namespace Mr.BrickAdventures.Progression.Adapters;

/// <summary>
/// Keeps each Playthrough in its own JSON file inside a directory.
/// </summary>
/// <remarks>
/// Takes a directory path rather than using Godot's FileAccess. Godot resolves <c>user://</c> to an
/// absolute path with <c>ProjectSettings.GlobalizePath</c> and passes it in, so this whole class has
/// no engine dependency and can be tested against a real temp directory.
/// </remarks>
public sealed class JsonPlaythroughStore : IPlaythroughStore
{
    /// <summary>Bump only alongside a migration for the version being replaced.</summary>
    private const int CurrentVersion = 1;

    private readonly string _directory;

    public JsonPlaythroughStore(string directory) => _directory = directory;

    /// <summary>One file per slot, so saving a run never rewrites the Profile or another slot.</summary>
    private string PathFor(PlaythroughId id) =>
        Path.Combine(_directory, $"playthrough_{id.Value:N}.json");

    public void Save(Playthrough playthrough) =>
        JsonFiles.WriteAtomic(PathFor(playthrough.Id), CurrentVersion, playthrough.Export());

    public LoadResult<Playthrough> Load(PlaythroughId id) =>
        JsonFiles.Read<PlaythroughSnapshot, Playthrough>(
            PathFor(id), CurrentVersion, Playthrough.Restore);
}