import { useDb } from '~~/server/database/client';
import { expenseParticipants, expenses } from '~~/server/database/schema';

export default defineEventHandler(async (event) => {
  const slug = getRouterParam(event, 'slug')!;
  await getPotOrThrow(slug);

  const body = await readBody(event);
  const description =
    typeof body?.description === 'string' ? body.description.trim() : '';
  const amountCents = Number(body?.amountCents);
  const payerId = Number(body?.payerId);
  const participantIds: number[] = Array.isArray(body?.participantIds)
    ? body.participantIds.map(Number)
    : [];

  if (!description) {
    throw createError({
      statusCode: 400,
      statusMessage: 'description is required',
    });
  }
  if (!Number.isInteger(amountCents) || amountCents <= 0) {
    throw createError({
      statusCode: 400,
      statusMessage: 'amountCents must be a positive integer',
    });
  }
  if (participantIds.length === 0) {
    throw createError({
      statusCode: 400,
      statusMessage: 'at least one participant must be selected',
    });
  }

  const potParticipants = await getParticipants(slug);
  const validIds = new Set(potParticipants.map((p) => p.id));
  if (
    !validIds.has(payerId) ||
    participantIds.some((id) => !validIds.has(id))
  ) {
    throw createError({
      statusCode: 400,
      statusMessage:
        'payerId and participantIds must reference participants of this Pot',
    });
  }

  const db = useDb(event);
  const [expense] = await db
    .insert(expenses)
    .values({ potSlug: slug, description, amountCents, payerId })
    .returning();
  await db.insert(expenseParticipants).values(
    participantIds.map((participantId) => ({
      expenseId: expense!.id,
      participantId,
    })),
  );

  return { ...expense, participantIds };
});