using System.IO;
using UnityEngine;
using YooAsset;

namespace AlicizaX.Resource.Runtime
{
    /// <summary>
    /// 远端资源地址查询服务类
    /// </summary>
    class RemoteServices : IRemoteServices
    {
        private readonly string _defaultHostServer;
        private readonly string _fallbackHostServer;

        public RemoteServices(string defaultHostServer, string fallbackHostServer)
        {
            _defaultHostServer = defaultHostServer;
            _fallbackHostServer = fallbackHostServer;
        }

        string IRemoteServices.GetRemoteMainURL(string fileName)
        {
            return $"{_defaultHostServer}/{fileName}";
        }

        string IRemoteServices.GetRemoteFallbackURL(string fileName)
        {
            return $"{_fallbackHostServer}/{fileName}";
        }
    }

    /// <summary>
    /// 资源文件流加载解密类
    /// </summary>
    class FileStreamDecryption : IDecryptionServices
    {
        DecryptResult IDecryptionServices.LoadAssetBundle(DecryptFileInfo fileInfo)
        {
            BundleStream bundleStream = new BundleStream(fileInfo.FileLoadPath, FileMode.Open, FileAccess.Read, FileShare.Read);
            DecryptResult decryptResult = new DecryptResult();
            decryptResult.ManagedStream = bundleStream;
            decryptResult.Result = AssetBundle.LoadFromStream(bundleStream, 0, GetManagedReadBufferSize());
            return decryptResult;
        }

        // AssetBundle解密方法
        DecryptResult IDecryptionServices.LoadAssetBundleAsync(DecryptFileInfo fileInfo)
        {
            BundleStream bundleStream = new BundleStream(fileInfo.FileLoadPath, FileMode.Open, FileAccess.Read, FileShare.Read);
            DecryptResult decryptResult = new DecryptResult();
            decryptResult.ManagedStream = bundleStream;
            decryptResult.CreateRequest = AssetBundle.LoadFromStreamAsync(bundleStream, 0, GetManagedReadBufferSize());
            return decryptResult;
        }

        public byte[] ReadFileData(DecryptFileInfo fileInfo)
        {
            throw new System.NotImplementedException();
        }

        public string ReadFileText(DecryptFileInfo fileInfo)
        {
            throw new System.NotImplementedException();
        }

        private static uint GetManagedReadBufferSize()
        {
            return 1024;
        }
    }

    /// <summary>
    /// 资源文件偏移加载解密类
    /// </summary>
    class FileOffsetDecryption : IDecryptionServices
    {
        DecryptResult IDecryptionServices.LoadAssetBundle(DecryptFileInfo fileInfo)
        {
            DecryptResult decryptResult = new DecryptResult();
            decryptResult.ManagedStream = null;
            decryptResult.Result = AssetBundle.LoadFromFile(fileInfo.FileLoadPath, 0, GetFileOffset());
            return decryptResult;
        }

        // AssetBundle解密方法
        DecryptResult IDecryptionServices.LoadAssetBundleAsync(DecryptFileInfo fileInfo)
        {
            DecryptResult decryptResult = new DecryptResult();
            decryptResult.ManagedStream = null;
            decryptResult.CreateRequest = AssetBundle.LoadFromFileAsync(fileInfo.FileLoadPath, 0, GetFileOffset());
            return decryptResult;
        }

        public byte[] ReadFileData(DecryptFileInfo fileInfo)
        {
            throw new System.NotImplementedException();
        }

        public string ReadFileText(DecryptFileInfo fileInfo)
        {
            throw new System.NotImplementedException();
        }

        private static ulong GetFileOffset()
        {
            return 32;
        }
    }


    /// <summary>
    /// 资源文件解密流
    /// </summary>
    public class BundleStream : FileStream
    {
        public const byte KEY = 64;

        public BundleStream(string path, FileMode mode, FileAccess access, FileShare share) : base(path, mode, access, share)
        {
        }

        public BundleStream(string path, FileMode mode) : base(path, mode)
        {
        }

        public override int Read(byte[] array, int offset, int count)
        {
            var index = base.Read(array, offset, count);
            for (int i = 0; i < array.Length; i++)
            {
                array[i] ^= KEY;
            }

            return index;
        }
    }
}