"""
HIPAA Compliance Implementation
Health Insurance Portability and Accountability Act compliance features.
"""

import time
import uuid
import logging
import threading
import hashlib
from typing import Dict, List, Optional, Any
from dataclasses import dataclass
from datetime import datetime
from enum import Enum

logger = logging.getLogger(__name__)


class PHIType(Enum):
    """Protected Health Information types."""
    DEMOGRAPHIC = "demographic"
    MEDICAL_RECORDS = "medical_records"
    BILLING = "billing"
    INSURANCE = "insurance"
    TREATMENT = "treatment"
    PRESCRIPTION = "prescription"


class AccessPurpose(Enum):
    """HIPAA access purposes."""
    TREATMENT = "treatment"
    PAYMENT = "payment"
    OPERATIONS = "operations"
    RESEARCH = "research"
    PUBLIC_HEALTH = "public_health"
    LEGAL = "legal"


class BreachRiskLevel(Enum):
    """Breach risk assessment levels."""
    LOW = "low"
    MEDIUM = "medium"
    HIGH = "high"


@dataclass
class PHIRecord:
    """Protected Health Information record."""
    phi_id: str
    patient_id: str
    phi_type: PHIType
    data_value: Any
    created_at: float
    accessed_by: List[str]
    encrypted: bool = True
    minimum_necessary: bool = True
    retention_years: int = 6
    
    def __post_init__(self):
        if not self.phi_id:
            self.phi_id = str(uuid.uuid4())
        if not self.accessed_by:
            self.accessed_by = []
    
    def is_expired(self) -> bool:
        """Check if PHI retention period has expired."""
        expiry_time = self.created_at + (self.retention_years * 365 * 24 * 3600)
        return time.time() > expiry_time


@dataclass
class AccessLog:
    """HIPAA access log entry."""
    log_id: str
    user_id: str
    patient_id: str
    phi_accessed: str
    access_time: float
    purpose: AccessPurpose
    ip_address: str
    user_agent: str
    authorized: bool = True
    
    def __post_init__(self):
        if not self.log_id:
            self.log_id = str(uuid.uuid4())


@dataclass
class BreachIncident:
    """HIPAA breach incident record."""
    incident_id: str
    discovered_at: float
    incident_type: str
    affected_individuals: int
    phi_involved: List[str]
    risk_assessment: BreachRiskLevel
    notification_required: bool
    reported_to_hhs: bool = False
    individuals_notified: bool = False
    media_notification: bool = False
    
    def __post_init__(self):
        if not self.incident_id:
            self.incident_id = str(uuid.uuid4())
        # Determine if breach notification required (500+ individuals)
        self.notification_required = self.affected_individuals >= 500


class PHIProtection:
    """Protected Health Information protection system."""
    
    def __init__(self):
        self.phi_records: Dict[str, PHIRecord] = {}
        self.access_logs: List[AccessLog] = []
        self.authorized_users: Dict[str, List[AccessPurpose]] = {}
        self.lock = threading.Lock()
    
    def store_phi(self, patient_id: str, phi_type: PHIType, data_value: Any,
                  encrypted: bool = True) -> str:
        """Store PHI with HIPAA protections."""
        phi_record = PHIRecord(
            phi_id=str(uuid.uuid4()),
            patient_id=patient_id,
            phi_type=phi_type,
            data_value=self._encrypt_data(data_value) if encrypted else data_value,
            created_at=time.time(),
            accessed_by=[],
            encrypted=encrypted
        )
        
        with self.lock:
            self.phi_records[phi_record.phi_id] = phi_record
        
        logger.info(f"Stored PHI record {phi_record.phi_id} for patient {patient_id}")
        return phi_record.phi_id
    
    def access_phi(self, user_id: str, phi_id: str, purpose: AccessPurpose,
                   ip_address: str = "", user_agent: str = "") -> Optional[Any]:
        """Access PHI with authorization and logging."""
        # Check authorization
        if not self._is_authorized(user_id, purpose):
            self._log_access(user_id, "", phi_id, purpose, ip_address, user_agent, False)
            raise PermissionError("User not authorized for this access purpose")
        
        with self.lock:
            phi_record = self.phi_records.get(phi_id)
            if not phi_record:
                return None
            
            # Log access
            self._log_access(user_id, phi_record.patient_id, phi_id, purpose, 
                           ip_address, user_agent, True)
            
            # Track access
            if user_id not in phi_record.accessed_by:
                phi_record.accessed_by.append(user_id)
            
            # Return decrypted data if encrypted
            if phi_record.encrypted:
                return self._decrypt_data(phi_record.data_value)
            return phi_record.data_value
    
    def _is_authorized(self, user_id: str, purpose: AccessPurpose) -> bool:
        """Check if user is authorized for access purpose."""
        with self.lock:
            user_purposes = self.authorized_users.get(user_id, [])
            return purpose in user_purposes
    
    def _log_access(self, user_id: str, patient_id: str, phi_id: str,
                   purpose: AccessPurpose, ip_address: str, user_agent: str,
                   authorized: bool):
        """Log PHI access."""
        access_log = AccessLog(
            log_id=str(uuid.uuid4()),
            user_id=user_id,
            patient_id=patient_id,
            phi_accessed=phi_id,
            access_time=time.time(),
            purpose=purpose,
            ip_address=ip_address,
            user_agent=user_agent,
            authorized=authorized
        )
        
        with self.lock:
            self.access_logs.append(access_log)
    
    def _encrypt_data(self, data: Any) -> str:
        """Encrypt PHI data (simplified)."""
        data_str = str(data)
        return hashlib.sha256(data_str.encode()).hexdigest()
    
    def _decrypt_data(self, encrypted_data: str) -> str:
        """Decrypt PHI data (simplified - in practice use proper encryption)."""
        return "[ENCRYPTED_PHI_DATA]"
    
    def authorize_user(self, user_id: str, purposes: List[AccessPurpose]):
        """Authorize user for specific access purposes."""
        with self.lock:
            self.authorized_users[user_id] = purposes
        logger.info(f"Authorized user {user_id} for purposes: {[p.value for p in purposes]}")


class SecurityRule:
    """HIPAA Security Rule implementation."""
    
    def __init__(self):
        self.security_controls: Dict[str, Dict[str, Any]] = {}
        self.risk_assessments: List[Dict[str, Any]] = []
        self.lock = threading.Lock()
    
    def implement_administrative_safeguards(self) -> bool:
        """Implement administrative safeguards."""
        safeguards = {
            "security_officer": {"assigned": True, "name": "HIPAA Security Officer"},
            "workforce_training": {"completed": True, "last_training": time.time()},
            "access_management": {"procedures_documented": True},
            "incident_procedures": {"documented": True, "tested": True}
        }
        
        with self.lock:
            self.security_controls["administrative"] = safeguards
        
        return True
    
    def implement_physical_safeguards(self) -> bool:
        """Implement physical safeguards."""
        safeguards = {
            "facility_access": {"controls_implemented": True},
            "workstation_use": {"restrictions_documented": True},
            "device_controls": {"inventory_maintained": True},
            "media_controls": {"procedures_documented": True}
        }
        
        with self.lock:
            self.security_controls["physical"] = safeguards
        
        return True
    
    def implement_technical_safeguards(self) -> bool:
        """Implement technical safeguards."""
        safeguards = {
            "access_control": {"unique_user_identification": True, "automatic_logoff": True},
            "audit_controls": {"logging_enabled": True, "review_procedures": True},
            "integrity": {"phi_alteration_protection": True},
            "transmission_security": {"encryption_enabled": True}
        }
        
        with self.lock:
            self.security_controls["technical"] = safeguards
        
        return True
    
    def conduct_risk_assessment(self) -> str:
        """Conduct HIPAA risk assessment."""
        assessment_id = str(uuid.uuid4())
        
        # Simplified risk assessment
        risks = [
            {"category": "Access Control", "risk_level": "medium", "mitigation": "Implement role-based access"},
            {"category": "Data Encryption", "risk_level": "low", "mitigation": "Encryption implemented"},
            {"category": "Audit Logging", "risk_level": "low", "mitigation": "Comprehensive logging in place"},
            {"category": "Incident Response", "risk_level": "medium", "mitigation": "Update incident procedures"}
        ]
        
        assessment = {
            "assessment_id": assessment_id,
            "conducted_at": time.time(),
            "risks_identified": risks,
            "overall_risk": "medium",
            "next_assessment": time.time() + (365 * 24 * 3600)  # Annual
        }
        
        with self.lock:
            self.risk_assessments.append(assessment)
        
        logger.info(f"Conducted HIPAA risk assessment {assessment_id}")
        return assessment_id


class PrivacyRule:
    """HIPAA Privacy Rule implementation."""
    
    def __init__(self):
        self.privacy_policies: Dict[str, Dict[str, Any]] = {}
        self.patient_rights: Dict[str, List[str]] = {}
        self.lock = threading.Lock()
    
    def implement_minimum_necessary_standard(self) -> bool:
        """Implement minimum necessary standard."""
        policy = {
            "policy_name": "Minimum Necessary Standard",
            "description": "Limit PHI use/disclosure to minimum necessary",
            "procedures": [
                "Identify minimum PHI needed for each purpose",
                "Implement role-based access controls",
                "Regular review of access permissions",
                "Training on minimum necessary principle"
            ],
            "implemented_at": time.time()
        }
        
        with self.lock:
            self.privacy_policies["minimum_necessary"] = policy
        
        return True
    
    def establish_patient_rights(self, patient_id: str) -> List[str]:
        """Establish patient rights under HIPAA."""
        rights = [
            "right_to_access",
            "right_to_amend",
            "right_to_accounting_of_disclosures",
            "right_to_request_restrictions",
            "right_to_request_confidential_communications",
            "right_to_complain"
        ]
        
        with self.lock:
            self.patient_rights[patient_id] = rights
        
        return rights


class BreachNotification:
    """HIPAA breach notification system."""
    
    def __init__(self):
        self.breach_incidents: Dict[str, BreachIncident] = {}
        self.notification_log: List[Dict[str, Any]] = []
        self.lock = threading.Lock()
    
    def report_breach(self, incident_type: str, affected_individuals: int,
                     phi_involved: List[str], risk_level: BreachRiskLevel) -> str:
        """Report a potential HIPAA breach."""
        incident = BreachIncident(
            incident_id=str(uuid.uuid4()),
            discovered_at=time.time(),
            incident_type=incident_type,
            affected_individuals=affected_individuals,
            phi_involved=phi_involved,
            risk_assessment=risk_level
        )
        
        with self.lock:
            self.breach_incidents[incident.incident_id] = incident
        
        logger.critical(f"HIPAA breach incident {incident.incident_id} reported")
        
        # Check if immediate notification required
        if incident.notification_required:
            self._schedule_notifications(incident.incident_id)
        
        return incident.incident_id
    
    def _schedule_notifications(self, incident_id: str):
        """Schedule required breach notifications."""
        # Individual notification: 60 days
        # HHS notification: 60 days
        # Media notification: 60 days (if 500+ individuals in same state/jurisdiction)
        
        notification = {
            "incident_id": incident_id,
            "individual_notification_deadline": time.time() + (60 * 24 * 3600),
            "hhs_notification_deadline": time.time() + (60 * 24 * 3600),
            "media_notification_deadline": time.time() + (60 * 24 * 3600),
            "scheduled_at": time.time()
        }
        
        with self.lock:
            self.notification_log.append(notification)
        
        logger.warning(f"Breach notifications scheduled for incident {incident_id}")


class BusinessAssociate:
    """Business Associate Agreement management."""
    
    def __init__(self):
        self.agreements: Dict[str, Dict[str, Any]] = {}
        self.lock = threading.Lock()
    
    def create_baa(self, associate_name: str, services: List[str],
                   phi_access: bool = True) -> str:
        """Create Business Associate Agreement."""
        baa_id = str(uuid.uuid4())
        
        agreement = {
            "baa_id": baa_id,
            "associate_name": associate_name,
            "services_provided": services,
            "phi_access_permitted": phi_access,
            "signed_at": time.time(),
            "expires_at": time.time() + (3 * 365 * 24 * 3600),  # 3 years
            "safeguards_required": [
                "Implement administrative safeguards",
                "Implement physical safeguards",
                "Implement technical safeguards",
                "Report breaches within 60 days",
                "Return or destroy PHI upon termination"
            ]
        }
        
        with self.lock:
            self.agreements[baa_id] = agreement
        
        logger.info(f"Created BAA {baa_id} for {associate_name}")
        return baa_id


class HIPAACompliance:
    """Main HIPAA compliance manager."""
    
    def __init__(self, config: Dict[str, Any] = None):
        self.config = config or {}
        self.phi_protection = PHIProtection()
        self.security_rule = SecurityRule()
        self.privacy_rule = PrivacyRule()
        self.breach_notification = BreachNotification()
        self.business_associates = BusinessAssociate()
        self.lock = threading.Lock()
        
        # Initialize safeguards
        self.security_rule.implement_administrative_safeguards()
        self.security_rule.implement_physical_safeguards()
        self.security_rule.implement_technical_safeguards()
        self.privacy_rule.implement_minimum_necessary_standard()
        
        logger.info("HIPAA Compliance Manager initialized")
    
    def process_phi(self, patient_id: str, phi_type: PHIType, data_value: Any,
                   user_id: str, purpose: AccessPurpose) -> str:
        """Process PHI with HIPAA compliance."""
        # Store PHI
        phi_id = self.phi_protection.store_phi(patient_id, phi_type, data_value)
        
        # Log initial access
        self.phi_protection._log_access(user_id, patient_id, phi_id, purpose, "", "", True)
        
        return phi_id
    
    def get_compliance_status(self) -> Dict[str, Any]:
        """Get HIPAA compliance status."""
        with self.lock:
            return {
                "hipaa_compliance": {
                    "phi_protection": {
                        "total_phi_records": len(self.phi_protection.phi_records),
                        "access_logs": len(self.phi_protection.access_logs),
                        "authorized_users": len(self.phi_protection.authorized_users)
                    },
                    "security_rule": {
                        "administrative_safeguards": bool(self.security_rule.security_controls.get("administrative")),
                        "physical_safeguards": bool(self.security_rule.security_controls.get("physical")),
                        "technical_safeguards": bool(self.security_rule.security_controls.get("technical")),
                        "risk_assessments_conducted": len(self.security_rule.risk_assessments)
                    },
                    "privacy_rule": {
                        "privacy_policies": len(self.privacy_rule.privacy_policies),
                        "patient_rights_established": len(self.privacy_rule.patient_rights)
                    },
                    "breach_notification": {
                        "breach_incidents": len(self.breach_notification.breach_incidents),
                        "notifications_scheduled": len(self.breach_notification.notification_log)
                    },
                    "business_associates": {
                        "active_agreements": len(self.business_associates.agreements)
                    }
                }
            }
    
    def cleanup_expired_phi(self) -> int:
        """Clean up expired PHI records."""
        expired_count = 0
        
        with self.lock:
            expired_ids = []
            for phi_id, phi_record in self.phi_protection.phi_records.items():
                if phi_record.is_expired():
                    expired_ids.append(phi_id)
                    expired_count += 1
            
            # Remove expired PHI
            for phi_id in expired_ids:
                del self.phi_protection.phi_records[phi_id]
        
        if expired_count > 0:
            logger.info(f"HIPAA cleanup: removed {expired_count} expired PHI records")
        
        return expired_count
