academia/tests/Common/Builders/SubjectBuilder.cs

namespace Common.Builders;

using Domain.Entities;

/// <summary>
/// Builder pattern for creating Subject test objects.
/// Encapsulates reflection-based ID and navigation property setting.
/// </summary>
public class SubjectBuilder
{
    private int _id = 1;
    private string _name = "Mathematics";
    private int _professorId = 1;
    private Professor? _professor;

    public SubjectBuilder WithId(int id)
    {
        _id = id;
        return this;
    }

    public SubjectBuilder WithName(string name)
    {
        _name = name;
        return this;
    }

    public SubjectBuilder WithProfessorId(int professorId)
    {
        _professorId = professorId;
        return this;
    }

    public SubjectBuilder WithProfessor(Professor professor)
    {
        _professor = professor;
        _professorId = professor.Id;
        return this;
    }

    public Subject Build()
    {
        var subject = new Subject(_name, _professorId);
        SetProperty(subject, "Id", _id);

        if (_professor is not null)
            SetProperty(subject, "Professor", _professor);

        return subject;
    }

    private static void SetProperty<T>(T obj, string propertyName, object value) where T : class =>
        typeof(T).GetProperty(propertyName)!.SetValue(obj, value);
}