import { useCallback, useEffect, useRef } from 'react'
import { View, StyleSheet } from 'react-native'
import { Stack, useRouter } from 'expo-router'
import { StatusBar } from 'expo-status-bar'
import * as SplashScreen from 'expo-splash-screen'
import * as Notifications from 'expo-notifications'
import * as Linking from 'expo-linking'
import { colors } from '../src/theme/mobile-theme'
import { OrcaLogo } from '../src/components/OrcaLogo'
import { RpcClientProvider } from '../src/transport/client-context'
import { getNotificationNavigationPath } from '../src/notifications/notification-routing'
import { loadHosts } from '../src/transport/host-store'

// Why: keeps the native splash screen visible until the React tree is mounted
// and ready to render. Without this the user sees a blank white/black frame
// between the native splash and the first React paint.
SplashScreen.preventAutoHideAsync()

// Why: without this, expo-notifications silently drops notifications when
// the app is in the foreground. Setting all three to true makes iOS/Android
// display the banner, play the sound, and show the badge even while the
// app is active. This runs once at module load time before any notification
// is scheduled.
Notifications.setNotificationHandler({
  handleNotification: async () => ({
    shouldShowBanner: true,
    shouldShowList: true,
    shouldPlaySound: true,
    shouldSetBadge: false
  })
})

// Why: extract the path+payload that follows the orca://pair anchor so we
// can route it to the confirm screen. Accept either a hash payload
// (`orca://pair#<base64>`, the QR / shared form) or a query param
// (`orca://pair?code=<...>`, future-proof for share sheets that strip
// fragments).
function extractPairCode(url: string): string | null {
  if (!url.startsWith('orca://pair')) return null
  const hashIndex = url.indexOf('#')
  if (hashIndex !== -1) {
    return url.slice(hashIndex + 1) || null
  }
  const queryIndex = url.indexOf('?')
  if (queryIndex !== -1) {
    const params = new URLSearchParams(url.slice(queryIndex + 1))
    return params.get('code')
  }
  return null
}

export default function RootLayout() {
  const router = useRouter()
  const handledNotificationIdsRef = useRef<Set<string>>(new Set())

  // Why: route `orca://pair#<code>` deep links to the confirm screen so
  // the same pairing flow runs whether the link arrived via QR scan,
  // paste, AirDrop, Messages, or `xcrun simctl openurl`. getInitialURL
  // covers cold-start (link tapped while app was closed); the listener
  // covers warm-start (link tapped while app is in memory).
  useEffect(() => {
    function handleUrl(url: string) {
      const code = extractPairCode(url)
      if (code) {
        router.push({ pathname: '/pair-confirm', params: { code } })
      }
    }

    void Linking.getInitialURL().then((url) => {
      if (url) handleUrl(url)
    })

    const sub = Linking.addEventListener('url', ({ url }) => handleUrl(url))
    return () => sub.remove()
  }, [router])

  // Why: iOS delivers local notification taps through expo-notifications,
  // not Linking. Route both cold-start and warm-start responses to the host
  // and worktree that scheduled the notification.
  useEffect(() => {
    let disposed = false

    function clearLastNotificationResponse() {
      try {
        Notifications.clearLastNotificationResponse()
      } catch {
        // Older native shells may not expose the clear API; duplicate guards
        // still protect the current JS runtime.
      }
    }

    function getInitialNotificationResponse(): Notifications.NotificationResponse | null {
      try {
        return Notifications.getLastNotificationResponse()
      } catch {
        return null
      }
    }

    async function getNavigationPath(data: unknown): Promise<string | null> {
      const hosts = await loadHosts().catch(() => null)
      return getNotificationNavigationPath(data, {
        knownHostIds: hosts ? new Set(hosts.map((host) => host.id)) : undefined
      })
    }

    async function handleNotificationResponse(response: Notifications.NotificationResponse) {
      if (response.actionIdentifier !== Notifications.DEFAULT_ACTION_IDENTIFIER) {
        clearLastNotificationResponse()
        return
      }

      const notificationId = response.notification.request.identifier
      if (handledNotificationIdsRef.current.has(notificationId)) {
        return
      }
      handledNotificationIdsRef.current.add(notificationId)

      const path = await getNavigationPath(response.notification.request.content.data)
      clearLastNotificationResponse()
      if (disposed) {
        return
      }
      if (path) {
        router.push(path)
      }
    }

    const initialResponse = getInitialNotificationResponse()
    if (initialResponse) {
      void handleNotificationResponse(initialResponse)
    }

    const sub = Notifications.addNotificationResponseReceivedListener((response) => {
      void handleNotificationResponse(response)
    })
    return () => {
      disposed = true
      sub.remove()
    }
  }, [router])

  // Why: hide the native splash only once the navigation Stack has been laid
  // out — this is the earliest moment the user will see actual app content.
  // Previously the splash hid when a placeholder View rendered, leaving a
  // grey gap before the real screen appeared.
  const onNavigatorLayout = useCallback(async () => {
    await SplashScreen.hideAsync()
  }, [])

  return (
    <RpcClientProvider>
      <View style={styles.root} onLayout={onNavigatorLayout}>
        <StatusBar style="light" />
        <Stack
          screenOptions={{
            headerStyle: { backgroundColor: colors.bgPanel },
            headerTintColor: colors.textPrimary,
            headerTitleStyle: { fontSize: 16, fontWeight: '600' },
            contentStyle: { backgroundColor: colors.bgBase },
            headerShadowVisible: false
          }}
        >
          <Stack.Screen
            name="index"
            options={{
              headerShown: false,
              headerTitle: () => <OrcaLogo size={22} />
            }}
          />
          <Stack.Screen name="pair-scan" options={{ headerShown: false }} />
          <Stack.Screen name="pair-confirm" options={{ headerShown: false }} />
          <Stack.Screen name="settings" options={{ headerShown: false }} />
          <Stack.Screen name="terminal-settings" options={{ headerShown: false }} />
          <Stack.Screen name="notifications" options={{ headerShown: false }} />
          <Stack.Screen name="troubleshoot" options={{ headerShown: false }} />
          <Stack.Screen name="about" options={{ headerShown: false }} />
          <Stack.Screen name="h" options={{ headerShown: false }} />
        </Stack>
      </View>
    </RpcClientProvider>
  )
}

const styles = StyleSheet.create({
  root: {
    flex: 1,
    backgroundColor: colors.bgBase
  }
})