import { useState, useCallback } from 'react'
import { View, Text, StyleSheet, Pressable, Switch } from 'react-native'
import { useSafeAreaInsets } from 'react-native-safe-area-context'
import { useRouter, useFocusEffect } from 'expo-router'
import { ChevronLeft } from 'lucide-react-native'
import { colors, spacing, typography } from '../src/theme/mobile-theme'
import {
  loadPushNotificationsEnabled,
  savePushNotificationsEnabled
} from '../src/storage/preferences'
import { ensureNotificationPermissions } from '../src/notifications/mobile-notifications'

export default function NotificationsScreen() {
  const router = useRouter()
  const insets = useSafeAreaInsets()
  const [pushEnabled, setPushEnabled] = useState(true)

  useFocusEffect(
    useCallback(() => {
      void loadPushNotificationsEnabled().then(setPushEnabled)
    }, [])
  )

  const togglePush = async (value: boolean) => {
    if (value) {
      const granted = await ensureNotificationPermissions()
      if (!granted) return
    }
    setPushEnabled(value)
    await savePushNotificationsEnabled(value)
  }

  return (
    <View style={[styles.container, { paddingTop: insets.top + spacing.sm }]}>
      <View style={styles.topRow}>
        <Pressable style={styles.backButton} onPress={() => router.back()}>
          <ChevronLeft size={22} color={colors.textSecondary} />
        </Pressable>
        <Text style={styles.heading}>Notifications</Text>
      </View>

      <View style={styles.section}>
        <View style={styles.row}>
          <Text style={styles.rowLabel}>Push Notifications</Text>
          <Switch
            value={pushEnabled}
            onValueChange={(v) => void togglePush(v)}
            trackColor={{ false: colors.bgRaised, true: colors.textSecondary }}
            thumbColor={colors.textPrimary}
          />
        </View>
        <Text style={styles.hint}>
          Receive notifications when an agent task completes on your desktop.
        </Text>
      </View>
    </View>
  )
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: colors.bgBase,
    padding: spacing.lg
  },
  topRow: {
    flexDirection: 'row',
    alignItems: 'center',
    marginBottom: spacing.xl
  },
  backButton: {
    width: 36,
    height: 36,
    borderRadius: 18,
    alignItems: 'center',
    justifyContent: 'center',
    marginRight: spacing.sm
  },
  heading: {
    fontSize: 20,
    fontWeight: '700',
    color: colors.textPrimary
  },
  section: {
    backgroundColor: colors.bgPanel,
    borderRadius: 12,
    overflow: 'hidden'
  },
  row: {
    flexDirection: 'row',
    alignItems: 'center',
    gap: spacing.sm + 2,
    paddingVertical: spacing.md,
    paddingHorizontal: spacing.md + 2
  },
  rowLabel: {
    flex: 1,
    fontSize: typography.bodySize,
    fontWeight: '500',
    color: colors.textPrimary
  },
  hint: {
    fontSize: typography.metaSize,
    color: colors.textMuted,
    lineHeight: 18,
    paddingHorizontal: spacing.md + 2,
    paddingBottom: spacing.md
  }
})