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

namespace Wayne.Lib.MessageBus
{
    /// <summary>
    /// A very basic, fully synchronous bus implementation. The publish method
    /// will execute all subscribe actions.
    /// </summary>
    public class BasicBus : IBus
    {
        readonly object subscriptionsLock = new object();
        readonly List<SubscriptionBase> subscriptions = new List<SubscriptionBase>();

        public void Publish(string topic, object message)
        {
            SubscriptionBase[] iterationSubscriptions;
            lock (subscriptionsLock)
            {
                iterationSubscriptions = subscriptions.ToArray();
            }

            iterationSubscriptions
                .Where(x => x.TopicFilter.IsMatch(topic)) 
                .Where(x => x.Type.IsInstanceOfType(message))
                .ForEach(x =>
                {
                    x.Invoke(topic, message);
                });
        }

        public IDisposable Subscribe<T>(string topicFilter, Action<string, T> action)
        {
            var subscription = new Subscription<T>()
            {
                TopicFilter = new Regex("^" + topicFilter.Replace("*", "[^/]*") + "$"),
                InvokeAction = action
            };

            lock (subscriptionsLock)
            {
                subscriptions.Add(subscription);
            }

            return new ActionDisposable(() =>
            {
                lock (subscriptionsLock)
                {
                    subscriptions.Remove(subscription);
                }
            });
        }
    }
}