const EventEmitter = require('events');
const io = require('../globals/io');
const logger = require('../globals/logger').child('roverManager');
const { sendAlert, COLORS } = require('./alertService');
const { parseSensorFrame } = require('../helpers/sensorDecoder');
const { MODES, getMode } = require('./modeManager');
const { isAdmin, roleEvents } = require('./roleService');
const { publishEvent } = require('./eventBus');
const videoSessions = require('./videoSessions');

const rovers = new Map(); // roverId -> record
const socketToRovers = new Map(); // socketId -> Set(roverId)
const spectatorSockets = new Set();
const turnService = require('./turnService');
const managerEvents = new EventEmitter();
const DOCK_GUARD_WINDOW_MS = 3 * 1000;
const BACKOFF_MS = 500;
const BACKOFF_SPEED = 120;
const backoffTimers = new Map(); // roverId -> Timeout

function ensureRecord(id) {
  if (!rovers.has(id)) {
    rovers.set(id, {
      id,
      meta: null,
      ws: null,
      lastSensor: null,
      docked: null,
      lastBumpAt: null,
      drivers: new Set(),
      locked: false,
      lockReason: null,
      batteryState: null,
      room: `rover:${id}`,
      lastSeen: Date.now(),
    });
  }
  return rovers.get(id);
}

function upsertRover(meta, ws) {
  const id = meta.name || meta.id;
  if (!meta.cameraServo) {
    logger.info('Rover hello missing camera servo block', { id, keys: Object.keys(meta || {}) });
  } else {
    logger.info('Rover hello camera servo', { id, servo: meta.cameraServo });
  }
  const isNew = !rovers.has(id);
  const record = ensureRecord(id);
  record.meta = meta;
  record.ws = ws;
  record.lastSeen = Date.now();
  rovers.set(id, record);
  spectatorSockets.forEach((socketId) => {
    const sock = io.sockets.sockets.get(socketId);
    sock?.join(record.room);
  });
  managerEvents.emit('rover', { roverId: id, action: 'upsert', record });
  if (isNew) {
    publishEvent({ source: 'roverManager', type: 'rover.online', payload: { roverId: id } });
  }
  broadcastRoster();
  return record;
}

function removeRover(id) {
  const record = rovers.get(id);
  if (!record) return;
  rovers.delete(id);
  turnService.cleanupRover(id);
  spectatorSockets.forEach((socketId) => {
    const sock = io.sockets.sockets.get(socketId);
    sock?.leave(record.room);
  });
  broadcastRoster();
  managerEvents.emit('rover', { roverId: id, action: 'removed' });
  publishEvent({ source: 'roverManager', type: 'rover.offline', payload: { roverId: id } });
}

function lockRover(id, locked, options = {}) {
  const record = rovers.get(id);
  if (!record) {
    throw new Error('Unknown rover');
  }
  const reason = locked ? options.reason || 'manual' : null;
  const silent = Boolean(options.silent);
  if (locked) {
    record.locked = true;
    record.lockReason = reason;
    if (!silent) {
      sendAlert({
        color: COLORS.warn,
        title: 'Rover Locked',
        message: `${id} locked${record.lockReason ? ` (${record.lockReason})` : ''}.`,
      });
    }
    publishEvent({
      source: 'roverManager',
      type: 'rover.locked',
      payload: { roverId: id, reason: record.lockReason },
    });
  } else {
    record.locked = false;
    record.lockReason = null;
    if (!silent) {
      sendAlert({ color: COLORS.success, title: 'Rover Unlocked', message: `${id} unlocked.` });
    }
    publishEvent({
      source: 'roverManager',
      type: 'rover.unlocked',
      payload: { roverId: id },
    });
  }
  broadcastRoster();
  managerEvents.emit('lock', { roverId: id, locked: record.locked, reason: record.lockReason });
  return record.locked;
}

function getRoster() {
  return Array.from(rovers.values()).map((record) => ({
    id: record.id,
    name: record.meta?.name || record.id,
    battery: record.meta?.battery,
    batteryState: record.batteryState,
    maxWheelSpeed: record.meta?.maxWheelSpeed,
    media: record.meta?.media,
    cameraServo: record.meta?.cameraServo,
    audio: record.meta?.audio,
    nightVision: record.meta?.nightVision,
    locked: record.locked,
    lockReason: record.lockReason,
    lastSeen: record.lastSeen,
  }));
}

function broadcastRoster() {
  io.emit('rovers', getRoster());
}

function computeBatteryState(record, sensors) {
  if (!record) return null;
  if (!sensors) return record.batteryState;
  const config = record.meta?.battery || null;
  const charge = sensors?.batteryChargeMah ?? null;
  const capacity = sensors?.batteryCapacityMah ?? null;
  const full = typeof config?.Full === 'number' ? config.Full : null;
  const warn = typeof config?.Warn === 'number' ? config.Warn : null;
  const urgent = typeof config?.Urgent === 'number' ? config.Urgent : null;
  let percent = null;
  if (charge != null && warn != null && full != null && full > warn) {
    const span = full - warn;
    percent = (charge - warn) / span;
  } else if (charge != null && capacity != null && capacity > 0) {
    percent = charge / capacity;
  }
  if (percent != null) {
    percent = Math.max(0, Math.min(1, percent));
  }
  return {
    charge,
    capacity,
    full,
    warn,
    urgent,
    percent,
    percentDisplay: percent == null ? null : Math.round(percent * 100),
    warnActive: Boolean(warn != null && charge != null && charge <= warn),
    urgentActive: Boolean(urgent != null && charge != null && charge <= urgent),
    updatedAt: Date.now(),
  };
}

function handleSensorFrame(roverId, frame) {
  const record = rovers.get(roverId);
  if (!record) return;
  record.lastSeen = Date.now();
  const decoded = parseSensorFrame(frame.data);
  record.lastSensor = { raw: frame, decoded };
  record.batteryState = computeBatteryState(record, decoded);
  const hasDockInfo = decoded?.chargingSources != null;
  if (hasDockInfo) {
    const prevDocked = record.docked;
    const docked = Boolean(decoded?.chargingSources?.homeBase);
    record.docked = docked;
    if (prevDocked === true && docked === false) {
      handleIdleUndock(record);
    }
  }
  const bumps = decoded?.bumpsAndWheelDrops;
  if (bumps?.bumpLeft || bumps?.bumpRight) {
    record.lastBumpAt = Date.now();
  }
  io.to(record.room).emit('sensorFrame', {
    roverId,
    frame,
    sensors: decoded,
  });
  managerEvents.emit('sensor', { roverId, sensors: decoded, batteryState: record.batteryState });
}

function handleIdleUndock(undockedRecord) {
  if (!undockedRecord || undockedRecord.drivers.size > 0) return;
  const now = Date.now();
  const { getRecentDriveActivity, setDriveCooldown, issueCommand } = require('./commandService');
  const candidates = getRecentDriveActivity(DOCK_GUARD_WINDOW_MS, { excludeAdmins: true })
    .filter((candidate) => candidate.roverId !== undockedRecord.id);
  if (candidates.length === 0) return;
  const candidatesWithBump = candidates.filter((candidate) => {
    const record = rovers.get(candidate.roverId);
    return record?.lastBumpAt && now - record.lastBumpAt <= DOCK_GUARD_WINDOW_MS;
  });
  const pool = candidatesWithBump.length > 0 ? candidatesWithBump : candidates;
  pool.sort((a, b) => b.ts - a.ts);
  const suspect = pool[0];
  if (!suspect) return;
  const suspectRecord = rovers.get(suspect.roverId);
  if (!suspectRecord) return;
  const bumpRecent =
    suspectRecord.lastBumpAt && now - suspectRecord.lastBumpAt <= DOCK_GUARD_WINDOW_MS;
  sendAlert({
    color: COLORS.warn,
    title: 'Dock protection',
    message: `${undockedRecord.id} undocked while idle; stopping ${suspect.roverId}.`,
  });
  try {
    issueCommand(suspect.roverId, { type: 'drive', driveDirect: { left: 0, right: 0 } });
    issueCommand(suspect.roverId, { type: 'motors', motorPwm: { main: 0, side: 0, vacuum: 0 } });
  } catch (err) {
    logger.warn('Dock protection stop failed', suspect.roverId, err.message);
  }
  setDriveCooldown(suspect.roverId, DOCK_GUARD_WINDOW_MS);
  if (bumpRecent) {
    backoffRover(suspect.roverId);
  }
}

function backoffRover(roverId) {
  if (!roverId) return;
  const { issueCommand } = require('./commandService');
  clearTimeout(backoffTimers.get(roverId));
  try {
    issueCommand(roverId, {
      type: 'drive',
      driveDirect: { left: -BACKOFF_SPEED, right: -BACKOFF_SPEED },
    });
  } catch (err) {
    logger.warn('Dock protection backoff failed', roverId, err.message);
    return;
  }
  backoffTimers.set(
    roverId,
    setTimeout(() => {
      try {
        issueCommand(roverId, { type: 'drive', driveDirect: { left: 0, right: 0 } });
      } catch (err) {
        logger.warn('Dock protection backoff stop failed', roverId, err.message);
      }
    }, BACKOFF_MS),
  );
}

function removeSocket(socket) {
  const joined = socketToRovers.get(socket.id);
  if (!joined) {
    disableSpectator(socket);
    return;
  }
  for (const roverId of joined) {
    const record = rovers.get(roverId);
    if (record) {
      record.drivers.delete(socket.id);
    }
    turnService.driverRemoved(roverId, socket.id);
    managerEvents.emit('driver', { socketId: socket.id, roverId, action: 'remove' });
  }
  socketToRovers.delete(socket.id);
  disableSpectator(socket);
}

function requestControl(roverId, socket, options = {}) {
  const { force = false, allowUser = false } = options;
  const record = rovers.get(roverId);
  if (!record) {
    throw new Error('Unknown rover');
  }
  if (!allowUser && !isAdmin(socket)) {
    throw new Error('Only admins can request control');
  }
  if (record.locked && !isAdmin(socket)) {
    throw new Error('Rover locked');
  }
  const mode = getMode();
  if (!allowUser && mode === MODES.ADMIN && !isAdmin(socket)) {
    throw new Error('Admins only');
  }
  if (!allowUser && mode === MODES.LOCKDOWN && !isAdmin(socket)) {
    throw new Error('Server in lockdown');
  }
  record.drivers.add(socket.id);
  if (!socketToRovers.has(socket.id)) {
    socketToRovers.set(socket.id, new Set());
  }
  socketToRovers.get(socket.id).add(roverId);
  socket.join(record.room);
  turnService.driverAdded(roverId, socket.id, force && isAdmin(socket));
  socket.emit('controlGranted', { roverId });
  managerEvents.emit('driver', { socketId: socket.id, roverId, action: 'add' });
  sendAlert({
    color: COLORS.success,
    title: 'Control Granted',
    message: `${socket.id} now driving ${roverId}`,
  });
  return { roverId, room: record.room };
}

function releaseControl(roverId, socket) {
  const record = rovers.get(roverId);
  if (!record) return;
  record.drivers.delete(socket.id);
  const joined = socketToRovers.get(socket.id);
  if (joined) {
    joined.delete(roverId);
    if (joined.size === 0) {
      socketToRovers.delete(socket.id);
    }
  }
  socket.leave(record.room);
  turnService.driverRemoved(roverId, socket.id);
  managerEvents.emit('driver', { socketId: socket.id, roverId, action: 'remove' });
}

function isDriver(roverId, socket) {
  const record = rovers.get(roverId);
  if (!record) return false;
  return record.drivers.has(socket.id);
}

function canDrive(roverId, socket) {
  return turnService.canDrive(roverId, socket) || isAdmin(socket);
}

function getRoversForSocket(socketId) {
  const joined = socketToRovers.get(socketId);
  if (!joined || joined.size === 0) {
    return [];
  }
  return Array.from(joined);
}

function getPrimaryRoverForSocket(socketId) {
  const joined = socketToRovers.get(socketId);
  if (!joined || joined.size === 0) {
    return null;
  }
  const iterator = joined.values();
  const first = iterator.next();
  return first.done ? null : first.value;
}

function isDockedAndCharging(record) {
  const sensors = record?.lastSensor?.decoded || record?.lastSensor?.sensors || null;
  if (!sensors) return false;
  const docked = Boolean(sensors.chargingSources?.homeBase);
  const code = sensors.chargingState?.code;
  const charging = code === 2 || code === 3 || code === 4;
  return docked && charging;
}

function hasOtherDrivers(record, socketId) {
  if (!record) return false;
  for (const driver of record.drivers) {
    if (driver !== socketId) return true;
  }
  return false;
}

function canSwitchRover(socket, targetRoverId) {
  const currentId = getPrimaryRoverForSocket(socket.id);
  if (!currentId || currentId === targetRoverId) {
    return { ok: true, currentId };
  }
  const currentRecord = rovers.get(currentId);
  if (!currentRecord) {
    return { ok: true, currentId };
  }
  if (hasOtherDrivers(currentRecord, socket.id)) {
    return { ok: true, currentId };
  }
  if (isDockedAndCharging(currentRecord)) {
    return { ok: true, currentId };
  }
  return { ok: false, currentId, message: 'Dock and charge your current rover before switching.' };
}

module.exports = {
  upsertRover,
  removeRover,
  lockRover,
  getRoster,
  broadcastRoster,
  handleSensorFrame,
  requestControl,
  releaseControl,
  removeSocket,
  isDriver,
  canDrive,
  enableSpectator,
  disableSpectator,
  rovers,
  managerEvents,
  getRoversForSocket,
  getPrimaryRoverForSocket,
};

roleEvents.on('change', ({ socket, role }) => {
  if (role === 'spectator') {
    enableSpectator(socket);
  } else {
    disableSpectator(socket);
  }
});

io.on('connection', (socket) => {
  socket.emit('rovers', getRoster());
  if (socket.data?.role === 'spectator') {
    enableSpectator(socket);
  }

  function handleRequestControl({ roverId, force } = {}, cb = () => {}) {
    try {
      if (socket.data?.role === 'spectator') {
        throw new Error('Spectators cannot drive');
      }
      const targetId = roverId || Array.from(rovers.keys())[0];
      if (!targetId) {
        throw new Error('No rovers available');
      }
      const previousJoined = getRoversForSocket(socket.id);
      if (!isAdmin(socket)) {
        const { ok, message } = canSwitchRover(socket, targetId);
        if (!ok) {
          throw new Error(message || 'Switch denied');
        }
      }
      logger.info('Request control', socket.id, targetId, { force });
      requestControl(targetId, socket, { force: Boolean(force), allowUser: true });
      previousJoined.forEach((rid) => {
        if (rid !== targetId) {
          releaseControl(rid, socket);
        }
      });
      videoSessions.revokeWhere(
        (info) =>
          info.socketId === socket.id &&
          info.sourceType === 'rover' &&
          info.sourceId !== targetId &&
          info.sourceId !== `${targetId}-audio`,
      );
      managerEvents.emit('switch', { socketId: socket.id, roverId: targetId });
      socket.emit('controlGranted', { roverId: targetId });
      cb({ success: true, roverId: targetId });
    } catch (err) {
      logger.warn('Request control failed', socket.id, err.message);
      sendAlert({ color: COLORS.warn, title: 'Control denied', message: err.message });
      cb({ error: err.message });
    }
  }

  function handleReleaseControl({ roverId } = {}, cb = () => {}) {
    if (!roverId) {
      cb({ error: 'roverId required' });
      return;
    }
    logger.info('Release control', socket.id, roverId);
    releaseControl(roverId, socket);
    cb({ success: true, roverId });
  }

  function handleLockToggle({ roverId, locked } = {}, cb = () => {}) {
    if (!isAdmin(socket)) {
      cb({ error: 'Not authorized' });
      return;
    }
    try {
      lockRover(roverId, locked, { reason: 'manual' });
      logger.info('Lock state changed', roverId, locked);
      cb({ success: true });
    } catch (err) {
      logger.warn('Lock change failed', roverId, err.message);
      sendAlert({ color: COLORS.error, title: 'Lock failed', message: err.message });
      cb({ error: err.message });
    }
  }

  function handleSubscribeAll(_, cb = () => {}) {
    if (socket.data?.role !== 'spectator') {
      cb({ error: 'Spectator role required' });
      return;
    }
    if (getMode() === MODES.LOCKDOWN) {
      cb({ error: 'Spectating disabled in lockdown' });
      return;
    }
    logger.info('Spectator subscribing to all rovers', socket.id);
    for (const record of rovers.values()) {
      socket.join(record.room);
    }
    cb({ success: true });
  }

  socket.on('requestControl', handleRequestControl);
  socket.on('session:requestControl', handleRequestControl);
  socket.on('releaseControl', handleReleaseControl);
  socket.on('session:releaseControl', handleReleaseControl);
  socket.on('lockRover', handleLockToggle);
  socket.on('session:lockRover', handleLockToggle);
  socket.on('subscribeAll', handleSubscribeAll);
  socket.on('session:subscribeAll', handleSubscribeAll);

  socket.on('disconnect', () => {
    logger.info('Socket disconnected', socket.id);
    removeSocket(socket);
  });
});

function enableSpectator(socket) {
  if (!socket?.id || spectatorSockets.has(socket.id)) return;
  spectatorSockets.add(socket.id);
  for (const record of rovers.values()) {
    socket.join(record.room);
  }
}

function disableSpectator(socket) {
  if (!socket?.id || !spectatorSockets.has(socket.id)) return;
  spectatorSockets.delete(socket.id);
  for (const record of rovers.values()) {
    socket.leave(record.room);
  }
}