using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;
using System.Text.RegularExpressions;

namespace YLPublishTool
{
    static class Helper
    {
        static readonly Dictionary<string, Type> _actionMap;

        static Helper()
        {
            _actionMap = new Dictionary<string, Type>();
            var bast = typeof(IPublishAction);
            var types = typeof(Helper).Assembly.GetTypes().Where(t => bast.IsAssignableFrom(t)).ToArray();
            foreach (var t in types)
            {
                var attr = t.GetCustomAttributes(typeof(DescriptionAttribute), false)?.FirstOrDefault();
                if (attr is DescriptionAttribute desc && desc.Description != null)
                {
                    _actionMap[desc.Description] = t;
                }
            }
        }

        public static IPublishAction GetAction(string actionName)
        {
            return actionName != null && _actionMap.TryGetValue(actionName, out var t) ?
                (IPublishAction)Activator.CreateInstance(t) : null;
        }

        public static bool ExistsAction(string actionName)
        {
            return _actionMap.ContainsKey(actionName);
        }

        public static string ConvertWildCardToRegex(string str)
        {
            if (string.IsNullOrWhiteSpace(str))
            {
                return null;
            }
            str = Regex.Replace(str, "\\*+", "*").Replace(" ", "").Replace("||", "|");
            return "^" + Regex.Escape(str).Replace("\\|", "|").Replace("\\*", ".*") + "$";
        }

        /// <summary>
        /// 解析url查询字符串，支持&amp;&amp;转义为&amp;,所以和标准规范有出入
        /// </summary>
        public static NameValueCollection ParseQueryString(string query, bool urlencoded = false)
        {
            if (string.IsNullOrWhiteSpace(query))
            {
                return null;
            }

            var len = query.Length;
            var buf = new char[len + 2];
            query.CopyTo(0, buf, 0, len);
            len += 2;

            //在下面的循环中正好排除最后一个处理
            buf[len - 2] = '&';
            buf[len - 1] = 'm';

            var start = 0;
            var hasEscape = false;
            var nv = new NameValueCollection(10);

            for (var index = 0; index < len; index++)
            {
                if (buf[index] != '&')
                {
                    continue;
                }

                if (buf[index + 1] == '&')
                {
                    index++;
                    hasEscape = true;
                    continue;
                }

                //处理遇到单个&的情况

                var substr = new string(buf, start, index - start).Trim();

                start = index + 1;

                if (substr.Length == 0)
                {
                    continue;
                }

                if (hasEscape)
                {
                    hasEscape = false;
                    substr = substr.Replace("&&", "&");
                }

                var index2 = substr.IndexOf('=');

                if (index2 > 0)
                {
                    var key = substr.Substring(0, index2);
                    var value = substr.Substring(index2 + 1);
                    if (urlencoded)
                    {
                        key = Uri.UnescapeDataString(key);
                        value = Uri.UnescapeDataString(value);
                    }
                    nv.Add(key.Trim(), value.Trim());
                }
                else
                {
                    var key = substr;
                    if (urlencoded)
                    {
                        key = Uri.UnescapeDataString(key);
                    }
                    nv.Add(key.Trim(), string.Empty);
                }
            }

            return nv;
        }
    }
}