cally/calendar-integration/google-calendar-utils.js

export async function fetchGoogleCalendarEvents(token) {

    const response = await fetch(
        'https://www.googleapis.com/calendar/v3/calendars/primary/events',
        {
            headers: {
                Authorization: `Bearer ${token}`,
            },
        }
    );

    const data = await response.json();
    const googleEvents = [];
    data.items?.forEach((item) => {

        let isAllDay = false;
        const start = item.start;
        let startDateTime;
        if (start !== undefined) {

            const timezone = start.timeZone;
            if (start.dateTime) {
                const stringDate = start.dateTime;
                startDateTime = new Date(stringDate).toLocaleString("en-us", {...options, timeZone: timezone});
            } else {
                const stringDate = start.date;
                startDateTime = new Date(stringDate).toLocaleString("en-us", {...options, timeZone: timezone});
                isAllDay = true;
            }
        }

        const end = item.end;
        let endDateTime;
        if (end !== undefined) {
            const timezone = end.timeZone;
            if (end.dateTime) {
                const stringDate = end.dateTime;
                endDateTime = new Date(stringDate).toLocaleString("en-us", {...options, timeZone: timezone});
            } else {
                const stringDate = end.date;
                endDateTime = new Date(stringDate).toLocaleString("en-us", {...options, timeZone: timezone});
            }
        }

        const googleEvent = {
            id: item.id,
            title: item.summary,
            startDate: startDateTime,
            endDate: endDateTime,
            allDay: isAllDay
        };
        googleEvents.push(googleEvent);
    });

    return googleEvents;
}

const options = {
    year: "numeric",
    month: "long",
    day: "numeric",
    hour: "numeric",
    minute: "numeric",
    second: "numeric",
    timeZoneName: "short"
};