ROLAC/API/ROLAC.API/Data/AppDbContext.cs

using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;
using ROLAC.API.Entities;

namespace ROLAC.API.Data;

public class AppDbContext : IdentityDbContext<AppUser, AppRole, string>
{
    public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) { }

    public DbSet<RefreshToken> RefreshTokens => Set<RefreshToken>();

    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);

        builder.Entity<RefreshToken>(entity =>
        {
            entity.HasKey(e => e.Id);

            // Unique index on hash — enables fast lookup and prevents duplicate tokens
            entity.HasIndex(e => e.TokenHash).IsUnique();

            entity.Property(e => e.TokenHash).HasMaxLength(64).IsRequired();
            entity.Property(e => e.UserId).HasMaxLength(450).IsRequired();
            entity.Property(e => e.DeviceInfo).HasMaxLength(200);
            entity.Property(e => e.IpAddress).HasMaxLength(45);
            entity.Property(e => e.ReplacedByHash).HasMaxLength(64);

            entity.HasOne(e => e.User)
                  .WithMany(u => u.RefreshTokens)
                  .HasForeignKey(e => e.UserId)
                  .OnDelete(DeleteBehavior.Cascade);

            // Computed properties are not DB columns
            entity.Ignore(e => e.IsExpired);
            entity.Ignore(e => e.IsRevoked);
            entity.Ignore(e => e.IsActive);
        });

        builder.Entity<AppUser>(entity =>
        {
            entity.Property(e => e.LanguagePreference).HasMaxLength(10).HasDefaultValue("en");
        });

        builder.Entity<AppRole>(entity =>
        {
            entity.Property(e => e.Description).HasMaxLength(500);
        });
    }
}