 0 ? evt : evt.slice(0, eq), val = eq < 0 ? "" : evt.slice(eq + 1);
  if (key === "play")  { if (!state.running) toggleTransport(); return; }
  if (key === "stop")  { if (state.running) toggleTransport(); return; }
  if (key === "bpm")   { setBpm(+val); return; }
  if (key === "vol")   { setVolume(+val); return; }
  if (key === "sel")   { var a = val.split("/"); loadItem(+a[1], +a[0]); return; }
  if (key === "beat")  {
    var p = val.split("/"), m = meters[+p[0]];
    if (m) { m.beatsOn[+p[1]] = +p[2] | 0; renderLaneStrip(m); }
    return;
  }
  if (key === "lane")  {
    var q = val.split("/"), L = meters[+q[0]], field = q[1], v = q.slice(2).join("/");
    if (!L) return;
    if (field === "sound")   L.sound = v;
    else if (field === "groups") { L.groupsStr = v; }
    else if (field === "sub")    { L.stepsPerBeat = parseInt(v, 10) || 1; }
    else if (field === "swing")  { L.swing = (v === "1"); }
    else if (field === "gain")   { L.gainDb = +v || 0; }
    else if (field === "poly")   { L.poly = (v === "1"); }
    else if (field === "enabled"){ setLaneEnabled(L, v === "1"); }
    if (field === "groups" || field === "sub" || field === "swing") recomputeLane(L);
    _syncLaneControls(L);
    return;
  }
}

// Full-state mirror: only rebuild if the groove actually differs (avoids
// flicker / lost focus when a heartbeat arrives and we're already in sync),
// then reconcile selection + transport.
//   sl/item — the peer's loaded set-list item (or -1 / NaN = free play). We mirror
//   the SELECTION HIGHLIGHT only (state-only setLoaded), never re-loading the item:
//   the groove itself already arrived in `patch`, so re-loading would double-apply
//   and could glitch audio. This keeps the "now loaded" row + history in sync.
function _applyFull(running, patch, sl, item) {
  var cur = null; try { cur = currentPatch(); } catch (e) {}
  if (patch && patch !== cur) applyPatch(patch);
  // Mirror which set-list item the peer has loaded, if it maps onto a list we have.
  if (typeof sl === "number" && sl >= 0 && typeof item === "number" && item >= 0 &&
      typeof setlists !== "undefined" && setlists[sl] && setlists[sl].items[item]) {
    if (loadedSL !== sl || activeItem !== item) {
      if (typeof setLoaded === "function") setLoaded(sl, item);
      if (activeSL !== loadedSL) { activeSL = loadedSL; if (typeof renderSetlists === "function") renderSetlists(); }
      else if (typeof renderItems === "function") renderItems();
      if (typeof renderLog === "function") renderLog();
    }
  }
  if (running && !state.running) toggleTransport();
  else if (!running && state.running) toggleTransport();
}

// Push a lane's model values back into its card's controls (for incoming
// fine-grained lane= deltas from the device; local edits drive these already).
function _syncLaneControls(m) {
  if (!m || !m.el) return;
  var q = function (s) { return m.el.querySelector(s); };
  var g = q("#m" + m.id + "_group"); if (g) g.value = m.groupsStr;
  var sub = q("#m" + m.id + "_sub"); if (sub) sub.value = m.swing ? (m.stepsPerBeat + "s") : String(m.stepsPerBeat);
  var snd = q("#m" + m.id + "_sound"); if (snd) snd.value = m.sound;
  var poly = q("#m" + m.id + "_poly"); if (poly) poly.checked = !!m.poly;
  var en = q("#m" + m.id + "_enable"); if (en) en.checked = !!m.enabled;
  var gain = q("#m" + m.id + "_gain");
  if (gain) { var d = m.gainDb || 0; gain.textContent = (d > 0 ? "+" : "") + d + " dB"; gain.classList.toggle("boost", d > 0); gain.classList.toggle("cut", d < 0); }
}

// ---- set-list content + practice-log sync (0x44 / 0x45) --------------------
// 7-bit-safe encode: escape any non-ASCII to \uXXXX (matches the editor's 0x10
// programsJSON path) so the SysEx stream stays clean and the firmware never sees
// a byte > 0x7F. (regex covers U+0080..U+FFFF, same class the editor's 0x10 uses)
function _ascii7(s) { return String(s).replace(/[\u0080-\uFFFF]/g, function (c) { return "\\u" + c.charCodeAt(0).toString(16).padStart(4, "0"); }); }
// Normalize a set-list title the same way the firmware's _slkey() does
// (lower-case, alphanumerics only) — the cross-half identity key for merge (§8).
function _slKey(t) { return String(t == null ? "" : t).toLowerCase().replace(/[^a-z0-9]/g, ""); }
// JSON manifest of OUR user set lists, in the 0x10 / programs.json shape.
function _userSetlistsJSON() {
  return JSON.stringify({ setlists: userSetlists().map(function (sl) {
    return { title: sl.title || "My set list",
             programs: sl.items.map(function (it) { return { name: it.name, prog: setupToPatch(it) }; }) };
  }) });
}
// Whole practice log, normalized to the wire schema {at,name,dur,bpm} (§9).
function _logBatchJSON() {
  var logs = lsGet(LS.logs, []);
  return JSON.stringify({ log: logs.map(_logToWire) });
}
function _logToWire(e) {
  return { at: e.at | 0, name: e.name, dur: Math.round(e.durationSec || 0), bpm: e.bpm | 0 };
}
// Apply a received 0x44 manifest: merge user lists by normalized title
// (replace-per-list / append unknown / never delete). Built-ins/seeded are
// untouched. Honors copy-on-write implicitly — the wire only carries user lists.
function _applySetlists(json) {
  var d; try { d = JSON.parse(json); } catch (e) { return; }
  var lists = (d && Array.isArray(d.setlists)) ? d.setlists : null;
  if (!lists) return;
  var seed = (typeof SEED_SETLISTS !== "undefined") ? new Set(SEED_SETLISTS.map(function (s) { return _slKey(s.title); })) : new Set();
  var changed = false;
  for (var i = 0; i < lists.length; i++) {
    var rl = lists[i], key = _slKey(rl.title);
    if (!key || seed.has(key)) continue;                    // never overwrite a built-in/seeded list
    var items = (rl.programs || []).map(function (p) {
      var su = patchToSetup(p.prog || ""); su.name = p.name || "Item"; return su;
    });
    var idx = -1;
    for (var j = 0; j < setlists.length; j++) { if (_slKey(setlists[j].title) === key && !seed.has(_slKey(setlists[j].title))) { idx = j; break; } }
    if (idx >= 0) { setlists[idx].items = items; }          // replace this list's contents wholesale
    else { setlists.push({ title: rl.title || "Device", description: "", items: items }); }
    changed = true;
  }
  if (!changed) return;
  if (typeof saveSetlists === "function") saveSetlists();
  if (typeof activeSL !== "undefined" && activeSL >= setlists.length) activeSL = Math.max(0, setlists.length - 1);
  if (typeof renderSetlists === "function") renderSetlists();
}
// Apply a received 0x45 batch: additive merge by (at,name); at==0 always appended.
function _applyLog(json) {
  var d; try { d = JSON.parse(json); } catch (e) { return; }
  var incoming = (d && Array.isArray(d.log)) ? d.log : null;
  if (!incoming) return;
  var logs = lsGet(LS.logs, []);
  var have = {};
  for (var k = 0; k < logs.length; k++) { if (logs[k].at) have[logs[k].at + "" + logs[k].name] = 1; }
  var added = 0;
  for (var i = 0; i < incoming.length; i++) {
    var w = incoming[i]; if (!w || !w.name) continue;
    var at = w.at | 0;
    if (at && have[at + "" + w.name]) continue;       // dedup (at==0 falls through -> always appended)
    logs.push({ at: at || Date.now(), name: w.name, durationSec: w.dur || 0, bpm: w.bpm | 0, lanes: [] });
    if (at) have[at + "" + w.name] = 1;
    added++;
  }
  if (!added) return;
  logs.sort(function (a, b) { return (b.at | 0) - (a.at | 0); });   // newest first
  lsSet(LS.logs, logs);
  if (typeof renderLog === "function") renderLog();
}

// ---- broadcast helpers called from the editor's mutation handlers ----------
// Each is a no-op unless mirroring is armed and we're not mid-apply.
function syncTransport() { LiveSync.broadcast(state.running ? "play" : "stop"); }
function syncBpm()       { LiveSync.broadcast("bpm=" + state.bpm); }
function syncVol()       { LiveSync.broadcast("vol=" + Math.round(state.volume * 100)); }
function syncSel(sl, i)  { LiveSync.broadcast("sel=" + sl + "/" + i); }
function syncBeat(m, i)  { var idx = meters.indexOf(m); if (idx >= 0) LiveSync.broadcast("beat=" + idx + "/" + i + "/" + (m.beatsOn[i] | 0)); }
// Structural / multi-field edits coalesce into one full-state push (small Pico
// RX buffer — don't flood the bus with a delta per keystroke).
var _patchSyncTimer = 0;
function syncPatchSoon() {
  if (!_syncOn || _applyingRemote) return;
  clearTimeout(_patchSyncTimer);
  _patchSyncTimer = setTimeout(function () { LiveSync.broadcastFull(); }, 150);
}
// Set-list CONTENT changes (add/rename/reorder list, add/remove/rename item,
// capture/update) coalesce into one 0x44 manifest push (§8).
var _slSyncTimer = 0;
function syncSetlistsSoon() {
  if (!_syncOn || _applyingRemote) return;
  clearTimeout(_slSyncTimer);
  _slSyncTimer = setTimeout(function () { LiveSync.broadcastSetlists(); }, 200);
}
// A newly logged practice session -> one 0x45 entry (§9).
function syncLog(entry) {
  if (!_syncOn || _applyingRemote || !entry) return;
  LiveSync.broadcastLog(_logToWire(entry));
}

function toggleSync() { if (_syncOn) LiveSync.disconnect(); else LiveSync.connect(); }
function updateSyncBtn() {
  var b = document.getElementById("syncBtn"); if (!b) return;
  if (!_syncOn) { b.textContent = "🔗 Live sync"; b.classList.remove("primary"); b.title = "Mirror a connected PM_K-1 live (Web MIDI · Chrome/Edge/Firefox)"; return; }
  b.classList.add("primary");
  b.textContent = LiveSync.connected ? "🔗 Synced" + (_loopback ? " (loop)" : "") : "🔗 Linking…";
  b.title = LiveSync.connected ? "Live-mirroring with " + (LiveSync.peerOrigin || "device") + " — click to stop" : "Waiting for the device to answer…";
}