YooAsset/Assets/YooAsset/Runtime/ResourcePackage/Operation/Internal/DownloadManifestOperation.cs

namespace YooAsset
{
    internal class DownloadManifestOperation : AsyncOperationBase
    {
        private enum ESteps
        {
            None,
            DownloadPackageHashFile,
            DownloadManifestFile,
            Done,
        }

        private readonly PersistentManager _persistent;
        private readonly IRemoteServices _remoteServices;
        private readonly string _packageVersion;
        private readonly int _timeout;
        private UnityWebFileRequester _downloader1;
        private UnityWebFileRequester _downloader2;
        private ESteps _steps = ESteps.None;
        private int _requestCount = 0;

        internal DownloadManifestOperation(PersistentManager persistent, IRemoteServices remoteServices, string packageVersion, int timeout)
        {
            _persistent = persistent;
            _remoteServices = remoteServices;
            _packageVersion = packageVersion;
            _timeout = timeout;
        }
        internal override void InternalOnStart()
        {
            _requestCount = RequestHelper.GetRequestFailedCount(_persistent.PackageName, nameof(DownloadManifestOperation));
            _steps = ESteps.DownloadPackageHashFile;
        }
        internal override void InternalOnUpdate()
        {
            if (_steps == ESteps.None || _steps == ESteps.Done)
                return;

            if (_steps == ESteps.DownloadPackageHashFile)
            {
                if (_downloader1 == null)
                {
                    string savePath = _persistent.GetSandboxPackageHashFilePath(_packageVersion);
                    string fileName = YooAssetSettingsData.GetPackageHashFileName(_persistent.PackageName, _packageVersion);
                    string webURL = GetDownloadRequestURL(_persistent.PackageName, fileName);
                    YooLogger.Log($"Beginning to download package hash file : {webURL}");
                    _downloader1 = new UnityWebFileRequester();
                    _downloader1.SendRequest(webURL, savePath, _timeout);
                }

                _downloader1.CheckTimeout();
                if (_downloader1.IsDone() == false)
                    return;

                if (_downloader1.HasError())
                {
                    _steps = ESteps.Done;
                    Status = EOperationStatus.Failed;
                    Error = _downloader1.GetError();
                    RequestHelper.RecordRequestFailed(_persistent.PackageName, nameof(DownloadManifestOperation));
                }
                else
                {
                    _steps = ESteps.DownloadManifestFile;
                }

                _downloader1.Dispose();
            }

            if (_steps == ESteps.DownloadManifestFile)
            {
                if (_downloader2 == null)
                {
                    string savePath = _persistent.GetSandboxPackageManifestFilePath(_packageVersion);
                    string fileName = YooAssetSettingsData.GetManifestBinaryFileName(_persistent.PackageName, _packageVersion);
                    string webURL = GetDownloadRequestURL(_persistent.PackageName, fileName);
                    YooLogger.Log($"Beginning to download package manifest file : {webURL}");
                    _downloader2 = new UnityWebFileRequester();
                    _downloader2.SendRequest(webURL, savePath, _timeout);
                }

                _downloader2.CheckTimeout();
                if (_downloader2.IsDone() == false)
                    return;

                if (_downloader2.HasError())
                {
                    _steps = ESteps.Done;
                    Status = EOperationStatus.Failed;
                    Error = _downloader2.GetError();
                    RequestHelper.RecordRequestFailed(_persistent.PackageName, nameof(DownloadManifestOperation));
                }
                else
                {
                    _steps = ESteps.Done;
                    Status = EOperationStatus.Succeed;
                }

                _downloader2.Dispose();
            }
        }

        private string GetDownloadRequestURL(string packageName, string fileName)
        {
            // 轮流返回请求地址
            if (_requestCount % 2 == 0)
                return _remoteServices.GetRemoteMainURL(packageName, fileName);
            else
                return _remoteServices.GetRemoteFallbackURL(packageName, fileName);
        }
    }
}