import { byuAuthConfig, generateCodeVerifier, generateCodeChallenge } from '@server/utils/auth.ts'
import { getQuery, setCookie } from 'h3'

export default defineEventHandler(async (event) => {
  const config = useRuntimeConfig()
  const { redirect } = getQuery(event) as { redirect?: string }
  
  const state = Math.random().toString(36).substring(2, 15) + Math.random().toString(36).substring(2, 15)
  const codeVerifier = generateCodeVerifier()
  const codeChallenge = await generateCodeChallenge(codeVerifier)

  setCookie(event, 'oauth_state', state, {
    httpOnly: true,
    secure: config.baseUrl !== 'http://localhost:3000',
    maxAge: 600,
    sameSite: 'lax'
  })

  setCookie(event, 'code_verifier', codeVerifier, {
    httpOnly: true,
    secure: config.baseUrl !== 'http://localhost:3000',
    maxAge: 600,
    sameSite: 'lax'
  })

  if (redirect) {
    // Store redirect URL in cookie to read it later in the callback
    setCookie(event, 'redirect_after_login', redirect, {
      httpOnly: true,
      secure: config.baseUrl !== 'http://localhost:3000',
      maxAge: 600,
      sameSite: 'lax'
    })
  }

  const authUrl = new URL(byuAuthConfig.authorizationUrl)
  authUrl.searchParams.set('client_id', byuAuthConfig.clientId)
  authUrl.searchParams.set('redirect_uri', byuAuthConfig.redirectUri)
  authUrl.searchParams.set('response_type', 'code')
  authUrl.searchParams.set('scope', byuAuthConfig.scopes.join(' '))
  authUrl.searchParams.set('state', state)
  authUrl.searchParams.set('code_challenge', codeChallenge)
  authUrl.searchParams.set('code_challenge_method', 'S256')

  return sendRedirect(event, authUrl.toString())
})