using System.IO;
using System.Net.Http;
using System.Windows.Controls;

namespace Zerolauncher.dialog
{
    /// <summary>
    /// DownloadControl.xaml 的交互逻辑
    /// </summary>
    public partial class DownloadControl : UserControl
    {
        const string cache_dir = "./.cache/auto.cache";

        public DownloadControl()
        {
            InitializeComponent();
        }

        private void OnError(Exception ex)
        {
            // UnityEngine.Debug.Log("捕获异常 >>> " + ex);
        }

        public async Task Download(string fileUrl) 
        {
            using (HttpClient client = new HttpClient())
            {
                // 获取文件大小
                HttpResponseMessage responseHead = await client.SendAsync(new HttpRequestMessage(HttpMethod.Head, fileUrl));
                long? contentLength = responseHead.Content.Headers.ContentLength;
                Console.WriteLine($"文件大小：{contentLength} 字节");

                // 计算块大小
                int blockSize = 1024 * 1024; // 1MB
                int blockCount = (int)Math.Ceiling((double)contentLength / blockSize);

                // 创建SemaphoreSlim以限制同时进行的下载任务的数量
                SemaphoreSlim semaphore = new SemaphoreSlim(4); // 最多允许4个并发下载任务

                using (FileStream fileStream = new FileStream(cache_dir, FileMode.Create, FileAccess.Write, FileShare.None, blockSize, true))
                {
                    // 创建任务列表
                    Task[] tasks = new Task[blockCount];

                    for (int i = 0; i < blockCount; i++)
                    {
                        int blockNumber = i;
                        tasks[i] = Task.Run(async () =>
                        {
                            await semaphore.WaitAsync(); // 等待获取许可

                            try
                            {
                                // 计算当前块的范围
                                var start = blockNumber * blockSize;
                                var end = (blockNumber == blockCount - 1) ? contentLength - 1 : start + blockSize - 1;

                                // 设置请求头，请求指定范围的数据
                                var request = new HttpRequestMessage { RequestUri = new Uri(fileUrl), Method = HttpMethod.Get };
                                request.Headers.Range = new System.Net.Http.Headers.RangeHeaderValue(start, end);

                                // 下载当前块
                                using (HttpResponseMessage response = await client.SendAsync(request))
                                {
                                    response.EnsureSuccessStatusCode();
                                    byte[] buffer = await response.Content.ReadAsByteArrayAsync();
                                    await fileStream.WriteAsync(buffer, 0, buffer.Length);
                                }

                                // 显示下载进度
                                double percent = (double)(blockNumber + 1) / blockCount * 100;
                                Console.WriteLine($"已下载：{percent:F2}%");
                            }
                            finally
                            {
                                semaphore.Release(); // 释放许可
                            }
                        });
                    }

                    // 等待所有任务完成
                    await Task.WhenAll(tasks);
                }
            }

            Console.WriteLine("下载完成！");
        }

        private void OnUpdate(long size, long count)
        {

        }

        private void OnDone(byte[] data)
        {

        }

        private void OnDestroy()
        {
        }

    }
}