import uuid
from datetime import datetime, timezone


def now_utc() -> datetime:
    return datetime.now(timezone.utc)


def as_uuid(record_id) -> uuid.UUID | None:
    """Parse a UUID from any id-ish value; None when blank or malformed."""
    if record_id in (None, ""):
        return None
    try:
        return uuid.UUID(str(record_id))
    except ValueError:
        return None


def location_options(search=None) -> list[str]:
    """`{City} - {Country}` for every city in global_cities.Countries, optionally filtered."""
    from global_cities import Countries

    term = (search or "").strip().lower()
    seen = set()
    options = []
    for country, cities in Countries.items():
        for city in cities:
            label = f"{city} - {country}"
            if label in seen or (term and term not in label.lower()):
                continue
            seen.add(label)
            options.append(label)
    return options


def department_job_metrics(job_rows, applicants_by_job) -> dict:
    """Roll job-level rows up to {department_id: {job_posts, open_roles, candidates}}.

    `job_rows` are (department_id, job_post_id, requisition_status); `applicants_by_job`
    maps str(job_post_id) -> unique applicants on that job. Open roles are job posts
    whose requisition_status is "open", the same meaning analytics uses.
    """
    metrics = {}
    for department_id, job_post_id, requisition_status in job_rows or []:
        m = metrics.setdefault(department_id, {"job_posts": 0, "open_roles": 0, "candidates": 0})
        m["job_posts"] += 1
        if requisition_status == "open":
            m["open_roles"] += 1
        m["candidates"] += int(applicants_by_job.get(str(job_post_id), 0))
    return metrics