using System.Collections.Generic;

namespace IgniteEngine
{
    /// <summary>
    /// Class that extends the use of the List class.
    /// </summary>
    public static class DictionaryExtensions
    {
        /// <summary>
        /// The object to lock for list access.
        /// </summary>
        private static readonly object lockObject = new object();

        /// <summary>
        /// Adds an object to the list in a thread-safe, exception-safe
        /// manner.
        /// </summary>
        /// <param name="source">The source list.</param>
        /// <param name="value">The value to add.</param>
        public static void AddSafe<TKey, TValue>(this Dictionary<TKey, TValue> source, TKey key, TValue value)
        {
            if (key == null || value == null)
            {
                return;
            }

            lock (lockObject)
            {
                if (source.ContainsKey(key))
                {
                    source[key] = value;
                    return;
                }

                source.Add(key, value);
            }
        }

        /// <summary>
        /// Tries to get the object at the specified key. Returns default if it does not exist,
        /// instead of throwing an exception.
        /// </summary>
        /// <typeparam name="TKey">The type of the key.</typeparam>
        /// <typeparam name="TValue">The type of the value.</typeparam>
        /// <param name="source">The dictionary being searched.</param>
        /// <param name="key">The key of the value.</param>
        public static TValue GetSafe<TKey, TValue>(this Dictionary<TKey, TValue> source, TKey key)
        {
            return source.ContainsKey(key) ? source[key] : default(TValue);
        }
    }
}