namespace PCLCS;

/// <summary>
/// 单个 Java 的实例。
/// </summary>
[Serializable] public class Java(string folder, Version? version = null) {

    /// <summary>
    /// java.exe 文件所在的文件夹路径，这通常是 bin 文件夹。以 \ 结尾。
    /// </summary>
    public readonly string Folder = PathUtils.AddSlashSuffix(PathUtils.ForCompare(folder));
    /// <summary>
    /// java.exe 文件的完整路径。
    /// </summary>
    [JsonIgnore] public string JavaExePath => Path.Combine(Folder, "java.exe");

    /// <summary>
    /// Java 的版本号（例如 16.0.1），保证 <see cref="Version.Major"/> 为其主版本。
    /// <para/> 若为 null，则还需要调用 <see cref="CheckAsync"/> 以获取版本号。
    /// </summary>
    public Version? Version = version;

    /// <summary>
    /// 检查该 Java 是否存在问题，并获取其版本号。
    /// 返回其是否通过了检查。
    /// </summary>
    public async Task<bool> CheckAsync(CancellationToken cancellationToken = default) {
        if (Interlocked.Exchange(ref isChecked, 1) == 1 && available != null) return available!.Value; // 已检查过
        string? output = null;
        try {
            if (!FileUtils.Exists(JavaExePath)) throw new FileNotFoundException("未找到 java.exe 文件", JavaExePath);

            // 运行 -version
            output = (await TaskUtils.RunProgramAsync(JavaExePath, "-version", 15000, cancellationToken: cancellationToken).NoCapture()).Output.Lower();
            if (output == "") throw new InvalidOperationException("尝试运行该 Java 失败");
            Logger.Trace($"Java 检查输出：{JavaExePath}{Environment.NewLine}{output}");
            if (output.Contains("/lib/ext exists")) throw new InvalidOperationException("无法运行该 Java，请在删除 Java 文件夹中的 /lib/ext 文件夹后再试");
            if (output.Contains("a fatal error") || output.Contains("error: ")) throw new InvalidOperationException("无法运行该 Java，该 Java 或系统存在问题");

            // 获取版本号
            var versionString = (output.RegexSeek(@"(?<=version "")[^""]+") ?? output.RegexSeek("(?<=openjdk )[0-9]+"))?.Replace("_", ".").Replace("+", ".").BeforeFirst("-");
            if (string.IsNullOrEmpty(versionString)) throw new InvalidOperationException($"未找到该 Java 的版本号{(output.Length < 500 ? $"\n原始输出为：\n{output}" : "")}");
            if (versionString.StartsWithF("1.")) versionString = versionString!.AfterFirst("."); // 去除开头的 1.
            var segments = versionString!.Split(".", true).ToList();
            while (segments.Count < 4) segments.Add("0");
            Version = new Version(segments.Take(4).Join("."));
            if (Version.Major is <= 4 or >= 100) throw new InvalidOperationException($"分析详细信息失败，获取的版本为 {Version}{(output.Length < 500 ? $"\n原始输出为：\n{output}" : "")}");

            if (!output.Contains("64-bit")) throw new InvalidOperationException("该 Java 为 32 位版本，请安装 64 位的 Java");
            Logger.Info($"检查 Java 成功：{this}");
            available = true;
        } catch (Exception ex) {
            if (ex.IsCanceled()) {
                isChecked = 0;
                throw;
            }
            Logger.Warn($"检查 Java 失败（{JavaExePath}），其输出为：\n{output ?? "无程序输出"}");
            available = false;
        }
        return available!.Value;
    }
    [JsonIgnore] private int isChecked = 0;
    /// <summary>若已进行过检查，表示该检查是否成功。若未检查，则为 null。</summary>
    [JsonIgnore] internal bool? available = null;

    /// <summary>用户友好的描述文本。</summary>
    public override string ToString()
        => $"Java {Version?.Major.ToString() ?? "尚未检查"} ({Version})：{Folder}";
}

public static class JavaUtils {

    /// <summary>
    /// 检查所有指定的 Java 是否存在问题，并获取其版本号。
    /// </summary>
    /// <returns>所有通过检查的 Java。</returns>
    public static async Task<List<Java>> CheckAllAsync(IEnumerable<Java> javas, CancellationToken cancellationToken = default, ProgressProvider? progress = null) {
        await TaskUtils.WhenAll(javas.Where(j => j.available == null).Select(
            async java => await java.CheckAsync(cancellationToken).NoCapture()
        ), progress).NoCapture();
        return javas.Where(j => j.available == true).ToList();
    }

    /// <summary>
    /// 将 Java 列表进行排序。
    /// 这同时会检查所有未检查的 Java。
    /// </summary>
    public static async Task<List<Java>> SortAsync(List<Java> javas, CancellationToken cancellationToken = default, ProgressProvider? progress = null) {
        javas = await JavaUtils.CheckAllAsync(javas, cancellationToken, progress).NoCapture();
        javas.Sort((left, right) => {
            // 优先使用带完整 Java 的文件夹列表中的 Java
            var isLeftInCandidateFolder = JavaUtils.CandidateFolders.Any(folder => PathUtils.IsParentOf(folder, left.Folder));
            var isRightInCandidateFolder = JavaUtils.CandidateFolders.Any(folder => PathUtils.IsParentOf(folder, right.Folder));
            if (isLeftInCandidateFolder != isRightInCandidateFolder) return isLeftInCandidateFolder ? -1 : 1;
            // 其次优先使用主版本号接近 25 的 Java
            var leftDistance = left.Version is null ? int.MaxValue : Math.Abs(left.Version.Major - 25);
            var rightDistance = right.Version is null ? int.MaxValue : Math.Abs(right.Version.Major - 25);
            return leftDistance.CompareTo(rightDistance);
        });
        return javas;
    }

    #region 搜索

    /// <summary>
    /// 存在完整 Java 的文件夹列表。
    /// </summary>
    internal static readonly List<string> CandidateFolders = [
        Paths.AppData + @".minecraft\runtime\", // 这也是 PCL 下载 Java 的路径
        Paths.AppData + @".hmcl\java\",
        Paths.AppData + @"ATLauncher\runtimes\minecraft\",
        Paths.AppData + @"ModrinthApp\meta\java_versions\",
        Paths.AppData + @"PrismLauncher\java\",
        Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) + @"\curseforge\minecraft\Install\runtime\",
        Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) + @"\.jdks\",
        Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) + @"\.sdkman\candidates\java\",
        Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData) + @"\.ftba\bin\runtime\",
        Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData) + @"\Packages\Microsoft.4297127D64EC6_8wekyb3d8bbwe\LocalCache\Local\runtime\",
        Environment.GetFolderPath(Environment.SpecialFolder.ProgramFilesX86) + @"\Minecraft Launcher\runtime\",
        Environment.GetFolderPath(Environment.SpecialFolder.ProgramFilesX86) + @"\Minecraft\runtime\",
        Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + @"\Curse\Minecraft\Install\runtime\",
        Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles) + @"\Java\",
        Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles) + @"\Eclipse Adoptium\",
        Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles) + @"\Amazon Corretto\",
        Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles) + @"\Zulu\",
        ..DirectoryUtils.EnumerateDirectories(Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles) + @"\Microsoft\", searchPattern: "jdk-*"),
        // 环境变量
        ..(Environment.GetEnvironmentVariable("JDK_HOME") + ";" + Environment.GetEnvironmentVariable("JAVA_HOME")).
            Split(";", true).Select(path => path.Trim(' ', '"'))
    ];

    /// <summary>
    /// 从常见文件夹和环境变量中搜索 Java，并将搜索结果写入设置。
    /// </summary>
    public static async Task RefreshListAsync(CancellationToken c = default, ProgressProvider? p = null) {
        // 搜索
        List<Java> javaList = await SearchFoldersAsync(true, CandidateFolders, c, p?.SplitTo(0.5)).NoCapture();
        // 将新发现的 Java 排在最前，原有列表保留既有顺序排在后面
        var oldJavaList = Configs.JavaList.Get()!;
        oldJavaList = await JavaUtils.CheckAllAsync(oldJavaList, c, p?.SplitTo(0.9)).NoCapture(); // 检查原有列表中的 Java
        HashSet<string> oldJavaFolders = new(oldJavaList.Select(j => j.Folder), StringComparer.OrdinalIgnoreCase);
        javaList.RemoveIf(j => oldJavaFolders.Contains(j.Folder)); // 此时 javaList 中只剩下新发现的 Java
        javaList = await JavaUtils.SortAsync(javaList, c).NoCapture(); // 将所有新发现的 Java 按优先级排序
        javaList.AddRange(oldJavaList);
        javaList = javaList.DistinctBy(j => j.Folder.Lower()).ToList();
        // 删掉已被移除的 Java
        javaList.RemoveIf(j => Configs.JavaRemovedList.Get()!.Contains(j.Folder, StringComparer.OrdinalIgnoreCase));
        // 写入设置
        Configs.JavaList.Set([..javaList]);
        Logger.Info($"Java 搜索完成，发现 {javaList.Count} 个 Java");
    }

    /// <summary>
    /// 并行搜索所有指定的文件夹及其子文件夹中的 Java，并检查其有效性。
    /// </summary>
    public static async Task<List<Java>> SearchFoldersAsync(bool includeSubDirectories, IEnumerable<string> folders, CancellationToken cancellationToken = default, ProgressProvider? progress = null) {
        // 并行搜索
        ConcurrentBag<(string Folder, bool HasReparsePoint, bool IsSpecialPath)> results = [];
        await TaskUtils.ForEachAsync(folders.Distinct(StringComparer.OrdinalIgnoreCase), 4, async (folder, cp) => {
            await Task.Run(() => {
                try {
                    foreach (var file in DirectoryUtils.EnumerateFiles(folder, includeSubDirectories, "java.exe")) {
                        cancellationToken.ThrowIfCancellationRequested();
                        string targetFolder = PathUtils.AddSlashSuffix(PathUtils.ForCompare(PathUtils.RemoveLastPart(file)));
                        // 判断文件夹是否包含重解析点（例如符号链接）
                        static bool HasReparsePoint(FileSystemInfo info) {
                            do {
                                if (info.Attributes.HasFlag(FileAttributes.ReparsePoint)) return true;
                                info = info is FileInfo fileInfo ? fileInfo.Directory : ((DirectoryInfo) info).Parent;
                            } while (info is not null);
                            return false;
                        }
                        // 结果
                        var hasReparsePoint = HasReparsePoint(FileUtils.GetInfo(Path.Combine(targetFolder, "java.exe")));
                        var isSpecialPath = targetFolder.Contains("java8path_target_") || targetFolder.Contains("javapath_target_") || targetFolder.Contains("javatmp") || targetFolder.Contains("system32");
                        results.Add((targetFolder, hasReparsePoint, isSpecialPath));
                    }
                } catch (UnauthorizedAccessException) {
                    Logger.Info($"快速查找 Java 时没有权限（{folder}）");
                } catch (Exception ex) {
                    ex.ThrowIfCanceled();
                    Logger.Warn(ex, $"快速查找 Java 时出错（{folder}）");
                }
            }, cancellationToken).NoCapture();
        }, cancellationToken, progress?.SplitTo(0.2)).NoCapture();
        if (!results.Any()) return [];

        // 筛除重解析点
        if (results.All(r => r.HasReparsePoint)) {
            Logger.Warn("找到的所有 Java 都包含重解析点，保留全部结果");
        } else if (results.Any(r => r.HasReparsePoint)) {
            Logger.Info($"找到以下的 Java 包含重解析点，将它们从列表中排除：{results.Where(r => r.HasReparsePoint).Select(r => r.Folder).Join('、')}");
            results = [..results.Where(r => !r.HasReparsePoint)];
        }
        // 筛除特殊路径
        if (results.All(r => r.IsSpecialPath)) {
            Logger.Warn("找到的所有 Java 都包含特殊路径，保留全部结果");
        } else if (results.Any(r => r.IsSpecialPath)) {
            Logger.Info($"找到以下的 Java 包含特殊路径，将它们从列表中排除：{results.Where(r => r.IsSpecialPath).Select(r => r.Folder).Join('、')}");
            results = [..results.Where(r => !r.IsSpecialPath)];
        }

        // 检查并返回
        List<Java> javaList = results.Select(r => r.Folder).Distinct(StringComparer.OrdinalIgnoreCase).Select(folder => new Java(folder)).ToList();
        javaList = (await JavaUtils.CheckAllAsync(javaList, cancellationToken, progress?.SplitTo(1)).NoCapture()).ToList();
        javaList = await JavaUtils.SortAsync(javaList, cancellationToken).NoCapture();
        Logger.Info($"快速查找 Java 完成，共有 {javaList.Count} 个候选：{javaList.Join('、')}");
        return javaList;
    }

    #endregion

}