using System.IO.Abstractions;

namespace Recyclarr.Platform;

public class DefaultAppDataSetup(IEnvironment env, IFileSystem fs)
{
    public IAppPaths CreateAppPaths(string? appDataDirectoryOverride = null)
    {
        var appDir = GetAppDataDirectory(appDataDirectoryOverride);
        return new AppPaths(fs.DirectoryInfo.New(appDir));
    }

    private string GetAppDataDirectory(string? appDataDirectoryOverride)
    {
        // If a specific app data directory is not provided, use the following environment variable to find the path.
        appDataDirectoryOverride ??= env.GetEnvironmentVariable("RECYCLARR_APP_DATA");

        // Ensure user-specified app data directory is created and use it.
        if (!string.IsNullOrEmpty(appDataDirectoryOverride))
        {
            return fs.Directory.CreateDirectory(appDataDirectoryOverride).FullName;
        }

        // Set app data path to application directory value (e.g. `$HOME/.config` on Linux) and ensure it is
        // created.
        var appData = env.GetFolderPath(
            Environment.SpecialFolder.ApplicationData,
            Environment.SpecialFolderOption.Create);

        if (string.IsNullOrEmpty(appData))
        {
            throw new NoHomeDirectoryException(
                "Unable to find or create the default app data directory. The application cannot determine where " +
                "to place data files. Please use the --app-data option to explicitly set a location for these files.");
        }

        return fs.Path.Combine(appData, AppPaths.DefaultAppDataDirectoryName);
    }
}