using System;
using System.IO;
using System.Threading.Tasks;

namespace VideoAnalysisCore.Common
{
    /// <summary>
    /// 
    /// </summary>
    public class DownloadFile
    {
        // 根据 Content-Type 映射文件后缀
        static string GetExtensionFromContentType(HttpResponseMessage res)
        {
            var contentType = res.Content.Headers.ContentType?.MediaType;
            return contentType switch
            {
                "application/pdf" => ".pdf",
                "image/jpeg" => ".jpg",
                "image/png" => ".png",
                "application/zip" => ".zip",
                "text/html" => ".html",
                "audio/wav" => ".wav",
                "audio/mp4" => ".mp4",
                "audio/mp3" => ".mp3",
                // 根据需要添加其他 Content-Type 映射
                _ => ".mp4", // 默认二进制文件
            };
        }

        /// <summary>
        /// 使用 HttpClient 下载任务的资源文件到本地
        /// </summary>
        /// <param name="task"></param>
        /// <returns></returns>
        public static async Task RunTask(string task)
        {
            //获取资源文件 地址
            var fileUrl = RedisExpand.Redis.HMGet(RedisExpandKey.Task(task), "MediaUrl")
                .FirstOrDefault();
            if (string.IsNullOrEmpty(fileUrl))
                throw new Exception($"任务id[{task}] 资源地址无效 {fileUrl}");

            using HttpClient client = new HttpClient();
            // 发送 GET 请求以下载文件
            var response = await client.GetAsync(fileUrl, HttpCompletionOption.ResponseHeadersRead);
            // 确保响应是成功的
            response.EnsureSuccessStatusCode();

            // 尝试从 URL 中获取文件后缀
            string fileExtension = Path.GetExtension(new Uri(fileUrl).AbsolutePath);
            //否则 获取 从Content-Type 获取文件后缀
            if (string.IsNullOrEmpty(fileExtension))
                fileExtension = GetExtensionFromContentType(response);

            //创建下载文件缓存路径
            if (!Directory.Exists(AppCommon.TaskCachedFile)) Directory.CreateDirectory(AppCommon.TaskCachedFile);
           
            // 获取文件大小
            var totalBytes = response.Content.Headers.ContentLength;
            if (!totalBytes.HasValue)
                throw new Exception(task+" 未能获取到下载文件的 ContentLength ");
            var localPath = task.LocalPath();
            var outputPath = Path.Combine(localPath, task  + fileExtension);
            if (!Directory.Exists(localPath)) Directory.CreateDirectory(localPath);


            //同步到redis
            RedisExpand.Redis.HSet(RedisExpandKey.Task(task), "LocalMediaPath", outputPath);
            // 打开本地文件流以写入文件
            using var fs = new FileStream(outputPath, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None);
            // 读取响应内容流
            using var contentStream = await response.Content.ReadAsStreamAsync();
            var buffer = new byte[512 * 1024]; // 512KB 缓冲区
            long totalBytesRead = 0;
            var count = 0;
            int bytesRead;
            while ((bytesRead = await contentStream.ReadAsync(buffer, 0, buffer.Length)) > 0)
            {
                count++;
                await fs.WriteAsync(buffer, 0, bytesRead);
                totalBytesRead += bytesRead;

                // 计算下载进度
                if (count % 30 == 0)
                {
                    var progress = (double)totalBytesRead / totalBytes.Value * 100;
                    RedisExpand.SetTaskProgress(task, progress);
                }
            }

            //加入下一队列
            RedisExpand.InsertChannel(Enum.RedisChannelEnum.SeparateAudio, task);
        }
    }
}