using System;
using System.Collections.Generic;
using Microsoft.AspNet.Http;
using Microsoft.AspNet.Routing;

namespace Microsoft.AspNet.SpaServices 
{
    internal class SpaRouteConstraint : IRouteConstraint
    {
        private readonly string clientRouteTokenName;
    
        public SpaRouteConstraint(string clientRouteTokenName) {
            if (string.IsNullOrEmpty(clientRouteTokenName)) {
                throw new ArgumentException("Value cannot be null or empty", "clientRouteTokenName");
            }
            
            this.clientRouteTokenName = clientRouteTokenName;
        }
        
        public bool Match(HttpContext httpContext, IRouter route, string routeKey, IDictionary<string, object> values, RouteDirection routeDirection)
        {
            var clientRouteValue = (values[this.clientRouteTokenName] as string) ?? string.Empty;
            return !HasDotInLastSegment(clientRouteValue);
        }
    
        private bool HasDotInLastSegment(string uri)
        {
            var lastSegmentStartPos = uri.LastIndexOf('/');
            return uri.IndexOf('.', lastSegmentStartPos + 1) >= 0;
        }
    }
}