"""Author RAG — Analytics Service.

Event tracking, session aggregation, and MaxMind geo-location.
Per implementation plan features #43-50.
"""

import hashlib
from datetime import datetime, timezone
from typing import Any

import structlog
from sqlalchemy.ext.asyncio import AsyncSession

logger = structlog.get_logger(__name__)


def fingerprint(ip: str, user_agent: str) -> str:
    """SHA-256 fingerprint from IP + User-Agent. No PII stored.

    Args:
        ip: Client IP address.
        user_agent: HTTP User-Agent header.

    Returns:
        32-character hex fingerprint.
    """
    combined = f"{ip}|{user_agent}"
    return hashlib.sha256(combined.encode()).hexdigest()[:32]


async def track_event(
    db: AsyncSession,
    author_id: str,
    event_type: str,
    session_id: str,
    book_id: str | None = None,
    metadata: dict[str, Any] | None = None,
) -> None:
    """Persist an analytics event.

    Event types: chat_start, message, buy_link_click, rating, session_end.

    Args:
        db: Database session.
        author_id: Author UUID.
        event_type: Event category string.
        session_id: Reader session UUID.
        book_id: Optional book UUID.
        metadata: Additional event data.
    """
    try:
        from app.models.analytics import AnalyticsEvent
        event = AnalyticsEvent(
            author_id=author_id,
            event_type=event_type,
            session_id=session_id,
            book_id=book_id,
            meta=metadata or {},
            created_at=datetime.now(timezone.utc),
        )
        db.add(event)
        await db.commit()
    except Exception as e:
        logger.warning("Failed to track event", event_type=event_type, error=str(e))


async def get_geo_country(ip: str) -> str | None:
    """Look up country for an IP via MaxMind GeoLite2.

    Returns None if GeoIP database is not available.
    """
    try:
        import geoip2.database
        from app.config import get_settings
        cfg = get_settings()
        with geoip2.database.Reader(cfg.GEO_DB_PATH) as reader:
            response = reader.country(ip)
            return response.country.iso_code
    except Exception:
        return None