using System.Collections.Generic;
using JD.Collections.ObjectModel;

namespace JD.Collections.Extensions
{
    /// <summary>
    /// Extension methods for IDictionary
    /// </summary>
    public static class DictionaryExtensions
    {
        #region AsReadOnly

        /// <summary>
        /// Returns a read-only wrapper over the given dictionary.
        /// </summary>
        public static ReadOnlyDictionary<TKey, TValue> AsReadOnly<TKey, TValue>(this IDictionary<TKey, TValue> dictionary)
        {
            return new ReadOnlyDictionary<TKey, TValue>(dictionary);
        }

        #endregion

        #region IsEqualTo

        /// <summary>
        /// Returns true if the given dictionary is equal (same key/value pairs) to this dictionary.
        /// </summary>
        public static bool IsEqualTo<TKey, TValue>(this IDictionary<TKey, TValue> a, IDictionary<TKey, TValue> collection)
        {
            return IsEqualTo(a, collection, EqualityComparer<TValue>.Default);
        }

        /// <summary>
        /// Returns true if the given dictionary is equal (same key/value pairs) to this dictionary.
        /// </summary>
        public static bool IsEqualTo<TKey, TValue>(this IDictionary<TKey, TValue> a, IDictionary<TKey, TValue> collection, IEqualityComparer<TValue> valueComparer)
        {
            if (a.Count != collection.Count)
            {
                return false;
            }

            foreach (KeyValuePair<TKey, TValue> pair in a)
            {
                TValue otherValue;
                if (!collection.TryGetValue(pair.Key, out otherValue))
                {
                    return false;
                }
                if (!valueComparer.Equals(pair.Value, otherValue))
                {
                    return false;
                }
            }

            return true;
        }

        #endregion

        #region ValueOrDefault

        /// <summary>
        /// Returns the value corresponding to the given key in the dictionary or the default value if the key is not in the dictionary.
        /// </summary>
        public static TValue ValueOrDefault<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key)
        {
            TValue result;
            dictionary.TryGetValue(key, out result);
            return result;
        }

        #endregion
    }
}