using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

//namespace Utils.Datas
namespace System.Collections.Generic
{
	public static class DictionaryUtil
	{
		/// <summary>
		/// 将第二个参数中的数据合并到第一个参数中。【通过Key判断。如果已存在，则忽略】
		/// <para>Key不能为类</para>
		/// </summary>
		public static void Combine<T1, T2>(this IDictionary<T1, T2> a, IDictionary<T1, T2> b)
		{
			if (a == null)
				a = new Dictionary<T1, T2>();
			if (b == null || b.Count == 0)
				return;
			foreach (var item in b) {
				if (!a.Keys.Contains(item.Key))
					a.Add(item.Key, item.Value);
			}
		}

		/// <summary>
		/// 找出两个参数中，Key相同的项的Key
		/// <para>Key不能为类</para>
		/// </summary>
		public static List<T1> FindSameKey<T1, T2>(this IDictionary<T1, T2> a, IDictionary<T1, T2> b)
		{
			List<T1> result = new List<T1>();
			foreach (var item in a) {
				if (b.Keys.Contains(item.Key))
					result.Add(item.Key);
			}
			return result;
		}

		/// <summary>
		/// 从第一个参数中去掉第二个参数中的所有项后，剩余项的Key。只比较Key
		/// <para>Key不能为类</para>
		/// </summary>
		public static List<T1> SubKey<T1, T2>(this IDictionary<T1, T2> a, IDictionary<T1, T2> b)
		{
			List<T1> result = new List<T1>();
			foreach (var item in a) {
				if (!b.Keys.Contains(item.Key))
					result.Add(item.Key);
			}
			return result;
		}

		public static Dictionary<T1, string> ChangeValueToString<T1>(this IDictionary<T1, object> dic)
		{//TODO:添加测试
			Dictionary<T1, string> result = new Dictionary<T1, string>();
			foreach (var detail in dic) {
				result.Add(detail.Key, detail.Value == null ? string.Empty : detail.Value.ToString());
			}
			return result;
		}
	}
}