//******************************
// Written by Peter Golde
// Copyright (c) 2004-2007, Wintellect
//
// Use and restribution of this code is subject to the license agreement 
// contained in the file "License.txt" accompanying this file.
//******************************

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

namespace Wintellect.PowerCollections
{
    /// <summary>
    /// ReadOnlyListBase is an abstract class that can be used as a base class for a read-only collection that needs 
    /// to implement the generic IList&lt;T&gt; and non-generic IList collections. The derived class needs
    /// to override the Count property and the get part of the indexer. The implementation
    /// of all the other methods in IList&lt;T&gt; and IList are handled by ListBase.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    [Serializable]
    public abstract class ReadOnlyListBase<T> : ReadOnlyCollectionBase<T>, IList<T>, IList
    {
        /// <summary>
        /// Throws an NotSupportedException stating that this collection cannot be modified.
        /// </summary>
        private void MethodModifiesCollection()
        {
            throw new NotSupportedException(string.Format(Strings.CannotModifyCollection, Util.SimpleClassName(this.GetType())));
        }

        /// <summary>
        /// The property must be overridden by the derived class to return the number of 
        /// items in the list.
        /// </summary>
        /// <value>The number of items in the list.</value>
        public abstract override int Count { get;}

        /// <summary>
        /// The get part of the indexer must be overridden by the derived class to get 
        /// values of the list at a particular index.
        /// </summary>
        /// <param name="index">The index in the list to get or set an item at. The
        /// first item in the list has index 0, and the last has index Count-1.</param>
        /// <returns>The item at the given index.</returns>
        /// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is
        /// less than zero or greater than or equal to Count.</exception>
        public virtual T this[int index]
        {
            get
            {
                throw new NotImplementedException(Strings.MustOverrideIndexerGet);
            }

            set
            {
                MethodModifiesCollection();
            }
        }

        /// <summary>
        /// Enumerates all of the items in the list, in order. The item at index 0
        /// is enumerated first, then the item at index 1, and so on.
        /// </summary>
        /// <returns>An IEnumerator&lt;T&gt; that enumerates all the
        /// items in the list.</returns>
        public override IEnumerator<T> GetEnumerator()
        {
            int count = Count;
            for (int i = 0; i < count; ++i) {
                yield return this[i];
            }
        }

        /// <summary>
        /// Determines if the list contains any item that compares equal to <paramref name="item"/>.
        /// The implementation simply checks whether IndexOf(item) returns a non-negative value.
        /// </summary>
        /// <remarks>Equality in the list is determined by the default sense of
        /// equality for T. If T implements IComparable&lt;T&gt;, the
        /// Equals method of that interface is used to determine equality. Otherwise, 
        /// Object.Equals is used to determine equality.</remarks>
        /// <param name="item">The item to search for.</param>
        /// <returns>True if the list contains an item that compares equal to <paramref name="item"/>.</returns>
        public override bool Contains(T item)
        {
            return (IndexOf(item) >= 0);
        }

        /// <summary>
        /// Copies all the items in the list, in order, to <paramref name="array"/>,
        /// starting at index 0.
        /// </summary>
        /// <param name="array">The array to copy to. This array must have a size
        /// that is greater than or equal to Count.</param>
        public virtual void CopyTo(T[] array)
        {
            this.CopyTo(array, 0);
        }

        /// <summary>
        /// Copies a range of elements from the list to <paramref name="array"/>,
        /// starting at <paramref name="arrayIndex"/>.
        /// </summary>
        /// <param name="index">The starting index in the source list of the range to copy.</param>
        /// <param name="array">The array to copy to. This array must have a size
        /// that is greater than or equal to Count + arrayIndex.</param>
        /// <param name="arrayIndex">The starting index in <paramref name="array"/>
        /// to copy to.</param>
        /// <param name="count">The number of items to copy.</param>
        public virtual void CopyTo(int index, T[] array, int arrayIndex, int count)
        {
            Range(index, count).CopyTo(array, arrayIndex);
        }

        /// <summary>
        /// Finds the first item in the list that satisfies the condition
        /// defined by <paramref name="predicate"/>. If no item matches the condition, than
        /// the default value for T (null or all-zero) is returned.
        /// </summary>
        /// <remarks>If the default value for T (null or all-zero) matches the condition defined by <paramref name="predicate"/>,
        /// and the list might contain the default value, then it is impossible to distinguish the different between finding
        /// the default value and not finding any item. To distinguish these cases, use <see cref="TryFind"/>.</remarks>
        /// <param name="predicate">A delegate that defined the condition to check for.</param>
        /// <returns>The first item that satisfies the condition <paramref name="predicate"/>. If no item satisfies that
        /// condition, the default value for T is returned.</returns>
        /// <seealso cref="TryFind"/>
        public virtual T Find(Predicate<T> predicate)
        {
            return Algorithms.FindFirstWhere(this, predicate);
        }

        /// <summary>
        /// Finds the first item in the list that satisfies the condition
        /// defined by <paramref name="predicate"/>. 
        /// </summary>
        /// <param name="predicate">A delegate that defines the condition to check for.</param>
        /// <param name="foundItem">If true is returned, this parameter receives the first item in the list
        /// that satifies the condition defined by <paramref name="predicate"/>.</param>
        /// <returns>True if an item that  satisfies the condition <paramref name="predicate"/> was found. False 
        /// if no item in the list satisfies that condition.</returns>
        public virtual bool TryFind(Predicate<T> predicate, out T foundItem)
        {
            return Algorithms.TryFindFirstWhere(this, predicate, out foundItem);
        }

        /// <summary>
        /// Finds the last item in the list that satisfies the condition
        /// defined by <paramref name="predicate"/>. If no item matches the condition, than
        /// the default value for T (null or all-zero) is returned.
        /// </summary>
        /// <remarks>If the default value for T (null or all-zero) matches the condition defined by <paramref name="predicate"/>,
        /// and the list might contain the default value, then it is impossible to distinguish the different between finding
        /// the default value and not finding any item. To distinguish these cases, use <see cref="TryFindLast"/>.</remarks>
        /// <param name="predicate">A delegate that defined the condition to check for.</param>
        /// <returns>The last item that satisfies the condition <paramref name="predicate"/>. If no item satisfies that
        /// condition, the default value for T is returned.</returns>
        /// <seealso cref="TryFindLast"/>
        public virtual T FindLast(Predicate<T> predicate)
        {
            return Algorithms.FindLastWhere(this, predicate);
        }

        /// <summary>
        /// Finds the last item in the list that satisfies the condition
        /// defined by <paramref name="predicate"/>. 
        /// </summary>
        /// <param name="predicate">A delegate that defines the condition to check for.</param>
        /// <param name="foundItem">If true is returned, this parameter receives the last item in the list
        /// that satifies the condition defined by <paramref name="predicate"/>.</param>
        /// <returns>True if an item that  satisfies the condition <paramref name="predicate"/> was found. False 
        /// if no item in the list satisfies that condition.</returns>
        public virtual bool TryFindLast(Predicate<T> predicate, out T foundItem)
        {
            return Algorithms.TryFindLastWhere(this, predicate, out foundItem);
        }

        /// <summary>
        /// Finds the index of the first item in the list that satisfies the condition
        /// defined by <paramref name="predicate"/>. If no item matches the condition, -1 is returned.
        /// </summary>
        /// <param name="predicate">A delegate that defined the condition to check for.</param>
        /// <returns>The index of the first item that satisfies the condition <paramref name="predicate"/>. If no item satisfies that
        /// condition, -1 is returned.</returns>
        public virtual int FindIndex(Predicate<T> predicate)
        {
            return Algorithms.FindFirstIndexWhere(this, predicate);
        }

        /// <summary>
        /// Finds the index of the first item, in the range of items extending from <paramref name="index"/> to the end, that satisfies the condition
        /// defined by <paramref name="predicate"/>. If no item matches the condition, -1 is returned.
        /// </summary>
        /// <param name="predicate">A delegate that defined the condition to check for.</param>
        /// <param name="index">The starting index of the range to check.</param>
        /// <returns>The index of the first item in the given range that satisfies the condition <paramref name="predicate"/>. If no item satisfies that
        /// condition, -1 is returned.</returns>
        public virtual int FindIndex(int index, Predicate<T> predicate)
        {
            int foundIndex = Algorithms.FindFirstIndexWhere(Range(index, Count - index), predicate);
            if (foundIndex < 0)
                return -1;
            else
                return foundIndex + index;
        }

        /// <summary>
        /// Finds the index of the first item, in the range of <paramref name="count"/> items starting from <paramref name="index"/>, that satisfies the condition
        /// defined by <paramref name="predicate"/>. If no item matches the condition, -1 is returned.
        /// </summary>
        /// <param name="predicate">A delegate that defined the condition to check for.</param>
        /// <param name="index">The starting index of the range to check.</param>
        /// <param name="count">The number of items in range to check.</param>
        /// <returns>The index of the first item in the given range that satisfies the condition <paramref name="predicate"/>. If no item satisfies that
        /// condition, -1 is returned.</returns>
        public virtual int FindIndex(int index, int count, Predicate<T> predicate)
        {
            int foundIndex = Algorithms.FindFirstIndexWhere(Range(index, count), predicate);
            if (foundIndex < 0)
                return -1;
            else
                return foundIndex + index;
        }

        /// <summary>
        /// Finds the index of the last item in the list that satisfies the condition
        /// defined by <paramref name="predicate"/>. If no item matches the condition, -1 is returned.
        /// </summary>
        /// <param name="predicate">A delegate that defined the condition to check for.</param>
        /// <returns>The index of the last item that satisfies the condition <paramref name="predicate"/>. If no item satisfies that
        /// condition, -1 is returned.</returns>
        public virtual int FindLastIndex(Predicate<T> predicate)
        {
            return Algorithms.FindLastIndexWhere(this, predicate);
        }

        /// <summary>
        /// Finds the index of the last item, in the range of items extending from the beginning
        /// of the list to <paramref name="index"/>, that satisfies the condition
        /// defined by <paramref name="predicate"/>. If no item matches the condition, -1 is returned.
        /// </summary>
        /// <param name="predicate">A delegate that defined the condition to check for.</param>
        /// <param name="index">The ending index of the range to check.</param>
        /// <returns>The index of the last item in the given range that satisfies the condition <paramref name="predicate"/>. If no item satisfies that
        /// condition, -1 is returned.</returns>
        public virtual int FindLastIndex(int index, Predicate<T> predicate)
        {
            return Algorithms.FindLastIndexWhere(Range(0, index + 1), predicate);
        }

        /// <summary>
        /// Finds the index of the last item, in the range of <paramref name="count"/> items ending at <paramref name="index"/>, that satisfies the condition
        /// defined by <paramref name="predicate"/>. If no item matches the condition, -1 is returned.
        /// </summary>
        /// <param name="predicate">A delegate that defined the condition to check for.</param>
        /// <param name="index">The ending index of the range to check.</param>
        /// <param name="count">The number of items in range to check.</param>
        /// <returns>The index of the last item in the given range that satisfies the condition <paramref name="predicate"/>. If no item satisfies that
        /// condition, -1 is returned.</returns>
        public virtual int FindLastIndex(int index, int count, Predicate<T> predicate)
        {
            int foundIndex = Algorithms.FindLastIndexWhere(Range(index - count + 1, count), predicate);

            if (foundIndex >= 0)
                return foundIndex + index - count + 1;
            else
                return -1;
        }

        /// <summary>
        /// Finds the index of the first item in the list that is equal to <paramref name="item"/>. 
        /// </summary>
        /// <remarks>The default implementation of equality for type T is used in the search. This is the
        /// equality defined by IComparable&lt;T&gt; or object.Equals.</remarks>
        /// <param name="item">The item to search fror.</param>
        /// <returns>The index of the first item in the list that that is equal to <paramref name="item"/>.  If no item is equal
        /// to <paramref name="item"/>, -1 is returned.</returns>
        public virtual int IndexOf(T item)
        {
            return Algorithms.FirstIndexOf(this, item, EqualityComparer<T>.Default);
        }

        /// <summary>
        /// Finds the index of the first item, in the range of items extending from <paramref name="index"/> to the end,  
        /// that is equal to <paramref name="item"/>. 
        /// </summary>
        /// <remarks>The default implementation of equality for type T is used in the search. This is the
        /// equality defined by IComparable&lt;T&gt; or object.Equals.</remarks>
        /// <param name="item">The item to search fror.</param>
        /// <param name="index">The starting index of the range to check.</param>
        /// <returns>The index of the first item in the given range that that is equal to <paramref name="item"/>.  If no item is equal
        /// to <paramref name="item"/>, -1 is returned.</returns>
        public virtual int IndexOf(T item, int index)
        {
            int foundIndex = Algorithms.FirstIndexOf(Range(index, Count - index), item, EqualityComparer<T>.Default);

            if (foundIndex >= 0)
                return foundIndex + index;
            else
                return -1;
        }

        /// <summary>
        /// Finds the index of the first item, in the range of <paramref name="count"/> items starting from <paramref name="index"/>,  
        /// that is equal to <paramref name="item"/>. 
        /// </summary>
        /// <remarks>The default implementation of equality for type T is used in the search. This is the
        /// equality defined by IComparable&lt;T&gt; or object.Equals.</remarks>
        /// <param name="item">The item to search fror.</param>
        /// <param name="index">The starting index of the range to check.</param>
        /// <param name="count">The number of items in range to check.</param>
        /// <returns>The index of the first item in the given range that that is equal to <paramref name="item"/>.  If no item is equal
        /// to <paramref name="item"/>, -1 is returned.</returns>
        public virtual int IndexOf(T item, int index, int count)
        {
            int foundIndex = Algorithms.FirstIndexOf(Range(index, count), item, EqualityComparer<T>.Default);

            if (foundIndex >= 0)
                return foundIndex + index;
            else
                return -1;
        }

        /// <summary>
        /// Finds the index of the last item in the list that is equal to <paramref name="item"/>. 
        /// </summary>
        /// <remarks>The default implementation of equality for type T is used in the search. This is the
        /// equality defined by IComparable&lt;T&gt; or object.Equals.</remarks>
        /// <param name="item">The item to search fror.</param>
        /// <returns>The index of the last item in the list that that is equal to <paramref name="item"/>.  If no item is equal
        /// to <paramref name="item"/>, -1 is returned.</returns>
        public virtual int LastIndexOf(T item)
        {
            return Algorithms.LastIndexOf(this, item, EqualityComparer<T>.Default);
        }

        /// <summary>
        /// Finds the index of the last item, in the range of items extending from the beginning
        /// of the list to <paramref name="index"/>, that is equal to <paramref name="item"/>. 
        /// </summary>
        /// <remarks>The default implementation of equality for type T is used in the search. This is the
        /// equality defined by IComparable&lt;T&gt; or object.Equals.</remarks>
        /// <param name="item">The item to search fror.</param>
        /// <param name="index">The ending index of the range to check.</param>
        /// <returns>The index of the last item in the given range that that is equal to <paramref name="item"/>.  If no item is equal
        /// to <paramref name="item"/>, -1 is returned.</returns>
        public virtual int LastIndexOf(T item, int index)
        {
            int foundIndex = Algorithms.LastIndexOf(Range(0, index + 1), item, EqualityComparer<T>.Default);

            return foundIndex;
        }

        /// <summary>
        /// Finds the index of the last item, in the range of <paramref name="count"/> items ending at <paramref name="index"/>, 
        /// that is equal to <paramref name="item"/>. 
        /// </summary>
        /// <remarks>The default implementation of equality for type T is used in the search. This is the
        /// equality defined by IComparable&lt;T&gt; or object.Equals.</remarks>
        /// <param name="item">The item to search for.</param>
        /// <param name="index">The ending index of the range to check.</param>
        /// <param name="count">The number of items in range to check.</param>
        /// <returns>The index of the last item in the given range that that is equal to <paramref name="item"/>.  If no item is equal
        /// to <paramref name="item"/>, -1 is returned.</returns>
        public virtual int LastIndexOf(T item, int index, int count)
        {
            int foundIndex = Algorithms.LastIndexOf(Range(index - count + 1, count), item, EqualityComparer<T>.Default);

            if (foundIndex >= 0)
                return foundIndex + index - count + 1;
            else
                return -1;
        }

        /// <summary>
        /// Returns a view onto a sub-range of this list. Items are not copied; the
        /// returned IList&lt;T&gt; is simply a different view onto the same underlying items. 
        /// </summary>
        /// <remarks>
        /// <para>This method can be used to apply an algorithm to a portion of a list. For example:</para>
        /// <code>Algorithms.Reverse(deque.Range(3, 6))</code>
        /// will return the reverse opf the 6 items beginning at index 3.</remarks>
        /// <param name="start">The starting index of the view.</param>
        /// <param name="count">The number of items in the view.</param>
        /// <returns>A list that is a view onto the given sub-part of this list. </returns>
        /// <exception cref="ArgumentOutOfRangeException"><paramref name="start"/> or <paramref name="count"/> is negative.</exception>
        /// <exception cref="ArgumentOutOfRangeException"><paramref name="start"/> + <paramref name="count"/> is greater than the
        /// size of the list.</exception>
        public virtual IList<T> Range(int start, int count)
        {
            return Algorithms.Range(this, start, count);
        }

        /// <summary>
        /// Inserts a new item at the given index. This implementation throws a NotSupportedException
        /// indicating that the list is read-only.
        /// </summary>
        /// <param name="index">The index in the list to insert the item at. After the
        /// insertion, the inserted item is located at this index. The
        /// first item in the list has index 0.</param>
        /// <param name="item">The item to insert at the given index.</param>
        /// <exception cref="NotSupportedException">Always thrown.</exception>
        void IList<T>.Insert(int index, T item)
        {
            MethodModifiesCollection();
        }

        /// <summary>
        /// Removes the item at the given index.  This implementation throws a NotSupportedException
        /// indicating that the list is read-only.
        /// </summary>
        /// <param name="index">The index in the list to remove the item at. The
        /// first item in the list has index 0.</param>
        /// <exception cref="NotSupportedException">Always thrown.</exception>
        void IList<T>.RemoveAt(int index)
        {
            MethodModifiesCollection();
        }

        /// <summary>
        /// Adds an item to the end of the list. This implementation throws a NotSupportedException
        /// indicating that the list is read-only.
        /// </summary>
        /// <param name="value">The item to add to the list.</param>
        /// <exception cref="NotSupportedException">Always thrown.</exception>
        int IList.Add(object value)
        {
            MethodModifiesCollection();
            return -1;
        }

        /// <summary>
        /// Removes all the items from the list, resulting in an empty list. This implementation throws a NotSupportedException
        /// indicating that the list is read-only.
        /// </summary>
        /// <exception cref="NotSupportedException">Always thrown.</exception>
        void IList.Clear()
        {
            MethodModifiesCollection();
        }

        /// <summary>
        /// Determines if the list contains any item that compares equal to <paramref name="value"/>.
        /// </summary>
        /// <remarks>Equality in the list is determined by the default sense of
        /// equality for T. If T implements IComparable&lt;T&gt;, the
        /// Equals method of that interface is used to determine equality. Otherwise, 
        /// Object.Equals is used to determine equality.</remarks>
        /// <param name="value">The item to search for.</param>
        bool IList.Contains(object value)
        {
            if (value is T || value == null)
                return Contains((T)value);
            else
                return false;
        }

        /// <summary>
        /// Find the first occurrence of an item equal to <paramref name="value"/>
        /// in the list, and returns the index of that item.
        /// </summary>
        /// <remarks>Equality in the list is determined by the default sense of
        /// equality for T. If T implements IComparable&lt;T&gt;, the
        /// Equals method of that interface is used to determine equality. Otherwise, 
        /// Object.Equals is used to determine equality.</remarks>
        /// <param name="value">The item to search for.</param>
        /// <returns>The index of <paramref name="value"/>, or -1 if no item in the 
        /// list compares equal to <paramref name="value"/>.</returns>
        int IList.IndexOf(object value)
        {
            if (value is T || value == null)
                return IndexOf((T)value);
            else
                return -1;
        }

        /// <summary>
        /// Insert a new item at the given index. This implementation throws a NotSupportedException
        /// indicating that the list is read-only.
        /// </summary>
        /// <param name="index">The index in the list to insert the item at. After the
        /// insertion, the inserted item is located at this index. The
        /// first item in the list has index 0.</param>
        /// <param name="value">The item to insert at the given index.</param>
        /// <exception cref="NotSupportedException">Always thrown.</exception>
        void IList.Insert(int index, object value)
        {
            MethodModifiesCollection();
        }

        /// <summary>
        /// Returns whether the list is a fixed size. This implementation always returns true.
        /// </summary>
        /// <value>Alway true, indicating that the list is fixed size.</value>
        bool IList.IsFixedSize
        {
            get { return true; }
        }

        /// <summary>
        /// Returns whether the list is read only. This implementation always returns true.
        /// </summary>
        /// <value>Alway true, indicating that the list is read-only.</value>
        bool IList.IsReadOnly
        {
            get { return true; }
        }

        /// <summary>
        /// Searches the list for the first item that compares equal to <paramref name="value"/>.
        /// If one is found, it is removed. Otherwise, the list is unchanged.  This implementation throws a NotSupportedException
        /// indicating that the list is read-only.
        /// </summary>
        /// <remarks>Equality in the list is determined by the default sense of
        /// equality for T. If T implements IComparable&lt;T&gt;, the
        /// Equals method of that interface is used to determine equality. Otherwise, 
        /// Object.Equals is used to determine equality.</remarks>
        /// <param name="value">The item to remove from the list.</param>
        /// <exception cref="NotSupportedException">Always thrown.</exception>
        void IList.Remove(object value)
        {
            MethodModifiesCollection();
        }

        /// <summary>
        /// Removes the item at the given index. This implementation throws a NotSupportedException
        /// indicating that the list is read-only.
        /// </summary>
        /// <param name="index">The index in the list to remove the item at. The
        /// first item in the list has index 0.</param>
        /// <exception cref="NotSupportedException">Always thrown.</exception>
        void IList.RemoveAt(int index)
        {
            MethodModifiesCollection();
        }

        /// <summary>
        /// Gets or sets the value at a particular index in the list.
        /// </summary>
        /// <param name="index">The index in the list to get or set an item at. The
        /// first item in the list has index 0, and the last has index Count-1.</param>
        /// <value>The item at the given index.</value>
        /// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is
        /// less than zero or greater than or equal to Count.</exception>
        /// <exception cref="ArgumentException"><paramref name="value"/> cannot be converted to T.</exception>
        /// <exception cref="NotSupportedException">Always thrown from the setter, indicating that the list
        /// is read-only.</exception>
        object IList.this[int index]
        {
            get
            {
                return this[index];
            }

            set
            {
                MethodModifiesCollection();
            }
        }
    }
}