using System;
using System.Collections.ObjectModel;
using Life.Automaton;
using Life.Misc;

namespace Life.ViewModel
{
    public class FieldViewModel : BaseViewModel
    {
        private int _width;
        private int _height;
        private IField _field;
        private int _size;
        private int _separation;
        private IDisposable _fieldObserverDisposal;

        public ObservableCollection<CellViewModel> Cells { get; set; } = new ObservableCollection<CellViewModel>();

        public int Width
        {
            get => _width;
            set
            {
                _width = value;
                OnPropertyChanged(nameof(Width));
            }
        }

        public int Height
        {
            get => _height;
            set
            {
                _height = value;
                OnPropertyChanged(nameof(Height));
            }
        }

        public IField Field
        {
            get => _field;
            set
            {
                _fieldObserverDisposal?.Dispose();
                _fieldObserverDisposal = value.Subscribe(new DelegateSubscriber<IField>
                {
                    Action = field => Sync()
                });
                
                _field = value;
                ResetFields();
            }
        }

        public int Size
        {
            get => _size;
            set
            {
                _size = value;
                OnPropertyChanged(nameof(Size));
                RecalculateSize();
            }
        }

        public int Separation
        {
            get => _separation;
            set
            {
                _separation = value;
                OnPropertyChanged(nameof(Separation));
                RecalculateSize();
            }
        }

        private void ResetFields()
        {
            Cells.Clear();
            
            for (int i = 0; i < Field.Size.Width; i++)
                for (int j = 0; j < Field.Size.Height; j++)
                    Cells.Add(CreateCellViewModel(i, j));
            
            Sync();
            RecalculateSize();
        }

        private void RecalculateSize()
        {
            if (Field == null) return;
            
            foreach (var cell in Cells)
            {
                cell.Left = cell.Position.X * (Separation + Size);
                cell.Top  = cell.Position.Y * (Separation + Size);
            }
            
            Width = Field.Size.Width * Size + (Field.Size.Width - 1) * Separation;
            Height = Field.Size.Height * Size + (Field.Size.Height - 1) * Separation;
        }

        private CellViewModel CreateCellViewModel(int x, int y)
        {
            return new CellViewModel(x, y);
        }

        public void Sync()
        {
            foreach (var cell in Cells)
            {
                cell.IsAlive = Field[cell.Position.X, cell.Position.Y].IsAlive;
            }
        }
    }
}