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 fromId = Number(body?.fromId)
  const toId = Number(body?.toId)
  const amountCents = Number(body?.amountCents)

  if (!Number.isInteger(amountCents) || amountCents <= 0) {
    throw createError({ statusCode: 400, statusMessage: 'amountCents must be a positive integer' })
  }
  if (fromId === toId) {
    throw createError({ statusCode: 400, statusMessage: 'fromId and toId must differ' })
  }

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

  const db = useDb()
  const [payment] = await db.insert(expenses)
    .values({ potSlug: slug, type: 'payment', description: 'Settlement', amountCents, payerId: fromId })
    .returning()
  await db.insert(expenseParticipants).values({ expenseId: payment!.id, participantId: toId })

  return { ...payment, participantIds: [toId] }
})