// apps/mobile/app/login.tsx
// OAuth 로그인 화면 — @d3ro/ui-native 사용

import { useState } from 'react'
import { View, StyleSheet, Alert } from 'react-native'
import * as WebBrowser from 'expo-web-browser'
import * as Linking from 'expo-linking'
import { MetalCard, PhosphorText, PhysicalButton, d3roNativePalette } from '@d3ro/ui-native'
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}>
      <MetalCard style={styles.card}>
        <View style={styles.header}>
          <PhosphorText variant="hero">D3RO VOICE</PhosphorText>
          <PhosphorText variant="label" color="secondary" style={styles.subtitle}>
            AI 음성 어시스턴트
          </PhosphorText>
        </View>

        {!configured && (
          <View style={styles.warningBox}>
            <PhosphorText variant="small" color="label">
              Supabase가 설정되지 않았습니다. app.json의 extra 필드를 확인하세요.
            </PhosphorText>
          </View>
        )}

        <View style={styles.buttons}>
          <PhysicalButton
            label="Google로 계속하기"
            variant="primary"
            disabled={!configured || busy}
            onPress={() => void signInWithProvider('google')}
          />
          <PhysicalButton
            label="GitHub로 계속하기"
            variant="secondary"
            disabled={!configured || busy}
            onPress={() => void signInWithProvider('github')}
          />
        </View>
      </MetalCard>
    </View>
  )
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: d3roNativePalette.bg.app,
    justifyContent: 'center',
    padding: 24
  },
  card: {
    padding: 32
  },
  header: {
    alignItems: 'center',
    marginBottom: 32
  },
  subtitle: {
    marginTop: 8
  },
  warningBox: {
    borderWidth: 1,
    borderColor: d3roNativePalette.tag.orange,
    padding: 12,
    borderRadius: 8,
    marginBottom: 16
  },
  buttons: {
    gap: 12
  }
})