import WebSocket from 'ws';
import { logger } from '../logger.js';
import type { AgentConfig } from '../config.js';
import type { TaskTracker } from '../router.js';
import type { TrackerEvent } from '../tracker/types.js';

export type EventHandler = (event: TrackerEvent) => Promise<void>;

/**
 * WebSocket client transport for connecting to the tracker.
 *
 * The tracker WS handler supports two field conventions:
 *   - WEBSOCKET-PROTOCOL.md uses "event" field
 *   - TRACKER-PROTOCOL.md uses "type" field
 *
 * We send BOTH fields in every message for compatibility.
 * We read whichever is present on incoming messages.
 */
export class WsClientTransport implements TaskTracker {
  private log = logger.child({ component: 'ws' });
  private ws: WebSocket | null = null;
  private handler: EventHandler | null = null;
  private currentTasks = new Set<string>();
  private processedIds = new Set<string>();
  private heartbeatTimer: ReturnType<typeof setInterval> | null = null;
  private reconnectTimer: ReturnType<typeof setTimeout> | null = null;
  private reconnectDelay = 1000;
  private stopped = false;
  private resolveStart: (() => void) | null = null;
  private rejectStart: ((err: Error) => void) | null = null;
  private authenticated = false;

  /** Lobby chat ID returned by auth.ok */
  lobbyChatId: string | null = null;
  /** Projects returned by auth.ok */
  projects: Array<{ id: string; slug: string; name: string; chat_id?: string }> = [];
  /** Online members from auth.ok */
  online: string[] = [];

  constructor(private config: AgentConfig) {}

  onEvent(handler: EventHandler): void {
    this.handler = handler;
  }

  addTask(taskId: string): void {
    this.currentTasks.add(taskId);
  }

  removeTask(taskId: string): void {
    this.currentTasks.delete(taskId);
  }

  async start(): Promise<void> {
    this.stopped = false;
    return new Promise<void>((resolve, reject) => {
      this.resolveStart = resolve;
      this.rejectStart = reject;
      this.connect();
    });
  }

  async stop(): Promise<void> {
    this.stopped = true;
    if (this.heartbeatTimer) {
      clearInterval(this.heartbeatTimer);
      this.heartbeatTimer = null;
    }
    if (this.reconnectTimer) {
      clearTimeout(this.reconnectTimer);
      this.reconnectTimer = null;
    }
    if (this.ws) {
      this.ws.close(1000, 'Agent shutting down');
      this.ws = null;
    }
    this.log.info('WS client transport stopped');
  }

  private buildWsUrl(): string {
    if (this.config.wsUrl) return this.config.wsUrl;

    const url = this.config.trackerUrl;
    if (url.startsWith('ws://') || url.startsWith('wss://')) return url;

    const base = url
      .replace(/^http:\/\//, 'ws://')
      .replace(/^https:\/\//, 'wss://');
    return `${base.replace(/\/$/, '')}/ws`;
  }

  private connect(): void {
    const url = this.buildWsUrl();
    this.log.info('━━━ CONNECTING to %s ━━━', url);

    const ws = new WebSocket(url);
    this.ws = ws;

    ws.on('open', () => {
      this.log.info('━━━ WS CONNECTED ━━━');
      // Send auth — Tracker expects "type" field only
      this.send('auth', {
        token: this.config.token,
      });
    });

    ws.on('message', (data) => {
      const raw = data.toString();
      this.log.info('← RAW: %s', raw.slice(0, 500));

      let msg: Record<string, unknown>;
      try {
        msg = JSON.parse(raw);
      } catch {
        this.log.warn('Non-JSON message, ignoring');
        return;
      }
      this.handleMessage(msg);
    });

    ws.on('close', (code, reason) => {
      this.log.info('━━━ WS CLOSED (code=%d reason=%s) ━━━', code, reason.toString());
      this.authenticated = false;
      if (this.heartbeatTimer) {
        clearInterval(this.heartbeatTimer);
        this.heartbeatTimer = null;
      }
      if (!this.stopped) {
        this.scheduleReconnect();
      }
    });

    ws.on('error', (err) => {
      this.log.error('━━━ WS ERROR: %s ━━━', err.message);
    });
  }

  /**
   * Send a JSON message with "type" field (Tracker protocol).
   */
  private send(eventType: string, payload: Record<string, unknown> = {}): void {
    const msg = { type: eventType, ...payload };
    const json = JSON.stringify(msg);
    this.log.info('→ SEND: %s', json.slice(0, 500));
    if (this.ws?.readyState === WebSocket.OPEN) {
      this.ws.send(json);
    } else {
      this.log.warn('WS not open, cannot send');
    }
  }

  private handleMessage(msg: Record<string, unknown>): void {
    // Read either "event" or "type" — tracker may use either
    const msgType = (msg.event as string) || (msg.type as string) || '';

    if (!msgType) {
      this.log.warn('Message without event/type field: %s', JSON.stringify(msg).slice(0, 200));
      return;
    }

    switch (msgType) {
      case 'auth.ok':
      case 'auth_ok':
        this.onAuthOk(msg);
        break;

      case 'auth.error':
      case 'auth_error':
        this.log.error('━━━ AUTH FAILED: %s ━━━', msg.message || msg.data);
        if (this.rejectStart) {
          this.rejectStart(new Error(`Auth failed: ${msg.message}`));
          this.resolveStart = null;
          this.rejectStart = null;
        }
        if (this.ws) {
          this.ws.close(1000, 'Auth failed');
          this.ws = null;
        }
        break;

      // Heartbeat ack (tracker may send as any of these)
      case 'agent.heartbeat.ack':
      case 'heartbeat.ack':
      case 'heartbeat_ack':
        this.log.info('← HEARTBEAT ACK');
        break;

      // Subscribe confirmations
      case 'subscribe.ok':
      case 'chat.subscribe.ok':
      case 'project.subscribe.ok':
        this.log.info('← SUBSCRIBE OK: %s', JSON.stringify(msg.data || {}).slice(0, 200));
        break;

      default:
        // Everything else is a tracker event — forward to handler
        this.onTrackerEvent(msgType, msg);
        break;
    }
  }

  private onAuthOk(msg: Record<string, unknown>): void {
    const data = (msg.data || msg.init || {}) as Record<string, unknown>;
    this.lobbyChatId = (data.lobby_chat_id as string) || null;
    this.projects = (data.projects as Array<{ id: string; slug: string; name: string; chat_id?: string }>) || [];
    this.online = (data.online as string[]) || (data.agents_online as string[]) || [];

    this.log.info('━━━ AUTH OK ━━━');
    this.log.info('  Lobby chat: %s', this.lobbyChatId || '(none)');
    this.log.info('  Projects: %s', this.projects.map(p => `${p.slug}(${p.id})`).join(', ') || '(none)');
    this.log.info('  Online: %s', this.online.join(', ') || '(nobody)');
    this.log.info('  Full auth data: %s', JSON.stringify(data, null, 2));

    this.authenticated = true;
    this.reconnectDelay = 1000;
    this.startHeartbeat();

    // Projects are auto-subscribed by Tracker on auth
    this.log.info('Auto-subscribed to %d projects: %s', this.projects.length,
      this.projects.map(p => p.slug).join(', ') || '(none)');

    if (this.resolveStart) {
      this.resolveStart();
      this.resolveStart = null;
      this.rejectStart = null;
    }
  }

  private onTrackerEvent(eventType: string, msg: Record<string, unknown>): void {
    const eventId = (msg.id as string) || `${eventType}-${Date.now()}`;
    const data = (msg.data || msg) as Record<string, unknown>;
    const ts = (msg.ts as number) || Date.now();

    this.log.info('┌── EVENT: %s', eventType);
    this.log.info('│  id: %s', eventId);
    this.log.info('│  data: %s', JSON.stringify(data, null, 2));

    const event: TrackerEvent = { event: eventType, data, ts, id: eventId };

    // Dedup
    if (msg.id) {
      if (this.processedIds.has(eventId)) {
        this.log.info('└── DUPLICATE, skipping');
        return;
      }
      this.processedIds.add(eventId);
      if (this.processedIds.size > 10000) {
        const entries = [...this.processedIds];
        this.processedIds = new Set(entries.slice(entries.length - 5000));
      }
    }

    // Ack
    this.send('ack', {});

    this.log.info('└── → forwarding to router');

    if (this.handler) {
      this.handler(event).catch((err) => {
        this.log.error({ err, eventId }, 'Event handler failed');
      });
    }
  }

  /** Send a chat message via WebSocket (with optional thinking) */
  sendChatMessage(chatId: string, content: string, mentions: string[] = [], thinking?: string, taskId?: string): void {
    const payload: Record<string, unknown> = { content, mentions };
    if (chatId) payload.chat_id = chatId;
    if (taskId) payload.task_id = taskId;
    if (thinking) payload.thinking = thinking;
    this.send('chat.send', payload);
  }

  /** Send a task comment via WebSocket */
  sendTaskComment(taskId: string, content: string, mentions: string[] = [], thinking?: string): void {
    this.send('chat.send', { task_id: taskId, content, mentions, ...(thinking ? { thinking } : {}) });
  }

  /** Send agent stream event via WebSocket */
  sendStreamEvent(eventType: string, data: Record<string, unknown>): void {
    this.send(eventType, data);
  }

  private startHeartbeat(): void {
    if (this.heartbeatTimer) clearInterval(this.heartbeatTimer);
    const intervalMs = this.config.heartbeatIntervalSec * 1000;

    this.sendHeartbeat();
    this.heartbeatTimer = setInterval(() => this.sendHeartbeat(), intervalMs);
    this.log.info('Heartbeat started (every %ds)', this.config.heartbeatIntervalSec);
  }

  private sendHeartbeat(): void {
    const status = this.currentTasks.size > 0 ? 'busy' : 'online';
    this.send('heartbeat', { status });
  }

  private scheduleReconnect(): void {
    this.log.info('━━━ RECONNECT in %dms ━━━', this.reconnectDelay);
    this.reconnectTimer = setTimeout(() => {
      this.reconnectTimer = null;
      this.connect();
    }, this.reconnectDelay);
    this.reconnectDelay = Math.min(this.reconnectDelay * 2, 30000);
  }
}