using System;
using System.Collections.Generic;
using UnityEngine;
using Cysharp.Threading.Tasks;

#if WECHAT_MINIGAME
using WeChatWASM;

#else
using System.IO;  // 仅在非微信平台使用
using ICSharpCode.SharpZipLib.Zip;
#endif

namespace Stary.Evo.Unzip
{
    public static class CrossPlatformUnzip
    {
        public static async UniTask UnzipAsync(string zipPath, string extractPath,
            Action<float> progressCallback = null, bool deleteAfterExtract = true)
        {
#if WECHAT_MINIGAME && UNITY_WEBGL
            // 微信小程序：使用原生 WX API，零 System.IO
            await UnzipWeChatNativeAsync(zipPath, extractPath, progressCallback, deleteAfterExtract);
#elif UNITY_WEBGL && !WECHAT_MINIGAME
            // WebGL：使用 SharpZipLib（虚拟文件系统）
            await UnzipWebGLAsync(zipPath, extractPath, progressCallback, deleteAfterExtract);
#else
            // PC/移动端：标准 System.IO
            await UnzipStandardAsync(zipPath, extractPath, progressCallback, deleteAfterExtract);
#endif
        }

        #region 1. 微信小程序实现（零 System.IO）

#if WECHAT_MINIGAME
        private static async UniTask UnzipWeChatNativeAsync(string zipPath, string extractPath,
            Action<float> progressCallback, bool deleteAfterExtract)
        {
            var tcs = new UniTaskCompletionSource();
            var fs = WX.GetFileSystemManager();

            // 检查 ZIP 存在（使用微信 API）
            bool fileExists = false;
            fs.Access(new AccessParam()
            {
                path = zipPath,
                success = (res) => fileExists = true,
                fail = (err) => { }
            });

            await UniTask.Delay(50); // 等待异步结果
            if (!fileExists)
                throw new Exception($"ZIP 不存在: {zipPath}");

            // 清理目标目录（递归删除）
            try
            {
                fs.RmdirSync(extractPath, true);
            }
            catch
            {
                // 目录不存在或已删除
            }

            // 创建目标目录
            fs.MkdirSync(extractPath, true);

            // 模拟进度（WX.Unzip 无细粒度进度）
            float reportedProgress = 0f;
            var progressTask = SimulateProgressAsync(progressCallback, () => reportedProgress >= 1f);

            // 微信原生解压（性能最佳，C++ 实现）
            WX.GetFileSystemManager().Unzip(new UnzipOption()
            {
                zipFilePath = zipPath,
                targetPath = extractPath,
                success = (res) =>
                {
                    reportedProgress = 1f;
                    progressCallback?.Invoke(1f);
                    tcs.TrySetResult();
                },
                fail = (err) => { tcs.TrySetException(new Exception($"微信解压失败: {err.errMsg}")); }
            });

            await tcs.Task;
            await progressTask;

            // 删除 ZIP 释放空间（微信 200MB 限制严格）
            if (deleteAfterExtract)
            {
                DeleteWeChatFileSafe(fs, zipPath);
            }
        }

        private static async UniTask SimulateProgressAsync(Action<float> callback, Func<bool> isCompleted)
        {
            if (callback == null) return;

            float progress = 0f;
            while (!isCompleted())
            {
                progress = Mathf.Min(progress + UnityEngine.Random.Range(0.02f, 0.08f), 0.95f);
                callback.Invoke(progress);
                await UniTask.Delay(200);
            }
        }

        private static void DeleteWeChatFileSafe(WXFileSystemManager fs, string path)
        {
            try
            {
                fs.UnlinkSync(path);
                Debug.Log($"[微信] 已删除 ZIP");
            }
            catch (Exception ex)
            {
                Debug.LogWarning($"[微信] 删除失败: {ex.Message}");
            }
        }

        /// <summary>
        /// 获取微信缓存路径（字符串拼接，不使用 Path.Combine）
        /// </summary>
        public static string GetWeChatPath(string relativePath)
        {
            // 手动拼接路径，避免使用 System.IO.Path
            string basePath = WX.env.USER_DATA_PATH;
            if (relativePath.StartsWith("/"))
                return basePath + relativePath;
            return basePath + "/" + relativePath;
        }
#endif

        #endregion

        #region 2. WebGL 实现（SharpZipLib + 虚拟文件系统）

#if UNITY_WEBGL && !WECHAT_MINIGAME
        private static async UniTask UnzipWebGLAsync(string zipPath, string extractPath, 
            Action<float> progressCallback, bool deleteAfterExtract)
        {
            // WebGL 使用 Unity 的虚拟文件系统（基于 IndexedDB）
            // 注意：虽然是 FileStream，但在 WebGL 中实际是虚拟 IO
            
            if (!File.Exists(zipPath))
                throw new FileNotFoundException($"ZIP 不存在: {zipPath}");

            string fullExtractPath = Path.GetFullPath(extractPath);
            
            // 清理目录
            if (Directory.Exists(extractPath))
                Directory.Delete(extractPath, true);
            Directory.CreateDirectory(extractPath);

            using (FileStream fs = File.OpenRead(zipPath))
            using (ZipFile zipFile = new ZipFile(fs))
            {
                int total = 0;
                var validEntries = new List<ZipEntry>();
                
                foreach (ZipEntry entry in zipFile)
                {
                    if (entry.IsFile && !string.IsNullOrEmpty(entry.Name))
                    {
                        validEntries.Add(entry);
                        total++;
                    }
                }

                // WebGL 分帧解压，避免卡死浏览器
                int processed = 0;
                const int FILES_PER_FRAME = 3;
                
                foreach (var entry in validEntries)
                {
                    // 安全检查
                    string fullPath = Path.GetFullPath(Path.Combine(extractPath, entry.Name));
                    if (!fullPath.StartsWith(fullExtractPath))
                    {
                        Debug.LogWarning($"跳过非法路径: {entry.Name}");
                        continue;
                    }

                    // 创建目录
                    string dir = Path.GetDirectoryName(fullPath);
                    if (!string.IsNullOrEmpty(dir))
                        Directory.CreateDirectory(dir);

                    // 解压单文件
                    using (Stream input = zipFile.GetInputStream(entry))
                    using (FileStream output = File.Create(fullPath))
                    {
                        byte[] buffer = new byte[4096]; // WebGL 使用更小缓冲区
                        int read;
                        while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
                        {
                            output.Write(buffer, 0, read);
                        }
                    }

                    processed++;
                    
                    // 每 N 个文件让出一帧，保持浏览器响应
                    if (processed % FILES_PER_FRAME == 0)
                    {
                        progressCallback?.Invoke((float)processed / total);
                        await UniTask.Yield();
                    }
                }
            }

            if (deleteAfterExtract)
            {
                File.Delete(zipPath);
            }
        }
#endif

        #endregion

        #region 3. PC/移动端实现（标准 System.IO）
#if !UNITY_WEBGL && !WECHAT_MINIGAME
        private static async UniTask UnzipStandardAsync(string zipPath, string extractPath,
            Action<float> progressCallback, bool deleteAfterExtract)
        {
            await UniTask.SwitchToThreadPool();

            try
            {
                if (!File.Exists(zipPath))
                    throw new FileNotFoundException($"ZIP 不存在: {zipPath}");

                string fullExtractPath = Path.GetFullPath(extractPath);

                if (Directory.Exists(extractPath))
                    Directory.Delete(extractPath, true);
                Directory.CreateDirectory(extractPath);

                using (FileStream fs = File.OpenRead(zipPath))
                using (ZipFile zipFile = new ZipFile(fs))
                {
                    int total = 0;
                    foreach (ZipEntry entry in zipFile)
                        if (entry.IsFile)
                            total++;

                    int processed = 0;
                    foreach (ZipEntry entry in zipFile)
                    {
                        if (!entry.IsFile) continue;

                        string fullPath = Path.GetFullPath(Path.Combine(extractPath, entry.Name));
                        if (!fullPath.StartsWith(fullExtractPath)) continue;

                        Directory.CreateDirectory(Path.GetDirectoryName(fullPath));

                        using (Stream input = zipFile.GetInputStream(entry))
                        using (FileStream output = File.Create(fullPath))
                        {
                            await input.CopyToAsync(output);
                        }

                        processed++;

                        await UniTask.SwitchToMainThread();
                        progressCallback?.Invoke((float)processed / total);
                        await UniTask.SwitchToThreadPool();
                    }
                }
            }
            finally
            {
                await UniTask.SwitchToMainThread();
                if (deleteAfterExtract && File.Exists(zipPath))
                    File.Delete(zipPath);
            }
        }
#endif
        #endregion

        #region 4. 公共工具（平台特定）

        /// <summary>
        /// 获取缓存路径（平台特定实现）
        /// </summary>
        public static string GetCachePath(string relativePath)
        {
#if WECHAT_MINIGAME
            return GetWeChatPath(relativePath);
#else
            return Path.Combine(Application.persistentDataPath, relativePath);
#endif
        }

        /// <summary>
        /// 检查文件存在（平台特定）
        /// </summary>
        public static bool FileExists(string path)
        {
#if WECHAT_MINIGAME
            bool exists = false;
            WX.GetFileSystemManager().Access(new AccessParam()
            {
                path = path,
                success = (res) => exists = true,
                fail = (err) => { }
            });
            return exists;
#else
            return File.Exists(path);
#endif
        }

        #endregion
    }
}