import { sessionOptions } from '@/lib/session';
import { withIronSessionApiRoute } from 'iron-session/next';
import type { NextApiRequest, NextApiResponse } from 'next'
import client from "@/lib/mongodb";

const db = client.db(process.env.MONGODB_DB);

export default withIronSessionApiRoute(handler, sessionOptions);

async function handler(req: NextApiRequest, res: NextApiResponse) {
  const { op } = req.query

  if (req.method === 'GET') {
    switch (op) {
      default:
        res.status(400).json({ error: 'Invalid operation!' })
    }
  }
  else if (req.method === 'POST') {
    switch (op) {
      case 'crossRefOwnership':
        res.status(200).json(await crossRefOwnership(req.body));
        break;
      case 'getIds':
        res.status(200).json(await getIds(req.body));
        break;
      default:
        res.status(400).json({ error: 'Invalid operation!' })
    }
  } else {
    res.status(400).end(`Method ${req.method} Not Allowed`)
  }
}

async function crossRefOwnership(body: any): Promise<string[]> {
  const { userId, classrooms } = body;

  // First find which classrooms from input exist
  const existingClassrooms = await db.collection('groups')
    .find({ name: { $in: classrooms } })
    .project({ name: 1, admin: 1, _id: 0 })
    .toArray();

  // From those existing classrooms, return the ones where user is NOT the admin
  return existingClassrooms
    .filter(classroom => classroom.admin !== userId)
    .map(classroom => classroom.name);
}

async function getIds(body: any): Promise<Record<string, string>> {
  const { names, userEmails } = body;
  
  const existingGroups: any[] = await db.collection('groups')
    .find({ name: { $in: names } })
    .project({ name: 1, id: 1, _id: 0 })
    .toArray();

  const users: any[] = await db.collection('users')
    .find({ email: { $in: userEmails } })
    .project({ email: 1, id: 1, _id: 0 })
    .toArray();

  return {
    groups: existingGroups.reduce((acc, group) => {
      acc[group.name] = group.id;
      return acc;
    }, {} as Record<string, string>),
    users: users.reduce((acc, user) => {
      acc[user.email] = user.id;
      return acc;
    }, {} as Record<string, string>)
  };
}