// apps/mobile/app/login.tsx
// OAuth 로그인 화면

import { useState } from 'react'
import { View, Text, Pressable, Alert, StyleSheet, ActivityIndicator } from 'react-native'
import * as WebBrowser from 'expo-web-browser'
import * as Linking from 'expo-linking'
import { supabase, isSupabaseConfigured } from '../lib/supabase'

WebBrowser.maybeCompleteAuthSession()

export default function LoginScreen(): React.ReactElement {
  const [busy, setBusy] = useState(false)
  const configured = isSupabaseConfigured()

  async function signInWithProvider(provider: 'google' | 'github'): Promise<void> {
    if (!configured) {
      Alert.alert('미설정', 'Supabase 환경변수가 설정되지 않았습니다.')
      return
    }
    setBusy(true)
    try {
      const redirectTo = Linking.createURL('auth-callback')
      const { data, error } = await supabase.auth.signInWithOAuth({
        provider,
        options: { redirectTo, skipBrowserRedirect: true }
      })

      if (error || !data.url) {
        Alert.alert('로그인 실패', error?.message ?? 'OAuth URL을 받지 못했습니다')
        return
      }

      const result = await WebBrowser.openAuthSessionAsync(data.url, redirectTo)
      if (result.type === 'success' && result.url) {
        const url = new URL(result.url)
        const code = url.searchParams.get('code')
        if (code) {
          const { error: exchangeErr } = await supabase.auth.exchangeCodeForSession(code)
          if (exchangeErr) {
            Alert.alert('세션 교환 실패', exchangeErr.message)
          }
        }
      }
    } finally {
      setBusy(false)
    }
  }

  return (
    <View style={styles.container}>
      <Text style={styles.title}>D3RO VOICE</Text>
      <Text style={styles.subtitle}>AI 음성 어시스턴트</Text>

      {!configured && (
        <Text style={styles.warning}>
          Supabase가 설정되지 않았습니다. app.json의 extra 필드를 확인하세요.
        </Text>
      )}

      <View style={styles.buttons}>
        <Pressable
          style={[styles.button, styles.google, (!configured || busy) && styles.disabled]}
          onPress={() => void signInWithProvider('google')}
          disabled={!configured || busy}
        >
          <Text style={styles.buttonText}>Google로 계속하기</Text>
        </Pressable>
        <Pressable
          style={[styles.button, styles.github, (!configured || busy) && styles.disabled]}
          onPress={() => void signInWithProvider('github')}
          disabled={!configured || busy}
        >
          <Text style={styles.buttonText}>GitHub로 계속하기</Text>
        </Pressable>
      </View>

      {busy && <ActivityIndicator size="small" color="#f25b29" style={{ marginTop: 16 }} />}
    </View>
  )
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#19191b',
    justifyContent: 'center',
    padding: 32
  },
  title: {
    color: '#f25b29',
    fontSize: 36,
    fontWeight: '300',
    textAlign: 'center',
    letterSpacing: 2,
    marginBottom: 8
  },
  subtitle: {
    color: '#8e8e93',
    fontSize: 14,
    textAlign: 'center',
    marginBottom: 48
  },
  warning: {
    color: '#f59e0b',
    fontSize: 12,
    textAlign: 'center',
    marginBottom: 24,
    padding: 12,
    borderWidth: 1,
    borderColor: '#f59e0b',
    borderRadius: 8
  },
  buttons: {
    gap: 12
  },
  button: {
    paddingVertical: 14,
    borderRadius: 8,
    alignItems: 'center'
  },
  google: {
    backgroundColor: '#f25b29'
  },
  github: {
    backgroundColor: 'transparent',
    borderWidth: 1,
    borderColor: '#8e8e93'
  },
  disabled: {
    opacity: 0.5
  },
  buttonText: {
    color: '#ffffff',
    fontSize: 14,
    fontWeight: '600'
  }
})