using PaintDotNet.Measurement.HistoryMementos;
using System.Collections.Generic;

namespace PaintDotNet.Measurement.HistoryFunctions
{
    public sealed class FlattenFunction
        : HistoryFunction
    {
        public static string StaticName
        {
            get
            {
                return PdnResources.GetString("FlattenFunction.Name");
            }
        }

        public override HistoryMemento OnExecute(IDocumentWorkspace historyWorkspace)
        {
            object savedSelection = null;
            List<HistoryMemento> actions = new List<HistoryMemento>();

            if (!historyWorkspace.GetSelection().IsEmpty)
            {
                savedSelection = historyWorkspace.GetSelection().Save();
                DeselectFunction da = new DeselectFunction();
                HistoryMemento hm = da.Execute(historyWorkspace);
                actions.Add(hm);
            }

            ReplaceDocumentHistoryMemento rdha = new ReplaceDocumentHistoryMemento(null, null, historyWorkspace);
            actions.Add(rdha);

            CompoundHistoryMemento chm = new CompoundHistoryMemento(
                StaticName,
                PdnResources.GetImageResource("Icons.MenuImageFlattenIcon.png"),
                actions);

            // TODO: we can save memory here by serializing, then flattening on to an existing layer
            Document flat = historyWorkspace.GetDocument().Flatten();

            EnterCriticalRegion();
            historyWorkspace.SetDocument(flat);

            if (savedSelection != null)
            {
                SelectionHistoryMemento shm = new SelectionHistoryMemento(null, null, historyWorkspace);
                historyWorkspace.GetSelection().Restore(savedSelection);
                chm.PushNewAction(shm);
            }

            return chm;
        }

        public FlattenFunction()
            : base(PaintDotNet.Measurement.Enum.ActionFlags.None)
        {
        }
    }
}