package com.tongran.agentserver.server.file;

import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.function.Consumer;

public class AdvancedAsyncDownloader {
    private static final ExecutorService downloadExecutor = 
        Executors.newFixedThreadPool(5);
    
    /**
     * 带进度回调的异步下载
     */
    public static CompletableFuture<String> downloadWithProgress(
            String fileUrl, 
            String saveDir, 
            String fileName,
            Consumer<Double> progressCallback) {
        
        return CompletableFuture.supplyAsync(() -> {
            try {
                URL url = new URL(fileUrl);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                
                // 获取文件大小
                long fileSize = connection.getContentLengthLong();
                
                // 创建保存目录
                java.nio.file.Path directory = java.nio.file.Paths.get(saveDir);
                if (!java.nio.file.Files.exists(directory)) {
                    java.nio.file.Files.createDirectories(directory);
                }
                
                String filePath = directory.resolve(fileName != null ? fileName : 
                    extractFileNameFromUrl(fileUrl)).toString();
                
                try (BufferedInputStream in = new BufferedInputStream(connection.getInputStream());
                     FileOutputStream out = new FileOutputStream(filePath)) {
                    
                    byte[] buffer = new byte[8192];
                    int bytesRead;
                    long totalRead = 0;
                    
                    while ((bytesRead = in.read(buffer)) != -1) {
                        out.write(buffer, 0, bytesRead);
                        totalRead += bytesRead;
                        
                        // 回调进度
                        if (progressCallback != null && fileSize > 0) {
                            double progress = (double) totalRead / fileSize * 100;
                            progressCallback.accept(progress);
                        }
                    }
                }
                
                return filePath;
            } catch (Exception e) {
                throw new RuntimeException("下载失败", e);
            }
        }, downloadExecutor);
    }
    
    private static String extractFileNameFromUrl(String fileUrl) {
        // 实现文件名提取逻辑
        return fileUrl.substring(fileUrl.lastIndexOf('/') + 1);
    }

    /**
     * 检查目录是否存在，不存在则创建（不创建父目录）
     * @param directoryPath 目录路径
     * @return 创建成功返回true，否则返回false
     */
    public static boolean createSingleDirectoryIfNotExists(String directoryPath) {
        try {
            Path path = Paths.get(directoryPath);

            if (!Files.exists(path)) {
                // 只创建单级目录（父目录必须存在）
                Files.createDirectory(path);
                System.out.println("目录创建成功: " + directoryPath);
                return true;
            } else {
                System.out.println("目录已存在: " + directoryPath);
                return true;
            }
        } catch (IOException e) {
            System.err.println("创建目录失败: " + directoryPath);
            System.err.println("错误信息: " + e.getMessage());
            return false;
        }
    }

    /**
     * 使用示例
     */
    public static void main(String[] args) {
        String fileUrl = "https://www.tzdsp.net/ksc-andromedae";
        String saveDir = "D:/down";
        
        downloadWithProgress(fileUrl, saveDir, null, progress -> {
            System.out.printf("下载进度: %.1f%%\n", progress);
        }).thenAccept(filePath -> {
            System.out.println("下载完成: " + filePath);
        }).exceptionally(ex -> {
            System.err.println("下载错误: " + ex.getMessage());
            return null;
        });
        
        // 主线程继续执行
        System.out.println("异步下载已启动...");
    }
}