using System;
using System.Collections.Generic;
using Chernobyl.Mathematics.Movement;

namespace Chernobyl.Mathematics.Geometry
{
    /// <summary>
    /// An <see cref="IShape"/> and <see cref="IList{T}"/> that holds 
    /// <see cref="IShape"/> instances. This class works like 
    /// <see cref="ShapeCollection"/> in that it can expand and contract to 
    /// fit a collection of other <see cref="IShape"/> instances inside of 
    /// it. 
    /// </summary>
    public class ShapeList : ShapeCollection, IList<IShape>
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="ShapeList"/> 
        /// class.
        /// </summary>
        public ShapeList()
            : this(0)
        { }

        /// <summary>
        /// Initializes a new instance of the <see cref="ShapeList"/> 
        /// class.
        /// </summary>
        /// <param name="capacity">The number of elements that the new list can 
        /// initially store.</param>
        public ShapeList(int capacity)
            : this(new List<IShape>(capacity))
        { }

        /// <summary>
        /// Initializes a new instance of the <see cref="ShapeList"/> class.
        /// </summary>
        /// <param name="geometries">The list to store <see cref="IShape"/>s 
        /// in or null if the default <see cref="List{T}"/> should be used.</param>
        public ShapeList(IList<IShape> geometries)
            : this(geometries, null)
        { }

        /// <summary>
        /// Initializes a new instance of the <see cref="ShapeList"/> class.
        /// </summary>
        /// <param name="geometries">The list to store <see cref="IShape"/>s 
        /// in or null if the default <see cref="List{T}"/> should be used.</param>
        /// <param name="childTransformList">The list to use for the 
        /// <see cref="ITransform.TransformChildren"/> list or null if the default 
        /// <see cref="List{T}"/> should be used..</param>
        public ShapeList(ICollection<IShape> geometries, IList<ITransform> childTransformList)
            : base(geometries, childTransformList)
        {
            GeometryList = (IList<IShape>) Geometries;
        }

        /// <summary>
        /// Determines the index of a specific item in the <see cref="IList{T}"/>.
        /// </summary>
        /// <param name="item">The object to locate in the <see cref="IList{T}"/>.</param>
        /// <returns>
        /// The index of <paramref name="item"/> if found in the list; otherwise, -1.
        /// </returns>
        public int IndexOf(IShape item)
        {
            return GeometryList.IndexOf(item);
        }

        /// <summary>
        /// Inserts an item to the <see cref="IList{T}"/> at the specified index.
        /// </summary>
        /// <param name="index">The zero-based index at which 
        /// <paramref name="item"/> should be inserted.</param>
        /// <param name="item">The object to insert into the 
        /// <see cref="IList{T}"/>.</param>
        /// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> 
        /// is not a valid index in the <see cref="IList{T}"/>.</exception>
        /// <exception cref="NotSupportedException">The <see cref="IList{T}"/> 
        /// is read-only.</exception>
        public void Insert(int index, IShape item)
        {
            item.TransformDirtied += Geometry2DTransformDirtied;
            IsUpdateNeeded = true;
            GeometryList.Insert(index, item);
        }

        /// <summary>
        /// Removes the <see cref="IList{T}"/> item at the specified index.
        /// </summary>
        /// <param name="index">The zero-based index of the item to remove.</param>
        /// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> 
        /// is not a valid index in the <see cref="IList{T}"/>.</exception>
        /// <exception cref="NotSupportedException">The <see cref="IList{T}"/> 
        /// is read-only.</exception>
        public void RemoveAt(int index)
        {
            if(index > 0 && index < Count)
            {
                GeometryList[index].TransformDirtied -= Geometry2DTransformDirtied;
                IsUpdateNeeded = true;
                GeometryList.RemoveAt(index);    
            }
        }

        /// <summary>
        /// Gets or sets the <see cref="IShape"/> at the specified index.
        /// </summary>
        public IShape this[int index]
        {
            get
            {
                return GeometryList[index];
            }
            set
            {
                GeometryList[index].TransformDirtied -= Geometry2DTransformDirtied;
                
                GeometryList[index] = value;
                value.TransformDirtied += Geometry2DTransformDirtied;

                IsUpdateNeeded = true;
            }
        }

        /// <summary>
        /// The <see cref="ShapeCollection.Geometries"/> collection casted 
        /// to an <see cref="IList{T}"/>
        /// </summary>
        IList<IShape> GeometryList { get; set; }
    }
}