import hashlib
import re


def normalize_for_fingerprint(text: str | None) -> str:
    if not text:
        return ""
    # lowercase, strip, collapse whitespace, remove punctuation variation
    t = text.lower().strip()
    t = re.sub(r"\s+", " ", t)
    return t


def compute_fingerprint(
    site_id: str,
    title: str | None,
    company: str | None,
    location: str | None,
    url: str | None,
    external_job_id: str | None = None,
) -> str:
    """Compute a SHA256 fingerprint for deduplication.

    When external_job_id is provided (e.g. LinkedIn job ID, Google htidocid),
    use site_id + external_job_id only — immune to title/location text drift.
    Otherwise fall back to title+company+location+canonical_url.
    """
    if external_job_id:
        parts = [normalize_for_fingerprint(site_id), external_job_id.strip()]
    else:
        canonical_url = _canonical_url(url) if url else ""
        parts = [
            normalize_for_fingerprint(site_id),
            normalize_for_fingerprint(title),
            normalize_for_fingerprint(company),
            normalize_for_fingerprint(location),
            canonical_url,
        ]
    raw = "|".join(parts)
    return hashlib.sha256(raw.encode("utf-8")).hexdigest()


def _canonical_url(url: str) -> str:
    """Strip tracking/session query parameters, keep path."""
    from urllib.parse import urlparse, urlunparse
    try:
        parsed = urlparse(url)
        # Drop query string entirely for canonicalization
        canonical = urlunparse((parsed.scheme, parsed.netloc, parsed.path, "", "", ""))
        return canonical.lower().rstrip("/")
    except Exception:
        return url.lower().strip()