import { format, addHours } from "date-fns";
import { TZDate } from "@date-fns/tz";
import { UTCDate, utc } from "@date-fns/utc";

export function dateFromInput(input: { dateQuery: string, timezone: string }) {
    let t: string;
    if (input.dateQuery == "today") {
        t = new Date();
        return format(t, "yyyy-MM-dd", { in: input.timezone });
    }
    else {
        t = new UTCDate(input.dateQuery);
        return format(t, "yyyy-MM-dd", { in: utc });
    }

}

function generateHour(d, t) {
    const dt: TZDate = addHours(d, t);
    return {
        date: format(dt, 'yyyy-MM-dd'),
        time: parseInt(format(dt, 'H')),
    };
}

export function hoursListInTimezone(input: { dateQuery: string, timezone: string }) {
    const dateStr = dateFromInput(input);
    const d = new TZDate(dateStr, input.timezone);
    return Array.from({ length: 24 }, (_, t) =>
        generateHour(d, t)
    );
}