Quick and easy OWIN pipeline hooks

gistfile1.cs

using AppFunc = Func<IDictionary<string, object>, Task>;

public static class OwinPipelineHookExtensions
{
    public static IAppBuilder UseHooks(
        this IAppBuilder app,
        Action<IDictionary<string, object>> before = null,
        Action<IDictionary<string, object>> after = null)
    {
        return app.Use(new Func<AppFunc, AppFunc>(next => (async env =>
        {
            if (before != null)
            {
                before.Invoke(env);
            }

            await next.Invoke(env);

            if (after != null)
            {
                after.Invoke(env);
            }
        })));
    }
    
    public static IAppBuilder UseHooks<TState>(
        this IAppBuilder app,
        Func<IDictionary<string, object>, TState> before = null,
        Action<TState, IDictionary<string, object>> after = null,
        TState defaultState = default(TState))
    {
        return app.Use(new Func<AppFunc, AppFunc>(next => (async env =>
        {
            TState state = defaultState;

            if (before != null)
            {
                state = before.Invoke(env);
            }
            
            await next.Invoke(env);

            if (after != null)
            {
                after.Invoke(state, env);
            }
        })));
    }

    public static IAppBuilder UseHooksAsync(
        this IAppBuilder app,
        Func<IDictionary<string, object>, Task> before = null,
        Func<IDictionary<string, object>, Task> after = null)
    {
        return app.Use(new Func<AppFunc, AppFunc>(next => (async env =>
        {
            if (before != null)
            {
                await before.Invoke(env);
            }

            await next.Invoke(env);

            if (after != null)
            {
                await after.Invoke(env);
            }
        })));
    }

    public static IAppBuilder UseHooksAsync<TState>(
        this IAppBuilder app,
        Func<IDictionary<string, object>, Task<TState>> before = null,
        Func<TState, IDictionary<string, object>, Task> after = null,
        TState defaultState = default(TState))
    {
        return app.Use(new Func<AppFunc, AppFunc>(next => (async env =>
        {
            TState state = defaultState;

            if (before != null)
            {
                state = await before.Invoke(env);
            }

            await next.Invoke(env);

            if (after != null)
            {
                await after.Invoke(state, env);
            }
        })));
    }
}