// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System.Collections.Generic;
using Microsoft.AspNet.Http;
using Microsoft.Framework.Internal;

namespace Microsoft.AspNet.Routing.Constraints
{
    /// <summary>
    /// Defines a constraint on an optional parameter. If the parameter is present, then it is constrained by InnerConstraint. 
    /// </summary>
    public class OptionalRouteConstraint : IRouteConstraint
    {
        public OptionalRouteConstraint([NotNull] IRouteConstraint innerConstraint)
        {
            InnerConstraint = innerConstraint;
        }

        public IRouteConstraint InnerConstraint { get; }

        public bool Match([NotNull] HttpContext httpContext,
                          [NotNull] IRouter route,
                          [NotNull] string routeKey,
                          [NotNull] IDictionary<string, object> values,
                          RouteDirection routeDirection)
        {
            object value;
            if (values.TryGetValue(routeKey, out value))
            {
                return InnerConstraint.Match(httpContext,
                                             route,
                                             routeKey,
                                             values,
                                             routeDirection);
            }

            return true;
        }
    }
}