Innovenergy_trunk/csharp/App/Backend/Relations/Session.cs

using InnovEnergy.App.Backend.Database;
using InnovEnergy.App.Backend.DataTypes;
using InnovEnergy.App.Backend.DataTypes.Methods;
using SQLite;

namespace InnovEnergy.App.Backend.Relations;

public class Session : Relation<String, Int64>
{
    public static TimeSpan MaxAge { get; } = TimeSpan.FromDays(1);

    [Unique ] public String   Token    { get => Left ; init => Left  = value;}
    [Indexed] public Int64    UserId   { get => Right; init => Right = value;}
    [Indexed] public DateTime LastSeen { get; set; }
    public Boolean AccessToSalimax     { get; set; } = false;
    public Boolean AccessToSalidomo    { get; set; } = false;
    [Ignore]  public Boolean Valid => DateTime.Now - LastSeen <=MaxAge ;
    
    // Private backing field
    private User? _User;

    [Ignore] public User User
    {
        get => _User ??= Db.GetUserById(UserId)!;
        set => _User =value;
    }
    

    [Obsolete("To be used only by deserializer")]
    public Session()
    {}

    //We need to return a session object to the frontend. Only the public fields can be included.
    //For this reason, we use the public User User. It is a public field but ignored, so it can be included to the object returned
    //to the frontend but it will not get inserted to the database.
    //When we initialize it like that: User =  Db.GetUserById(user.Id)!, the set will be called and the private member will be initialized as well.
    //What if the getSession method is called from another function of the controller?
    //GetSession will retrieve a session object from the database, but this does not have the metadata included (the private fields and the ignored public fields)
    //Thus, the get will be called and the private field _User will be initialized on the fly.
    public Session(User user)
    {
        User =  Db.GetUserById(user.Id)!;
        Token    = CreateToken();
        UserId   = user.Id;
        LastSeen = DateTime.Now;
        AccessToSalimax = user.AccessibleInstallations(product: 0).ToList().Count > 0;
        AccessToSalidomo = user.AccessibleInstallations(product: 1).ToList().Count > 0;
    }
    
    private static String CreateToken()
    {
        return Guid.NewGuid().ToString("N");
    }
    
}