// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.

namespace osu.Game.Screens.Edit.Commands
{
public abstract class PropertyChangeCommand<TTarget, TProperty> : IEditorCommand, IMergeableCommand where TTarget : class
{
    protected abstract TProperty ReadValue(TTarget target);

    protected abstract void WriteValue(TTarget target, TProperty value);

    protected abstract PropertyChangeCommand<TTarget, TProperty> CreateInstance(TTarget target, TProperty value);

    public readonly TTarget Target;

    public readonly TProperty Value;

    protected PropertyChangeCommand(TTarget target, TProperty value)
    {
        Target = target;
        Value = value;
    }

    public void Apply() => WriteValue(Target, Value);

    public IEditorCommand CreateUndo() => CreateInstance(Target, Value);

    public IEditorCommand? MergeWith(IEditorCommand previous)
    {
        if (previous is PropertyChangeCommand<TTarget, TProperty> command && command.Target == Target)
            return this;

        return null;
    }
}
}