import { NextRequest, NextResponse } from "next/server"
import {
  computeEbayChallengeResponse,
  getEbayNotificationEndpoint,
  getEbayNotificationVerificationToken,
  verifyEbayNotificationSignature,
} from "@/lib/ebay-notifications"

export const runtime = "nodejs"

type EbayNotificationPayload = {
  metadata?: {
    topic?: string
    schemaVersion?: string
    deprecated?: boolean
  }
  notification?: {
    notificationId?: string
    eventDate?: string
    publishDate?: string
    publishAttemptCount?: number
    data?: {
      username?: string
      userId?: string
      eiasToken?: string
    }
  }
}

function parseNotificationBody(rawBody: string) {
  if (!rawBody.trim()) {
    return null
  }

  try {
    return JSON.parse(rawBody) as EbayNotificationPayload
  } catch {
    return null
  }
}

function getChallengeCode(request: NextRequest) {
  return (
    request.nextUrl.searchParams.get("challenge_code") ||
    request.nextUrl.searchParams.get("challengeCode") ||
    ""
  ).trim()
}

export async function GET(request: NextRequest) {
  const challengeCode = getChallengeCode(request)
  if (!challengeCode) {
    return NextResponse.json(
      { error: "Missing challenge_code query parameter." },
      { status: 400 }
    )
  }

  const verificationToken = getEbayNotificationVerificationToken()
  if (!verificationToken) {
    return NextResponse.json(
      { error: "EBAY_NOTIFICATION_VERIFICATION_TOKEN is not configured." },
      { status: 500 }
    )
  }

  const endpoint = getEbayNotificationEndpoint(request.url)
  if (!endpoint) {
    return NextResponse.json(
      { error: "EBAY_NOTIFICATION_ENDPOINT is not configured." },
      { status: 500 }
    )
  }

  const challengeResponse = computeEbayChallengeResponse({
    challengeCode,
    endpoint,
    verificationToken,
  })

  return NextResponse.json(
    { challengeResponse },
    {
      headers: {
        "Cache-Control": "no-store",
      },
    }
  )
}

export async function POST(request: NextRequest) {
  const body = await request.text()
  const signatureHeader = request.headers.get("x-ebay-signature")

  try {
    const verification = await verifyEbayNotificationSignature({
      body,
      signatureHeader,
    })

    if (!verification.verified) {
      if (
        verification.reason ===
        "Notification verification credentials are not configured."
      ) {
        console.warn(
          "[ebay/notifications] accepted notification without signature verification",
          {
            reason: verification.reason,
          }
        )
        const payload = parseNotificationBody(body)
        const notification = payload?.notification

        console.info(
          "[ebay/notifications] accepted notification without verification",
          {
            topic: payload?.metadata?.topic || "unknown",
            notificationId: notification?.notificationId || "unknown",
            publishAttemptCount: notification?.publishAttemptCount ?? null,
          }
        )

        return new NextResponse(null, { status: 204 })
      }

      console.warn("[ebay/notifications] signature rejected", {
        reason: verification.reason,
      })
      return NextResponse.json({ error: verification.reason }, { status: 412 })
    }

    const payload = parseNotificationBody(body)
    const notification = payload?.notification

    console.info("[ebay/notifications] accepted notification", {
      keyId: verification.keyId,
      topic: payload?.metadata?.topic || "unknown",
      notificationId: notification?.notificationId || "unknown",
      publishAttemptCount: notification?.publishAttemptCount ?? null,
    })

    return new NextResponse(null, { status: 204 })
  } catch (error) {
    console.error("[ebay/notifications] failed to process notification", {
      error: error instanceof Error ? error.message : String(error),
    })

    return NextResponse.json(
      {
        error:
          error instanceof Error
            ? error.message
            : "Failed to verify eBay notification.",
      },
      { status: 500 }
    )
  }
}