import React, { useEffect, useState } from "react";
import { View, Text, StyleSheet, Alert, BackHandler } from "react-native";
import { NativeStackScreenProps } from "@react-navigation/native-stack";
import { RootStackParamList } from "../App";
import RNFS from "react-native-fs";
import { startDfu, DfuProgressEvent, DfuStateEvent } from "@systemic-games/react-native-nordic-nrf5-dfu";

type Props = NativeStackScreenProps<RootStackParamList, "Dfu">;

interface DeviceInfo {
  hardware: number;
  latestFirmware: string;
  download: string;
}

export default function DfuScreen({ route, navigation }: Props) {
  const { deviceId, name, firmware: deviceFirmware } = route.params;

  const [progress, setProgress] = useState(0);
  const [state, setState] = useState("准备中...");
  const [error, setError] = useState<string>();
  const [latestVersion, setLatestVersion] = useState<string>("读取中...");
  const [isDfuRunning, setIsDfuRunning] = useState(false);

  const mapDfuStateToChinese = (state: string): string => {
    switch (state) {
      case "connecting": return "连接中…";
      case "starting": return "初始化中…";
      case "enablingDfuMode": return "启用 DFU 模式…";
      case "uploading": return "上传固件中…";
      case "validating": return "校验固件…";
      case "disconnecting": return "断开连接…";
      case "completed": return "升级完成";
      case "aborted": return "已取消";
      case "failed":
      case "dfu_failed": return "升级失败";
      case "initializing": return "启动中…";
      case "errored": return "升级出错！";
      default: return state;
    }
  };

  
  // ✅ 拦截所有导航返回（iOS + Android）
  useEffect(() => {
    const unsubscribe = navigation.addListener("beforeRemove", (e) => {
      if (!isDfuRunning) return;

      // 阻止返回
      e.preventDefault();
      Alert.alert("请稍候", "正在升级，请勿返回或关闭应用！");
    });

    return unsubscribe;
  }, [navigation, isDfuRunning]);

  


  useEffect(() => {
    const runDfu = async () => {
      try {
        setIsDfuRunning(true);

        const manifestUrl = "https://powerfun.oss-cn-shanghai.aliyuncs.com/yecongdfu/latest.json";
        const manifestPath = RNFS.CachesDirectoryPath + "/latest.json";

        await RNFS.downloadFile({ fromUrl: manifestUrl, toFile: manifestPath }).promise;
        const manifestContent = await RNFS.readFile(manifestPath);
        const manifest = JSON.parse(manifestContent) as { devices: DeviceInfo[] };

        const [deviceHWStr, deviceFWStr] = deviceFirmware.split(".");
        const deviceHW = parseInt(deviceHWStr);
        const deviceFW = parseInt(deviceFWStr);

        const deviceInfo = manifest.devices.find(d => d.hardware === deviceHW);
        if (!deviceInfo) {
          setIsDfuRunning(false);
          Alert.alert("无法升级", `未找到硬件版本 ${deviceHW} 的固件`, [
            { text: "确认", onPress: () => navigation.goBack() },
          ]);
          return;
        }

        setLatestVersion(deviceInfo.latestFirmware);

        const [, latestFWStr] = deviceInfo.latestFirmware.split(".");
        const latestFW = parseInt(latestFWStr);

        if (latestFW <= deviceFW) {
          setIsDfuRunning(false);
          Alert.alert("无需升级", "已是最新固件，无需升级", [
            { text: "确认", onPress: () => navigation.goBack() },
          ]);
          return;
        }

        const localPath = RNFS.CachesDirectoryPath + "/firmware.zip";
        await RNFS.downloadFile({ fromUrl: deviceInfo.download, toFile: localPath }).promise;

        await startDfu(deviceId, "file://" + localPath, {
          dfuStateListener: (ev: DfuStateEvent) => setState(ev.state),
          dfuProgressListener: (ev: DfuProgressEvent) => setProgress(ev.percent),
        });

        setIsDfuRunning(false);
        Alert.alert("升级成功", "升级成功，请重连设备", [
          { text: "确认", onPress: () => navigation.navigate("Home") },
        ]);
      } catch (err: any) {
        setIsDfuRunning(false);
        setError(err.message || "DFU失败");
        Alert.alert("升级失败", err.message || "DFU失败", [
          { text: "确认", onPress: () => navigation.goBack() },
        ]);
      }
    };

    runDfu();
  }, [deviceId, deviceFirmware, navigation]);

  return (
    <View style={{ flex: 1, padding: 20 }}>
      <View style={styles.row}>
        <Text style={{ fontSize: 16 }}>蓝牙名称: {name}</Text>
      </View>
      <View style={styles.row}>
        <Text style={{ fontSize: 16 }}>最新版本: {latestVersion}</Text>
      </View>
      <View style={styles.row}>
        <Text style={{ fontSize: 16 }}>当前版本: {deviceFirmware}</Text>
      </View>
      <View style={styles.row}>
        <Text style={{ fontSize: 16 }}>升级状态: {mapDfuStateToChinese(state)}</Text>
      </View>

      {/* 横向进度条 */}
      <View style={styles.progressContainer}>
        <View style={[styles.progressBar, { width: `${progress}%` }]} />
        <Text style={styles.progressText}>{progress}%</Text>
      </View>

      {error && <Text style={{ color: "red", marginTop: 20 }}>{error}</Text>}
    </View>
  );
}

const styles = StyleSheet.create({
  row: {
    borderBottomWidth: 1,
    borderBottomColor: "red",
    paddingBottom: 4,
    marginBottom: 8,
  },
  progressContainer: {
    height: 30,
    backgroundColor: "#eee",
    borderRadius: 15,
    overflow: "hidden",
    marginTop: 40,
    justifyContent: "center",
  },
  progressBar: {
    height: "100%",
    backgroundColor: "#E7141E",
  },
  progressText: {
    position: "absolute",
    alignSelf: "center",
    fontWeight: "bold",
    color: "#000",
  },
});