namespace Nerfed.Runtime.Scene;

/// <summary>
/// Root data model for a scene. A scene and a prefab are the same thing —
/// there is no distinction between the two, mirroring Godot's design.
/// </summary>
public sealed class SceneData
{
    /// <summary>Incremented when the file format changes in a breaking way.</summary>
    public int Version { get; set; } = SceneData.CurrentVersion;
    public string Name { get; set; } = string.Empty;
    public List<SceneEntityData> Entities { get; set; } = new();
    /// <summary>All user-defined relations between entities in this scene.</summary>
    public List<SceneRelationData> Relations { get; set; } = new();

    public const int CurrentVersion = 1;
}

/// <summary>
/// Serialized representation of a single entity.
/// The <see cref="Id"/> is a scene-local identifier that only exists in the
/// serialized data and is used to reconstruct parent–child and relation references.
/// It is never stored as a component on a live entity.
/// An entity is included if it owns at least one <see cref="SceneComponentAttribute"/> component
/// OR participates in at least one <see cref="SceneRelationAttribute"/> relation.
/// </summary>
public sealed class SceneEntityData
{
    public Guid Id { get; set; } = Guid.NewGuid();
    public string Tag { get; set; } = string.Empty;

    /// <summary>
    /// Scene-local <see cref="Id"/> of this entity's <see cref="Components.ChildParentRelation"/>
    /// parent, or <c>null</c> if this is a root entity.
    /// </summary>
    public Guid? ParentId { get; set; }

    public List<SceneComponentData> Components { get; set; } = new();
}

/// <summary>
/// Serialized representation of a single component value on an entity.
/// <see cref="Type"/> is the fully-qualified CLR type name used to resolve the component on load.
/// <see cref="Value"/> is the boxed runtime value; each <see cref="ISceneSerializer"/> is
/// responsible for converting it to/from its wire format.
/// </summary>
public sealed class SceneComponentData
{
    public string Type { get; set; } = string.Empty;
    public ValueType Value { get; set; } = default!;
}

/// <summary>
/// Serialized representation of a relation between two entities.
/// <see cref="EntityA"/> and <see cref="EntityB"/> reference scene-local <see cref="SceneEntityData.Id"/> values.
/// <see cref="Type"/> identifies the relation kind (must be marked with <see cref="SceneRelationAttribute"/>).
/// <see cref="Value"/> holds the relation data payload (may be an empty struct).
/// </summary>
public sealed class SceneRelationData
{
    public string Type { get; set; } = string.Empty;
    public Guid EntityA { get; set; }
    public Guid EntityB { get; set; }
    public ValueType Value { get; set; } = default!;
}