import type {
	SlaveDriver,
	DriverJointState,
	ConnectionStatus,
	RobotCommand,
	RemoteServerSlaveConfig,
	StateUpdateCallback,
	StatusChangeCallback,
	UnsubscribeFn
} from "$lib/types/robotDriver";
import { getWebSocketConfig, getCommunicationConfig } from "$lib/configs/performanceConfig";

/**
 * Remote Server Slave Driver
 * Connects to FastAPI WebSocket server as a slave to receive and execute commands
 */
export class RemoteServerSlave implements SlaveDriver {
	readonly type = "slave" as const;
	readonly id: string;
	readonly name: string;

	private _status: ConnectionStatus = { isConnected: false };
	private config: RemoteServerSlaveConfig;

	// Joint states
	private jointStates: DriverJointState[] = [];

	// WebSocket connection
	private ws?: WebSocket;
	private reconnectAttempts = 0;
	private maxReconnectAttempts = getWebSocketConfig().MAX_RECONNECT_ATTEMPTS;
	private reconnectDelay = getWebSocketConfig().INITIAL_RECONNECT_DELAY_MS;
	private heartbeatInterval?: number;

	// Event callbacks
	private stateCallbacks: StateUpdateCallback[] = [];
	private statusCallbacks: StatusChangeCallback[] = [];

	constructor(config: RemoteServerSlaveConfig, initialJointStates: DriverJointState[]) {
		this.config = config;
		this.id = `remote-slave-${config.robotId}-${Date.now()}`;
		this.name = `Remote Server Slave (${config.robotId})`;

		// Initialize joint states
		this.jointStates = initialJointStates.map((state) => ({ ...state }));

		console.log(
			`Created RemoteServerSlave for robot ${config.robotId} with ${this.jointStates.length} joints`
		);
	}

	get status(): ConnectionStatus {
		return this._status;
	}

	async connect(): Promise<void> {
		console.log(`Connecting ${this.name} to ${this.config.url}...`);

		try {
			// Build WebSocket URL
			const wsUrl = this.buildWebSocketUrl();

			// Create WebSocket connection
			this.ws = new WebSocket(wsUrl);

			// Set up event handlers
			this.setupWebSocketHandlers();

			// Wait for connection
			await this.waitForConnection();

			this._status = {
				isConnected: true,
				lastConnected: new Date(),
				error: undefined
			};
			this.notifyStatusChange();

			console.log(`${this.name} connected successfully`);

			// Send initial status
			await this.sendStatusUpdate();
		} catch (error) {
			this._status = {
				isConnected: false,
				error: `Connection failed: ${error}`
			};
			this.notifyStatusChange();
			throw error;
		}
	}

	async disconnect(): Promise<void> {
		console.log(`Disconnecting ${this.name}...`);

		this.stopHeartbeat();

		if (this.ws) {
			this.ws.close();
			this.ws = undefined;
		}

		this._status = { isConnected: false };
		this.notifyStatusChange();

		console.log(`${this.name} disconnected`);
	}

	async executeCommand(command: RobotCommand): Promise<void> {
		if (!this._status.isConnected) {
			throw new Error("Cannot execute command: slave not connected");
		}

		console.log(`RemoteServerSlave executing command with ${command.joints.length} joint updates`);

		try {
			// Update joint states (simulate execution)
			for (const jointUpdate of command.joints) {
				const joint = this.jointStates.find((j) => j.name === jointUpdate.name);
				if (joint) {
					joint.virtualValue = jointUpdate.value;
					joint.realValue = jointUpdate.value; // For remote slaves, assume perfect execution
				}
			}

			// Notify state update
			this.notifyStateUpdate();

			// Send joint states to server (so master can receive updates)
			await this.sendJointStates();

			// Send status update to server
			await this.sendStatusUpdate();
		} catch (error) {
			console.error("Error executing command:", error);
			await this.sendError(`Command execution failed: ${error}`);
			throw error;
		}
	}

	async executeCommands(commands: RobotCommand[]): Promise<void> {
		console.log(`RemoteServerSlave executing batch of ${commands.length} commands`);

		for (const command of commands) {
			await this.executeCommand(command);

			// Use optimized delay between commands
			if (commands.length > 1) {
				await new Promise((resolve) =>
					setTimeout(resolve, getCommunicationConfig().BATCH_COMMAND_DELAY_MS)
				);
			}
		}
	}

	async readJointStates(): Promise<DriverJointState[]> {
		return [...this.jointStates];
	}

	async writeJointState(jointName: string, value: number): Promise<void> {
		const command: RobotCommand = {
			timestamp: Date.now(),
			joints: [{ name: jointName, value }]
		};

		await this.executeCommand(command);
	}

	async writeJointStates(updates: { jointName: string; value: number }[]): Promise<void> {
		const command: RobotCommand = {
			timestamp: Date.now(),
			joints: updates.map((update) => ({ name: update.jointName, value: update.value }))
		};

		await this.executeCommand(command);
	}

	// Event subscription methods
	onStateUpdate(callback: StateUpdateCallback): UnsubscribeFn {
		this.stateCallbacks.push(callback);
		return () => {
			const index = this.stateCallbacks.indexOf(callback);
			if (index >= 0) {
				this.stateCallbacks.splice(index, 1);
			}
		};
	}

	onStatusChange(callback: StatusChangeCallback): UnsubscribeFn {
		this.statusCallbacks.push(callback);
		return () => {
			const index = this.statusCallbacks.indexOf(callback);
			if (index >= 0) {
				this.statusCallbacks.splice(index, 1);
			}
		};
	}

	// Private methods
	private buildWebSocketUrl(): string {
		const baseUrl = this.config.url.replace(/^http/, "ws");
		return `${baseUrl}/ws/slave/${this.config.robotId}`;
	}

	private setupWebSocketHandlers(): void {
		if (!this.ws) return;

		this.ws.onopen = () => {
			console.log(`WebSocket connected for slave ${this.config.robotId}`);
			this.reconnectAttempts = 0; // Reset on successful connection
			this.startHeartbeat();
		};

		this.ws.onmessage = (event) => {
			try {
				const message = JSON.parse(event.data);
				this.handleServerMessage(message);
			} catch (error) {
				console.error("Failed to parse WebSocket message:", error);
			}
		};

		this.ws.onclose = (event) => {
			console.log(`WebSocket closed for slave ${this.config.robotId}:`, event.code, event.reason);
			this.handleDisconnection();
		};

		this.ws.onerror = (error) => {
			console.error(`WebSocket error for slave ${this.config.robotId}:`, error);
			this._status = {
				isConnected: false,
				error: `WebSocket error: ${error}`
			};
			this.notifyStatusChange();
		};
	}

	private async waitForConnection(): Promise<void> {
		if (!this.ws) throw new Error("WebSocket not created");

		return new Promise((resolve, reject) => {
			const timeout = setTimeout(() => {
				reject(new Error("Connection timeout"));
			}, getWebSocketConfig().CONNECTION_TIMEOUT_MS);

			if (this.ws!.readyState === WebSocket.OPEN) {
				clearTimeout(timeout);
				resolve();
				return;
			}

			this.ws!.onopen = () => {
				clearTimeout(timeout);
				resolve();
			};

			this.ws!.onerror = (error) => {
				clearTimeout(timeout);
				reject(error);
			};
		});
	}

	private async sendMessage(message: Record<string, unknown>): Promise<void> {
		if (!this.ws || this.ws.readyState !== WebSocket.OPEN) {
			throw new Error("WebSocket not connected");
		}

		this.ws.send(JSON.stringify(message));
	}

	private handleServerMessage(message: Record<string, unknown>): void {
		const { type, data } = message;

		switch (type) {
			case "execute_command":
				if (data) {
					this.executeCommand(data as RobotCommand).catch((error) => {
						console.error("Failed to execute command from server:", error);
					});
				}
				break;

			case "execute_sequence":
				if (data && typeof data === "object" && "commands" in data) {
					const sequence = data as { commands: RobotCommand[] };
					this.executeCommands(sequence.commands).catch((error) => {
						console.error("Failed to execute sequence from server:", error);
					});
				}
				break;

			case "play_sequence":
				if (data && typeof data === "object" && "commands" in data) {
					console.log(`Playing sequence from server on remote slave ${this.config.robotId}`);
					const sequence = data as { commands: RobotCommand[] };
					this.executeCommands(sequence.commands).catch((error) => {
						console.error("Failed to play sequence from server:", error);
					});
				}
				break;

			case "stop_sequence":
				console.log(`Stopping sequences on remote slave ${this.config.robotId}`);
				// For a simple slave, we don't track running sequences, so just log
				break;

			case "status_request":
				this.sendStatusUpdate().catch((error) => {
					console.error("Failed to send status update:", error);
				});
				break;

			default:
				console.warn(`Unknown message type from server: ${type}`);
		}
	}

	private handleDisconnection(): void {
		this._status = { isConnected: false };
		this.notifyStatusChange();
		this.stopHeartbeat();

		// Attempt reconnection if not manually disconnected
		if (this.reconnectAttempts < this.maxReconnectAttempts) {
			this.attemptReconnection();
		}
	}

	private async attemptReconnection(): Promise<void> {
		this.reconnectAttempts++;
		const maxDelay = getWebSocketConfig().MAX_RECONNECT_DELAY_MS;
		const delay = Math.min(
			this.reconnectDelay * Math.pow(1.5, this.reconnectAttempts - 1),
			maxDelay
		);

		console.log(
			`Attempting slave reconnection ${this.reconnectAttempts}/${this.maxReconnectAttempts} in ${delay}ms...`
		);

		setTimeout(async () => {
			try {
				await this.connect();
			} catch (error) {
				console.error(`Slave reconnection attempt ${this.reconnectAttempts} failed:`, error);
			}
		}, delay);
	}

	private startHeartbeat(): void {
		this.heartbeatInterval = setInterval(async () => {
			if (this._status.isConnected && this.ws) {
				try {
					await this.sendStatusUpdate();
				} catch (error) {
					console.error("Failed to send heartbeat status:", error);
				}
			}
		}, getWebSocketConfig().HEARTBEAT_INTERVAL_MS);
	}

	private stopHeartbeat(): void {
		if (this.heartbeatInterval) {
			clearInterval(this.heartbeatInterval);
			this.heartbeatInterval = undefined;
		}
	}

	private async sendStatusUpdate(): Promise<void> {
		if (!this._status.isConnected) return;

		try {
			await this.sendMessage({
				type: "status_update",
				timestamp: new Date().toISOString(),
				data: {
					slave_id: this.id,
					robot_id: this.config.robotId,
					is_connected: this._status.isConnected,
					joint_count: this.jointStates.length
				}
			});
		} catch (error) {
			console.error("Failed to send status update:", error);
		}
	}

	private async sendJointStates(): Promise<void> {
		if (!this._status.isConnected) return;

		try {
			await this.sendMessage({
				type: "joint_states",
				timestamp: new Date().toISOString(),
				data: {
					slave_id: this.id,
					robot_id: this.config.robotId,
					joints: this.jointStates.map((joint) => ({
						name: joint.name,
						virtual_value: joint.virtualValue,
						real_value: joint.realValue
					}))
				}
			});
		} catch (error) {
			console.error("Failed to send joint states:", error);
		}
	}

	private async sendError(errorMessage: string): Promise<void> {
		if (!this._status.isConnected) return;

		try {
			await this.sendMessage({
				type: "error",
				timestamp: new Date().toISOString(),
				data: {
					slave_id: this.id,
					robot_id: this.config.robotId,
					error: errorMessage
				}
			});
		} catch (error) {
			console.error("Failed to send error message:", error);
		}
	}

	private notifyStateUpdate(): void {
		this.stateCallbacks.forEach((callback) => {
			try {
				callback([...this.jointStates]);
			} catch (error) {
				console.error("Error in state update callback:", error);
			}
		});
	}

	private notifyStatusChange(): void {
		this.statusCallbacks.forEach((callback) => {
			try {
				callback(this._status);
			} catch (error) {
				console.error("Error in status change callback:", error);
			}
		});
	}
}