// 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;
using System.Collections.Generic;
using Microsoft.AspNet.Http;
using Moq;
using Xunit;

namespace Microsoft.AspNet.Mvc
{
    public class SessionStateTempDataProviderTest
    {
        [Fact]
        public void Load_NullSession_ReturnsEmptyDictionary()
        {
            // Arrange
            var testProvider = new SessionStateTempDataProvider();

            // Act
            var tempDataDictionary = testProvider.LoadTempData(
                GetHttpContext(session: null, sessionEnabled: true));

            // Assert
            Assert.Empty(tempDataDictionary);
        }

        [Fact]
        public void Load_NonNullSession_NoSessionData_ReturnsEmptyDictionary()
        {
            // Arrange
            var testProvider = new SessionStateTempDataProvider();

            // Act
            var tempDataDictionary = testProvider.LoadTempData(
                GetHttpContext(Mock.Of<ISessionCollection>()));

            // Assert
            Assert.Empty(tempDataDictionary);
        }

        [Fact]
        public void Save_NullSession_NullDictionary_DoesNotThrow()
        {
            // Arrange
            var testProvider = new SessionStateTempDataProvider();

            // Act & Assert (does not throw)
            testProvider.SaveTempData(GetHttpContext(session: null, sessionEnabled: false), null);
        }

        [Fact]
        public void Save_NullSession_EmptyDictionary_DoesNotThrow()
        {
            // Arrange
            var testProvider = new SessionStateTempDataProvider();

            // Act & Assert (does not throw)
            testProvider.SaveTempData(
                GetHttpContext(session: null, sessionEnabled: false), new Dictionary<string, object>());
        }

        [Fact]
        public void Save_NullSession_NonEmptyDictionary_Throws()
        {
            // Arrange
            var testProvider = new SessionStateTempDataProvider();

            // Act & Assert
            Assert.Throws<InvalidOperationException>(() =>
            {
                testProvider.SaveTempData(
                    GetHttpContext(session: null, sessionEnabled: false),
                    new Dictionary<string, object> { { "foo", "bar" } }
                );
            });
        }

        private HttpContext GetHttpContext(ISessionCollection session, bool sessionEnabled=true)
        {
            var httpContext = new Mock<HttpContext>();
            if (session != null)
            {
                httpContext.Setup(h => h.Session).Returns(session);
            }
            else if (!sessionEnabled)
            {
                httpContext.Setup(h => h.Session).Throws<InvalidOperationException>();
            }
            if (sessionEnabled)
            {
                httpContext.Setup(h => h.GetFeature<ISessionFeature>()).Returns(Mock.Of<ISessionFeature>());
                httpContext.Setup(h => h.Session[It.IsAny<string>()]);
            }
            return httpContext.Object;
        }
    }
}