import logging

logger = logging.getLogger("MatroskaConstraints")

class ConstraintEngine:
    """
    Protocol 15: Matroska Shell Constraints.
    Enforces Topological Rules.
    """
    
    @staticmethod
    def validate_transport(data_entropy, target_shell):
        """
        Validates if Data Entropy is compatible with Target Shell.
        Returns (True, None) or (False, Reason).
        """
        # Rule 1: High Entropy (Hot) cannot be in Cold Storage (Inner Shell)
        if data_entropy > 0.6 and target_shell == "INNER_SHELL":
            return False, "CONTAMINATION_RISK: High Entropy Data in Structural Shell"
            
        # Rule 2: Low Entropy (Cold) cannot waste Fast Lane (Outer Shell)
        # (Soft Warning - we allow it but flag it)
        if data_entropy < 0.2 and target_shell == "OUTER_SHELL":
            logger.warning("Inefficient Transport: Cold Data in Fast Lane")
            
        return True, None

    @staticmethod
    def filter_payload(payload_bytes, shell):
        """
        Filters payload based on Shell Physics.
        """
        # Implementation of 2-bit Bucket Logic filtering
        # If Shell is Inner (Structure), we only allow Context/Bucket bits,
        # filtering out high-frequency Cycle bits if needed.
        return payload_bytes # Passthrough for V1