"""
Department contact resolution helpers.

Used by the "Send to Department" flow across modules to auto-target a
department's champion and manager (instead of asking the user to pick a
contact person). Each target is returned with the contact channels available.
"""

import logging

logger = logging.getLogger(__name__)


def _staff_contact(staff):
    """Return (email, phone) for a Staff instance, with user fallbacks."""
    email = staff.email or ""
    phone = staff.phone or ""
    user_id = getattr(staff, "user_id", None)
    if user_id:
        user = getattr(staff, "user", None)
        if user:
            email = email or (user.email or "")
            phone = phone or (getattr(user, "phone", "") or "")
    return email, phone


def get_champion_and_manager(department):
    """Return a list of contact targets for a department's champion and manager.

    Each item is a dict:
        {
            "label": "Champion" | "Manager",
            "email": str,        # may be ""
            "phone": str,        # may be ""
            "staff": <Staff>|None,   # present for the champion
            "user": <User>|None,     # present for the manager
        }

    Only targets that actually exist (the role FK is set) are included.
    De-duplicates the case where the champion and manager are the same person.
    """
    targets = []
    seen_emails = set()

    # Champion (a Staff)
    champion = getattr(department, "champion", None)
    if champion is not None:
        email, phone = _staff_contact(champion)
        email = email or (getattr(department, "champion_email", "") or "")
        key = (email or "").lower()
        if key not in seen_emails:
            seen_emails.add(key)
            targets.append(
                {"label": "Champion", "email": email, "phone": phone, "staff": champion, "user": None}
            )

    # Manager (a User)
    manager = getattr(department, "manager", None)
    if manager is not None:
        email = manager.email or ""
        phone = getattr(manager, "phone", "") or ""
        # If the manager also has a linked Staff profile, prefer its contact details.
        staff_profile = getattr(manager, "staff_profile", None)
        if staff_profile:
            s_email, s_phone = _staff_contact(staff_profile)
            email = email or s_email
            phone = phone or s_phone
        key = (email or "").lower()
        if key and key not in seen_emails:
            seen_emails.add(key)
            targets.append(
                {"label": "Manager", "email": email, "phone": phone, "staff": None, "user": manager}
            )

    return targets


def has_contact_target(department):
    """True if the department has at least a champion or a manager to notify."""
    return bool(get_champion_and_manager(department))