import { NextResponse } from 'next/server'
import { auth } from '@/lib/auth'
import { prisma } from '@/lib/prisma'
import { createBudgetRuleSchema } from '@/lib/validations/budget-rule'

export async function GET() {
  const session = await auth()
  if (!session?.user?.id) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })

  const rules = await prisma.budgetRule.findMany({
    where: { userId: session.user.id },
    orderBy: { createdAt: 'asc' },
    select: { id: true, budgetId: true, pattern: true },
  })
  return NextResponse.json(rules)
}

export async function POST(req: Request) {
  const session = await auth()
  if (!session?.user?.id) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })

  const body = await req.json()
  const parsed = createBudgetRuleSchema.safeParse(body)
  if (!parsed.success) return NextResponse.json({ error: parsed.error.flatten() }, { status: 400 })

  const { budgetId, pattern } = parsed.data

  // Verify budget belongs to this user
  const budget = await prisma.budget.findFirst({ where: { id: budgetId, userId: session.user.id } })
  if (!budget) return NextResponse.json({ error: 'Budget not found' }, { status: 404 })

  const existing = await prisma.budgetRule.findFirst({
    where: { budgetId, pattern: { equals: pattern, mode: 'insensitive' } },
  })
  if (existing) return NextResponse.json({ error: 'Duplicate rule pattern' }, { status: 409 })

  const rule = await prisma.budgetRule.create({
    data: { userId: session.user.id, budgetId, pattern },
    select: { id: true, budgetId: true, pattern: true },
  })
  return NextResponse.json(rule, { status: 201 })
}