import { NextResponse } from "next/server"
import { and, eq, lte } from "drizzle-orm"
import { db } from "@/lib/db"
import { rent_payments, expenses } from "@/lib/db/schema"
import { isAuthorizedCron } from "@/lib/cron-auth"

// Scheduled task: runs daily at 8am UTC (scheduled via DigitalOcean Functions — see DIGITALOCEAN.md)
export async function GET(request: Request) {
  if (!isAuthorizedCron(request)) {
    return NextResponse.json({ error: "Unauthorized" }, { status: 401 })
  }

  // Find overdue payments older than grace period (default 5 days) that don't yet have a late fee
  const graceDays = 5
  const cutoff = new Date()
  cutoff.setDate(cutoff.getDate() - graceDays)
  const cutoffDate = cutoff.toISOString().slice(0, 10)

  const overduePayments = await db
    .select({
      id: rent_payments.id,
      user_id: rent_payments.user_id,
      tenant_id: rent_payments.tenant_id,
      property_id: rent_payments.property_id,
      unit_id: rent_payments.unit_id,
      amount: rent_payments.amount,
      due_date: rent_payments.due_date,
    })
    .from(rent_payments)
    .where(
      and(
        eq(rent_payments.status, "overdue"),
        lte(rent_payments.due_date, cutoffDate),
        eq(rent_payments.late_fee_applied, false)
      )
    )

  if (!overduePayments.length) {
    return NextResponse.json({ processed: 0 })
  }

  let processed = 0

  for (const payment of overduePayments) {
    const lateFeeAmount = Math.round(Number(payment.amount) * 0.05 * 100) / 100 // 5% late fee

    // Insert late fee as a separate expense
    await db.insert(expenses).values({
      user_id:      payment.user_id,
      property_id:  payment.property_id,
      unit_id:      payment.unit_id ?? null,
      category:     "other",
      description:  `Late fee — rent due ${payment.due_date}`,
      amount:       lateFeeAmount,
      expense_date: new Date().toISOString().slice(0, 10),
      vendor:       "Auto-generated",
    })

    // Mark late fee applied
    await db
      .update(rent_payments)
      .set({ late_fee_applied: true })
      .where(eq(rent_payments.id, payment.id))

    processed++
  }

  return NextResponse.json({ processed, message: `Applied late fees to ${processed} overdue payment(s).` })
}