using System.Collections;

namespace VberZero.Tools.StringModel;

public static class ListHelper
{
    /// <summary>
    /// 自定义Distinct扩展方法
    /// </summary>
    /// <typeparam name="T">要去重的对象类</typeparam>
    /// <typeparam name="TC">自定义去重的字段类型</typeparam>
    /// <param name="source">要去重的对象</param>
    /// <param name="getField">获取自定义去重字段的委托</param>
    /// <returns></returns>
    public static IEnumerable<T> VzDistinct<T, TC>(this IEnumerable<T> source, Func<T, TC> getField)
    {
        return source.Distinct(new Compare<T, TC>(getField));
    }

    /// <summary>
    /// 合并字典
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="first">字典1</param>
    /// <param name="second">字典2</param>
    /// <param name="isCover">字典2是否覆盖字典1，默认 true</param>
    /// <returns></returns>
    public static Dictionary<string, T> MergeDictionary<T>(this Dictionary<string, T>? first, Dictionary<string, T>? second, bool isCover = true)
    {
        first ??= new Dictionary<string, T>();
        if (second == null) return first;

        foreach (string key in second.Keys)
        {
            if (first.ContainsKey(key))
            {
                if (isCover)
                {
                    first[key] = second[key];
                }
            }
            else
            {
                first.Add(key, second[key]);
            }
        }
        return first;
    }

    /// <summary>
    /// 合并字典
    /// </summary>
    /// <param name="first">字典1</param>
    /// <param name="second">字典2</param>
    /// <param name="isCover">字典2是否覆盖字典1，默认 true</param>
    /// <returns></returns>
    public static Hashtable MergeHashtable(this Hashtable? first, Hashtable? second, bool isCover = true)
    {
        first ??= new Hashtable();
        if (second == null) return first;

        foreach (string key in second.Keys)
        {
            if (first.ContainsKey(key))
            {
                if (isCover)
                {
                    first[key] = second[key];
                }
            }
            else
            {
                first.Add(key, second[key]);
            }
        }
        return first;
    }
}

public class Compare<T, TC> : IEqualityComparer<T>
{
    private Func<T, TC> GetField { get; }

    public Compare(Func<T, TC> getField)
    {
        GetField = getField;
    }

    public bool Equals(T? x, T? y)
    {
        return y != null && x != null && EqualityComparer<TC>.Default.Equals(GetField(x), GetField(y));
    }

    public int GetHashCode(T obj)
    {
        return EqualityComparer<TC>.Default.GetHashCode(GetField(obj)!);
    }
}