import { useCallback, useRef, useState } from 'react';
import type { EventInput } from '@fullcalendar/core';
import { useAppointmentServiceContext } from '../services/AppointmentService';
import type { MyVisitInvitation } from '../types/visitInvitation';
import { visitTitle } from '../utils/visitInvitationWords';

/**
 * The caller's accepted team video visits in the visible range, for their own calendar. They come from the self-scoped
 * invitation route (`view=calendar`), so a visit hosted by another organization appears even though this organization's
 * appointment read cannot see it. Only the latest range's answer is kept, so a slow read for an old range is dropped.
 */
export const useAcceptedTeamVisits = () => {
    const { fetchMyVisitCalendar } = useAppointmentServiceContext();
    const [visits, setVisits] = useState<MyVisitInvitation[]>([]);
    const [failed, setFailed] = useState(false);
    const latest = useRef(0);

    const load = useCallback(async (start: Date, end: Date) => {
        const ticket = ++latest.current;
        try {
            const rows = await fetchMyVisitCalendar(start.toISOString(), end.toISOString());
            if (ticket !== latest.current) return;
            setVisits(rows);
            setFailed(false);
        } catch (error) {
            if (ticket !== latest.current) return;
            const status = (error as { status?: number })?.status;
            // A caller the route does not serve has no team visits; anything else is a failure worth saying.
            setVisits([]);
            setFailed(status !== 401 && status !== 403 && status !== 404);
        }
    }, [fetchMyVisitCalendar]);

    return { visits, failed, load };
};

// A visit that will not take place, or never did: it would sit beside a live one at the same time and read the same.
const NOT_A_VISIT = new Set(['cancelled', 'entered-in-error']);

/** Calendar events for accepted team visits, leaving out any this organization's own appointments already show. */
export const teamVisitEvents = (visits: MyVisitInvitation[], shownAppointmentIds: Set<string>): EventInput[] =>
    visits
        .filter((visit) => visit.start && !NOT_A_VISIT.has(visit.appointmentStatus ?? '') && !shownAppointmentIds.has(visit.appointmentId))
        .map((visit) => ({
            id: `team-visit-${visit.appointmentId}`,
            title: `Team video · ${visitTitle(visit)}`,
            start: visit.start,
            end: visit.end,
            extendedProps: { type: 'team-visit', appointmentId: visit.appointmentId },
        }));