using System;
using System.Threading.Tasks;
using Microsoft.VisualStudio.TestTools.UnitTesting;

// Import XamChat Libraries
using XamChat3.Mocks;
using XamChat3.Interfaces;
using XamChat3.ViewModels;

namespace XamChat3.Tests
{
    [TestClass]
    public class LoginViewModelTest
    {
        // Add fields for dependencies
        LoginViewModel viewModel;
        ISettings settings;

        // A method for performing test setup - initialisation steps
        [TestInitialize]
        public void Setup()
        {
            // Register and initialise the Service Container IoC dependencies.
            ServiceContainer.Register<IWebService>(() => new MockWebService { SleepDuration = 0 });
            ServiceContainer.Register<ISettings>(() => new MockSettings());

            // Retrieve injected dependencies from the Service Container IoC and store references to them.
            settings = ServiceContainer.Resolve<ISettings>();
            viewModel = new LoginViewModel();
        }

        [TestMethod]
        public async Task LoginSuccessful_WhenValidLoginDetails()
        {
            // Arrange
            viewModel.Username = "testuser";
            viewModel.Password = "password";

            // Act
            await viewModel.LoginAsync();

            // Assert
            Assert.IsNotNull(settings.User);
        }


        // This test expects an exception to be returned, but it does not check the exception method.
        // To check agains the exception message you will need to write an extension method or SEE the next example
        // See more: https://stackoverflow.com/questions/20494105/expectedexception-assert
        //      https://github.com/bbraithwaite/MSTestExtensions
        [TestMethod, ExpectedException(typeof(Exception))]
        public async Task LoginThrowsException_WhenNoLoginDetails()
        {
            // Arrange - nothing to arrange

            // Act - should throw an exception
            await viewModel.LoginAsync();

            // Assert - nothing to assert as exception is expected in previous step
        }


        // Alternative test which checks the specific exception message returned.
        [TestMethod]
        public async Task LoginThrowsException_WhenUsernameIsBlank()
        {
            // Arrange
            Exception resultException = null;
            viewModel.Username = null;
            viewModel.Password = "password";

            // Act - use try { } catch { } block to catch the expected exception
            try
            {
                await viewModel.LoginAsync();
            } catch (Exception ex)
            {
                resultException = ex;
            }

            // Assert - make sure the message you are comparing with is what you have written in your LoginViewModel
            Assert.AreEqual("Username is blank.", resultException.Message);
        }


        [TestMethod]
        public async Task LoginThrowsException_WhenPasswordIsBlank()
        {
            // Arrange
            Exception resultException = null;
            viewModel.Username = "testuser";
            viewModel.Password = null;

            // Act - use try { } catch { } block to catch the expected exception
            try
            {
                await viewModel.LoginAsync();
            }
            catch (Exception ex)
            {
                resultException = ex;
            }

            // Assert - make sure the message you are comparing with is what you have written in your LoginViewModel
            Assert.AreEqual("Password is blank.", resultException.Message);
        }

        // This test will fail as the MockWebService does not currently have this functionality
        [TestMethod]
        public async Task LoginThrowsException_WhenUsernameIsInvalid()
        {
            // Arrange
            Exception resultException = null;
            viewModel.Username = "someuser";
            viewModel.Password = "password";

            // Act - use try { } catch { } block to catch the expected exception
            try
            {
                await viewModel.LoginAsync();
            }
            catch (Exception ex)
            {
                resultException = ex;
            }

            // Assert - make sure the message you are comparing with is what you have written in your LoginViewModel
            Assert.AreEqual("Invalid login details.", resultException.Message);
        }

        // This test will fail as the MockWebService does not currently have this functionality
        [TestMethod]
        public async Task LoginThrowsException_WhenPasswordIsInvalid()
        {
            // Arrange
            Exception resultException = null;
            viewModel.Username = "testuser";
            viewModel.Password = "nopassword";

            // Act - use try { } catch { } block to catch the expected exception
            try
            {
                await viewModel.LoginAsync();
            }
            catch (Exception ex)
            {
                resultException = ex;
            }

            // Assert - make sure the message you are comparing with is what you have written in your LoginViewModel
            Assert.AreEqual("Invalid login details.", resultException.Message);
        }

    }
}