using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ln.http
{
    public class QueryStringParameters : IDictionary<String,String>
    {
        Dictionary<string, string> parameters = new Dictionary<string, string>();

        public QueryStringParameters(String query)
        {
            if (query.StartsWith("?"))
                query = query.Substring(1);
            
            String[] pairs = query.Split(new char[] { '&' }, StringSplitOptions.RemoveEmptyEntries);

            foreach (String pair in pairs)
            {
                String[] kv = pair.Split(new char[] { '=' }, 2, StringSplitOptions.RemoveEmptyEntries);
                string key = Uri.UnescapeDataString(kv[0].Replace('+',' '));
                string value = kv.Length == 2 ? Uri.UnescapeDataString(kv[1].Replace('+',' ')) : "";
                if (!key.Equals(String.Empty)){
                    parameters[key] = value;
                }
            }
        }

        public string this[string key] {
            get => parameters[key];
            set => throw new NotImplementedException(); }

        public ICollection<string> Keys => parameters.Keys;
        public ICollection<string> Values => parameters.Values;
        public int Count => parameters.Count;
        public bool IsReadOnly => true;

        public void Add(string key, string value) => throw new NotImplementedException();
        public void Add(KeyValuePair<string, string> item) => throw new NotImplementedException();
        public void Clear() => throw new NotImplementedException();
        public bool Remove(string key) => throw new NotImplementedException();
        public bool Remove(KeyValuePair<string, string> item) => throw new NotImplementedException();

        public bool Contains(KeyValuePair<string, string> item) => parameters.Contains(item);
        public bool ContainsKey(string key) => parameters.ContainsKey(key);
        public void CopyTo(KeyValuePair<string, string>[] array, int arrayIndex) => ((IDictionary<string, string>)parameters).CopyTo(array, arrayIndex);
        public IEnumerator<KeyValuePair<string, string>> GetEnumerator() => parameters.GetEnumerator();
        public bool TryGetValue(string key, out string value) => parameters.TryGetValue(key, out value);
        IEnumerator IEnumerable.GetEnumerator() => parameters.GetEnumerator();

        public string GetValue(string key,string defaultValue)
        {
            if (!ContainsKey(key))
                return defaultValue;
            return parameters[key];
        }

        public override string ToString()
        {
            StringBuilder stringBuilder = new StringBuilder();

            stringBuilder.Append("[Query");
            foreach (String key in parameters.Keys){
                stringBuilder.AppendFormat(" {0}={1}", key, parameters[key]);
            }
            stringBuilder.Append("]");

            return stringBuilder.ToString();
        }
    }
}