using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Windows;
using BS.Shared.DataContracts;
using BS.Shared.Extensions;

namespace BeWo.ViewModel.ListViewModel
{
    public abstract class AbstractDCListMapperVM<DCType, VMType> : AbstractBaseVM where VMType : AbstractDCMapperVM<DCType> where DCType : new()
    {

        public static string PropertyName_EditVM = "EditVM";

        public static string PropertyName_NewVM = "NewVM";

        private readonly ObservableCollection<DCType> _DCBackup;

        private VMType _EditVM;

        private VMType _NewVM;

        private VMType _SelectedVM;

        private BindingList<VMType> _VMList;

        //public AbstractDCListMapperVM(IEnumerable<AbstractDCListMapperVM<DCType, VMType>> listVMs, bool ignore)
        //{
        //    var dcLists = listVMs.SelectMany(x => x.DCBackup);

        //    _DCBackup = dcLists != null ? dcLists.ToObservableCollection() : new ObservableCollection<DCType>();

        //    _DCBackup.CollectionChanged += (s, e) => _VMList.AddRange(e.NewItems.Cast<DCType>().Select(CreateVM));

        //    var vmLists = listVMs.SelectMany(x => x.VMList).ToList();

        //    _VMList = new BindingList<VMType>(vmLists);
        //}

        public AbstractDCListMapperVM(IEnumerable<DCType> pDCList)
        {
            _DCBackup = pDCList != null ? pDCList.ToObservableCollection() : new ObservableCollection<DCType>();

            _DCBackup.CollectionChanged += (s, e) => _VMList.AddRange(e.NewItems.Cast<DCType>().Select(CreateVM));
        }

        public AbstractDCListMapperVM() : this(null) { }


        public virtual int AddedCount
        {
            get
            {
                return this.VMList.Where(vm => vm.IsNew).Count();
            }
        }

        public virtual int ChangedCount
        {
            get
            {
                return this.VMList.Where(vm => vm.IsDirty && !vm.IsNew).Count();
            }
        }

        public ObservableCollection<DCType> DCBackup
        {
            get
            {
                return this._DCBackup;
            }
        }

        public VMType EditVM
        {
            get
            {
                return _EditVM;
            }

            set
            {
                _EditVM = value;
                FirePropertyChanged(PropertyName_EditVM);
            }
        }

        public VMType SelectedVM
        {
            get => _SelectedVM;
            set
            {
                _SelectedVM = value;
                FirePropertyChanged(nameof(SelectedVM));
            }
        }

        public override bool IsDirty
        {
            get
            {
                return ChangedCount != 0 || RemovedCount != 0 || AddedCount != 0;
            }
        }

        public VMType NewVM
        {
            get
            {
                return _NewVM ?? (NewVM = CreateVM(new DCType()));
            }

            set
            {
                _NewVM = value;
                FirePropertyChanged(PropertyName_NewVM);
            }
        }

        public virtual int RemovedCount
        {
            get
            {
                return GetRemoved().Count;
            }
        }

        public BindingList<VMType> VMList
        {
            get
            {
                if (_VMList == null)
                {
                    _VMList = new BindingList<VMType>(_DCBackup.Select(CreateVM).ToList()) { AllowNew = true };
                    _VMList.AddingNew += (s, e) => e.NewObject = CreateVM(new DCType());
                }

                return _VMList;
            }

            set
            {
                _VMList = value;
            }
        }

        protected virtual Comparison<VMType> Comparison
        {
            get
            {
                return null;
            }
        }

        public virtual VMType AddNewVMToList()
        {
            VMList.Add(NewVM);

            // VMList.Sort();
            VMType lVM = NewVM;
            NewVM = null;

            //FirePropertyChanged("VMList");
            return lVM;
        }

        public VMType AddNewVMToList(bool pSetAsEdit)
        {
            _VMList.Add(_NewVM);

            // _VMList.Sort();
            if (pSetAsEdit)
            {
                EditVM = _NewVM;
            }

            NewVM = null;
            return EditVM;
        }

        public virtual VMType AddNewVMToListAndSelect(bool select)
        {
            // Wichtig! NewVM, wenn _NewVM null ist
            var vm = NewVM;

            VMList.Add(vm);

            // _VMList.Sort();
            if (select)
            {
                SelectedVM = vm;
            }

            NewVM = null;

            FirePropertyChanged(nameof(VMList));

            return vm;
        }

        public virtual List<DCType> CommitAdded()
        {
            return this.VMList.Where(vm => vm.IsNew).Select(vm => vm.CommitToDataContract()).ToList();
        }

        public virtual List<DCType> CommitChanged()
        {
            return this.VMList.Where(vm => vm.IsDirty && !vm.IsNew).Select(vm => vm.CommitToDataContract()).ToList();
        }

        public virtual List<DCType> CopyToDCList(bool doCommit)
        {
            if (doCommit && this._VMList != null)
            {
                return doCommit
                           ? this._VMList.Select(vm => vm.CommitToDataContract()).ToList()
                           : this._VMList.Select(i => i.CopyToEmptyDataContract()).ToList();
            }

            return null;
        }

        public void DeleteEditVM()
        {
            this._VMList.Remove(this._EditVM);
            this.EditVM = null;
        }

        public bool DeleteSelectedVM(string displayname = null)
            => DeleteSelectedVM(SelectedVM, displayname);
        public bool DeleteSelectedVM(VMType remove, string displayname = null)
        {
            if (displayname is object)
            {
                var res = MessageBox.Show($"Möchten Sie {displayname} wirklich löschen?", "Löschen bestätigen", MessageBoxButton.YesNo);

                if (res != MessageBoxResult.Yes)
                    return false;
            }

            VMList.Remove(remove);

            FirePropertyChanged(nameof(VMList));

            return true;
        }

        public virtual List<DCType> GetRemoved()
        {
            return this._DCBackup.Where(dc => !this._VMList.Select(vm => vm.DataContract).Contains(dc)).ToList();
        }


        protected virtual VMType CreateVM(DCType pDC)
        {
            var lConstr = typeof(VMType).GetConstructor(new[] { typeof(DCType) });

            return lConstr.Invoke(new object[] { pDC }) as VMType;
        }

        public void SetSelectByIndex(int index)
		{
            if(-1 < index  && index < VMList.Count){
                var x = VMList[index];

                SelectedVM = x;
			}
		}

        public virtual string GetVisibleInformationString()
        {
            return null;
        }
    }
}