using System.Text.Json;

namespace Lumi.Companion.Overlay;

public sealed class OverlaySettingsStore(string path)
{
    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web) { WriteIndented = true };
    public LumiOverlaySettings Current { get; private set; } = new();

    public async Task LoadAsync(CancellationToken cancellationToken = default)
    {
        if (!File.Exists(path)) { Current.Normalize(); return; }
        try
        {
            await using var stream = File.OpenRead(path);
            Current = await JsonSerializer.DeserializeAsync<LumiOverlaySettings>(stream, JsonOptions, cancellationToken).ConfigureAwait(false) ?? new();
        }
        catch (JsonException)
        {
            var backup = path + $".invalid-{DateTimeOffset.UtcNow:yyyyMMddHHmmss}";
            File.Copy(path, backup, true);
            Current = new();
        }
        Current.Normalize();
    }

    public async Task SaveAsync(LumiOverlaySettings value, CancellationToken cancellationToken = default)
    {
        value.Normalize();
        Directory.CreateDirectory(Path.GetDirectoryName(path)!);
        var temporary = path + ".tmp";
        await using (var stream = new FileStream(temporary, FileMode.Create, FileAccess.Write, FileShare.None))
        {
            await JsonSerializer.SerializeAsync(stream, value, JsonOptions, cancellationToken).ConfigureAwait(false);
            await stream.FlushAsync(cancellationToken).ConfigureAwait(false);
        }
        File.Move(temporary, path, true);
        Current = value;
    }
}