// Real BLE Manager для физических устройств

import { BleManager, Device, State } from 'react-native-ble-plx';
import { Platform } from 'react-native';
import { IBLEManager, WPDevice, WiFiNetwork, WiFiStatus, BLE_CONFIG, BLE_COMMANDS } from './types';
import { requestBLEPermissions, checkBluetoothEnabled } from './permissions';
import base64 from 'react-native-base64';

export class RealBLEManager implements IBLEManager {
  private _manager: BleManager | null = null;
  private connectedDevices = new Map<string, Device>();
  private scanning = false;

  // Lazy initialization to prevent crash on app startup
  private get manager(): BleManager {
    if (!this._manager) {
      this._manager = new BleManager();
    }
    return this._manager;
  }

  constructor() {
    // Don't initialize BleManager here - use lazy initialization
  }

  async scanDevices(): Promise<WPDevice[]> {
    // Check permissions with graceful fallback
    const permissionStatus = await requestBLEPermissions();
    if (!permissionStatus.granted) {
      throw new Error(permissionStatus.error || 'Bluetooth permissions not granted');
    }

    // Check Bluetooth state
    const bluetoothStatus = await checkBluetoothEnabled(this.manager);
    if (!bluetoothStatus.enabled) {
      throw new Error(bluetoothStatus.error || 'Bluetooth is disabled. Please enable it in settings.');
    }

    const foundDevices = new Map<string, WPDevice>();

    return new Promise((resolve, reject) => {
      this.scanning = true;

      this.manager.startDeviceScan(
        null,
        { allowDuplicates: false },
        (error, device) => {
          if (error) {
            this.scanning = false;
            reject(error);
            return;
          }

          if (device && device.name?.startsWith(BLE_CONFIG.DEVICE_NAME_PREFIX)) {
            // Parse well_id from name (WP_497_81a14c -> 497)
            const wellIdMatch = device.name.match(/WP_(\d+)_/);
            const wellId = wellIdMatch ? parseInt(wellIdMatch[1], 10) : undefined;

            // Extract MAC from device name (last part after underscore)
            const macMatch = device.name.match(/_([a-fA-F0-9]{6})$/);
            const mac = macMatch ? macMatch[1].toUpperCase() : '';

            foundDevices.set(device.id, {
              id: device.id,
              name: device.name,
              mac: mac,
              rssi: device.rssi || -100,
              wellId,
            });
          }
        }
      );

      // Stop scan after timeout
      setTimeout(() => {
        this.stopScan();
        resolve(Array.from(foundDevices.values()));
      }, BLE_CONFIG.SCAN_TIMEOUT);
    });
  }

  stopScan(): void {
    if (this.scanning) {
      this.manager.stopDeviceScan();
      this.scanning = false;
    }
  }

  async connectDevice(deviceId: string): Promise<boolean> {
    try {
      // Step 0: Check permissions (required for Android 12+)
      const permissionStatus = await requestBLEPermissions();
      if (!permissionStatus.granted) {
        throw new Error(permissionStatus.error || 'Bluetooth permissions not granted');
      }

      // Step 0.5: Check Bluetooth is enabled
      const bluetoothStatus = await checkBluetoothEnabled(this.manager);
      if (!bluetoothStatus.enabled) {
        throw new Error(bluetoothStatus.error || 'Bluetooth is disabled. Please enable it in settings.');
      }

      // Check if already connected
      const existingDevice = this.connectedDevices.get(deviceId);
      if (existingDevice) {
        const isConnected = await existingDevice.isConnected();
        if (isConnected) {
          return true;
        }
        // Device was in map but disconnected, remove it
        this.connectedDevices.delete(deviceId);
      }

      const device = await this.manager.connectToDevice(deviceId, {
        timeout: 10000, // 10 second timeout
      });

      await device.discoverAllServicesAndCharacteristics();

      // Request larger MTU for Android (default is 23 bytes which is too small)
      if (Platform.OS === 'android') {
        try {
          const mtu = await device.requestMTU(512);
        } catch (mtuError) {
        }
      }

      this.connectedDevices.set(deviceId, device);
      return true;
    } catch (error: any) {
      return false;
    }
  }

  async disconnectDevice(deviceId: string): Promise<void> {
    const device = this.connectedDevices.get(deviceId);
    if (device) {
      try {
        // Cancel any pending operations before disconnecting
        // This helps prevent Android NullPointerException in monitor callbacks
        await device.cancelConnection();
      } catch (error: any) {
        // Log but don't throw - device may already be disconnected
      } finally {
        this.connectedDevices.delete(deviceId);
      }
    }
  }

  isDeviceConnected(deviceId: string): boolean {
    return this.connectedDevices.has(deviceId);
  }

  async sendCommand(deviceId: string, command: string): Promise<string> {

    const device = this.connectedDevices.get(deviceId);
    if (!device) {
      throw new Error('Device not connected');
    }

    // Verify device is still connected
    try {
      const isConnected = await device.isConnected();
      if (!isConnected) {
        this.connectedDevices.delete(deviceId);
        throw new Error('Device disconnected');
      }
    } catch (checkError: any) {
      throw new Error('Failed to verify connection');
    }

    // Generate unique transaction ID to prevent Android null pointer issues
    const transactionId = `cmd_${Date.now()}_${Math.random().toString(36).substring(2, 9)}`;

    return new Promise(async (resolve, reject) => {
      let responseReceived = false;
      let subscription: any = null;
      let timeoutId: ReturnType<typeof setTimeout> | null = null;

      const cleanup = () => {
        if (timeoutId) {
          clearTimeout(timeoutId);
          timeoutId = null;
        }
        if (subscription) {
          try {
            subscription.remove();
          } catch (removeError) {
            // Ignore errors during cleanup - device may already be disconnected
          }
          subscription = null;
        }
      };

      // Safe reject wrapper to handle null error messages (Android BLE crash fix)
      const safeReject = (error: any) => {
        if (responseReceived) return;

        // Extract error code (numeric or string)
        const errorCode = error?.errorCode || error?.code || 'BLE_ERROR';

        // Ignore "Operation was cancelled" (code 2) - this is expected when we cleanup
        // This happens when subscription is removed but BLE still tries to send callback
        if (errorCode === 2 || errorCode === 'OperationCancelled' ||
            (error?.message && error.message.includes('cancelled'))) {
          return;
        }

        responseReceived = true;
        cleanup();

        // Ensure error has a valid message (fixes Android NullPointerException)
        const errorMessage = error?.message || error?.reason || 'BLE operation failed';

        reject(new Error(`[${errorCode}] ${errorMessage}`));
      };

      try {
        // Subscribe to notifications with explicit transactionId
        subscription = device.monitorCharacteristicForService(
          BLE_CONFIG.SERVICE_UUID,
          BLE_CONFIG.CHAR_UUID,
          (error, characteristic) => {
            // Wrap callback in try-catch to prevent crashes
            try {
              if (error) {
                const errCode = (error as any)?.errorCode;
                // errorCode 2 = "Operation was cancelled" — normal BLE cleanup, not a real error
                if (errCode === 2) {
                } else {
                  // Notification error
                }
                safeReject(error);
                return;
              }

              if (characteristic?.value) {
                const decoded = base64.decode(characteristic.value);
                if (!responseReceived) {
                  responseReceived = true;
                  cleanup();
                  resolve(decoded);
                }
              }
            } catch (callbackError: any) {
              safeReject(callbackError);
            }
          },
          transactionId // Explicit transaction ID prevents Android null pointer
        );

        // Send command
        const encoded = base64.encode(command);
        await device.writeCharacteristicWithResponseForService(
          BLE_CONFIG.SERVICE_UUID,
          BLE_CONFIG.CHAR_UUID,
          encoded
        );

        // Timeout
        timeoutId = setTimeout(() => {
          if (!responseReceived) {
            safeReject(new Error('Command timeout'));
          }
        }, BLE_CONFIG.COMMAND_TIMEOUT);
      } catch (error: any) {
        safeReject(error);
      }
    });
  }

  async getWiFiList(deviceId: string): Promise<WiFiNetwork[]> {

    // Step 1: Unlock device
    const unlockResponse = await this.sendCommand(deviceId, BLE_COMMANDS.PIN_UNLOCK);
    if (!unlockResponse.includes('ok')) {
      throw new Error('Failed to unlock device');
    }

    // Step 2: Get WiFi list
    const listResponse = await this.sendCommand(deviceId, BLE_COMMANDS.GET_WIFI_LIST);

    // Parse response: "mac,XXXXXX|w|COUNT|SSID1,RSSI1|SSID2,RSSI2|..."
    const parts = listResponse.split('|');
    if (parts.length < 3) {
      throw new Error('Invalid WiFi list response');
    }

    const count = parseInt(parts[2], 10);
    if (count < 0) {
      if (count === -1) {
        throw new Error('WiFi scan in progress, please wait');
      }
      if (count === -2) {
        return []; // No networks found
      }
    }

    // Use Map to deduplicate by SSID, keeping the strongest signal
    const networksMap = new Map<string, WiFiNetwork>();
    for (let i = 3; i < parts.length; i++) {
      const [ssid, rssiStr] = parts[i].split(',');
      if (ssid && rssiStr) {
        const trimmedSsid = ssid.trim();
        const rssi = parseInt(rssiStr, 10);

        // Skip empty SSIDs
        if (!trimmedSsid) continue;

        // Keep the one with strongest signal if duplicate
        const existing = networksMap.get(trimmedSsid);
        if (!existing || rssi > existing.rssi) {
          networksMap.set(trimmedSsid, {
            ssid: trimmedSsid,
            rssi: rssi,
          });
        }
      }
    }

    // Convert to array and sort by signal strength (strongest first)
    return Array.from(networksMap.values()).sort((a, b) => b.rssi - a.rssi);
  }

  async setWiFi(deviceId: string, ssid: string, password: string): Promise<boolean> {

    // Step 1: Unlock device
    const unlockResponse = await this.sendCommand(deviceId, BLE_COMMANDS.PIN_UNLOCK);
    if (!unlockResponse.includes('ok')) {
      throw new Error(`Device unlock failed: ${unlockResponse}`);
    }

    // Step 1.5: Check if already connected to the target WiFi
    // This prevents "W|fail" when sensor uses old saved credentials
    try {
      const statusResponse = await this.sendCommand(deviceId, BLE_COMMANDS.GET_WIFI_STATUS);

      // Parse: "mac,XXXXXX|a|SSID,RSSI" or "mac,XXXXXX|a|,0" (not connected)
      const parts = statusResponse.split('|');
      if (parts.length >= 3) {
        const [currentSsid] = parts[2].split(',');
        if (currentSsid && currentSsid.trim().toLowerCase() === ssid.toLowerCase()) {
          return true;
        }
      }
    } catch (statusError) {
    }

    // Step 2: Set WiFi credentials
    const command = `${BLE_COMMANDS.SET_WIFI}|${ssid},${password}`;
    const setResponse = await this.sendCommand(deviceId, command);

    // Parse response: "mac,XXXXXX|W|ok" or "mac,XXXXXX|W|fail" or other errors
    if (setResponse.includes('|W|ok')) {
      return true;
    }

    // WiFi config failed - check if sensor is still connected (using old credentials)
    if (setResponse.includes('|W|fail')) {

      try {
        const recheckResponse = await this.sendCommand(deviceId, BLE_COMMANDS.GET_WIFI_STATUS);
        const parts = recheckResponse.split('|');
        if (parts.length >= 3) {
          const [currentSsid, rssiStr] = parts[2].split(',');
          const rssi = parseInt(rssiStr, 10);

          // If connected to target SSID (using old credentials), consider it success
          if (currentSsid && currentSsid.trim().toLowerCase() === ssid.toLowerCase() && rssi < 0) {
            return true;
          }
        }
      } catch (recheckError) {
      }

      throw new Error('WiFi credentials rejected by sensor. Check password.');
    }

    if (setResponse.includes('timeout') || setResponse.includes('Timeout')) {
      throw new Error('Sensor did not respond to WiFi config. Try again.');
    }

    // Unknown error - include raw response for debugging
    throw new Error(`WiFi config failed: ${setResponse.substring(0, 100)}`);
  }

  async getCurrentWiFi(deviceId: string): Promise<WiFiStatus | null> {
    // Step 1: Unlock device
    const unlockResponse = await this.sendCommand(deviceId, BLE_COMMANDS.PIN_UNLOCK);
    if (!unlockResponse.includes('ok')) {
      throw new Error('Failed to unlock device');
    }

    // Step 2: Get current WiFi status
    const statusResponse = await this.sendCommand(deviceId, BLE_COMMANDS.GET_WIFI_STATUS);

    // Parse response: "mac,XXXXXX|a|SSID,RSSI" or "mac,XXXXXX|a|,0" (not connected)
    const parts = statusResponse.split('|');
    if (parts.length < 3) {
      return null;
    }

    const [ssid, rssiStr] = parts[2].split(',');
    if (!ssid || ssid.trim() === '') {
      return null; // Not connected
    }

    return {
      ssid: ssid.trim(),
      rssi: parseInt(rssiStr, 10),
      connected: true,
    };
  }

  async rebootDevice(deviceId: string): Promise<void> {
    // Step 1: Unlock device
    await this.sendCommand(deviceId, BLE_COMMANDS.PIN_UNLOCK);

    // Step 2: Reboot (device will disconnect)
    await this.sendCommand(deviceId, BLE_COMMANDS.REBOOT);

    // Remove from connected devices
    this.connectedDevices.delete(deviceId);
  }

  /**
   * Cleanup all BLE connections and state
   * Should be called on app logout to properly release resources
   */
  async cleanup(): Promise<void> {

    // Stop any ongoing scan
    if (this.scanning) {
      this.stopScan();
    }

    // Disconnect all connected devices
    const deviceIds = Array.from(this.connectedDevices.keys());
    for (const deviceId of deviceIds) {
      try {
        await this.disconnectDevice(deviceId);
      } catch (error) {
        // Continue cleanup even if one device fails
      }
    }

    // Clear the map
    this.connectedDevices.clear();

  }
}