/**
 * Turtle - Server-side turtle wrapper with state machine and command correlation
 * 
 * Each connected turtle gets a Turtle instance that manages:
 * - State machine (idle, mining, exploring, etc.)
 * - UUID-based command-response correlation with promise chaining
 * - Position/facing/inventory tracking
 * - Event emission for real-time UI updates
 * - Turn-to-direction, equip, rename, inventory transfer
 * - External inventory interaction (connectToInventory)
 * - Block deletion on movement
 * - State recovery on reconnection
 * 
 * Inspired by runi95/turtle-control-panel Turtle class.
 */
import { randomUUID } from 'crypto';
import { EventEmitter } from 'events';
import {
  IdleState,
  MovingState,
  MiningState,
  ExploringState,
  GoHomeState,
  RefuelingState,
  DumpInventoryState,
  FarmingState,
  ScanState,
  ExtractionState,
  BuildingState,
  AutocraftState,
} from './states/index.js';

// Random name list for unnamed turtles (inspired by reference)
const TURTLE_NAMES = [
  'Atlas', 'Bolt', 'Chip', 'Dash', 'Echo', 'Flint', 'Gizmo', 'Hex',
  'Iron', 'Jazz', 'Kit', 'Lumen', 'Miko', 'Nova', 'Onyx', 'Pixel',
  'Quartz', 'Rust', 'Spark', 'Terra', 'Volt', 'Widget', 'Xenon', 'Zinc',
  'Amber', 'Blaze', 'Cobalt', 'Drake', 'Ember', 'Forge', 'Granite', 'Haze',
  'Ingot', 'Jasper', 'Kindle', 'Lapis', 'Marble', 'Nickel', 'Opal', 'Prism',
];

const STATE_MAP = {
  idle: IdleState,
  moving: MovingState,
  mining: MiningState,
  exploring: ExploringState,
  goHome: GoHomeState,
  returning: GoHomeState,
  refueling: RefuelingState,
  dumpInventory: DumpInventoryState,
  dumping: DumpInventoryState,
  farming: FarmingState,
  scanning: ScanState,
  scan: ScanState,
  extracting: ExtractionState,
  extraction: ExtractionState,
  building: BuildingState,
  build: BuildingState,
  autocrafting: AutocraftState,
  autocraft: AutocraftState,
};

// Timeout for exec() commands (ms)
const EXEC_TIMEOUT = 30000;

// Direction enum matching reference: 0=North(-Z), 1=East(+X), 2=South(+Z), 3=West(-X)
const DIRECTION = { NORTH: 0, EAST: 1, SOUTH: 2, WEST: 3 };

export class Turtle extends EventEmitter {
  /**
   * @param {number} id - The ComputerCraft turtle ID
   * @param {Object} server - Reference to server context (worldBlocks, broadcastToClients, etc.)
   */
  constructor(id, server) {
    super();
    this.id = id;
    this.server = server;

    // Turtle state
    this._position = null;
    this._homePosition = null;
    this._facing = 0;
    this._fuel = 0;
    this._fuelLimit = 100000;
    this._inventory = {};
    this._selectedSlot = 1;
    this._label = null;
    this._peripherals = {}; // { side: { types: [...], data: {...} } }
    this._error = null;
    this._warning = null;

    // State machine
    this._state = null;
    this._stateRunner = null; // The running async generator loop

    // Command correlation with promise chaining (prevents concurrent commands racing)
    this._pendingCommands = new Map(); // uuid -> { resolve, reject, timeout }
    this._messageIndex = 0;
    this._lastPromise = Promise.resolve(); // Promise chain for sequential exec

    // Fuel efficiency tracking
    this._stepsSinceLastRefuel = 0;
    this._totalSteps = 0;
    this._totalFuelUsed = 0;

    // Connection tracking
    this.connected = false;
    this.lastUpdate = Date.now();
    this.lastStatusBroadcast = 0;

    // Command queue for eval commands sent to webbridge
    this.pendingCommands = [];

    // Start in idle state
    this.setState('idle');
  }

  // ========== Property Getters/Setters with Change Events ==========

  get position() {
    return this._position;
  }

  set position(value) {
    const changed = !this._position || 
      this._position.x !== value?.x || 
      this._position.y !== value?.y || 
      this._position.z !== value?.z;
    
    this._position = value;
    if (changed) this._emitUpdate();
  }

  get homePosition() {
    return this._homePosition;
  }

  set homePosition(value) {
    this._homePosition = value;
    this._emitUpdate();
  }

  get facing() {
    return this._facing;
  }

  set facing(value) {
    this._facing = value;
    this._emitUpdate();
  }

  get fuel() {
    return this._fuel;
  }

  set fuel(value) {
    this._fuel = value;
  }

  get inventory() {
    return this._inventory;
  }

  set inventory(value) {
    this._inventory = value;
    this._emitUpdate();
  }

  get peripherals() {
    return this._peripherals;
  }

  set peripherals(value) {
    this._peripherals = value;
    this._emitUpdate();
  }

  get selectedSlot() {
    return this._selectedSlot;
  }

  set selectedSlot(value) {
    this._selectedSlot = value;
    this._emitUpdate();
  }

  get fuelLimit() {
    return this._fuelLimit;
  }

  set fuelLimit(value) {
    this._fuelLimit = value;
  }

  get label() {
    return this._label;
  }

  set label(value) {
    this._label = value;
    this._emitUpdate();
  }

  get error() {
    return this._error;
  }

  set error(value) {
    this._error = value;
    if (value) this._emitUpdate();
  }

  get warning() {
    return this._warning;
  }

  set warning(value) {
    this._warning = value;
    if (value) this._emitUpdate();
  }

  get stateName() {
    return this._state?.name || 'idle';
  }

  get stateDescription() {
    return this._state?.description || 'Idle';
  }

  // ========== State Machine ==========

  /**
   * Set the turtle's state. Cancels the current state and starts the new one.
   * @param {string} stateName - The state name (e.g., 'mining', 'idle')
   * @param {Object} data - State-specific initialization data
   */
  setState(stateName, data = {}) {
    // Cancel current state
    if (this._state) {
      this._state.cancel();
    }

    // Create new state
    const StateClass = STATE_MAP[stateName];
    if (!StateClass) {
      console.error(`[Turtle ${this.id}] Unknown state: ${stateName}`);
      return;
    }

    this._state = new StateClass(this, data);
    console.log(`[Turtle ${this.id}] State: ${this._state.name} - ${this._state.description}`);

    // Persist state for recovery (skip idle to avoid DB noise)
    if (stateName !== 'idle' && this.server?.db) {
      try {
        this.server.db.saveTurtleState(this.id, stateName, data);
      } catch (e) {
        // Ignore errors in state persistence
      }
    } else if (stateName === 'idle' && this.server?.db) {
      try {
        this.server.db.deleteTurtleState(this.id);
      } catch (e) { /* ignore */ }
    }

    // Run the state's act() generator loop
    this._runStateLoop();
    this._emitUpdate();
  }

  /**
   * Recover state from database on reconnection
   */
  recoverState() {
    if (!this.server?.db) return false;
    
    try {
      const saved = this.server.db.getTurtleState(this.id);
      if (saved && saved.stateName && saved.stateName !== 'idle') {
        const StateClass = STATE_MAP[saved.stateName];
        if (StateClass) {
          console.log(`[Turtle ${this.id}] Recovering state: ${saved.stateName}`);
          this.setState(saved.stateName, saved.stateData || {});
          return true;
        }
      }
    } catch (e) {
      console.error(`[Turtle ${this.id}] Error recovering state:`, e.message);
    }
    return false;
  }

  /**
   * Run the current state's act() generator in a loop
   */
  async _runStateLoop(consecutiveErrors = 0) {
    const state = this._state;
    const MAX_CONSECUTIVE_ERRORS = 5;
    
    try {
      const generator = state.act();
      
      for await (const _ of generator) {
        // Check if state was cancelled/changed while running
        if (this._state !== state) {
          return; // State changed, stop this generator
        }
        // Reset error counter on successful iteration
        consecutiveErrors = 0;
      }
    } catch (error) {
      if (this._state !== state) return;
      
      consecutiveErrors++;
      const isTimeout = error.message?.includes('timed out');
      
      if (isTimeout && consecutiveErrors < MAX_CONSECUTIVE_ERRORS) {
        console.warn(`[Turtle ${this.id}] Timeout in ${state.name} (${consecutiveErrors}/${MAX_CONSECUTIVE_ERRORS}), retrying...`);
        // Wait a bit then restart the state loop, passing the error count
        await new Promise(r => setTimeout(r, 2000));
        if (this._state === state) {
          this._runStateLoop(consecutiveErrors);
        }
      } else {
        console.error(`[Turtle ${this.id}] State error in ${state.name}:`, error.message);
        // Don't transition idle→idle (causes infinite loop)
        if (state.name !== 'idle') {
          this.setState('idle');
        } else {
          // Already idle and erroring — just wait and retry the idle loop
          console.log(`[Turtle ${this.id}] Idle loop paused, will retry in 60s`);
          await new Promise(r => setTimeout(r, 60000));
          if (this._state === state) {
            this._runStateLoop(0);
          }
        }
      }
    }
  }

  // ========== Command Execution (UUID-based with Promise Chaining) ==========

  /**
   * Execute Lua code on the turtle and return the result.
   * Uses UUID-based command-response correlation.
   * Commands are chained sequentially via lastPromise to prevent race conditions.
   * 
   * @param {string} luaCode - The Lua code to execute
   * @param {number} timeout - Timeout in ms (default: 30s)
   * @returns {Promise<any>} The result of the Lua execution
   */
  exec(luaCode, timeout = EXEC_TIMEOUT) {
    // Chain through lastPromise to ensure sequential execution
    const execPromise = new Promise((resolve, reject) => {
      this._lastPromise.catch(() => {}).finally(() => {
        const uuid = randomUUID();
        const messageIndex = this._messageIndex++;

        // Set up timeout
        const timer = setTimeout(() => {
          const pending = this._pendingCommands.get(uuid);
          if (pending) {
            console.warn(`[Turtle ${this.id}] ⏰ Command timed out uuid:${uuid.substring(0, 8)} (pending: ${this._pendingCommands.size}, code: ${luaCode.substring(0, 50)})`);
          }
          this._pendingCommands.delete(uuid);
          reject(new Error(`Command timed out after ${timeout}ms`));
        }, timeout);

        // Store the pending command
        this._pendingCommands.set(uuid, {
          resolve: (result) => {
            clearTimeout(timer);
            this._pendingCommands.delete(uuid);
            resolve(result);
          },
          reject: (error) => {
            clearTimeout(timer);
            this._pendingCommands.delete(uuid);
            reject(error);
          },
          timeout: timer,
          luaCode,
          sentAt: Date.now(),
        });

        // Send the command to the turtle (via webbridge modem relay)
        this._sendExecCommand(uuid, messageIndex, luaCode);
      });
    });

    this._lastPromise = execPromise;
    return execPromise;
  }

  /**
   * Send an eval command to the turtle
   */
  _sendExecCommand(uuid, index, luaCode) {
    const command = {
      type: 'eval',
      uuid,
      index,
      code: luaCode,
      target: this.id,
    };

    // Emit to server for forwarding to webbridge
    this.emit('sendCommand', command);
  }

  // ========== Turtle API Methods ==========

  /**
   * Turn the turtle to face a specific cardinal direction.
   * Calculates the optimal turn direction (left or right).
   * @param {number} direction - 0=North, 1=East, 2=South, 3=West
   */
  async turnToDirection(direction) {
    if (this._facing === direction) return;
    
    const turn = (direction - this._facing + 4) % 4;
    if (turn === 1) {
      await this.exec(`turtle.turnRight(); _G._turtleFacing = ${direction}`);
      this._facing = direction;
      this._emitUpdate();
    } else if (turn === 2) {
      await this.exec(`turtle.turnLeft(); turtle.turnLeft(); _G._turtleFacing = ${direction}`);
      this._facing = direction;
      this._emitUpdate();
    } else if (turn === 3) {
      await this.exec(`turtle.turnLeft(); _G._turtleFacing = ${direction}`);
      this._facing = direction;
      this._emitUpdate();
    }
  }

  /**
   * Turn the turtle left
   */
  async turnLeft() {
    const result = await this.exec('return turtle.turnLeft()');
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      this._facing = (this._facing + 3) % 4;
      // Sync facing on turtle side
      this.exec(`_G._turtleFacing = ${this._facing}`).catch(() => {});
      this._emitUpdate();
    }
    return result;
  }

  /**
   * Turn the turtle right
   */
  async turnRight() {
    const result = await this.exec('return turtle.turnRight()');
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      this._facing = (this._facing + 1) % 4;
      // Sync facing on turtle side
      this.exec(`_G._turtleFacing = ${this._facing}`).catch(() => {});
      this._emitUpdate();
    }
    return result;
  }

  /**
   * Move the turtle forward. Updates position and deletes block at destination.
   */
  async forward() {
    const result = await this.exec('return turtle.forward()');
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      this.updatePositionForward();
      this._deleteBlockAtPosition(this._position);
      this._stepsSinceLastRefuel++;
      this._totalSteps++;
    }
    return result;
  }

  /**
   * Move the turtle backward.
   */
  async back() {
    const result = await this.exec('return turtle.back()');
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      // Update position for backward movement
      if (this._position) {
        const pos = { ...this._position };
        if (this._facing === 0) pos.z += 1;
        else if (this._facing === 1) pos.x -= 1;
        else if (this._facing === 2) pos.z -= 1;
        else if (this._facing === 3) pos.x += 1;
        this.position = pos;
        this._deleteBlockAtPosition(pos);
      }
      this._stepsSinceLastRefuel++;
      this._totalSteps++;
    }
    return result;
  }

  /**
   * Move the turtle up. Updates position and deletes block at destination.
   */
  async up() {
    const result = await this.exec('return turtle.up()');
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      this.updatePositionUp();
      this._deleteBlockAtPosition(this._position);
      this._stepsSinceLastRefuel++;
      this._totalSteps++;
    }
    return result;
  }

  /**
   * Move the turtle down. Updates position and deletes block at destination.
   */
  async down() {
    const result = await this.exec('return turtle.down()');
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      this.updatePositionDown();
      this._deleteBlockAtPosition(this._position);
      this._stepsSinceLastRefuel++;
      this._totalSteps++;
    }
    return result;
  }

  /**
   * Dig the block in front
   */
  async dig() {
    const result = await this.exec('return turtle.dig()');
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      const pos = this.getBlockPositionInDirection('forward');
      if (pos) this._deleteBlockAtPosition(pos);
    }
    return result;
  }

  /**
   * Dig the block above
   */
  async digUp() {
    const result = await this.exec('return turtle.digUp()');
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      const pos = this.getBlockPositionInDirection('up');
      if (pos) this._deleteBlockAtPosition(pos);
    }
    return result;
  }

  /**
   * Dig the block below
   */
  async digDown() {
    const result = await this.exec('return turtle.digDown()');
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      const pos = this.getBlockPositionInDirection('down');
      if (pos) this._deleteBlockAtPosition(pos);
    }
    return result;
  }

  /**
   * Select an inventory slot
   */
  async select(slot = 1) {
    const result = await this.exec(`return turtle.select(${slot})`);
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      this._selectedSlot = slot;
    }
    return result;
  }

  /**
   * Transfer items from current slot to another slot
   */
  async transferTo(slot, count) {
    const cmd = count != null 
      ? `return turtle.transferTo(${slot}, ${count})`
      : `return turtle.transferTo(${slot})`;
    return this.exec(cmd);
  }

  /**
   * Transfer items between inventory slots (select from, transferTo target, reselect)
   */
  async inventoryTransfer(fromSlot, toSlot, count) {
    const currentSlot = this._selectedSlot;
    await this.select(fromSlot);
    await this.transferTo(toSlot, count);
    await this.select(currentSlot);
  }

  /**
   * Drop items from current slot (front direction)
   */
  async drop(count) {
    const cmd = count != null ? `return turtle.drop(${count})` : 'return turtle.drop()';
    const result = await this.exec(cmd);
    // Auto-refresh adjacent inventory if present
    if (this._peripherals?.front?.types?.includes('inventory')) {
      try { await this.connectToInventory('front'); } catch (e) { /* ignore */ }
    }
    return result;
  }

  /**
   * Drop items upward
   */
  async dropUp(count) {
    const cmd = count != null ? `return turtle.dropUp(${count})` : 'return turtle.dropUp()';
    const result = await this.exec(cmd);
    if (this._peripherals?.top?.types?.includes('inventory')) {
      try { await this.connectToInventory('top'); } catch (e) { /* ignore */ }
    }
    return result;
  }

  /**
   * Drop items downward
   */
  async dropDown(count) {
    const cmd = count != null ? `return turtle.dropDown(${count})` : 'return turtle.dropDown()';
    const result = await this.exec(cmd);
    if (this._peripherals?.bottom?.types?.includes('inventory')) {
      try { await this.connectToInventory('bottom'); } catch (e) { /* ignore */ }
    }
    return result;
  }

  /**
   * Suck items from front
   */
  async suck(count) {
    const cmd = count != null ? `return turtle.suck(${count})` : 'return turtle.suck()';
    return this.exec(cmd);
  }

  /**
   * Suck items from above
   */
  async suckUp(count) {
    const cmd = count != null ? `return turtle.suckUp(${count})` : 'return turtle.suckUp()';
    return this.exec(cmd);
  }

  /**
   * Suck items from below
   */
  async suckDown(count) {
    const cmd = count != null ? `return turtle.suckDown(${count})` : 'return turtle.suckDown()';
    return this.exec(cmd);
  }

  /**
   * Place block in front
   */
  async place(text) {
    const cmd = text ? `return turtle.place("${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}")` : 'return turtle.place()';
    const result = await this.exec(cmd);
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      await this.inspect(); // Auto-inspect to update world map
    }
    return result;
  }

  /**
   * Place block above
   */
  async placeUp(text) {
    const cmd = text ? `return turtle.placeUp("${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}")` : 'return turtle.placeUp()';
    const result = await this.exec(cmd);
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      await this.inspectUp();
    }
    return result;
  }

  /**
   * Place block below
   */
  async placeDown(text) {
    const cmd = text ? `return turtle.placeDown("${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}")` : 'return turtle.placeDown()';
    const result = await this.exec(cmd);
    if (result === true || (Array.isArray(result) && result[0] === true)) {
      await this.inspectDown();
    }
    return result;
  }

  /**
   * Inspect block in front and update world map
   */
  async inspect() {
    const result = await this.exec('local h, d = turtle.inspect(); if h then return d else return nil end');
    if (result && result.name) {
      const pos = this.getBlockPositionInDirection('forward');
      if (pos) this.emit('blocksDiscovered', [{ ...pos, name: result.name, metadata: result.metadata || 0, discoveredBy: this.id }]);
    }
    return result;
  }

  /**
   * Inspect block above
   */
  async inspectUp() {
    const result = await this.exec('local h, d = turtle.inspectUp(); if h then return d else return nil end');
    if (result && result.name) {
      const pos = this.getBlockPositionInDirection('up');
      if (pos) this.emit('blocksDiscovered', [{ ...pos, name: result.name, metadata: result.metadata || 0, discoveredBy: this.id }]);
    }
    return result;
  }

  /**
   * Inspect block below
   */
  async inspectDown() {
    const result = await this.exec('local h, d = turtle.inspectDown(); if h then return d else return nil end');
    if (result && result.name) {
      const pos = this.getBlockPositionInDirection('down');
      if (pos) this.emit('blocksDiscovered', [{ ...pos, name: result.name, metadata: result.metadata || 0, discoveredBy: this.id }]);
    }
    return result;
  }

  /**
   * Batched 3-direction inspect (up/down/forward) in a single eval call.
   * More efficient than 3 separate calls.
   */
  async explore() {
    const result = await this.exec(`
      local results = {}
      local h, d
      h, d = turtle.inspect()
      if h then results.forward = d end
      h, d = turtle.inspectUp()
      if h then results.up = d end
      h, d = turtle.inspectDown()
      if h then results.down = d end
      return results
    `);
    if (result && typeof result === 'object') {
      this.processScanResults(result);
    }
    return result;
  }

  /**
   * Refuel the turtle
   */
  async refuel(count) {
    const cmd = count != null ? `return turtle.refuel(${count})` : 'return turtle.refuel()';
    const fuelBefore = this._fuel;
    const result = await this.exec(cmd);
    // Update fuel level
    const fuelLevel = await this.exec('return turtle.getFuelLevel()');
    if (fuelLevel != null) {
      this._totalFuelUsed += (fuelLevel - fuelBefore);
      this._fuel = fuelLevel;
      this._stepsSinceLastRefuel = 0;
    }
    return result;
  }

  /**
   * Craft using workbench peripheral
   */
  async craft() {
    const result = await this.exec(`
      local hasWorkbench = peripheral.find("workbench") ~= nil
      if not hasWorkbench then return false, "No workbench" end
      return peripheral.find("workbench").craft()
    `);
    return result;
  }

  /**
   * Equip an item on the left side of the turtle
   */
  async equipLeft() {
    return this.exec('return turtle.equipLeft()');
  }

  /**
   * Equip an item on the right side of the turtle
   */
  async equipRight() {
    return this.exec('return turtle.equipRight()');
  }

  /**
   * Rename the turtle (set computer label)
   */
  async rename(name) {
    // Escape quotes and backslashes for safe Lua string interpolation
    const safeName = name.replace(/\\/g, '\\\\').replace(/"/g, '\\"');
    await this.exec(`os.setComputerLabel("${safeName}")`);
    this._label = name;
    this._emitUpdate();
  }

  /**
   * Auto-assign a random name if the turtle has no label
   */
  autoName() {
    if (!this._label) {
      const name = TURTLE_NAMES[Math.floor(Math.random() * TURTLE_NAMES.length)];
      this._label = name;
      // Send rename command to turtle when connected
      if (this.connected) {
        this.rename(name).catch(() => {});
      }
      return name;
    }
    return this._label;
  }

  /**
   * GPS locate
   */
  async gpsLocate() {
    const result = await this.exec('local x,y,z = gps.locate(5); if x then return {x=x, y=y, z=z} else return nil end');
    if (result && result.x != null) {
      this.position = { x: Math.floor(result.x), y: Math.floor(result.y), z: Math.floor(result.z) };
    }
    return this._position;
  }

  /**
   * Write content to a file on the turtle's filesystem
   * @param {string} path - The file path on the turtle (e.g., 'log.txt', 'scripts/miner.lua')
   * @param {string} content - The content to write
   * @param {boolean} append - Whether to append instead of overwrite
   */
  async writeToFile(path, content, append = false) {
    const safePath = path.replace(/\\/g, '\\\\').replace(/"/g, '\\"');
    // Encode content as base64-like hex to avoid Lua string escaping issues
    const mode = append ? 'a' : 'w';
    // Split content into chunks to avoid oversized eval commands
    const chunkSize = 4000;
    const chunks = [];
    for (let i = 0; i < content.length; i += chunkSize) {
      chunks.push(content.substring(i, i + chunkSize));
    }

    if (chunks.length <= 1) {
      // Single write for small files
      const safeContent = (chunks[0] || '').replace(/\\/g, '\\\\').replace(/"/g, '\\"').replace(/\n/g, '\\n').replace(/\r/g, '');
      return this.exec(`
        local f = fs.open("${safePath}", "${mode}")
        if f then
          f.write("${safeContent}")
          f.close()
          return true
        end
        return false, "Cannot open file"
      `);
    }

    // Multi-chunk write for large files
    for (let i = 0; i < chunks.length; i++) {
      const safeChunk = chunks[i].replace(/\\/g, '\\\\').replace(/"/g, '\\"').replace(/\n/g, '\\n').replace(/\r/g, '');
      const writeMode = i === 0 ? mode : 'a';
      const result = await this.exec(`
        local f = fs.open("${safePath}", "${writeMode}")
        if f then
          f.write("${safeChunk}")
          f.close()
          return true
        end
        return false, "Cannot open file"
      `);
      if (result !== true) return result;
    }
    return true;
  }

  /**
   * Refresh detailed inventory state for all 16 slots.
   * Gets name, count, damage, and maxCount for each slot.
   */
  async refreshInventoryState() {
    const result = await this.exec(`
      local inv = {}
      for slot = 1, 16 do
        local item = turtle.getItemDetail(slot)
        if item then
          inv[tostring(slot)] = {
            name = item.name,
            count = item.count,
            damage = item.damage or 0,
            maxCount = turtle.getItemSpace(slot) + item.count
          }
        end
      end
      return inv
    `);

    if (result && typeof result === 'object') {
      this._inventory = result;
      this._emitUpdate();
    }
    return result;
  }

  /**
   * Connect to an adjacent inventory peripheral and read its contents
   */
  async connectToInventory(side) {
    const safeSide = side.replace(/\\/g, '\\\\').replace(/"/g, '\\"');
    const result = await this.exec(`
      local size = peripheral.call("${safeSide}", "size")
      local content = peripheral.call("${safeSide}", "list")
      if next(content) == nil then content = nil end
      return {size = size, content = content}
    `);
    
    if (result) {
      this._peripherals = {
        ...this._peripherals,
        [side]: {
          ...this._peripherals[side],
          data: {
            size: result.size,
            content: result.content,
          },
        },
      };
      this._emitUpdate();
    }
    return result;
  }

  /**
   * Update all attached peripherals (scan what's connected)
   */
  async updateAllAttachedPeripherals() {
    const result = await this.exec(`
      local peripherals = {}
      local names = peripheral.getNames()
      for _, name in ipairs(names) do
        local types = {peripheral.getType(name)}
        peripherals[name] = {types = types}
      end
      return peripherals
    `);
    
    if (result && typeof result === 'object') {
      this._peripherals = result;
      this._emitUpdate();
    }
    return result;
  }

  /**
   * Use a peripheral method by side
   */
  async usePeripheralWithSide(side, method, ...args) {
    const safeSide = side.replace(/\\/g, '\\\\').replace(/"/g, '\\"');
    const safeMethod = method.replace(/\\/g, '\\\\').replace(/"/g, '\\"');
    const argsStr = args.map(a => {
      if (a === null) return 'nil';
      if (typeof a === 'string') return `"${a.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
      return String(a);
    }).join(', ');
    
    return this.exec(`return peripheral.call("${safeSide}", "${safeMethod}"${argsStr ? ', ' + argsStr : ''})`);
  }

  /**
   * Sleep for a duration (on the turtle side)
   */
  async sleep(seconds) {
    return this.exec(`sleep(${seconds})`);
  }

  // ========== Real-time Event Handling ==========

  /**
   * Handle real-time events from the turtle (inventory, peripherals, etc.)
   * These come via the webbridge as separate event messages.
   */
  handleEvent(eventType, eventData) {
    switch (eventType) {
      case 'INVENTORY_UPDATE':
        this._inventory = eventData;
        this._emitUpdate();
        break;
      case 'PERIPHERAL_ATTACHED':
        // Merge new peripherals
        this._peripherals = { ...this._peripherals, ...eventData };
        this._emitUpdate();
        break;
      case 'PERIPHERAL_DETACHED':
        // eventData is the side name string
        if (typeof eventData === 'string' && this._peripherals[eventData]) {
          const { [eventData]: _, ...rest } = this._peripherals;
          this._peripherals = rest;
          this._emitUpdate();
        }
        break;
      default:
        console.log(`[Turtle ${this.id}] Unknown event type: ${eventType}`);
    }
  }

  /**
   * Check if turtle has a peripheral with the given type name
   */
  hasPeripheral(typeName) {
    return Object.values(this._peripherals).some(p => 
      p.types && p.types.includes(typeName)
    );
  }

  /**
   * Get the chunk coordinates for this turtle's position
   */
  get chunk() {
    if (!this._position) return null;
    return [Math.floor(this._position.x / 16), Math.floor(this._position.z / 16)];
  }

  /**
   * Handle a response from the turtle (matched by UUID)
   */
  handleResponse(uuid, result, error) {
    const pending = this._pendingCommands.get(uuid);
    if (!pending) {
      // Response for unknown/expired command - ignore
      return false;
    }

    if (error) {
      pending.reject(new Error(error));
    } else {
      pending.resolve(result);
    }

    return true;
  }

  // ========== Position Tracking ==========

  updatePositionForward() {
    if (!this._position) return;
    const pos = { ...this._position };
    if (this._facing === 0) pos.z -= 1;
    else if (this._facing === 1) pos.x += 1;
    else if (this._facing === 2) pos.z += 1;
    else if (this._facing === 3) pos.x -= 1;
    this.position = pos;
  }

  updatePositionUp() {
    if (!this._position) return;
    this.position = { ...this._position, y: this._position.y + 1 };
  }

  updatePositionDown() {
    if (!this._position) return;
    this.position = { ...this._position, y: this._position.y - 1 };
  }

  /**
   * Get the world position of a block in a given direction from the turtle
   */
  getBlockPositionInDirection(direction) {
    if (!this._position) return null;
    const pos = { ...this._position };

    if (direction === 'up') {
      pos.y += 1;
    } else if (direction === 'down') {
      pos.y -= 1;
    } else if (direction === 'forward') {
      if (this._facing === 0) pos.z -= 1;
      else if (this._facing === 1) pos.x += 1;
      else if (this._facing === 2) pos.z += 1;
      else if (this._facing === 3) pos.x -= 1;
    }

    return pos;
  }

  /**
   * Delete a block from both in-memory world map and database (turtle moved into it = now air)
   */
  _deleteBlockAtPosition(pos) {
    if (!pos) return;
    const key = `${pos.x},${pos.y},${pos.z}`;
    if (this.server?.worldBlocks) {
      this.server.worldBlocks.delete(key);
    }
    if (this.server?.db) {
      try {
        this.server.db.deleteBlock(pos.x, pos.y, pos.z);
      } catch (e) { /* ignore */ }
    }
    // Broadcast block deletion to web clients
    if (this.server?.broadcastToClients) {
      this.server.broadcastToClients({
        type: 'block_deleted',
        x: pos.x, y: pos.y, z: pos.z,
      });
    }
  }

  /**
   * Process scan results and update world blocks on the server
   */
  processScanResults(scanResult) {
    if (!scanResult || !this._position) return;

    const blocks = [];

    // Handle directional scan results
    for (const [dir, blockData] of Object.entries(scanResult)) {
      let blockPos;
      if (dir === 'up') {
        blockPos = { x: this._position.x, y: this._position.y + 1, z: this._position.z };
      } else if (dir === 'down') {
        blockPos = { x: this._position.x, y: this._position.y - 1, z: this._position.z };
      } else if (dir === 'forward') {
        blockPos = this.getBlockPositionInDirection('forward');
      } else if (dir.startsWith('h')) {
        // Horizontal direction by facing number (h0, h1, h2, h3)
        const facingNum = parseInt(dir.substring(1));
        const tempPos = { ...this._position };
        if (facingNum === 0) tempPos.z -= 1;
        else if (facingNum === 1) tempPos.x += 1;
        else if (facingNum === 2) tempPos.z += 1;
        else if (facingNum === 3) tempPos.x -= 1;
        blockPos = tempPos;
      }

      if (blockPos && blockData && blockData.name) {
        blocks.push({
          x: blockPos.x,
          y: blockPos.y,
          z: blockPos.z,
          name: blockData.name,
          metadata: blockData.metadata || 0,
          discoveredBy: this.id,
        });
      }
    }

    // Store blocks in server world map
    if (blocks.length > 0) {
      this.emit('blocksDiscovered', blocks);
    }
  }

  // ========== Status & Serialization ==========

  /**
   * Update from a legacy status message (modem protocol)
   */
  updateFromStatus(statusData) {
    this.lastUpdate = Date.now();
    this.connected = true;

    if (statusData.position) {
      this._position = statusData.position;
    }
    if (statusData.homePosition) {
      this._homePosition = statusData.homePosition;
    }
    if (statusData.facing !== undefined) {
      this._facing = statusData.facing;
    }
    if (statusData.fuel !== undefined) {
      this._fuel = statusData.fuel;
    }
    if (statusData.inventory) {
      this._inventory = statusData.inventory;
    }
    if (statusData.label) {
      this._label = statusData.label;
    }

    this._emitUpdate();
  }

  /**
   * Get serializable turtle data for clients
   */
  toJSON() {
    return {
      turtleID: this.id,
      position: this._position,
      homePosition: this._homePosition,
      facing: this._facing,
      fuel: this._fuel,
      fuelLimit: this._fuelLimit,
      selectedSlot: this._selectedSlot,
      inventory: this._inventory,
      inventoryCount: Array.isArray(this._inventory) 
        ? this._inventory.length 
        : Object.keys(this._inventory).length,
      mode: this.stateName,
      state: this.stateName,
      stateDescription: this.stateDescription,
      connected: this.connected,
      lastUpdate: this.lastUpdate,
      label: this._label,
      peripherals: this._peripherals,
      error: this._error,
      warning: this._warning,
      stepsSinceLastRefuel: this._stepsSinceLastRefuel,
      totalSteps: this._totalSteps,
      totalFuelUsed: this._totalFuelUsed,
    };
  }

  /**
   * Emit an update event for broadcasting to clients
   */
  _emitUpdate() {
    // Throttle updates to max once per 100ms
    const now = Date.now();
    if (now - this.lastStatusBroadcast < 100) return;
    this.lastStatusBroadcast = now;

    this.emit('update', this.toJSON());
  }

  /**
   * Clean up when turtle disconnects
   */
  disconnect() {
    this.connected = false;
    
    // Cancel current state
    if (this._state) {
      this._state.cancel();
    }

    // Reject all pending commands
    for (const [uuid, pending] of this._pendingCommands) {
      pending.reject(new Error('Turtle disconnected'));
    }
    this._pendingCommands.clear();

    this.emit('disconnect', this.id);
  }
}