/**
 * Google Gmail Integration (OAuth + scan trigger)
 */

import { NextRequest, NextResponse } from 'next/server'
import { auth } from '@/auth'
import {
  getGoogleOAuthCredentials,
  getGoogleTokens,
  readIntegrationMeta,
  writeIntegrationMeta,
} from '@/lib/integrations/google-integration-tokens'
import { gmailScannerService } from '@/lib/integrations/gmail-scanner.service'

const GMAIL_SCOPE = 'https://www.googleapis.com/auth/gmail.readonly'
const GOOGLE_AUTH_URL = 'https://accounts.google.com/o/oauth2/v2/auth'

function redirectUri(origin: string) {
  return `${origin}/api/integrations/gmail/callback`
}

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

  const url = new URL(req.url)
  const userId = session.user.id

  if (url.searchParams.get('connect') === '1') {
    const { clientId } = getGoogleOAuthCredentials()
    if (!clientId) {
      return NextResponse.json({ error: 'Google OAuth not configured' }, { status: 503 })
    }
    const authUrl = new URL(GOOGLE_AUTH_URL)
    authUrl.searchParams.set('client_id', clientId)
    authUrl.searchParams.set('redirect_uri', redirectUri(url.origin))
    authUrl.searchParams.set('response_type', 'code')
    authUrl.searchParams.set('scope', GMAIL_SCOPE)
    authUrl.searchParams.set('access_type', 'offline')
    authUrl.searchParams.set('prompt', 'consent')
    authUrl.searchParams.set('state', userId)
    return NextResponse.redirect(authUrl.toString())
  }

  if (url.searchParams.get('scan') === '1') {
    const result = await gmailScannerService.scanUser(userId)
    return NextResponse.json(result)
  }

  const status = await gmailScannerService.getStatus(userId)
  return NextResponse.json(status)
}

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

  const meta = await readIntegrationMeta(session.user.id)
  delete meta.gmailAccessToken
  delete meta.gmailRefreshToken
  await writeIntegrationMeta(session.user.id, meta)
  return NextResponse.json({ success: true })
}