from collections import OrderedDict


ROLE_PRIORITY = {"lead": 0, "leader": 0, "organizer": 1, "collaborator": 2}
ROLE_TITLES = {0: "Lead / Leader", 1: "Organizers", 2: "Collaborators"}


def person_sort_key(person):
    role = (person.role or "").strip().casefold()
    return (ROLE_PRIORITY.get(role, 3), role if role not in ROLE_PRIORITY else "", person.order, person.pk or 0)


def group_people(people):
    groups = OrderedDict()
    for person in sorted(people, key=person_sort_key):
        role = (person.role or "").strip()
        priority = ROLE_PRIORITY.get(role.casefold(), 3)
        key = priority if priority < 3 else role.casefold()
        if key not in groups:
            groups[key] = {
                "title": ROLE_TITLES[priority] if priority < 3 else role or "Other contributors",
                "people": [],
            }
        groups[key]["people"].append(person)
    return list(groups.values())