# routers.py

class ProjectDatabaseRouter:
    """
    A router to control all database operations on models in the
    simpsons and cloudmanager applications.
    """

    def db_for_read(self, model, **hints):
        """Attempts to read simpsons and cloudmanager models go to their specific dbs."""
        if model._meta.app_label == 'simpsons':
            return 'simpsons_db'
        if model._meta.app_label == 'redirect':
            return 'redirect_db'
        if model._meta.app_label == 'cloudmanager':
            return 'cloudmanager_db'
        return 'default'

    def db_for_write(self, model, **hints):
        """Attempts to write simpsons and cloudmanager models go to their specific dbs."""
        if model._meta.app_label == 'simpsons':
            return 'simpsons_db'
        if model._meta.app_label == 'cloudmanager':
            return 'cloudmanager_db'
        if model._meta.app_label == 'redirect':
            return 'redirect_db'
        return 'default'

    def allow_relation(self, obj1, obj2, **hints):
        """Allow relations if both models are in the same database."""
        # Prevents accidental foreign key relationships across different physical DBs
        if (
                obj1._meta.app_label in ['simpsons', 'cloudmanager','redirect'] or
                obj2._meta.app_label in ['simpsons', 'cloudmanager','redirect']
        ):
            return obj1._meta.app_label == obj2._meta.app_label
        return None

    def allow_migrate(self, db, app_label, model_name=None, **hints):
        """Ensure the app's models only show up in the designated database."""
        if app_label == 'simpsons':
            return db == 'simpsons_db'
        if app_label == 'cloudmanager':
            return db == 'cloudmanager_db'
        if app_label == 'redirect':
            return 'redirect_db'
        # Ensure default Django apps (auth, sessions, etc.) don't migrate into simpsons/cloudmanager
        if db in ['simpsons_db', 'cloudmanager_db','redirect_db']:
            return False

        return None