from __future__ import annotations

import re

from app.models import NormalizedEvent


def _norm(value: str | None) -> str:
    if not value:
        return "unknown"
    value = value.strip().lower()
    value = re.sub(r"\s+", "_", value)
    value = re.sub(r"[^a-z0-9_\-\.]+", "_", value)
    return value.strip("_") or "unknown"


def build_fingerprint(event: NormalizedEvent) -> str:
    host = _norm(event.host)
    service = _norm(event.service)
    trigger = _norm(event.trigger_name)

    return f"{host}|{service}|{trigger}"