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

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

namespace Microsoft.Extensions.Configuration.Memory
{
    /// <summary>
    /// Provides configuration key-value pairs that are obtained from memory.
    /// </summary>
    public class MemoryConfigurationProvider : ConfigurationProvider, IEnumerable<KeyValuePair<string, string?>>
    {
        private readonly MemoryConfigurationSource _source;

        /// <summary>
        /// Initialize a new instance from the source.
        /// </summary>
        /// <param name="source">The source settings.</param>
        public MemoryConfigurationProvider(MemoryConfigurationSource source)
        {
            ArgumentNullException.ThrowIfNull(source);

            _source = source;

            if (_source.InitialData != null)
            {
                foreach (KeyValuePair<string, string?> pair in _source.InitialData)
                {
                    Data.Add(pair.Key, pair.Value);
                }
            }
        }

        /// <summary>
        /// Adds a new key-value pair.
        /// </summary>
        /// <param name="key">The configuration key.</param>
        /// <param name="value">The configuration value.</param>
        public void Add(string key, string? value)
        {
            Data.Add(key, value);
        }

        /// <summary>
        /// Returns an enumerator that iterates through the collection.
        /// </summary>
        /// <returns>An enumerator that can be used to iterate through the collection.</returns>
        public IEnumerator<KeyValuePair<string, string?>> GetEnumerator()
        {
            return Data.GetEnumerator();
        }

        /// <summary>
        /// Returns an enumerator that iterates through the collection.
        /// </summary>
        /// <returns>An enumerator that can be used to iterate through the collection.</returns>
        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
    }
}