public class Student
{
    public int Id {get;set;}

    [Required(ErrorMessage = "请输入姓名")]
    [Display(Name="名字")]
    public string Name {get; set;}

    [Required]
    [Display(Name="主修科目")]
    public MajorEnum? Major {get;set;}

    [Display(Name = "电子邮件")]
    public string Email{get;set;}
}

public enum MajorEnum
{
    语文,
    英语,
    数学,
    化学 
}

public class HomeDetailsViewModel
{
   public Student student {get;set;}

    public string PageTitle {get;set;}

}

public interface IStudentRepository
{
    Student GetStudent(int id);

    IEnumerable<Student> GetAllStudents();

    Student Add(Student student);
}

public class MockStudentRepositry:IStudentRepository
   {
       private List<Student> _studentList ;

       public MockStudentRepositry()
       {
           _studentList = new List<Student>()
           {
               new Student() { Id = 1, Name = "张三", Major = MajorEnum.化学, Email = "[email protected]" },
               new Student() { Id = 2, Name = "李四", Major = MajorEnum.英语, Email = "[email protected]" },
               new Student() { Id = 3, Name = "王二麻子", Major = MajorEnum.数学, Email = "[email protected]" },
           };
       }


       public Student Add(Student student)
       {
           student.Id = _studentList.Max(s => s.Id) + 1;
           _studentList.Add(student);
           return student;
       }


       public IEnumerable<Student> GetAllStudents()
       {
           return _studentList;
       }

       public Student GetStudent(int id)
       {
           return _studentList.FirstOrDefault(a => a.Id == id);
       } 
   }

public class HomeController : Controller
{
    private readonly ILogger<HomeController> _logger;
    private readonly IStudentRepository _studentRepository;

    public HomeController(ILogger<HomeController> logger, IStudentRepository studentRepository)
    {
        _studentRepository = studentRepository;
        _logger = logger;
    }

    public IActionResult Index()
    {
        IEnumerable<Student> students = _studentRepository.GetAllStudents();
        return View(students);
    }

    public IActionResult Details(int? id)
    {
        HomeDetailsViewModel homeDetailsViewModel = new HomeDetailsViewModel()
        {
            student = _studentRepository.GetStudent(id ?? 1),
            PageTitle = "学生详细信息"
        };
        return View(homeDetailsViewModel);
    }

   [HttpGet]
   public ViewResult Create()
   {
       return View();
   }

   [HttpPost]
   public IActionResult Create(Student student)
   {
       if(ModelState.IsValid)
       {
           Student newStudent = _studentRepository.Add(student);
           return View();//RedirectToAction("Details", new {id = newStudent.Id});
       }
       return View();
   }
}