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

namespace Defining_Classes_Part_2
{
    public class GenericList<T> : ICountable, IGenericList<T>, IGenericList
    {

        private const int _defaultCapacity = 4;
        private T[] _elements;
        private int _count;
        private int _capacity;

        public GenericList()
        {
            this._elements = new T[_defaultCapacity];
            this._capacity = _defaultCapacity;
        }

        public GenericList(int capacity)
        {
            this._elements = new T[capacity];
            this._capacity = capacity;
        }

        public int Count
        {
            get
            {
                return this._count;
            }
        }

        public void Add(T element)
        {
            if (_count == _elements.Length)
            {
                Expand();
            }
            this._elements[this._count++] = element;
        }

        public T this[int index]
        {
            get
            {
                if (index >= _count)
                {
                    throw new IndexOutOfRangeException();
                }
                return this._elements[index];
            }
            set
            {
                if (index >= _count)
                {
                    throw new IndexOutOfRangeException();
                }
                this._elements[index] = value;
            }
        }

        public void RemoveAt(int index)
        {
            if (index >= _count)
            {
                throw new IndexOutOfRangeException();
            }
            for (int i = index; i < this._count -1; i++)
            {
                _elements[i] = _elements[i + 1];
            }
            _elements[this._count - 1] = default(T);
            _count--;
        }

        public override string ToString()
        {
            var result = new StringBuilder();

            for (var i = 0; i < this.Count; i++)
            {
                result.Append(this._elements[i]);

                if (i != this.Count - 1)
                {
                    result.Append(", ");
                }
            }
            return result.ToString();
        }

        private void Expand()
        {
            var newElements = new T[2 * this._capacity];
            this._capacity *= 2;

            for (int i = 0; i < _count; i++)
            {
                newElements[i] = _elements[i];
            }

            this._elements = newElements;
        }

        public void Clear()
        {
            for (int i = 0; i < _count; i++)
            {
                this._elements[i] = default(T);
            }
        }

        public int Find(T element)
        {
            string searchFor = element.ToString();
            for (int i = 0; i < _count; i++)
            {
                if (this._elements[i].ToString() == searchFor)
                {
                    return i;
                }
            }
            return -1;
        }

        public void InsertAt(T element, int index)
        {
            if (_count == _elements.Length)
            {
                Expand();
            }

            this.Add(this._elements[_elements.Length - 1]);

            for (int i = _count - 1; i > index; i--)
            {
                _elements[i] = _elements[i - 1];
            }

            _elements[index] = element;
        }
    }

	interface ICountable
    {
        int Count { get; }
    }

	interface IGenericList<T>
    {
        void Add(T element);
        void RemoveAt(int index);
        void Clear();
        void InsertAt(T element, int Index);
    }

    interface IGenericList
    {
        void RemoveAt(int index);
        void Clear();
    }
}