import json
from datetime import datetime, timezone
from typing import Dict, Any, List, Optional
from uuid import uuid4

from sqlalchemy.orm import Session
from app.database.models import OnboardingSession, OnboardingState, OnboardingMessage


def export_session_to_fhir_bundle(session_id: str, db: Session) -> Dict[str, Any]:
    """
    Exports a completed or in-progress onboarding session state into standard HL7 FHIR R4 Bundle.
    Resources Generated:
    1. Patient (Demographics)
    2. Encounter (Clinical Intake Session)
    3. Condition (Symptoms & Past Medical History)
    4. MedicationStatement (Current Active Medications)
    5. AllergyIntolerance (Confirmed Allergies)
    """
    sess = db.query(OnboardingSession).filter(OnboardingSession.session_id == session_id).first()
    if not sess:
        raise ValueError(f"Session {session_id} not found.")

    state_obj = db.query(OnboardingState).filter(OnboardingState.session_id == session_id).first()
    state_data = json.loads(state_obj.state_json) if state_obj and state_obj.state_json else {}

    now_iso = datetime.now(timezone.utc).isoformat()
    patient_ref = f"Patient/{sess.patient_id or 'PAT-UNKNOWN'}"
    encounter_id = f"enc-{session_id.lower()}"

    entries: List[Dict[str, Any]] = []

    # 1. FHIR Patient Resource
    patient_resource = {
        "resourceType": "Patient",
        "id": sess.patient_id or "PAT-UNKNOWN",
        "identifier": [{
            "system": "http://hospital.org/patients",
            "value": sess.patient_id or "PAT-UNKNOWN"
        }],
        "name": [{
            "text": sess.patient_name or "Patient",
            "family": (sess.patient_name or "Patient").split()[-1],
            "given": (sess.patient_name or "Patient").split()[:-1] or [sess.patient_name or "Patient"]
        }],
        "gender": sess.gender if sess.gender in ["male", "female", "other"] else "unknown"
    }
    entries.append({"resource": patient_resource})

    # 2. FHIR Encounter Resource
    encounter_resource = {
        "resourceType": "Encounter",
        "id": encounter_id,
        "status": "finished" if sess.status == "completed" else "in-progress",
        "class": {
            "system": "http://terminology.hl7.org/CodeSystem/v3-ActCode",
            "code": "AMB",
            "display": "ambulatory"
        },
        "type": [{
            "coding": [{
                "system": "http://snomed.info/sct",
                "code": "32485007",
                "display": "Hospital admission intake"
            }],
            "text": sess.category_name or "General Intake"
        }],
        "subject": {"reference": patient_ref},
        "period": {
            "start": sess.created_at.isoformat() if sess.created_at else now_iso
        }
    }
    entries.append({"resource": encounter_resource})

    # 3. FHIR Condition Resources (Symptoms)
    symptoms = state_data.get("symptoms", [])
    if isinstance(symptoms, list):
        for idx, sym in enumerate(symptoms):
            if isinstance(sym, dict) and sym.get("name"):
                cond_resource = {
                    "resourceType": "Condition",
                    "id": f"cond-sym-{idx+1}-{uuid4().hex[:4]}",
                    "clinicalStatus": {
                        "coding": [{
                            "system": "http://terminology.hl7.org/CodeSystem/condition-clinical",
                            "code": "active"
                        }]
                    },
                    "category": [{
                        "coding": [{
                            "system": "http://terminology.hl7.org/CodeSystem/condition-category",
                            "code": "encounter-diagnosis",
                            "display": "Encounter Diagnosis"
                        }]
                    }],
                    "code": {
                        "text": sym["name"]
                    },
                    "subject": {"reference": patient_ref},
                    "encounter": {"reference": f"Encounter/{encounter_id}"},
                    "onsetDateTime": now_iso,
                    "note": [{"text": f"Duration: {sym.get('duration', 'N/A')}, Severity: {sym.get('severity', 'N/A')}"}]
                }
                entries.append({"resource": cond_resource})

    # 4. FHIR Condition Resources (Medical History)
    history = state_data.get("medical_history", [])
    if isinstance(history, list):
        for idx, hist in enumerate(history):
            cond_name = hist.get("condition") if isinstance(hist, dict) else str(hist)
            if cond_name:
                cond_resource = {
                    "resourceType": "Condition",
                    "id": f"cond-hist-{idx+1}-{uuid4().hex[:4]}",
                    "clinicalStatus": {
                        "coding": [{
                            "system": "http://terminology.hl7.org/CodeSystem/condition-clinical",
                            "code": "active"
                        }]
                    },
                    "category": [{
                        "coding": [{
                            "system": "http://terminology.hl7.org/CodeSystem/condition-category",
                            "code": "problem-list-item",
                            "display": "Problem List Item"
                        }]
                    }],
                    "code": {
                        "text": cond_name
                    },
                    "subject": {"reference": patient_ref}
                }
                entries.append({"resource": cond_resource})

    # 5. FHIR MedicationStatement Resources
    medications = state_data.get("medications", [])
    if isinstance(medications, list):
        for idx, med in enumerate(medications):
            med_name = med.get("name") if isinstance(med, dict) else str(med)
            dosage_str = med.get("dosage", "") if isinstance(med, dict) else ""
            if med_name:
                med_resource = {
                    "resourceType": "MedicationStatement",
                    "id": f"med-{idx+1}-{uuid4().hex[:4]}",
                    "status": "active",
                    "medicationCodeableConcept": {
                        "text": med_name
                    },
                    "subject": {"reference": patient_ref},
                    "dosage": [{"text": dosage_str}] if dosage_str else []
                }
                entries.append({"resource": med_resource})

    # 6. FHIR AllergyIntolerance Resources
    allergies = state_data.get("allergies", [])
    if isinstance(allergies, list):
        for idx, alg in enumerate(allergies):
            alg_name = alg.get("name") if isinstance(alg, dict) else str(alg)
            if alg_name:
                alg_resource = {
                    "resourceType": "AllergyIntolerance",
                    "id": f"alg-{idx+1}-{uuid4().hex[:4]}",
                    "clinicalStatus": {
                        "coding": [{
                            "system": "http://terminology.hl7.org/CodeSystem/allergyintolerance-clinical",
                            "code": "active"
                        }]
                    },
                    "code": {
                        "text": alg_name
                    },
                    "patient": {"reference": patient_ref}
                }
                entries.append({"resource": alg_resource})

    # Assemble FHIR R4 Bundle
    fhir_bundle = {
        "resourceType": "Bundle",
        "id": f"bundle-{session_id.lower()}",
        "type": "collection",
        "timestamp": now_iso,
        "total": len(entries),
        "entry": entries
    }

    return fhir_bundle