import React, { useMemo, useEffect, useState } from "react";
import { StatusBar } from "expo-status-bar";
import { ActivityIndicator, View, StyleSheet } from "react-native";
import * as Updates from "expo-updates";
import { NavigationContainer } from "@react-navigation/native";
import { createNativeStackNavigator } from "@react-navigation/native-stack";

import { AuthProvider, useAuth } from "./src/auth/AuthContext";
import { ThemeProvider, useTheme } from "./src/context/ThemeContext";
import type { Colors } from "./src/theme";
import { spacing } from "./src/theme";
import { initServerBaseUrl } from "./src/api/client";

import ServerConfigScreen from "./src/screens/auth/ServerConfigScreen";
import RoleSelectScreen from "./src/screens/auth/RoleSelectScreen";
import AdminLoginScreen from "./src/screens/auth/AdminLoginScreen";
import CabineLoginScreen from "./src/screens/auth/CabineLoginScreen";
import DeliveryLoginScreen from "./src/screens/auth/DeliveryLoginScreen";

import AdminNavigator from "./src/navigation/AdminNavigator";
import CabineNavigator from "./src/navigation/CabineNavigator";
import DeliveryNavigator from "./src/navigation/DeliveryNavigator";

import type { AuthStackParamList } from "./src/navigation/types";

const Stack = createNativeStackNavigator<AuthStackParamList>();

function AuthStack() {
    const { colors } = useTheme();

    return (
        <Stack.Navigator
            initialRouteName="ServerConfig"
            screenOptions={{
                headerStyle: { backgroundColor: colors.bgSecondary },
                headerTintColor: colors.textWhite,
            }}
        >
            <Stack.Screen
                name="ServerConfig"
                component={ServerConfigScreen}
                options={{ headerShown: false }}
            />
            <Stack.Screen
                name="RoleSelect"
                component={RoleSelectScreen}
                options={{ title: "Admin Panel" }}
            />
            <Stack.Screen
                name="AdminLogin"
                component={AdminLoginScreen}
                options={{ title: "Connexion Admin" }}
            />
            <Stack.Screen
                name="CabineLogin"
                component={CabineLoginScreen}
                options={{ title: "Connexion Cabine" }}
            />
            <Stack.Screen
                name="DeliveryLogin"
                component={DeliveryLoginScreen}
                options={{ title: "Connexion Livreur" }}
            />
        </Stack.Navigator>
    );
}

function RootNavigator() {
    const { isAuthenticated, isLoading, role } = useAuth();
    const { colors } = useTheme();

    if (isLoading) {
        return (
            <View
                style={{
                    flex: 1,
                    justifyContent: "center",
                    alignItems: "center",
                    backgroundColor: colors.bgPrimary,
                }}
            >
                <ActivityIndicator size="large" color={colors.accent} />
            </View>
        );
    }

    if (isAuthenticated) {
        switch (role) {
            case "admin":
                return <AdminNavigator />;
            case "cabine":
                return <CabineNavigator />;
            case "livreur":
                return <DeliveryNavigator />;
        }
    }

    return <AuthStack />;
}

export default function App() {
    useEffect(() => {
        if (__DEV__) return;
        const checkForUpdate = async () => {
            try {
                const update = await Updates.checkForUpdateAsync();
                if (update.isAvailable) {
                    await Updates.fetchUpdateAsync();
                    await Updates.reloadAsync();
                }
            } catch (e) {
                console.error("[OTA] Échec de la vérification/application de la mise à jour:", e);
            }
        };
        checkForUpdate();
    }, []);

    return (
        <ThemeProvider>
            <ServerGate>
                <AuthProvider>
                    <NavigationContainer>
                        <RootNavigator />
                        <DynamicStatusBar />
                    </NavigationContainer>
                </AuthProvider>
            </ServerGate>
        </ThemeProvider>
    );
}

// Restores a previously saved backend server URL before any screen
// (including the auth restore flow) can issue an API call.
function ServerGate({ children }: { children: React.ReactNode }) {
    const [ready, setReady] = useState(false);
    const { colors } = useTheme();

    useEffect(() => {
        initServerBaseUrl().finally(() => setReady(true));
    }, []);

    if (!ready) {
        return (
            <View
                style={{
                    flex: 1,
                    justifyContent: "center",
                    alignItems: "center",
                    backgroundColor: colors.bgPrimary,
                }}
            >
                <ActivityIndicator size="large" color={colors.accent} />
            </View>
        );
    }

    return <>{children}</>;
}

function DynamicStatusBar() {
    const { isDark } = useTheme();
    return <StatusBar style={isDark ? "light" : "dark"} />;
}