using System.Diagnostics;
using System.Runtime.InteropServices;
using Explorer.Domain;
using Explorer.Domain.Abstractions;
using Microsoft.Extensions.Logging;

namespace Explorer.Windows;

public sealed class WindowsShellFileOperations : IShellFileOperations
{
    private readonly ILogger<WindowsShellFileOperations> _logger;

    public WindowsShellFileOperations(ILogger<WindowsShellFileOperations> logger) => _logger = logger;

    public void Open(string path)
    {
        var psi = new ProcessStartInfo
        {
            FileName = PathRules.FromExtended(path),
            UseShellExecute = true
        };
        Process.Start(psi);
    }

    public bool DeleteToRecycleBin(IReadOnlyList<string> paths, out string? error)
        => Delete(paths, recycle: true, out error);

    public bool Delete(IReadOnlyList<string> paths, bool recycle, out string? error)
    {
        error = null;
        if (paths.Count == 0)
        {
            return true;
        }

        var packed = string.Join("\0", paths.Select(PathRules.FromExtended)) + "\0\0";
        var pFrom = Marshal.StringToHGlobalUni(packed);
        try
        {
            var flags = NativeMethods.FofNoConfirmation | NativeMethods.FofNoErrorUi;
            if (recycle)
            {
                flags |= NativeMethods.FofAllowUndo;
            }

            var op = new NativeMethods.ShFileOpStruct
            {
                hwnd = NativeMethods.GetForegroundWindow(),
                wFunc = (uint)NativeMethods.FoDelete,
                pFrom = pFrom,
                pTo = 0,
                fFlags = (ushort)flags,
                fAnyOperationsAborted = 0,
                hNameMappings = 0,
                lpszProgressTitle = null
            };

            var rc = NativeMethods.SHFileOperation(ref op);
            if (op.fAnyOperationsAborted != 0)
            {
                error = "Cancelled";
                return false;
            }

            if (rc != 0)
            {
                error = recycle ? $"Recycle failed ({rc})" : $"Delete failed ({rc})";
                _logger.LogWarning("SHFileOperation delete returned {Code} recycle={Recycle}", rc, recycle);
                return false;
            }

            return true;
        }
        finally
        {
            Marshal.FreeHGlobal(pFrom);
        }
    }

    public bool CopyFileWithProgress(string source, string destination, bool overwrite, IProgress<long>? progress, CancellationToken cancellationToken, out string? error)
    {
        error = null;
        Directory.CreateDirectory(Path.GetDirectoryName(PathRules.FromExtended(destination))!);
        var cancel = 0;
        NativeMethods.CopyProgressRoutine cb = (total, transferred, _, _, _, _, _, _, _) =>
        {
            progress?.Report(transferred);
            return cancellationToken.IsCancellationRequested ? NativeMethods.ProgressCancel : NativeMethods.ProgressContinue;
        };

        var flags = overwrite ? 0u : NativeMethods.CopyFileFailIfExists;
        var ok = NativeMethods.CopyFileEx(
            PathRules.ToExtended(source),
            PathRules.ToExtended(destination),
            cb,
            0,
            ref cancel,
            flags);
        if (!ok)
        {
            var code = Marshal.GetLastWin32Error();
            if (cancellationToken.IsCancellationRequested || code == 1235)
            {
                error = "Cancelled";
                return false;
            }

            error = new System.ComponentModel.Win32Exception(code).Message;
            return false;
        }

        return true;
    }

    public bool MoveFileWithProgress(string source, string destination, bool overwrite, IProgress<long>? progress, CancellationToken cancellationToken, out string? error)
    {
        error = null;
        Directory.CreateDirectory(Path.GetDirectoryName(PathRules.FromExtended(destination))!);
        NativeMethods.CopyProgressRoutine cb = (total, transferred, _, _, _, _, _, _, _) =>
        {
            progress?.Report(transferred);
            return cancellationToken.IsCancellationRequested ? NativeMethods.ProgressCancel : NativeMethods.ProgressContinue;
        };

        var flags = NativeMethods.MoveFileCopyAllowed | NativeMethods.MoveFileWriteThrough;
        if (overwrite)
        {
            flags |= NativeMethods.MoveFileReplaceExisting;
        }

        var ok = NativeMethods.MoveFileWithProgress(
            PathRules.ToExtended(source),
            PathRules.ToExtended(destination),
            cb,
            0,
            flags);
        if (!ok)
        {
            var code = Marshal.GetLastWin32Error();
            if (cancellationToken.IsCancellationRequested)
            {
                error = "Cancelled";
                return false;
            }

            error = new System.ComponentModel.Win32Exception(code).Message;
            return false;
        }

        return true;
    }

    public bool CreateShortcut(string targetPath, string shortcutPath, out string? error)
    {
        error = null;
        try
        {
            var type = Type.GetTypeFromProgID("WScript.Shell");
            if (type is null)
            {
                error = "Shortcut service is unavailable.";
                return false;
            }

            dynamic shell = Activator.CreateInstance(type)!;
            dynamic shortcut = shell.CreateShortcut(PathRules.FromExtended(shortcutPath));
            var target = PathRules.FromExtended(targetPath);
            shortcut.TargetPath = target;
            shortcut.WorkingDirectory = Directory.Exists(target) ? target : PathRules.Parent(target);
            shortcut.Save();
            return true;
        }
        catch (Exception ex)
        {
            error = ex.Message;
            _logger.LogDebug(ex, "CreateShortcut failed for {Target}", targetPath);
            return false;
        }
    }
}

public static class BackgroundIo
{
    public static IDisposable Begin()
    {
        NativeMethods.SetPriorityClass(NativeMethods.GetCurrentProcess(), NativeMethods.ProcessModeBackgroundBegin);
        return new Reset();
    }

    private sealed class Reset : IDisposable
    {
        public void Dispose()
            => NativeMethods.SetPriorityClass(NativeMethods.GetCurrentProcess(), NativeMethods.ProcessModeBackgroundEnd);
    }
}