using ProjectCruiser.Exceptions;

namespace ProjectCruiser.CollectionGenericObj;

public class ArrayGenObj<T> : ICollectionGenObj<T>
    where T : class
{
    // Массив объектов, которые храним
    private T?[] _collection;

    // Максимально допустимое число объектов в массиве
    private int _maxCount;
    public int Count => _collection.Count(s => s != null);

    public int MaxCount
    {
        get { return _maxCount; }
        set
        {
            if (value > 0)
            {
                if (_collection.Length == 0) _collection = new T?[value];
                else Array.Resize(ref _collection, value);

                _maxCount = value;
            }
        }
    }

    public CollectionType GetCollectionType => CollectionType.Array;

    public ArrayGenObj()
    {
        _collection = Array.Empty<T?>();
    }

    // methods :
    public T? GetItem(int index)
    {
        try
        {
            if (index > Count)
                throw new CollectionOverflowException(index);
            if (index < 0)
                throw new PositionOutOfCollectionException(index);

            if (_collection[index] == null)
                throw new ObjectNotFoundException(index);

            return _collection[index];
        }
        catch (CollectionOverflowException ex)
        {
            Console.WriteLine(ex.Message);
            return null;
        }
        catch (ObjectNotFoundException ex)
        {
            Console.WriteLine(ex.Message);
            return null;
        }
        catch (PositionOutOfCollectionException ex)
        {
            Console.WriteLine(ex.Message);
            return null;
        }
    }

    public int Insert(T? item)
    {
        if (item == null) { return -1; }

        try // выход за границы, курируется CollectionOverflowException
        {
            if (Count >= _maxCount)
            {
                throw new CollectionOverflowException(Count);
            }

            // any empty place -> fill immediately
            for (int i = 0; i < _collection.Length; i++)
            {
                if (_collection[i] == null)
                {
                    _collection[i] = item;
                    return i;
                }
            }
            return Count;
        }
        catch (CollectionOverflowException ex)
        {
            Console.WriteLine(ex.Message);
            return -1;
        }
    }

    public int Insert(T? item, int index)
    {
        try
        {
            if (index < 0 || index >= _maxCount) throw new PositionOutOfCollectionException(index);
            if (Count >= _maxCount) throw new CollectionOverflowException(Count);

            if (item == null) throw new ObjectNotFoundException(index);

            if (_collection[index] == null)
            {
                _collection[index] = item;
                return index;
            }
            else
            {
                int min_diff = 100, firstNullIndex = 100;

                for (int i = 0; i < Count; i++)
                {
                    if (_collection[i] == null && min_diff > Math.Abs(index - i))
                    {
                        min_diff = Math.Abs(index - i);
                        firstNullIndex = i;
                    }
                }

                _collection[firstNullIndex] = item;
                return firstNullIndex;
            }
        }
        catch (CollectionOverflowException ex)
        {
            Console.WriteLine(ex.Message);
            return -1;
        }
        catch (ObjectNotFoundException ex)
        {
            Console.WriteLine(ex.Message);
            return -1;
        }
        catch (PositionOutOfCollectionException ex)
        {
            Console.WriteLine(ex.Message);
            return -1;
        }
    }

    public T? Remove(int index)
    {
        try
        {
            if (index >= _maxCount || index < 0)
            // on the other positions items don't exist
            {
                throw new CollectionOverflowException(index);
                // [?] PositionOutOfCollectionException <<<
            }

            T? item = _collection[index];
            _collection[index] = null;

            if (item == null) throw new ObjectNotFoundException(index);

            return item;
        }
        catch (CollectionOverflowException ex)
        {
            Console.WriteLine(ex.Message);
            return null;
        }
        catch (ObjectNotFoundException ex)
        {
            Console.WriteLine(ex.Message);
            return null;
        }
    }

    public IEnumerable<T?> GetItems()
    {
        for (int i = 0; i < MaxCount; ++i)
        { 
            yield return _collection[i];
        }
    }
}