// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.


namespace System.Collections.Specialized
{
    /// <devdoc>
    ///    <para>Represents a collection of strings.</para>
    /// </devdoc>
    [Serializable]
    [System.Runtime.CompilerServices.TypeForwardedFrom("System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
    public class StringCollection : IList
    {
        private readonly ArrayList data = new ArrayList(); // Do not rename (binary serialization)

        /// <devdoc>
        /// <para>Represents the entry at the specified index of the <see cref='System.Collections.Specialized.StringCollection'/>.</para>
        /// </devdoc>
        public string? this[int index]
        {
            get
            {
                return ((string?)data[index]);
            }
            set
            {
                data[index] = value;
            }
        }

        /// <devdoc>
        ///    <para>Gets the number of strings in the
        ///    <see cref='System.Collections.Specialized.StringCollection'/> .</para>
        /// </devdoc>
        public int Count
        {
            get
            {
                return data.Count;
            }
        }

        bool IList.IsReadOnly
        {
            get
            {
                return false;
            }
        }

        bool IList.IsFixedSize
        {
            get
            {
                return false;
            }
        }


        /// <devdoc>
        ///    <para>Adds a string with the specified value to the
        ///    <see cref='System.Collections.Specialized.StringCollection'/> .</para>
        /// </devdoc>
        public int Add(string? value)
        {
            return data.Add(value);
        }

        /// <devdoc>
        /// <para>Copies the elements of a string array to the end of the <see cref='System.Collections.Specialized.StringCollection'/>.</para>
        /// </devdoc>
        public void AddRange(string?[] value)
        {
            ArgumentNullException.ThrowIfNull(value);

            data.AddRange(value);
        }

        /// <devdoc>
        ///    <para>Removes all the strings from the
        ///    <see cref='System.Collections.Specialized.StringCollection'/> .</para>
        /// </devdoc>
        public void Clear()
        {
            data.Clear();
        }

        /// <devdoc>
        ///    <para>Gets a value indicating whether the
        ///    <see cref='System.Collections.Specialized.StringCollection'/> contains a string with the specified
        ///       value.</para>
        /// </devdoc>
        public bool Contains(string? value)
        {
            return data.Contains(value);
        }

        /// <devdoc>
        /// <para>Copies the <see cref='System.Collections.Specialized.StringCollection'/> values to a one-dimensional <see cref='System.Array'/> instance at the
        ///    specified index.</para>
        /// </devdoc>
        public void CopyTo(string?[] array, int index)
        {
            data.CopyTo(array, index);
        }

        /// <devdoc>
        ///    <para>Returns an enumerator that can iterate through
        ///       the <see cref='System.Collections.Specialized.StringCollection'/> .</para>
        /// </devdoc>
        public StringEnumerator GetEnumerator()
        {
            return new StringEnumerator(this);
        }

        /// <devdoc>
        ///    <para>Returns the index of the first occurrence of a string in
        ///       the <see cref='System.Collections.Specialized.StringCollection'/> .</para>
        /// </devdoc>
        public int IndexOf(string? value)
        {
            return data.IndexOf(value);
        }

        /// <devdoc>
        /// <para>Inserts a string into the <see cref='System.Collections.Specialized.StringCollection'/> at the specified
        ///    index.</para>
        /// </devdoc>
        public void Insert(int index, string? value)
        {
            data.Insert(index, value);
        }

        /// <devdoc>
        /// <para>Gets a value indicating whether the <see cref='System.Collections.Specialized.StringCollection'/> is read-only.</para>
        /// </devdoc>
        public bool IsReadOnly
        {
            get
            {
                return false;
            }
        }

        /// <devdoc>
        ///    <para>Gets a value indicating whether access to the
        ///    <see cref='System.Collections.Specialized.StringCollection'/>
        ///    is synchronized (thread-safe).</para>
        /// </devdoc>
        public bool IsSynchronized
        {
            get
            {
                return false;
            }
        }

        /// <devdoc>
        ///    <para> Removes a specific string from the
        ///    <see cref='System.Collections.Specialized.StringCollection'/> .</para>
        /// </devdoc>
        public void Remove(string? value)
        {
            data.Remove(value);
        }

        /// <devdoc>
        /// <para>Removes the string at the specified index of the <see cref='System.Collections.Specialized.StringCollection'/>.</para>
        /// </devdoc>
        public void RemoveAt(int index)
        {
            data.RemoveAt(index);
        }

        /// <devdoc>
        /// <para>Gets an object that can be used to synchronize access to the <see cref='System.Collections.Specialized.StringCollection'/>.</para>
        /// </devdoc>
        public object SyncRoot
        {
            get
            {
                return data.SyncRoot;
            }
        }

        object? IList.this[int index]
        {
            get
            {
                return this[index];
            }
            set
            {
                this[index] = (string?)value;
            }
        }

        int IList.Add(object? value)
        {
            return Add((string?)value);
        }

        bool IList.Contains(object? value)
        {
            return Contains((string?)value);
        }


        int IList.IndexOf(object? value)
        {
            return IndexOf((string?)value);
        }

        void IList.Insert(int index, object? value)
        {
            Insert(index, (string?)value);
        }

        void IList.Remove(object? value)
        {
            Remove((string?)value);
        }

        void ICollection.CopyTo(Array array, int index)
        {
            data.CopyTo(array, index);
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return data.GetEnumerator();
        }
    }

    public class StringEnumerator
    {
        private readonly System.Collections.IEnumerator _baseEnumerator;

        internal StringEnumerator(StringCollection mappings)
        {
            _baseEnumerator = ((IEnumerable)mappings).GetEnumerator();
        }

        public string? Current
        {
            get
            {
                return (string?)(_baseEnumerator.Current);
            }
        }

        public bool MoveNext()
        {
            return _baseEnumerator.MoveNext();
        }

        public void Reset()
        {
            _baseEnumerator.Reset();
        }
    }
}