QueryStringBuilder.cs

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

namespace MicrosoftAccount.WindowsForms
{
    public class QueryStringBuilder
    {
        private readonly Dictionary<string, string> parameters = new Dictionary<string, string>();

        public QueryStringBuilder()
        {
            StartCharacter = null;
            SeperatorCharacter = '&';
            KeyValueJoinCharacter = '=';
        }

        public QueryStringBuilder(string key, string value) => this[key] = value;

        public void Clear() => parameters.Clear();

        public bool HasKeys => parameters.Count > 0;

        public char? StartCharacter { get; set; }

        public char SeperatorCharacter { get; set; }

        public char KeyValueJoinCharacter { get; set; }

        public string this[string key]
        {
            get => parameters.ContainsKey(key) ? parameters[key] : null;
            set => parameters[key] = value;
        }

        public bool ContainsKey(string key) => parameters.ContainsKey(key);

        public string[] Keys => parameters.Keys.ToArray();

        public void Add(string key, string value) => parameters[key] = value;

        public void Remove(string key) => parameters.Remove(key);

        public override string ToString()
        {
            var sb = new StringBuilder();
            foreach (var param in parameters)
            {
                if ((sb.Length == 0) && (null != StartCharacter))
                    sb.Append(StartCharacter);
                if ((sb.Length > 0) && (sb[sb.Length - 1] != StartCharacter))
                    sb.Append(SeperatorCharacter);

                sb.Append(param.Key);
                sb.Append('=');
                sb.Append(Uri.EscapeDataString(param.Value));
            }
            return sb.ToString();
        }
    }
}