import { proxyRefs, readonly, ref } from 'vue';
import { useYtpConfig } from '~/composables/useYtpConfig';
import { useQueueState } from '~/composables/useQueueState';
import type { StoreItem } from '~/types/store';
import type {
  ConfigUpdatePayload,
  WebSocketClientEmits,
  WebSocketEnvelope,
  WSEP as WSEP,
} from '~/types/sockets';

export type connectionStatus = 'connected' | 'disconnected' | 'connecting';

type SocketHandler = (...args: unknown[]) => void;
type HandlerRegistry = Map<SocketHandler, SocketHandler>;
type KnownEvent = keyof WSEP;

const getRuntimeConfig = () => useRuntimeConfig();
const getConfig = () => useYtpConfig();
const getQueueState = () => useQueueState();
const getToast = () => useNotification();

const socket = ref<WebSocket | null>(null);
const isConnected = ref<boolean>(false);
const connectionStatus = ref<connectionStatus>('disconnected');
const error = ref<string | null>(null);
const error_count = ref<number>(0);
const wasHidden = ref<boolean>(false);
const reconnectTimeout = ref<NodeJS.Timeout | null>(null);
const manualDisconnect = ref<boolean>(false);
const reconnectAttempts = ref<number>(0);

const handlers = new Map<string, HandlerRegistry>();

const emit = <K extends keyof WebSocketClientEmits>(
  event: K,
  data: WebSocketClientEmits[K],
): void => {
  if (!socket.value || WebSocket.OPEN !== socket.value.readyState) {
    return;
  }
  socket.value.send(JSON.stringify({ event, data }));
};

function on<K extends KnownEvent>(event: K | K[], callback: (payload: WSEP[K]) => void): void;
function on<K extends KnownEvent>(
  event: K | K[],
  callback: (event: K, payload: WSEP[K]) => void,
  withEvent: true,
): void;
function on(event: string | string[], callback: SocketHandler, withEvent?: boolean): void;
function on(event: string | string[], callback: SocketHandler, withEvent: boolean = false): void {
  const events = Array.isArray(event) ? event : [event];
  events.forEach((eventName) => {
    if (!handlers.has(eventName)) {
      handlers.set(eventName, new Map());
    }

    const registry = handlers.get(eventName) as HandlerRegistry;
    const handler =
      true === withEvent
        ? (payload: unknown) => callback(eventName, payload)
        : (payload: unknown) => callback(payload);

    registry.set(callback, handler);
  });
}

function off<K extends KnownEvent>(event: K | K[], callback?: (payload: WSEP[K]) => void): void;
function off(event: string | string[], callback?: SocketHandler): void;
function off(event: string | string[], callback?: SocketHandler): void {
  const events = Array.isArray(event) ? event : [event];
  events.forEach((eventName) => {
    const registry = handlers.get(eventName);
    if (!registry) {
      return;
    }

    if (!callback) {
      registry.clear();
      handlers.delete(eventName);
      return;
    }

    registry.delete(callback);
    if (0 === registry.size) {
      handlers.delete(eventName);
    }
  });
}

const getSessionId = (): string | null => null;

const dispatch = (eventName: string, payload: unknown): void => {
  const registry = handlers.get(eventName);
  if (!registry) {
    return;
  }

  registry.forEach((handler) => handler(payload));
};

const handleVisibilityChange = () => {
  if (document.hidden) {
    wasHidden.value = true;
    return;
  }

  if (true === wasHidden.value && false === isConnected.value) {
    if (null !== reconnectTimeout.value) {
      clearTimeout(reconnectTimeout.value);
      reconnectTimeout.value = null;
    }

    reconnectTimeout.value = setTimeout(() => {
      if (false === isConnected.value) {
        console.debug('[SocketStore] Page visible after background, reconnecting...');
        reconnect();
      }
      reconnectTimeout.value = null;
    }, 100);
  }

  wasHidden.value = false;
};

const setupVisibilityListener = () => {
  if (typeof document !== 'undefined') {
    document.addEventListener('visibilitychange', handleVisibilityChange);
  }
};

const cleanupVisibilityListener = () => {
  if (typeof document !== 'undefined') {
    document.removeEventListener('visibilitychange', handleVisibilityChange);
  }
  if (null !== reconnectTimeout.value) {
    clearTimeout(reconnectTimeout.value);
    reconnectTimeout.value = null;
  }
};

const scheduleReconnect = () => {
  if (true === manualDisconnect.value || true === isConnected.value) {
    return;
  }

  if (reconnectAttempts.value >= 50) {
    return;
  }

  if (null !== reconnectTimeout.value) {
    return;
  }

  reconnectTimeout.value = setTimeout(() => {
    reconnectAttempts.value += 1;
    reconnectTimeout.value = null;
    connect();
  }, 5000);
};

const reconnect = () => {
  if (true === isConnected.value) {
    return;
  }
  connect();
  connectionStatus.value = 'connecting';
};

const disconnect = () => {
  manualDisconnect.value = true;
  if (null === socket.value) {
    return;
  }
  socket.value.close();
  socket.value = null;
  isConnected.value = false;
  connectionStatus.value = 'disconnected';
  cleanupVisibilityListener();
};

const buildWsUrl = (): string => {
  const runtimeConfig = getRuntimeConfig();
  const basePath = runtimeConfig.app.baseURL.replace(/\/$/, '');
  const wsPath = `${basePath}/ws?_=${Date.now()}`;
  const configuredBase = runtimeConfig.public.wss?.trim();

  if (configuredBase) {
    return new URL(wsPath, configuredBase).toString();
  }

  const scheme = 'https:' === window.location.protocol ? 'wss' : 'ws';
  return new URL(wsPath, `${scheme}://${window.location.host}`).toString();
};

const connect = () => {
  const runtimeConfig = getRuntimeConfig();

  if (socket.value && WebSocket.OPEN === socket.value.readyState) {
    return;
  }

  if (socket.value && WebSocket.CONNECTING === socket.value.readyState) {
    return;
  }

  manualDisconnect.value = false;
  connectionStatus.value = 'connecting';

  socket.value = new WebSocket(buildWsUrl());

  if ('development' === runtimeConfig.public?.APP_ENV) {
    window.ws = socket.value;
  }

  socket.value.addEventListener('open', () => {
    isConnected.value = true;
    connectionStatus.value = 'connected';
    error.value = null;
    error_count.value = 0;
    reconnectAttempts.value = 0;
    dispatch('connect', null);
  });

  socket.value.addEventListener('close', () => {
    isConnected.value = false;
    connectionStatus.value = 'disconnected';
    error.value = 'Disconnected from server.';
    dispatch('disconnect', null);
    scheduleReconnect();
  });

  socket.value.addEventListener('error', () => {
    isConnected.value = false;
    connectionStatus.value = 'disconnected';
    error.value = 'Connection error: Unknown error';
    error_count.value += 1;
    dispatch('connect_error', { message: 'Unknown error' });
    scheduleReconnect();
  });

  socket.value.addEventListener('message', (event: MessageEvent<string>) => {
    let payload: WebSocketEnvelope | null = null;
    try {
      payload = JSON.parse(event.data);
    } catch {
      return;
    }

    if (!payload?.event || 'string' != typeof payload.event) {
      return;
    }

    let data = payload.data;
    if ('string' === typeof data) {
      try {
        data = JSON.parse(data);
      } catch {
        data = payload.data;
      }
    }

    dispatch(payload.event, data);
  });

  setupVisibilityListener();
};

on('connect', () => getConfig().loadConfig(false));

on('connected', () => {
  error.value = null;
  getConfig().loadConfig(false);
});

on('item_added', (data: WSEP['item_added']) => {
  const queueState = getQueueState();
  const toast = getToast();

  queueState.add(data.data._id, data.data);
  toast.success(`Item queued: ${ag(queueState.get(data.data._id, {} as StoreItem), 'title')}`);
});

on(
  ['log_info', 'log_success', 'log_warning', 'log_error'],
  (event, data: WSEP['log_info']) => {
    const toast = getToast();
    const message =
      'string' === typeof data?.message
        ? data.message
        : String((data?.data as Record<string, unknown>)?.message ?? '');
    const extra = (data?.data as Record<string, unknown>)?.data || data?.data || {};
    switch (event) {
      case 'log_info':
        toast.info(message, extra);
        break;
      case 'log_success':
        toast.success(message, extra);
        break;
      case 'log_warning':
        toast.warning(message, extra);
        break;
      case 'log_error':
        toast.error(message, extra);
        break;
    }
  },
  true,
);

on('item_cancelled', (data: WSEP['item_cancelled']) => {
  const queueState = getQueueState();
  const toast = getToast();
  const id = data.data._id;

  if (true !== queueState.has(id)) {
    return;
  }

  toast.warning(`Download cancelled: ${ag(queueState.get(id, {} as StoreItem), 'title')}`);

  if (true === queueState.has(id)) {
    queueState.remove(id);
  }
});

on('item_deleted', (data: WSEP['item_deleted']) => {
  const queueState = getQueueState();
  const id = data.data._id;

  if (true === queueState.has(id)) {
    queueState.remove(id);
  }
});

on('item_updated', (data: WSEP['item_updated']) => {
  const queueState = getQueueState();
  const id = data.data._id;

  if (true === queueState.has(id)) {
    queueState.update(id, data.data);
  }
});

on('item_moved', (data: WSEP['item_moved']) => {
  const queueState = getQueueState();
  const to = data.data.to;
  const id = data.data.item._id;

  if ('queue' === to) {
    queueState.add(id, data.data.item);
  }

  if ('history' === to) {
    if (true === queueState.has(id)) {
      queueState.remove(id);
    }
  }
});

on(
  ['paused', 'resumed'],
  (event, data: WSEP['paused']) => {
    const config = getConfig();
    const toast = getToast();
    const pausedState = Boolean(data.data.paused);
    config.update('paused', pausedState);

    if ('resumed' === event) {
      toast.success('Download queue resumed.');
      return;
    }

    toast.warning('Download queue paused.', { timeout: 10000 });
  },
  true,
);

on('config_update', (data: WSEP['config_update']) => {
  const config = getConfig();
  const configUpdate = data.data as ConfigUpdatePayload;
  if (!configUpdate) {
    return;
  }
  config.patch(configUpdate.feature, configUpdate.action, configUpdate.data);
});

const appSocketApi = proxyRefs({
  connect,
  reconnect,
  disconnect,
  on,
  off,
  emit,
  isConnected,
  getSessionId,
  connectionStatus: readonly(connectionStatus),
  error: readonly(error),
  error_count: readonly(error_count),
});

export const useAppSocket = () => appSocketApi;