import { Status } from '$lib';
import { kvStore } from '$lib/server/db/index.js';
import { json } from '@sveltejs/kit';

interface SubscribedTo {
  subscribed: string[]; // any ID (including channels, dms, et cetera can be added in here, to send SSE data to any group of users)
  userId: string;
  controller: ReadableStreamDefaultController;
}

export const _clients = new Map<string, SubscribedTo>();

export function _sendToSubscribers(id: string, payload: unknown) {
  for (const [key, client] of _clients) {
    if (client.subscribed.includes(id)) {
      try {
        client.controller.enqueue(`data: ${JSON.stringify(payload)}\n\n`);
      } catch {
        _clients.delete(key);
      }
    }
  }
}
export function _sendToUser(userId: string, payload: unknown) {
  for (const [, client] of _clients) {
    if (client.userId == userId) {
      client.controller.enqueue(`data: ${JSON.stringify(payload)}\n\n`);
    }
  }
}

export function _isUserConnected(userId: string): boolean {
  for (const client of _clients.values()) {
    if (client.userId === userId) return true;
  }
  return false;
}

export async function GET({ locals, request }) {
  if (!locals.user) {
    return json({ error: 'Unauthorized' }, { status: 401 });
  }

  const userId = locals.user.id;
  //@TODO add more to subscribed eventually, server members, et cetera
  const subscribed = locals.user.friends.map((f) => f.id);
  subscribed.push(userId); // shit such as friend requests

  const overwrite = locals.user.statusOverwrite;

  const sessionId = crypto.randomUUID();

  const stream = new ReadableStream({
    start(controller) {
      _clients.set(sessionId, { subscribed, userId, controller });
      console.log(`SSE Client opened. total: ${_clients.size}`);

      controller.enqueue(`data: ${JSON.stringify({ type: 'connected', sessionId })}\n\n`);

      if (overwrite === Status.DND) {
        kvStore.set(`user-${userId}-state`, Status.DND);
        _sendToSubscribers(userId, {
          type: 'status',
          id: userId,
          status: Status.DND,
          statusMessage:
            kvStore.get('user-' + userId + '-state') != Status.OFFLINE
              ? kvStore.get('user-' + userId + '-message')
              : ''
        });
      }

      request.signal.addEventListener('abort', () => {
        _clients.delete(sessionId);
        console.log(`SSE Client aborted. total: ${_clients.size}`);

        if (_isUserConnected(userId)) return;

        if (overwrite === Status.OFFLINE) return;

        kvStore.set(`user-${userId}-state`, Status.OFFLINE);
        _sendToSubscribers(userId, {
          type: 'status',
          id: userId,
          status: Status.OFFLINE,
          statusMessage: ''
        });
      });
    },
    cancel() {
      console.log(`SSE Client cancelled. total: ${_clients.size}`);

      if (_isUserConnected(userId)) return;

      if (overwrite === Status.OFFLINE) return;

      kvStore.set(`user-${userId}-state`, Status.OFFLINE);
      _sendToSubscribers(userId, {
        type: 'status',
        id: userId,
        status: Status.OFFLINE,
        statusMessage: ''
      });
    }
  });

  return new Response(stream, {
    headers: {
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      Connection: 'keep-alive'
    }
  });
}