import re
from typing import Dict, Any, List

# RxNorm / FDA Clinical Interaction Rules
KNOWN_DRUG_INTERACTIONS = [
    {
        "pair": ("warfarin", "aspirin"),
        "severity": "CRITICAL",
        "category": "Drug-Drug Interaction",
        "description": "Concurrent use of Warfarin and Aspirin significantly increases risk of major gastrointestinal and systemic bleeding."
    },
    {
        "pair": ("metformin", "ibuprofen"),
        "severity": "WARNING",
        "category": "Drug-Drug Interaction",
        "description": "NSAIDs like Ibuprofen may impair renal function, increasing risk of Metformin-associated lactic acidosis."
    },
    {
        "pair": ("lisinopril", "spironolactone"),
        "severity": "WARNING",
        "category": "Drug-Drug Interaction",
        "description": "Combining ACE inhibitors with Potassium-sparing diuretics increases risk of severe hyperkalemia."
    },
    {
        "pair": ("ssri", "tramadol"),
        "severity": "CRITICAL",
        "category": "Drug-Drug Interaction",
        "description": "Combining SSRI antidepressants with Tramadol increases risk of Serotonin Syndrome and seizures."
    }
]

# Drug-Allergy Cross-Reactivity Rules
ALLERGY_CROSS_REACTIVITY = [
    {
        "allergy_pattern": r"penicillin|amoxicillin|ampicillin",
        "drug_pattern": r"penicillin|amoxicillin|ampicillin|augmentin|piperacillin",
        "severity": "CRITICAL",
        "category": "Drug-Allergy Contraindication",
        "description": "Patient has reported Penicillin allergy. Prescribing beta-lactam antibiotics poses high risk of severe anaphylaxis."
    },
    {
        "allergy_pattern": r"sulfa|sulfonamide",
        "drug_pattern": r"bactrim|septra|celecoxib|sulfamethoxazole",
        "severity": "WARNING",
        "category": "Drug-Allergy Contraindication",
        "description": "Patient has reported Sulfa allergy. Use caution with sulfonamide medications."
    },
    {
        "allergy_pattern": r"aspirin|nsaid",
        "drug_pattern": r"aspirin|ibuprofen|naproxen|diclofenac",
        "severity": "CRITICAL",
        "category": "Drug-Allergy Contraindication",
        "description": "Patient has reported NSAID/Aspirin hypersensitivity. Risk of acute bronchospasm and urticaria."
    }
]


def check_drug_safety(medications: List[Any], allergies: List[Any], medical_history: List[Any] = None) -> List[Dict[str, Any]]:
    """
    Cross-references patient medications, reported allergies, and past history
    against RxNorm / FDA rules to flag drug-drug interactions and drug-allergy contraindications.
    """
    warnings: List[Dict[str, Any]] = []

    # Extract medication names
    med_names: List[str] = []
    if isinstance(medications, list):
        for m in medications:
            if isinstance(m, dict) and m.get("name"):
                med_names.append(m["name"].lower().strip())
            elif isinstance(m, str):
                med_names.append(m.lower().strip())

    # Extract allergy names
    alg_names: List[str] = []
    if isinstance(allergies, list):
        for a in allergies:
            if isinstance(a, dict) and a.get("name"):
                alg_names.append(a["name"].lower().strip())
            elif isinstance(a, str):
                alg_names.append(a.lower().strip())

    # 1. Check Drug-Drug Interactions
    for rule in KNOWN_DRUG_INTERACTIONS:
        d1, d2 = rule["pair"]
        d1_found = any(d1 in m for m in med_names)
        d2_found = any(d2 in m for m in med_names)

        if d1_found and d2_found:
            warnings.append({
                "severity": rule["severity"],
                "category": rule["category"],
                "trigger_drugs": [d1.capitalize(), d2.capitalize()],
                "description": rule["description"]
            })

    # 2. Check Drug-Allergy Contraindications
    for rule in ALLERGY_CROSS_REACTIVITY:
        alg_pattern = rule["allergy_pattern"]
        drug_pattern = rule["drug_pattern"]

        alg_match = any(re.search(alg_pattern, alg, re.IGNORECASE) for alg in alg_names)
        drug_match = any(re.search(drug_pattern, med, re.IGNORECASE) for med in med_names)

        if alg_match and drug_match:
            warnings.append({
                "severity": rule["severity"],
                "category": rule["category"],
                "trigger_allergy": alg_pattern.capitalize(),
                "trigger_drug": drug_pattern.capitalize(),
                "description": rule["description"]
            })

    return warnings