using OmniNX.DesktopInstaller.Models;

namespace OmniNX.DesktopInstaller.Services;

public sealed class InstallEngine
{
    private readonly DeletionService _deletion = new();
    private readonly BackupService _backup = new();
    private readonly ExtrasService _extras = new();

    public async Task RunAsync(
        InstallOptions options,
        IProgress<InstallProgressReport> progress,
        CancellationToken cancellationToken = default)
    {
        var driveRoot = PathUtils.NormalizeDriveRoot(options.DriveRoot);
        var staging = options.StagingPath
            ?? throw new InvalidOperationException("Staging path is required.");

        if (!Directory.Exists(staging))
            throw new DirectoryNotFoundException($"Staging path not found: {staging}");

        Report(progress, $"Install mode: {options.Mode}");
        Report(progress, $"Pack variant: {VariantHelper.GetDisplayName(options.Variant)}");

        if (options.Mode == InstallMode.Update)
        {
            await RunUpdateAsync(driveRoot, staging, options, progress, cancellationToken);
        }
        else
        {
            await RunCleanAsync(driveRoot, staging, options, progress, cancellationToken);
        }

        Report(progress, options.Mode == InstallMode.Update
            ? "Update completed successfully."
            : "Installation completed successfully.");
    }

    private async Task RunUpdateAsync(
        string driveRoot,
        string staging,
        InstallOptions options,
        IProgress<InstallProgressReport> progress,
        CancellationToken cancellationToken)
    {
        if (options.Variant == OmniNxVariant.Oc)
        {
            Report(progress, "HorizonOC: backing up config.ini...");
            _backup.BackupHorizonOcConfig(driveRoot, StringProgress(progress));
        }

        Report(progress, "Step 1: Cleanup...");
        await Task.Run(() => _deletion.RunUpdateDeletion(driveRoot, StringProgress(progress)), cancellationToken);

        Report(progress, "Step 2: Copying files...");
        await Task.Run(() => CopyPackFiles(staging, driveRoot, options.Variant, progress), cancellationToken);

        Report(progress, "Applying RAM / Hekate-AMS extras...");
        await Task.Run(() => _extras.ApplyExtras(driveRoot, options.Use8GbRam, options.UseHekateAmsPro,
            StringProgress(progress)), cancellationToken);

        if (options.Variant == OmniNxVariant.Oc)
        {
            Report(progress, "HorizonOC: restoring config.ini...");
            await Task.Run(() =>
            {
                _backup.RestoreHorizonOcConfig(driveRoot, StringProgress(progress));
                _backup.CleanupHorizonOcBackup(driveRoot);
            }, cancellationToken);
        }
    }

    private async Task RunCleanAsync(
        string driveRoot,
        string staging,
        InstallOptions options,
        IProgress<InstallProgressReport> progress,
        CancellationToken cancellationToken)
    {
        Report(progress, "Step 1: Backing up user data...");
        await Task.Run(() => _backup.BackupUserData(driveRoot, StringProgress(progress)), cancellationToken);

        Report(progress, "Step 2: Cleaning old installation...");
        await Task.Run(() => _deletion.RunCleanDeletion(driveRoot, StringProgress(progress)), cancellationToken);

        Report(progress, "Step 3: Restoring user data...");
        await Task.Run(() =>
        {
            _backup.RestoreUserData(driveRoot, StringProgress(progress));
            _deletion.RunPostRestoreCleanup(driveRoot);
            _backup.CleanupBackup(driveRoot);
        }, cancellationToken);

        Report(progress, "Step 4: Copying files...");
        await Task.Run(() => CopyPackFiles(staging, driveRoot, options.Variant, progress), cancellationToken);

        Report(progress, "Applying RAM / Hekate-AMS extras...");
        await Task.Run(() => _extras.ApplyExtras(driveRoot, options.Use8GbRam, options.UseHekateAmsPro,
            StringProgress(progress)), cancellationToken);
    }

    private static void CopyPackFiles(
        string staging,
        string driveRoot,
        OmniNxVariant variant,
        IProgress<InstallProgressReport> progress)
    {
        CopyFolderIfExists(staging, driveRoot, "atmosphere", progress);
        CopyFolderIfExists(staging, driveRoot, "bootloader", progress);
        CopyFolderIfExists(staging, driveRoot, "config", progress);
        CopyFolderIfExists(staging, driveRoot, "switch", progress);
        CopyFolderIfExists(staging, driveRoot, "themes", progress);
        CopyFolderIfExists(staging, driveRoot, "warmboot_mariko", progress);
        CopyFolderIfExists(staging, driveRoot, "hwtest", progress);

        if (variant == OmniNxVariant.Oc)
            CopyFolderIfExists(staging, driveRoot, "SaltySD", progress);

        CopyFolderIfExists(staging, driveRoot, "extras", progress);
        CopyRootFiles(staging, driveRoot, progress);
    }

    private static void CopyFolderIfExists(
        string staging,
        string driveRoot,
        string folder,
        IProgress<InstallProgressReport> progress)
    {
        var src = Path.Combine(staging, folder);
        if (!Directory.Exists(src))
            return;

        var dst = Path.Combine(PathUtils.NormalizeDriveRoot(driveRoot), folder);
        Report(progress, $"Copying {folder}/...");
        PathUtils.CopyDirectory(src, dst, new Progress<(int current, int total, string file)>(copyProgress =>
        {
            var (current, total, file) = copyProgress;
            var pct = total > 0 ? current * 100 / total : 0;
            progress.Report(new InstallProgressReport
            {
                Message = $"  {folder}/ {file}",
                Percent = pct,
            });
        }));
    }

    private static void CopyRootFiles(
        string staging,
        string driveRoot,
        IProgress<InstallProgressReport> progress)
    {
        Report(progress, "Copying root files...");
        var skipDirs = new HashSet<string>(StringComparer.OrdinalIgnoreCase)
        {
            "atmosphere", "bootloader", "config", "switch", "themes",
            "warmboot_mariko", "hwtest", "SaltySD", "extras",
        };

        foreach (var file in Directory.GetFiles(staging))
        {
            var name = Path.GetFileName(file);
            if (name.StartsWith('.'))
                continue;

            var dst = Path.Combine(PathUtils.NormalizeDriveRoot(driveRoot), name);
            PathUtils.CopyFile(file, dst);
            Report(progress, $"  {name}");
        }

        foreach (var dir in Directory.GetDirectories(staging))
        {
            var name = Path.GetFileName(dir);
            if (skipDirs.Contains(name))
                continue;
            Report(progress, $"Skipping unexpected directory at pack root: {name}");
        }
    }

    private static void Report(IProgress<InstallProgressReport> progress, string message, bool isError = false)
    {
        progress.Report(new InstallProgressReport { Message = message, IsError = isError });
    }

    private static IProgress<string> StringProgress(IProgress<InstallProgressReport> progress) =>
        new Progress<string>(msg => Report(progress, msg));
}