using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading;

namespace jive
{
  public class PerThread : Context
  {
    readonly IDictionary<int, LocalDataStoreSlot> slots;
    readonly object mutex = new object();

    public PerThread()
    {
      slots = new Dictionary<int, LocalDataStoreSlot>();
    }

    public bool contains<T>(Key<T> key)
    {
      return key.is_found_in(get_items());
    }

    public void add<T>(Key<T> key, T value)
    {
      key.add_value_to(get_items(), value);
    }

    public T value_for<T>(Key<T> key)
    {
      return key.parse_from(get_items());
    }

    public void remove<T>(Key<T> key)
    {
      key.remove_from(get_items());
    }

    IDictionary get_items()
    {
      var id = Thread.CurrentThread.ManagedThreadId;
      within_lock(() =>
          {
          if (!slots.ContainsKey(id))
          {
          var slot = Thread.GetNamedDataSlot(GetType().FullName);
          slots.Add(id, slot);
          Thread.SetData(slot, new Hashtable());
          }
          });
      return (IDictionary) Thread.GetData(slots[id]);
    }

    void within_lock(Action action)
    {
      lock (mutex) action();
    }
  }
}