import prisma from '@/lib/prisma'

export function getGoogleOAuthCredentials() {
  return {
    clientId: process.env.GOOGLE_CALENDAR_CLIENT_ID || process.env.AUTH_GOOGLE_ID || '',
    clientSecret: process.env.GOOGLE_CALENDAR_CLIENT_SECRET || process.env.AUTH_GOOGLE_SECRET || '',
  }
}

export async function readIntegrationMeta(userId: string): Promise<Record<string, unknown>> {
  const aiSettings = await prisma.userAISettings.findUnique({
    where: { userId },
    select: { integrationTokens: true },
  })
  try {
    const raw = aiSettings?.integrationTokens
    if (!raw) return {}
    return typeof raw === 'string' ? JSON.parse(raw) : (raw as Record<string, unknown>)
  } catch {
    return {}
  }
}

export async function writeIntegrationMeta(userId: string, meta: Record<string, unknown>) {
  await prisma.userAISettings.upsert({
    where: { userId },
    update: { integrationTokens: JSON.stringify(meta) },
    create: { userId, integrationTokens: JSON.stringify(meta) },
  })
}

export async function getGoogleTokens(
  userId: string,
  prefix: 'calendar' | 'gmail',
): Promise<{ accessToken: string; refreshToken: string } | null> {
  const meta = await readIntegrationMeta(userId)
  const accessToken = meta[`${prefix}AccessToken`] as string | undefined
  const refreshToken = meta[`${prefix}RefreshToken`] as string | undefined
  if (accessToken && refreshToken) return { accessToken, refreshToken }
  return null
}

export async function refreshGoogleAccessToken(
  userId: string,
  prefix: 'calendar' | 'gmail',
  refreshToken: string,
): Promise<string | null> {
  const { clientId, clientSecret } = getGoogleOAuthCredentials()
  const res = await fetch('https://oauth2.googleapis.com/token', {
    method: 'POST',
    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
    body: new URLSearchParams({
      client_id: clientId,
      client_secret: clientSecret,
      refresh_token: refreshToken,
      grant_type: 'refresh_token',
    }),
  })
  const data = await res.json()
  if (!data.access_token) return null

  const meta = await readIntegrationMeta(userId)
  meta[`${prefix}AccessToken`] = data.access_token
  await writeIntegrationMeta(userId, meta)
  return data.access_token as string
}