import { NextResponse } from "next/server"
import { verifyPaypalWebhook } from "@/lib/paypal/webhook"
import { decodeCustomId, getSubscription } from "@/lib/paypal/checkout"
import { fulfillSubscription, fulfillLifetime, markPaypalSubscriptionInactive } from "@/lib/paypal/fulfill"

// Inbound PayPal webhook. Signature is verified via PayPal's API using
// PAYPAL_WEBHOOK_ID; unverified events are rejected.
export async function POST(request: Request) {
  const body = await request.text()

  const valid = await verifyPaypalWebhook(request.headers, body)
  if (!valid) return NextResponse.json({ error: "invalid signature" }, { status: 400 })

  let event: { event_type?: string; resource?: Record<string, unknown> }
  try {
    event = JSON.parse(body)
  } catch {
    return NextResponse.json({ ok: true })
  }

  const type = event.event_type ?? ""
  const resource = (event.resource ?? {}) as Record<string, any>

  try {
    switch (type) {
      case "BILLING.SUBSCRIPTION.ACTIVATED":
      case "BILLING.SUBSCRIPTION.UPDATED": {
        const decoded = decodeCustomId(resource.custom_id)
        if (decoded && resource.id) {
          await fulfillSubscription(
            decoded.userId,
            decoded.plan,
            resource.id,
            resource.billing_info?.next_billing_time,
            "active"
          )
        }
        break
      }

      case "PAYMENT.SALE.COMPLETED": {
        // A recurring payment cleared — refresh status + next billing date.
        const subId = resource.billing_agreement_id as string | undefined
        if (subId) {
          const sub = await getSubscription(subId)
          const decoded = decodeCustomId(sub?.custom_id)
          if (sub && decoded) {
            await fulfillSubscription(
              decoded.userId,
              decoded.plan,
              subId,
              sub.billing_info?.next_billing_time,
              "active"
            )
          }
        }
        break
      }

      case "BILLING.SUBSCRIPTION.CANCELLED":
      case "BILLING.SUBSCRIPTION.EXPIRED": {
        if (resource.id) {
          await markPaypalSubscriptionInactive(
            resource.id,
            type.endsWith("CANCELLED") ? "canceled" : "expired",
            true
          )
        }
        break
      }

      case "BILLING.SUBSCRIPTION.SUSPENDED": {
        if (resource.id) await markPaypalSubscriptionInactive(resource.id, "suspended", false)
        break
      }

      case "PAYMENT.CAPTURE.COMPLETED": {
        // Lifetime order capture (backup to the return handler).
        const decoded = decodeCustomId(resource.custom_id)
        if (decoded && decoded.plan === "lifetime") await fulfillLifetime(decoded.userId)
        break
      }
    }
  } catch {
    // Never loop forever on a handler bug — PayPal retries non-2xx.
  }

  return NextResponse.json({ received: true })
}