using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace UA_AtlasEditor
{
    public partial class MainForm
    {
        public class UndoData
        {
            public bool _needSave;
            public List<AtlasShape>    _shapes;
            public UndoData(Atlas atlas, bool needSave )
            {
                _needSave = needSave;
                _shapes = atlas.DuplicateShapeList();
            }
        }

        int _undoCursor = 0;
        int _undoMarkSave = 0;
        bool _needSave = false;
        readonly List<UndoData> _Done = new List<UndoData>();

        const int c_maxUndo = 100;

        public void undoClear()
        {
            _Done.Clear();
            _undoMarkSave = 0;
            _undoCursor = 0;
            _needSave = false;
        }

        public void undoSave()
        {
            _needSave = false;
            _undoMarkSave = _undoCursor;
        }

        public bool undoNeedSave()
        {
            return _needSave || (_undoMarkSave != _undoCursor);
        }

        public void undoPush(bool needSave, bool refresh = true)
        {
            while (_undoCursor != _Done.Count)
            {
                if (_undoMarkSave == _Done.Count)
                {
                    _undoMarkSave--;
                    if (_Done[_Done.Count - 1]._needSave)
                        _needSave = true;
                }
                _Done.RemoveAt(_Done.Count - 1);
            }

            if (_undoMarkSave == _undoCursor && !needSave)
                _undoMarkSave++;
            _undoCursor++;
            
            UndoData undo = new UndoData(_atlas, needSave );
            _Done.Add(undo);

            while (_Done.Count >= c_maxUndo)
            {
                _undoCursor--;
                if (_undoMarkSave > 0)
                    _undoMarkSave--;
                else
                    _needSave = _Done[0]._needSave;
                _Done.RemoveAt(0);
            }

            if (!refresh) return;
            atlasSetTitle();
        }

        public bool canUndo()
        {
            return _undoCursor > 0;
        }

        public bool canRedo()
        {
            return _undoCursor < _Done.Count;
        }

        public void undoRecallLast()
        {
            UndoData undo = _Done[_undoCursor - 1];
            _atlas.ReplaceShapeList(undo._shapes);
        }

        public void doUndo(bool refresh = true)
        {
            if (!canUndo()) return;

            UndoData save = new UndoData(_atlas, false);
            UndoData undo = _Done[_undoCursor - 1];
            _atlas.ReplaceShapeList(undo._shapes);
            undo._shapes = save._shapes;
            
            if (_undoMarkSave == _undoCursor && !_Done[_undoCursor - 1]._needSave)
                _undoMarkSave--;
            _undoCursor--;

            if (!refresh) return;
            atlasSetTitle();
            MainFor_TreatResult(c_result_invalidate | c_result_updatelist | c_result_updatelistselection | c_result_updatelistselecteditems);
            infoUpdate();
        }

        public void doRedo(bool refresh = true)
        {
            if (!canRedo()) return;

            UndoData save = new UndoData(_atlas, false);
            UndoData undo = _Done[_undoCursor];
            _atlas.ReplaceShapeList(undo._shapes);
            undo._shapes = save._shapes;

            if (_undoMarkSave == _undoCursor && !_Done[_undoCursor]._needSave)
                _undoMarkSave++;
            _undoCursor++;

            if (!refresh) return;
            atlasSetTitle();
            MainFor_TreatResult(c_result_invalidate | c_result_updatelist | c_result_updatelistselection | c_result_updatelistselecteditems);
        }
    }
}