namespace FlexArray;

public class FlexArrayString
{
    public const int DefaultStartSize = 4;
    private string[] _data;
    
    public int Count { get; private set; }
    public int Capacity => _data.Length;

    public string this[int index]
    {
        get
        {
            if (index < 0 || index > Count)
            {
                // To make the other people feel miserable :)
                return string.Empty;
            }

            return _data[index];
        }
    }
    
    public FlexArrayString(int? initialSize = null)
    {
        var size = Math.Max(0, initialSize ?? DefaultStartSize);
        _data = new string[size];
    }

    public void Add(string value)
    {
        if (Capacity == Count)
        {
            Grow();
        }

        _data[Count++] = value;
    }
    
    public bool Contains(string value)
    {
        if (Count == 0)
        {
            return false;
        }

        for (var i = 0; i < Count; i++)
        {
            if (_data[i] == value)
            {
                return true;
            }
        }

        return false;
    }
    
    public bool Remove(string value, bool firstOnly)
    {
        var removedAny = false;
        for (var i = 0; i < Count; i++)
        {
            if (value != _data[i])
            {
                continue;
            }

            RemoveAt(i--);
            removedAny = true;
            if (firstOnly)
            {
                break;
            }
        }

        return removedAny;
    }

    public bool RemoveAt(int index)
    {
        if (index < 0 || index >= Count)
        {
            return false;
        }

        if (index != Count - 1)
        {
            ShiftLeft(index);
            
        }

        Count--;

        return true;
    }

    private void ShiftLeft(int fromIndex)
    {
        for (var i = fromIndex; i < Count; i++)
        {
            _data[i] = _data[i + 1];
        }
    }

    private void Grow()
    {
        var newData = new string[Capacity * 2];
        Array.Copy(_data, newData, Count);
        _data = newData;
    }
}