EHR Integration: HL7, FHIR Standards, and Healthcare Interoperability

class HL7Parser:
    """Parse HL7 v2 messages"""
    
    def parse_hl7_message(self, message: str) -> dict:
        """Parse HL7 message"""
        
        segments = message.split('\r')
        parsed = {}
        
        for segment in segments:
            fields = segment.split('|')
            segment_type = fields[0]
            
            if segment_type == 'MSH':  # Message header
                parsed['message_type'] = fields[9]
                parsed['message_id'] = fields[10]
            
            elif segment_type == 'PID':  # Patient identification
                parsed['patient'] = {
                    'id': fields[3],
                    'name': fields[5],
                    'dob': fields[7],
                    'gender': fields[8]
                }
            
            elif segment_type == 'OBX':  # Observation
                parsed['observation'] = {
                    'type': fields[3],
                    'value': fields[5],
                    'units': fields[6]
                }
        
        return parsed

# Example HL7 message
hl7_message = """MSH|^~\\&|SendingApp|SendingFac|ReceivingApp|ReceivingFac|20250122120000||ADT^A01|MSG00001|P|2.5
PID|||12345^^^MRN||Doe^John||19800101|M|||123 Main St^^City^State^12345
OBX|1|NM|72514-3^GLUCOSE^LN||95|mg/dL|70-100|N|||F"""

parser = HL7Parser()
parsed = parser.parse_hl7_message(hl7_message)
print(f"Patient: {parsed['patient']['name']}")

from fastapi import FastAPI, HTTPException
from pydantic import BaseModel
from typing import Optional
import json

app = FastAPI()

class PatientResource(BaseModel):
    """FHIR Patient resource"""
    resourceType: str = "Patient"
    id: str
    name: list
    birthDate: str
    gender: str
    address: Optional[list] = None
    telecom: Optional[list] = None

@app.get("/fhir/Patient/{patient_id}")
async def get_patient(patient_id: str) -> PatientResource:
    """Get patient by ID (FHIR API)"""
    
    # Query database
    patient = db.query("SELECT * FROM patients WHERE id = ?", (patient_id,))
    
    if not patient:
        raise HTTPException(status_code=404, detail="Patient not found")
    
    p = patient[0]
    
    return PatientResource(
        id=p['id'],
        name=[{'given': [p['first_name']], 'family': p['last_name']}],
        birthDate=p['dob'],
        gender=p['gender'],
        address=[{
            'line': [p['address']],
            'city': p['city'],
            'state': p['state'],
            'postalCode': p['zip']
        }],
        telecom=[{'system': 'phone', 'value': p['phone']}]
    )

@app.post("/fhir/Patient")
async def create_patient(patient: PatientResource) -> PatientResource:
    """Create new patient (FHIR API)"""
    
    # Validate FHIR resource
    if patient.resourceType != "Patient":
        raise HTTPException(status_code=400, detail="Invalid resource type")
    
    # Store in database
    db.insert('patients', {
        'id': patient.id,
        'first_name': patient.name[0]['given'][0],
        'last_name': patient.name[0]['family'],
        'dob': patient.birthDate,
        'gender': patient.gender
    })
    
    return patient

class HL7ToFHIRConverter:
    """Convert HL7 v2 to FHIR"""
    
    def convert_patient(self, hl7_patient: dict) -> dict:
        """Convert HL7 patient to FHIR"""
        
        return {
            'resourceType': 'Patient',
            'id': hl7_patient['id'],
            'name': [{
                'given': [hl7_patient['first_name']],
                'family': hl7_patient['last_name']
            }],
            'birthDate': hl7_patient['dob'],
            'gender': hl7_patient['gender'].lower()
        }
    
    def convert_observation(self, hl7_obs: dict) -> dict:
        """Convert HL7 observation to FHIR"""
        
        return {
            'resourceType': 'Observation',
            'status': 'final',
            'code': {
                'coding': [{
                    'system': 'http://loinc.org',
                    'code': hl7_obs['code'],
                    'display': hl7_obs['display']
                }]
            },
            'valueQuantity': {
                'value': float(hl7_obs['value']),
                'unit': hl7_obs['units']
            }
        }

# Usage
converter = HL7ToFHIRConverter()

hl7_patient = {
    'id': '12345',
    'first_name': 'John',
    'last_name': 'Doe',
    'dob': '1980-01-01',
    'gender': 'M'
}

fhir_patient = converter.convert_patient(hl7_patient)
print(json.dumps(fhir_patient, indent=2))