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using System;
using System.Collections.Generic;

namespace MySql.Data.MySqlClient
{
    /// <summary>
    /// Represents a collection of query attributes relevant to a <see cref="MySqlCommand"/>.
    /// </summary>
    /// <include file='docs/mySqlattributecollection.xml' path='docs/ClassSummary/*'/>
    public class MySqlAttributeCollection
    {
        readonly List<MySqlAttribute> _items = new List<MySqlAttribute>();

        internal MySqlAttributeCollection(MySqlCommand cmd)
        {
            this.Clear();
        }

        #region Public Methods

        /// <summary>
        /// Gets the <see cref="MySqlAttribute"/> at the specified index.
        /// </summary>
        public MySqlAttribute this[int index]
        {
            get { return this.InternalGetParameter(index); }
        }

        /// <summary>
        /// Gets the number of <see cref="MySqlAttribute"/> objects in the collection.
        /// </summary>
        public int Count => this._items.Count;

        /// <summary>
        /// Adds the specified <see cref="MySqlAttribute"/> object to the <see cref="MySqlAttributeCollection"/>.
        /// </summary>
        /// <param name="value"><see cref="MySqlAttribute"/> object to add.</param>
        public MySqlAttribute SetAttribute(MySqlAttribute value)
        {
            return this.InternalAdd(value);
        }

        /// <summary>
        /// Adds a query attribute and its value.
        /// </summary>
        /// <param name="attributeName">Name of the query attribute.</param>
        /// <param name="value">Value of the query attribute.</param>
        public MySqlAttribute SetAttribute(string attributeName, object value)
        {
            return this.InternalAdd(new MySqlAttribute(attributeName, value));
        }

        /// <summary>
        /// Removes all items from the collection.
        /// </summary>
        public void Clear()
        {
            foreach (MySqlAttribute attr in this._items)
            {
                attr.Collection = null;
            }

            this._items.Clear();
        }
        #endregion

        #region Private Methods
        private MySqlAttribute InternalAdd(MySqlAttribute value)
        {
            if (value == null)
            {
                throw new ArgumentException("The MySqlAttributeCollection only accepts non-null MySqlAttribute type objects.", "value");
            }

            this._items.Add(value);
            value.Collection = this;
            return value;
        }

        private void CheckIndex(int index)
        {
            if (index < 0 || index >= this.Count)
            {
                throw new IndexOutOfRangeException("Attribute index is out of range.");
            }
        }

        private MySqlAttribute InternalGetParameter(int index)
        {
            this.CheckIndex(index);
            return this._items[index];
        }
        #endregion

        #region MySqlCollection Implementation

        /// <summary>
        /// Returns an enumerator that iterates through the <see cref="MySqlAttributeCollection"/>. 
        /// </summary>
        public IEnumerator<MySqlAttribute> GetEnumerator()
        {
            return this._items.GetEnumerator();
        }
        #endregion
    }
}