using System.Runtime.InteropServices;
using System.Text;

namespace FluidExplorer.Services.Shell;

/// <summary>
/// 用外壳自己的 API（SHGetKnownFolderPath）解析系统文件夹，
/// 保证和资源管理器指向同一批真实位置（含 OneDrive 重定向后的"桌面/文档"等）。
/// </summary>
public static class KnownFolders
{
    public static string Profile { get; } = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
    public static string Desktop { get; } = Get(FolderId.Desktop);
    public static string Documents { get; } = Get(FolderId.Documents);
    public static string Downloads { get; } = Get(FolderId.Downloads);
    public static string Pictures { get; } = Get(FolderId.Pictures);
    public static string Music { get; } = Get(FolderId.Music);
    public static string Videos { get; } = Get(FolderId.Videos);
    public static string RecycleBin { get; } = @"shell:RecycleBinFolder";

    /// <summary>此电脑 / 回收站等虚拟外壳对象的解析名，交给外壳取图标与打开。</summary>
    public const string ThisPcParsingName = "::{20D04FE0-3AEA-1069-A2D8-08002B30309D}";
    public const string RecycleBinParsingName = "::{645FF040-5081-101B-9F08-00AA002F954E}";
    public const string NetworkParsingName = "::{F02C1A0D-BE21-4350-88B0-7367FC96EF3C}";
    public const string HomeParsingName = "::{F874310E-B6B7-47DC-BC84-B9E6B38F5903}";   // 主页
    public const string GalleryParsingName = "::{E88865EA-0E1C-4E20-9AA6-EDCD0212C87C}"; // 图库

    private static string Get(Guid id)
    {
        try
        {
            var hr = SHGetKnownFolderPath(ref id, 0, IntPtr.Zero, out var ptr);
            if (hr != 0 || ptr == IntPtr.Zero) return string.Empty;
            try { return Marshal.PtrToStringUni(ptr) ?? string.Empty; }
            finally { Marshal.FreeCoTaskMem(ptr); }
        }
        catch
        {
            return string.Empty;
        }
    }

    [DllImport("shell32.dll", CharSet = CharSet.Unicode, ExactSpelling = true)]
    private static extern int SHGetKnownFolderPath(ref Guid rfid, uint dwFlags, IntPtr hToken, out IntPtr ppszPath);

    private static class FolderId
    {
        public static Guid Desktop = new("B4BFCC3A-DB2C-424C-B029-7FE99A87C641");
        public static Guid Documents = new("FDD39AD0-238F-46AF-ADB4-6C85480369C7");
        public static Guid Downloads = new("374DE290-123F-4565-9164-39C4925E467B");
        public static Guid Pictures = new("33E28130-4E1E-4676-835A-98395C3BC3BB");
        public static Guid Music = new("4BD8D571-6D19-48D3-BE97-422220080E43");
        public static Guid Videos = new("18989B1D-99B5-455B-841C-AB7C74E4DDFC");
    }
}

/// <summary>
/// 卷信息（用于侧边栏"此电脑"和状态栏）：显示名、总容量、可用空间、就绪状态。
/// </summary>
public sealed class DriveItem
{
    public required string RootPath { get; init; }
    public required string DisplayName { get; init; }
    public required string VolumeLabel { get; init; }
    public required string FileSystem { get; init; }
    public long TotalBytes { get; init; }
    public long FreeBytes { get; init; }
    public int DriveType { get; init; }
    public bool IsReady { get; init; }

    public double UsedRatio => TotalBytes <= 0 ? 0 : 1.0 - (double)FreeBytes / TotalBytes;

    public string CapacityText => !IsReady || TotalBytes <= 0
        ? "不可用"
        : $"{FluidExplorer.Models.FileEntry.FormatSize(FreeBytes)} 可用，共 {FluidExplorer.Models.FileEntry.FormatSize(TotalBytes)}";

    public string Glyph => DriveType switch
    {
        2 => "\uE88E",   // 可移动磁盘
        3 => "\uEDA2",   // 本地磁盘
        4 => "\uE8CE",   // 网络驱动器
        5 => "\uE958",   // 光驱
        _ => "\uEDA2"
    };

    public static IReadOnlyList<DriveItem> Enumerate()
    {
        var list = new List<DriveItem>();
        foreach (var drive in DriveInfo.GetDrives())
        {
            try
            {
                var label = drive.IsReady ? drive.VolumeLabel : string.Empty;
                var display = string.IsNullOrWhiteSpace(label)
                    ? (drive.Name.TrimEnd('\\') is { Length: > 0 } letter ? $"本地磁盘 ({letter})" : drive.Name)
                    : $"{label} ({drive.Name.TrimEnd('\\')})";
                list.Add(new DriveItem
                {
                    RootPath = drive.Name,
                    DisplayName = display,
                    VolumeLabel = label,
                    FileSystem = drive.IsReady ? drive.DriveFormat : string.Empty,
                    TotalBytes = drive.IsReady ? drive.TotalSize : 0,
                    FreeBytes = drive.IsReady ? drive.TotalFreeSpace : 0,
                    DriveType = (int)drive.DriveType,
                    IsReady = drive.IsReady
                });
            }
            catch
            {
                // 未就绪的驱动器（空读卡器等）直接跳过
            }
        }
        return list;
    }
}