import * as plugins from './plugins.js';
import { LineScanner } from './classes.linescanner.js';
import type { IRustBridgeLogger } from './interfaces/index.js';
import type { IRustTransport } from './interfaces/transport.js';

export interface ISocketTransportOptions {
  /** Path to Unix socket (Linux/macOS) or named pipe path (Windows) */
  socketPath: string;
  /** Maximum inbound message size in bytes */
  maxPayloadSize: number;
  /** Logger instance */
  logger: IRustBridgeLogger;
  /** Enable auto-reconnect on unexpected disconnect (default: false) */
  autoReconnect?: boolean;
  /** Initial delay between reconnect attempts in ms (default: 100) */
  reconnectBaseDelayMs?: number;
  /** Maximum delay between reconnect attempts in ms (default: 30000) */
  reconnectMaxDelayMs?: number;
  /** Maximum number of reconnect attempts before giving up (default: 10) */
  maxReconnectAttempts?: number;
}

interface IResolvedSocketTransportOptions {
  socketPath: string;
  maxPayloadSize: number;
  logger: IRustBridgeLogger;
  autoReconnect: boolean;
  reconnectBaseDelayMs: number;
  reconnectMaxDelayMs: number;
  maxReconnectAttempts: number;
}

/**
 * Transport that connects to an already-running process via Unix socket or Windows named pipe.
 * The JSON-over-newline protocol is identical to stdio; only the transport changes.
 */
export class SocketTransport extends plugins.events.EventEmitter implements IRustTransport {
  private options: IResolvedSocketTransportOptions;
  private socket: plugins.net.Socket | null = null;
  private lineScanner: LineScanner;
  private _connected: boolean = false;
  private intentionalDisconnect: boolean = false;
  private reconnectAttempts: number = 0;
  private reconnectTimer: ReturnType<typeof setTimeout> | null = null;

  constructor(options: ISocketTransportOptions) {
    super();
    this.options = {
      autoReconnect: false,
      reconnectBaseDelayMs: 100,
      reconnectMaxDelayMs: 30000,
      maxReconnectAttempts: 10,
      ...options,
    };
    this.lineScanner = new LineScanner(options.maxPayloadSize, options.logger);
  }

  public get connected(): boolean {
    return this._connected;
  }

  /**
   * Connect to the socket. Resolves when the TCP/Unix connection is established.
   */
  public async connect(): Promise<void> {
    this.intentionalDisconnect = false;
    this.reconnectAttempts = 0;
    return this.doConnect();
  }

  private doConnect(): Promise<void> {
    return new Promise<void>((resolve, reject) => {
      let settled = false;

      this.socket = plugins.net.connect({ path: this.options.socketPath });

      this.socket.on('connect', () => {
        if (!settled) {
          settled = true;
          this._connected = true;
          this.reconnectAttempts = 0;
          resolve();
        }
      });

      this.socket.on('data', (chunk: Buffer) => {
        this.lineScanner.push(chunk, (line) => {
          this.emit('line', line);
        });
      });

      this.socket.on('close', () => {
        const wasConnected = this._connected;
        this._connected = false;
        this.lineScanner.clear();

        if (!this.intentionalDisconnect && wasConnected && this.options.autoReconnect) {
          this.attemptReconnect();
        }
        this.emit('close');
      });

      this.socket.on('error', (err: Error) => {
        this._connected = false;
        if (!settled) {
          settled = true;
          reject(err);
        } else if (!this.intentionalDisconnect) {
          this.emit('error', err);
        }
      });
    });
  }

  private attemptReconnect(): void {
    if (this.reconnectAttempts >= this.options.maxReconnectAttempts) {
      this.options.logger.log('error', `Max reconnect attempts (${this.options.maxReconnectAttempts}) reached`);
      this.emit('reconnect_failed');
      return;
    }

    const delay = Math.min(
      this.options.reconnectBaseDelayMs * Math.pow(2, this.reconnectAttempts),
      this.options.reconnectMaxDelayMs,
    );
    this.reconnectAttempts++;

    this.options.logger.log('info', `Reconnecting in ${delay}ms (attempt ${this.reconnectAttempts}/${this.options.maxReconnectAttempts})`);

    this.reconnectTimer = setTimeout(async () => {
      this.reconnectTimer = null;
      try {
        await this.doConnect();
        this.emit('reconnected');
      } catch {
        // doConnect rejected — the 'close' handler on the new socket will trigger another attempt
      }
    }, delay);
  }

  /**
   * Write data to the socket with backpressure support.
   */
  public async write(data: string): Promise<void> {
    return new Promise<void>((resolve, reject) => {
      if (!this.socket || !this._connected) {
        reject(new Error('Socket not connected'));
        return;
      }

      const canContinue = this.socket.write(data, 'utf8', (err) => {
        if (err) {
          reject(err);
        }
      });

      if (canContinue) {
        resolve();
      } else {
        this.socket.once('drain', () => {
          resolve();
        });
      }
    });
  }

  /**
   * Close the socket connection. Does NOT kill the remote daemon.
   */
  public disconnect(): void {
    this.intentionalDisconnect = true;

    if (this.reconnectTimer) {
      clearTimeout(this.reconnectTimer);
      this.reconnectTimer = null;
    }

    if (this.socket) {
      const sock = this.socket;
      this.socket = null;
      this._connected = false;
      this.lineScanner.clear();
      sock.removeAllListeners();
      sock.destroy();
    }
  }
}