"""
Password State Tracker

Tracks password state for students after password reset to prevent ambiguity.
After a successful password reset, we update the tracked password so subsequent
tests use the correct password.
"""
from typing import Dict, Optional


class PasswordTracker:
    """
    Tracks password state for students.
    
    After a successful password reset, the password is updated in memory
    so subsequent tests use the correct password.
    """
    
    _instance: Optional['PasswordTracker'] = None
    _passwords: Dict[str, str] = {}  # CPID -> current password
    
    def __new__(cls):
        """Singleton pattern"""
        if cls._instance is None:
            cls._instance = super().__new__(cls)
        return cls._instance
    
    def get_password(self, cpid: str, default_password: str) -> str:
        """
        Get current password for a student.
        
        Args:
            cpid: Student CPID
            default_password: Default/initial password (if not tracked)
            
        Returns:
            str: Current password (tracked or default)
        """
        return self._passwords.get(cpid, default_password)
    
    def update_password(self, cpid: str, new_password: str):
        """
        Update password for a student after successful reset.
        
        Args:
            cpid: Student CPID
            new_password: New password (after reset)
        """
        self._passwords[cpid] = new_password
        print(f"✅ Password updated for {cpid} - future tests will use new password")
    
    def reset_tracker(self):
        """Reset all tracked passwords (useful for test cleanup)"""
        self._passwords.clear()
        print("✅ Password tracker reset")
    
    def clear_student(self, cpid: str):
        """Clear password tracking for a specific student"""
        if cpid in self._passwords:
            del self._passwords[cpid]
            print(f"✅ Password tracking cleared for {cpid}")


# Global instance
password_tracker = PasswordTracker()