import { useEffect, useMemo, useState } from "react";
import type { PractitionerRole } from "fhir/r4";
import { usePractitionerServiceContext, type PractitionerWithRoles } from "../services";

// The door's staff list covers only the door's practice. Every other practice's people are read under
// that practice's own organization, then merged with the door's list; someone at two practices keeps the
// roles from both, because roles are what place a person in a practice.
export const usePracticeStaff = (
    organizationIds: string[],
    doorOrganizationId: string | undefined,
    doorStaff: PractitionerWithRoles[],
): PractitionerWithRoles[] => {
    const { fetchPractitioners } = usePractitionerServiceContext();
    const [byOrganization, setByOrganization] = useState<Record<string, PractitionerWithRoles[]>>({});
    const key = organizationIds.filter((id) => id && id !== doorOrganizationId).sort().join(",");

    useEffect(() => {
        let active = true;
        setByOrganization({});
        for (const id of key ? key.split(",") : []) {
            fetchPractitioners(id)
                .then((bundle) => {
                    if (active) setByOrganization((current) => ({ ...current, [id]: (bundle.entry ?? []).flatMap((entry) => (entry.resource ? [entry.resource] : [])) }));
                })
                .catch((err) => console.error(`Error loading the people at practice ${id}:`, err));
        }
        return () => {
            active = false;
        };
    }, [key, fetchPractitioners]);

    return useMemo(() => {
        const merged = new Map<string, PractitionerWithRoles>();
        for (const person of [doorStaff, ...Object.values(byOrganization)].flat()) {
            const id = person.practitioner.id;
            if (!id) continue;
            const known = merged.get(id);
            if (!known) {
                merged.set(id, person);
                continue;
            }
            const roleKey = (role: PractitionerRole) => role.id ?? JSON.stringify(role);
            const seen = new Set(known.roles.map(roleKey));
            merged.set(id, { ...known, roles: [...known.roles, ...person.roles.filter((role) => !seen.has(roleKey(role)))] });
        }
        return [...merged.values()];
    }, [doorStaff, byOrganization]);
};