import {
  type RealtimeEvent,
  type RealtimeRequestEnvelope,
  type RealtimeSubscribeEnvelope,
  type RealtimeUnsubscribeEnvelope,
} from '@affine/realtime';
import {
  Manager as SocketIOManager,
  type Socket as SocketIO,
} from 'socket.io-client';

import { AutoReconnectConnection } from '../../connection';
import type { TelemetryAck, TelemetryBatch } from '../../telemetry/types';
import { throwIfAborted } from '../../utils/throw-if-aborted';

// TODO(@forehalo): use [UserFriendlyError]
interface EventError {
  name: string;
  message: string;
}

type WebsocketResponse<T> =
  | {
      error: EventError;
    }
  | {
      data: T;
    };

interface ServerEvents {
  'space:broadcast-doc-update': {
    spaceType: string;
    spaceId: string;
    docId: string;
    update: string;
    timestamp: number;
    editor: string;
  };
  'space:broadcast-doc-updates': {
    spaceType: string;
    spaceId: string;
    docId: string;
    updates: string[];
    timestamp: number;
    editor?: string;
    compressed?: boolean;
  };

  'space:collect-awareness': {
    spaceType: string;
    spaceId: string;
    docId: string;
  };

  'space:broadcast-awareness-update': {
    spaceType: string;
    spaceId: string;
    docId: string;
    awarenessUpdate: string;
  };

  'realtime:event': RealtimeEvent;
}

interface ClientEvents {
  'space:join': [
    { spaceType: string; spaceId: string; clientVersion: string },
    { clientId: string },
  ];
  'space:leave': { spaceType: string; spaceId: string };
  'space:join-awareness': [
    {
      spaceType: string;
      spaceId: string;
      docId: string;
      clientVersion: string;
    },
    { clientId: string },
  ];
  'space:leave-awareness': {
    spaceType: string;
    spaceId: string;
    docId: string;
  };

  'space:update-awareness': {
    spaceType: string;
    spaceId: string;
    docId: string;
    awarenessUpdate: string;
  };

  'space:load-awarenesses': {
    spaceType: string;
    spaceId: string;
    docId: string;
  };

  'space:push-doc-update': [
    { spaceType: string; spaceId: string; docId: string; update: string },
    { timestamp: number },
  ];
  'space:load-doc-timestamps': [
    {
      spaceType: string;
      spaceId: string;
      timestamp?: number;
    },
    Record<string, number>,
  ];
  'space:load-doc': [
    {
      spaceType: string;
      spaceId: string;
      docId: string;
      stateVector?: string;
    },
    {
      missing: string;
      state: string;
      timestamp: number;
    },
  ];
  'space:delete-doc': { spaceType: string; spaceId: string; docId: string };

  'telemetry:batch': [TelemetryBatch, TelemetryAck];

  'realtime:request': [RealtimeRequestEnvelope, unknown];
  'realtime:subscribe': [RealtimeSubscribeEnvelope, { subscriptionId: string }];
  'realtime:unsubscribe': [RealtimeUnsubscribeEnvelope, { ok: true }];
}

export type ServerEventsMap = {
  [Key in keyof ServerEvents]: (data: ServerEvents[Key]) => void;
};

export type ClientEventsMap = {
  [Key in keyof ClientEvents]: ClientEvents[Key] extends Array<any>
    ? (
        data: ClientEvents[Key][0],
        ack: (res: WebsocketResponse<ClientEvents[Key][1]>) => void
      ) => void
    : (data: ClientEvents[Key]) => void;
};

export type Socket = SocketIO<ServerEventsMap, ClientEventsMap>;

type BufferConstructorLike = {
  from(
    data: Uint8Array | string,
    encoding?: string
  ): Uint8Array & {
    toString(encoding: string): string;
  };
};

const BufferCtor = (globalThis as { Buffer?: BufferConstructorLike }).Buffer;
const CHUNK_SIZE = 0x8000;

export async function uint8ArrayToBase64(array: Uint8Array): Promise<string> {
  if (BufferCtor) {
    return BufferCtor.from(array).toString('base64');
  }

  let binary = '';
  for (let i = 0; i < array.length; i += CHUNK_SIZE) {
    const chunk = array.subarray(i, i + CHUNK_SIZE);
    binary += String.fromCharCode(...chunk);
  }
  return btoa(binary);
}

export function base64ToUint8Array(base64: string) {
  if (BufferCtor) {
    return new Uint8Array(BufferCtor.from(base64, 'base64'));
  }

  const binaryString = atob(base64);
  const bytes = new Uint8Array(binaryString.length);
  for (let i = 0; i < binaryString.length; i++) {
    bytes[i] = binaryString.charCodeAt(i);
  }
  return bytes;
}

let authMethod:
  | ((endpoint: string, cb: (data: object) => void) => void)
  | undefined;

export function configureSocketAuthMethod(
  cb: (endpoint: string, cb: (data: object) => void) => void
) {
  authMethod = cb;
}

class SocketManager {
  private readonly socketIOManager: SocketIOManager;
  socket: Socket;
  refCount = 0;

  constructor(endpoint: string, isSelfHosted: boolean) {
    this.socketIOManager = new SocketIOManager(endpoint, {
      autoConnect: false,
      transports: isSelfHosted ? ['polling', 'websocket'] : ['websocket'], // self-hosted server may not support websocket
      secure: new URL(endpoint).protocol === 'https:',
      // we will handle reconnection by ourselves
      reconnection: false,
    });
    this.socket = this.socketIOManager.socket('/', {
      auth(cb) {
        if (authMethod) {
          authMethod(endpoint, cb);
        } else {
          cb({});
        }
      },
    });
  }

  connect() {
    let disconnected = false;
    this.refCount++;
    this.socket.connect();
    return {
      socket: this.socket,
      disconnect: () => {
        if (disconnected) {
          return;
        }
        disconnected = true;
        this.refCount--;
        if (this.refCount === 0) {
          this.socket.disconnect();
        }
      },
    };
  }
}

const SOCKET_MANAGER_CACHE = new Map<string, SocketManager>();
function getSocketManager(endpoint: string, isSelfHosted: boolean) {
  const key = `${endpoint}:${isSelfHosted ? 'selfhosted' : 'cloud'}`;
  let manager = SOCKET_MANAGER_CACHE.get(key);
  if (!manager) {
    manager = new SocketManager(endpoint, isSelfHosted);
    SOCKET_MANAGER_CACHE.set(key, manager);
  }
  return manager;
}

export class SocketConnection extends AutoReconnectConnection<{
  socket: Socket;
  disconnect: () => void;
}> {
  manager = getSocketManager(this.endpoint, this.isSelfHosted);

  constructor(
    private readonly endpoint: string,
    private readonly isSelfHosted: boolean
  ) {
    super();
  }

  override async doConnect(signal?: AbortSignal) {
    const { socket, disconnect } = this.manager.connect();
    try {
      throwIfAborted(signal);
      await Promise.race([
        new Promise<void>((resolve, reject) => {
          if (socket.connected) {
            resolve();
            return;
          }
          socket.once('connect', () => {
            resolve();
          });
          socket.once('connect_error', err => {
            reject(err);
          });
        }),
        new Promise<void>((_resolve, reject) => {
          signal?.addEventListener('abort', () => {
            reject(signal.reason);
          });
        }),
      ]);
    } catch (err) {
      disconnect();
      throw err;
    }

    socket.on('disconnect', this.handleDisconnect);

    return {
      socket,
      disconnect,
    };
  }

  override doDisconnect(conn: { socket: Socket; disconnect: () => void }) {
    conn.socket.off('disconnect', this.handleDisconnect);
    conn.disconnect();
  }

  handleDisconnect = (reason: SocketIO.DisconnectReason) => {
    this.error = new Error(reason);
  };
}