import type { BleDevice, BleConnectOptionsExt, BleConnectionState, BleConnectionStateChangeCallback, ScanDevicesOptions } from '../interface.uts';

declare const wx: any;

type PendingConnect = {
	resolve: () => void;
	reject: (err?: any) => void;
	timer?: number;
};

function now(): number {
	return Date.now();
}

export class DeviceManager {
	private static instance: DeviceManager | null = null;
	private devices = new Map<string, BleDevice>();
	private connectionStates = new Map<string, BleConnectionState>();
	private connectionListeners: BleConnectionStateChangeCallback[] = [];
	private pendingConnects = new Map<string, PendingConnect>();
	private scanOptions: ScanDevicesOptions | null = null;
	private scanTimer: number | null = null;
	private adapterReady: boolean = false;
	private adapterPromise: Promise<void> | null = null;
	private discoveryActive: boolean = false;
	private deviceFoundRegistered: boolean = false;
	private connectionEventRegistered: boolean = false;

	private constructor() {}

	static getInstance(): DeviceManager {
		if (DeviceManager.instance == null) {
			DeviceManager.instance = new DeviceManager();
		}
		return DeviceManager.instance!;
	}

	private ensureAdapter(): Promise<void> {
		if (this.adapterReady) return Promise.resolve();
		if (this.adapterPromise != null) return this.adapterPromise!;
		this.adapterPromise = new Promise<void>((resolve, reject) => {
			wx.openBluetoothAdapter({
				success: () => {
					this.adapterReady = true;
					this.adapterPromise = null;
					this.ensureEventHandlers();
					resolve();
				},
				fail: (err: any) => {
					this.adapterPromise = null;
					reject(err ?? new Error('openBluetoothAdapter failed'));
				}
			});
		});
		return this.adapterPromise!;
	}

	private ensureEventHandlers() {
		if (!this.deviceFoundRegistered) {
			this.deviceFoundRegistered = true;
			wx.onBluetoothDeviceFound((res: any) => {
				try { this.handleDeviceFound(res); } catch (e) { }
			});
		}
		if (!this.connectionEventRegistered) {
			this.connectionEventRegistered = true;
			wx.onBLEConnectionStateChange((res: any) => {
				try { this.handleConnectionState(res); } catch (e) { }
			});
		}
	}

	startScan(options: ScanDevicesOptions): Promise<void> {
		return this.ensureAdapter().then(() => {
			return this.beginScan(options ?? {} as ScanDevicesOptions);
		});
	}

	private beginScan(options: ScanDevicesOptions): Promise<void> {
		if (this.discoveryActive) {
			this.stopScanInternal();
		}
		this.scanOptions = options;
		const services = options.optionalServices ?? null;
		return new Promise<void>((resolve, reject) => {
			wx.startBluetoothDevicesDiscovery({
				services: services ?? undefined,
				allowDuplicatesKey: false,
				success: () => {
					this.discoveryActive = true;
					if (options.timeout != null && options.timeout > 0) {
						this.scanTimer = setTimeout(() => {
							this.stopScanInternal();
						}, options.timeout);
					}
					resolve();
				},
				fail: (err: any) => {
					this.discoveryActive = false;
					reject(err ?? new Error('startBluetoothDevicesDiscovery failed'));
				}
			});
		});
	}

	stopScan(): void {
		this.stopScanInternal();
	}

	private stopScanInternal() {
		if (!this.discoveryActive) return;
		this.discoveryActive = false;
		try {
			wx.stopBluetoothDevicesDiscovery({});
		} catch (e) { }
		if (this.scanTimer != null) {
			clearTimeout(this.scanTimer);
			this.scanTimer = null;
		}
		const finished = this.scanOptions?.onScanFinished;
		this.scanOptions = null;
		if (finished != null) {
			try { finished(); } catch (e) { }
		}
	}

	private handleDeviceFound(res: any) {
		const list: any[] = res?.devices ?? [];
		for (let i = 0; i < list.length; i++) {
			const item = list[i];
			if (item == null) continue;
			const deviceId = item.deviceId ?? item.deviceId ?? '';
			if (!deviceId) continue;
			const name = item.name ?? item.localName ?? 'Unknown';
			const rssi = item.RSSI ?? item.rssi ?? 0;
			let device = this.devices.get(deviceId);
			if (device == null) {
				device = { deviceId, name, rssi, lastSeen: now() };
				this.devices.set(deviceId, device);
			} else {
				device.name = name;
				device.rssi = rssi;
				device.lastSeen = now();
			}
			const cb = this.scanOptions?.onDeviceFound;
			if (cb != null) {
				try { cb(device); } catch (e) { }
			}
		}
	}

	private handleConnectionState(res: any) {
		const deviceId = res?.deviceId ?? '';
		if (!deviceId) return;
		const connected = res?.connected === true;
		const state: BleConnectionState = connected ? 2 : 0;
		this.connectionStates.set(deviceId, state);
		const pending = this.pendingConnects.get(deviceId);
		if (pending != null) {
			this.pendingConnects.delete(deviceId);
			if (pending.timer != null) clearTimeout(pending.timer);
			if (connected) {
				try { pending.resolve(); } catch (e) { }
			} else {
				try { pending.reject(new Error('连接断开')); } catch (e) { }
			}
		}
		for (let i = 0; i < this.connectionListeners.length; i++) {
			const listener = this.connectionListeners[i];
			try { listener(deviceId, state); } catch (e) { }
		}
	}

	connectDevice(deviceId: string, options?: BleConnectOptionsExt): Promise<void> {
		return this.ensureAdapter().then(() => {
			const timeout = options?.timeout ?? 15000;
			return new Promise<void>((resolve, reject) => {
				const timer = setTimeout(() => {
					this.pendingConnects.delete(deviceId);
					reject(new Error('连接超时'));
				}, timeout);
				this.pendingConnects.set(deviceId, { resolve, reject, timer });
				wx.createBLEConnection({
					deviceId,
					timeout,
					success: () => {
						this.pendingConnects.delete(deviceId);
						clearTimeout(timer);
						this.connectionStates.set(deviceId, 2);
						resolve();
					},
					fail: (err: any) => {
						this.pendingConnects.delete(deviceId);
						clearTimeout(timer);
						reject(err ?? new Error('createBLEConnection failed'));
					}
				});
			});
		});
	}

	disconnectDevice(deviceId: string): Promise<void> {
		return new Promise((resolve, reject) => {
			wx.closeBLEConnection({
				deviceId,
				success: () => {
					this.connectionStates.set(deviceId, 0);
					resolve();
				},
				fail: (err: any) => {
					reject(err ?? new Error('closeBLEConnection failed'));
				}
			});
		});
	}

	reconnectDevice(deviceId: string, options?: BleConnectOptionsExt): Promise<void> {
		const attempts = options?.maxAttempts ?? 3;
		const interval = options?.interval ?? 3000;
		let count = 0;
		const attempt = (): Promise<void> => {
			return this.connectDevice(deviceId, options).catch((err) => {
				count++;
				if (count >= attempts) throw err;
				return new Promise<void>((resolve) => {
					setTimeout(() => resolve(attempt()), interval);
				});
			});
		};
		return attempt();
	}

	getConnectedDevices(): BleDevice[] {
		const result: BleDevice[] = [];
		this.devices.forEach((device, id) => {
			if (this.connectionStates.get(id) == 2) {
				result.push(device);
			}
		});
		return result;
	}

	onConnectionStateChange(listener: BleConnectionStateChangeCallback) {
		this.connectionListeners.push(listener);
	}

	getDevice(deviceId: string): BleDevice | null {
		return this.devices.get(deviceId) ?? null;
	}
}