TH1/Unity/Assets/Scripts/TH1_Logic/Editor/OssDownloadService.cs

/*
 * @Author: Copilot
 * @Description: OSS文件下载服务（Editor Only），从阿里云OSS下载Collect数据文件
 * @Date: 2026年04月17日
 * @Modify: 
 */


using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Linq;
using UnityEngine;


namespace Logic.Editor
{
    /// <summary>
    /// Editor-only service for downloading files from Aliyun OSS.
    /// Uses OSS REST API with V1 HMAC-SHA1 signature.
    /// </summary>
    public class OssDownloadService
    {
        private readonly string _accessKeyId;
        private readonly string _accessKeySecret;
        private readonly string _endpoint;
        private readonly string _bucket;

        private static readonly HttpClient SharedHttpClient = new() { Timeout = TimeSpan.FromMinutes(10) };

        public OssDownloadService(string accessKeyId, string accessKeySecret,
            string endpoint = "oss-cn-shanghai.aliyuncs.com", string bucket = "th1-oss")
        {
            _accessKeyId = accessKeyId?.Trim();
            _accessKeySecret = accessKeySecret?.Trim();
            _endpoint = endpoint?.Trim();
            _bucket = bucket?.Trim();

            // 打印密钥信息帮助排查问题
            if (!string.IsNullOrEmpty(_accessKeySecret))
            {
                var secretLen = _accessKeySecret.Length;
                var maskedSecret = secretLen > 4 
                    ? $"{_accessKeySecret.Substring(0, 2)}***{_accessKeySecret.Substring(secretLen - 2)}" 
                    : "***";
                Debug.Log($"[OSS配置检查] AccessKeyId: {_accessKeyId}, Secret长度: {secretLen}, Secret首尾: {maskedSecret}");
            }
        }

        /// <summary>
        /// 生成 OSS V1 签名
        /// StringToSign = VERB + "\n" + "\n" + "\n" + Date + "\n" + CanonicalizedResource
        /// </summary>
        private string Sign(string verb, string date, string canonicalizedResource)
        {
            var stringToSign = $"{verb}\n\n\n{date}\n{canonicalizedResource}";
            using var hmac = new HMACSHA1(Encoding.UTF8.GetBytes(_accessKeySecret));
            var hash = hmac.ComputeHash(Encoding.UTF8.GetBytes(stringToSign));
            return Convert.ToBase64String(hash);
        }

        /// <summary>
        /// 列出指定前缀下的所有对象（自动分页）
        /// </summary>
        public async Task<List<string>> ListObjectsAsync(string prefix)
        {
            var keys = new List<string>();
            string continuationToken = null;
            bool isTruncated = true;

            while (isTruncated)
            {
                var queryParams = $"list-type=2&prefix={Uri.EscapeDataString(prefix)}&max-keys=1000";
                var canonicalizedResource = $"/{_bucket}/";
                
                if (!string.IsNullOrEmpty(continuationToken))
                {
                    var encodedToken = Uri.EscapeDataString(continuationToken);
                    queryParams += $"&continuation-token={encodedToken}";
                    canonicalizedResource += $"?continuation-token={encodedToken}";
                }

                var url = $"https://{_bucket}.{_endpoint}/?{queryParams}";
                
                var now = DateTimeOffset.UtcNow;
                var date = now.ToString("R");
                var signature = Sign("GET", date, canonicalizedResource);

                using var request = new HttpRequestMessage(HttpMethod.Get, url);
                request.Headers.Date = now; // 强制使用完全一致的时间对象，避免 HttpClient 覆盖 Date
                request.Headers.TryAddWithoutValidation("Authorization", $"OSS {_accessKeyId}:{signature}");

                var response = await SharedHttpClient.SendAsync(request);
                var xml = await response.Content.ReadAsStringAsync();

                if (!response.IsSuccessStatusCode)
                {
                    Debug.LogError($"<color=red>OSS ListObjects 失败: {response.StatusCode}</color>\n{xml}");
                    break;
                }

                var doc = XDocument.Parse(xml);
                var ns = doc.Root?.GetDefaultNamespace() ?? XNamespace.None;

                foreach (var content in doc.Root!.Elements(ns + "Contents"))
                {
                    var key = content.Element(ns + "Key")?.Value;
                    if (!string.IsNullOrEmpty(key) && !key.EndsWith("/"))
                        keys.Add(key);
                }

                isTruncated = bool.TryParse(doc.Root.Element(ns + "IsTruncated")?.Value, out var t) && t;
                continuationToken = doc.Root.Element(ns + "NextContinuationToken")?.Value;
            }

            return keys;
        }

        /// <summary>
        /// 下载单个 OSS 对象到本地文件
        /// </summary>
        public async Task<bool> DownloadObjectAsync(string objectKey, string localPath)
        {
            try
            {
                var now = DateTimeOffset.UtcNow;
                var date = now.ToString("R");
                var canonicalizedResource = $"/{_bucket}/{objectKey}";
                var signature = Sign("GET", date, canonicalizedResource);

                // 对 objectKey 中的每个路径段分别编码，保留 '/'
                var encodedKey = string.Join("/",
                    objectKey.Split('/').Select(seg => Uri.EscapeDataString(seg)));
                var url = $"https://{_bucket}.{_endpoint}/{encodedKey}";

                using var request = new HttpRequestMessage(HttpMethod.Get, url);
                request.Headers.Date = now; // 强制使用完全一致的时间对象
                request.Headers.TryAddWithoutValidation("Authorization", $"OSS {_accessKeyId}:{signature}");

                var response = await SharedHttpClient.SendAsync(request);
                if (!response.IsSuccessStatusCode)
                {
                    var error = await response.Content.ReadAsStringAsync();
                    Debug.LogError($"<color=red>OSS 下载失败 {objectKey}: {response.StatusCode}</color>\n{error}");
                    return false;
                }

                var dir = Path.GetDirectoryName(localPath);
                if (!string.IsNullOrEmpty(dir) && !Directory.Exists(dir))
                    Directory.CreateDirectory(dir);

                var data = await response.Content.ReadAsByteArrayAsync();
                File.WriteAllBytes(localPath, data);
                return true;
            }
            catch (Exception ex)
            {
                Debug.LogError($"<color=red>OSS 下载异常 {objectKey}: {ex.Message}</color>");
                return false;
            }
        }
    }
}