# api_clients/openfda_client.py
"""
Client for the OpenFDA API.
This module specializes in fetching critical, real-world drug safety data,
including the most frequent adverse events and active enforcement reports (recalls).
"""
import asyncio
import aiohttp
from urllib.parse import quote
from .config import OPENFDA_BASE_URL, REQUEST_HEADERS

async def get_adverse_events(session: aiohttp.ClientSession, drug_name: str, top_n: int = 5) -> list[dict]:
    """
    Finds the most frequently reported adverse events for a given drug.

    This function uses the 'count' feature of the OpenFDA API to get a summary
    of the most common patient reactions, which is far more efficient than
    downloading individual reports.

    Args:
        session (aiohttp.ClientSession): The active HTTP session.
        drug_name (str): The brand or generic name of the drug.
        top_n (int): The number of top adverse events to return.

    Returns:
        list[dict]: A list of top adverse events, e.g., [{'term': 'Nausea', 'count': 5000}].
                    Returns an empty list on failure or if no results are found.
    """
    if not drug_name:
        return []

    # OpenFDA uses Lucene query syntax. We search in both brand name and generic name fields.
    search_query = f'(patient.drug.openfda.brand_name:"{drug_name}" OR patient.drug.openfda.generic_name:"{drug_name}")'
    
    params = {
        'search': search_query,
        'count': 'patient.reaction.reactionmeddrapt.exact', # The field for patient reactions
        'limit': top_n
    }
    
    url = f"{OPENFDA_BASE_URL}/drug/event.json"

    try:
        async with session.get(url, params=params, headers=REQUEST_HEADERS, timeout=10) as resp:
            if resp.status == 404: # 404 means no results found for the query
                return []
            resp.raise_for_status()
            data = await resp.json()
            return data.get('results', [])

    except aiohttp.ClientError as e:
        print(f"An error occurred fetching adverse events for '{drug_name}': {e}")
        return []

async def check_for_recalls(session: aiohttp.ClientSession, drug_name: str, limit: int = 3) -> list[dict]:
    """
    Checks for recent, ongoing drug enforcement reports (recalls) for a given drug.
    It prioritizes finding active and serious recalls.

    Args:
        session (aiohttp.ClientSession): The active HTTP session.
        drug_name (str): The brand or generic name of the drug.
        limit (int): The maximum number of recall reports to return.

    Returns:
        list[dict]: A list of recall reports, containing reason and severity.
                    Returns an empty list on failure or if no recalls are found.
    """
    if not drug_name:
        return []

    # We search for the drug name and filter for 'Ongoing' status to find active recalls.
    search_query = f'"{quote(drug_name)}" AND status:Ongoing'
    
    params = {
        'search': search_query,
        'sort': 'report_date:desc', # Get the most recent ones first
        'limit': limit
    }
    
    url = f"{OPENFDA_BASE_URL}/drug/enforcement.json"
    
    try:
        async with session.get(url, params=params, headers=REQUEST_HEADERS, timeout=10) as resp:
            if resp.status == 404:
                return []
            resp.raise_for_status()
            data = await resp.json()
            
            results = data.get('results', [])
            # We parse the complex result into a clean, simple structure
            parsed_recalls = [
                {
                    "reason": r.get("reason_for_recall", "N/A"),
                    "classification": r.get("classification", "N/A"), # Class I is most serious
                    "report_date": r.get("report_date", "N/A")
                } 
                for r in results
            ]
            return parsed_recalls
            
    except aiohttp.ClientError as e:
        print(f"An error occurred fetching recalls for '{drug_name}': {e}")
        return []

async def get_safety_profile(session: aiohttp.ClientSession, drug_name: str) -> dict:
    """
    A high-level orchestrator that gathers a complete safety profile for a single drug
    by concurrently fetching adverse events and recalls.

    Args:
        session (aiohttp.ClientSession): The active HTTP session.
        drug_name (str): The drug to profile.

    Returns:
        dict: A dictionary containing 'adverse_events' and 'recalls' keys.
    """
    # Run both API calls in parallel for maximum efficiency
    tasks = {
        "adverse_events": get_adverse_events(session, drug_name),
        "recalls": check_for_recalls(session, drug_name)
    }
    
    results = await asyncio.gather(*tasks.values(), return_exceptions=True)
    
    # Map results back, handling potential errors from gather()
    safety_data = dict(zip(tasks.keys(), results))
    for key, value in safety_data.items():
        if isinstance(value, Exception):
            print(f"Sub-task for {key} failed for {drug_name}: {value}")
            safety_data[key] = [] # Ensure return type is consistent (list)

    return safety_data