/**
 * #33 등록 디바이스 관리
 * GET    /api/auth/devices       — 디바이스 목록
 * DELETE /api/auth/devices/{id}  — 등록 해제
 * 현재 기기는 삭제 버튼 비활성화
 */
import { useCallback, useEffect, useState } from 'react'
import {
  View, Text, FlatList, TouchableOpacity, StyleSheet,
  RefreshControl, Alert, ActivityIndicator, Platform,
} from 'react-native'
import { COLORS } from '../../constants/Config'
import { getDevices, deleteDevice } from '../../services/api'
import LineIcon from '../../components/LineIcon'

interface Device {
  id: string | number
  name?: string
  device_name?: string
  os?: string
  platform?: string
  last_seen?: string
  last_active_at?: string
  is_current?: boolean
  current?: boolean
}

function osIcon(os?: string): Parameters<typeof LineIcon>[0]['name'] {
  const v = (os ?? '').toLowerCase()
  if (v.includes('ios') || v.includes('iphone') || v.includes('mac')) return 'lock'
  if (v.includes('android')) return 'server'
  return 'dashboard'
}

function fmt(d?: string): string {
  if (!d) return '-'
  try {
    const dt = new Date(d)
    if (isNaN(dt.getTime())) return d
    return dt.toLocaleString('ko-KR', { dateStyle: 'medium', timeStyle: 'short' })
  } catch {
    return d
  }
}

export default function DevicesScreen() {
  const [devices, setDevices] = useState<Device[]>([])
  const [loading, setLoading] = useState(true)
  const [refresh, setRefresh] = useState(false)

  const load = useCallback(async (isRefresh = false) => {
    isRefresh ? setRefresh(true) : setLoading(true)
    try {
      const r = await getDevices()
      const list: Device[] = Array.isArray(r.data) ? r.data : r.data?.items ?? []
      setDevices(list)
    } catch {
      setDevices([])
    } finally {
      setLoading(false)
      setRefresh(false)
    }
  }, [])

  useEffect(() => { load() }, [load])

  const handleRemove = (dev: Device) => {
    const name = dev.name ?? dev.device_name ?? '이 기기'
    Alert.alert('디바이스 등록 해제', `"${name}"의 등록을 해제하시겠습니까?\n해당 기기는 다시 로그인해야 합니다.`, [
      { text: '취소', style: 'cancel' },
      {
        text: '해제', style: 'destructive',
        onPress: async () => {
          try {
            await deleteDevice(dev.id)
            setDevices((prev) => prev.filter((d) => d.id !== dev.id))
          } catch (e: any) {
            Alert.alert('오류', e.response?.data?.detail ?? '등록 해제에 실패했습니다.')
          }
        },
      },
    ])
  }

  if (loading) {
    return (
      <View style={s.center}>
        <ActivityIndicator color={COLORS.accent} size="large" />
      </View>
    )
  }

  return (
    <FlatList
      style={{ flex: 1, backgroundColor: COLORS.bg }}
      data={devices}
      keyExtractor={(d) => String(d.id)}
      refreshControl={<RefreshControl refreshing={refresh} onRefresh={() => load(true)} tintColor={COLORS.accent} />}
      ListHeaderComponent={
        <View style={s.header}>
          <Text style={s.headerTitle}>등록된 디바이스</Text>
          <Text style={s.headerSub}>이 계정으로 로그인된 기기 {devices.length}대</Text>
        </View>
      }
      ListEmptyComponent={
        <View style={s.empty}>
          <Text style={s.emptyText}>등록된 디바이스가 없습니다.</Text>
        </View>
      }
      contentContainerStyle={devices.length === 0 ? { flexGrow: 1 } : undefined}
      renderItem={({ item }) => {
        const isCurrent = item.is_current ?? item.current ?? false
        return (
          <View style={s.card}>
            <View style={s.iconBox}>
              <LineIcon name={osIcon(item.os ?? item.platform)} size={20} color={COLORS.accent} />
            </View>
            <View style={{ flex: 1 }}>
              <View style={s.row}>
                <Text style={s.name}>{item.name ?? item.device_name ?? '알 수 없는 기기'}</Text>
                {isCurrent && (
                  <View style={s.currentBadge}>
                    <Text style={s.currentText}>현재 기기</Text>
                  </View>
                )}
              </View>
              <Text style={s.meta}>{item.os ?? item.platform ?? Platform.OS}</Text>
              <Text style={s.meta}>마지막 접속: {fmt(item.last_seen ?? item.last_active_at)}</Text>
            </View>
            <TouchableOpacity
              style={[s.removeBtn, isCurrent && s.removeDisabled]}
              disabled={isCurrent}
              onPress={() => handleRemove(item)}
            >
              <Text style={[s.removeText, isCurrent && s.removeTextDisabled]}>
                {isCurrent ? '사용 중' : '해제'}
              </Text>
            </TouchableOpacity>
          </View>
        )
      }}
    />
  )
}

const s = StyleSheet.create({
  center: { flex: 1, alignItems: 'center', justifyContent: 'center', backgroundColor: COLORS.bg },
  header: { padding: 20, paddingBottom: 8 },
  headerTitle: { fontSize: 18, fontWeight: '800', color: COLORS.text },
  headerSub: { fontSize: 13, color: COLORS.muted, marginTop: 4 },
  card: {
    flexDirection: 'row', alignItems: 'center', gap: 12,
    backgroundColor: '#fff', marginHorizontal: 16, marginTop: 10,
    borderRadius: 14, padding: 16,
    borderWidth: 1, borderColor: COLORS.border,
  },
  iconBox: {
    width: 42, height: 42, borderRadius: 11,
    backgroundColor: 'rgba(0,160,200,.08)', alignItems: 'center', justifyContent: 'center',
  },
  row: { flexDirection: 'row', alignItems: 'center', gap: 8 },
  name: { fontSize: 15, fontWeight: '700', color: COLORS.text },
  currentBadge: { backgroundColor: '#dcfce7', paddingHorizontal: 8, paddingVertical: 2, borderRadius: 8 },
  currentText: { fontSize: 10, fontWeight: '700', color: '#15803d' },
  meta: { fontSize: 12, color: COLORS.muted, marginTop: 2 },
  removeBtn: {
    paddingHorizontal: 14, paddingVertical: 8, borderRadius: 10,
    backgroundColor: '#fee2e2',
  },
  removeDisabled: { backgroundColor: '#f1f5f9' },
  removeText: { fontSize: 13, fontWeight: '700', color: COLORS.danger },
  removeTextDisabled: { color: COLORS.muted },
  empty: { flex: 1, alignItems: 'center', justifyContent: 'center' },
  emptyText: { color: COLORS.muted, fontSize: 14 },
})