$(function () {
    update_reltimes($("time"));

    setInterval(() => {
        update_reltimes($("time"));
    }, 60000);
});

function update_reltimes(elements) {
    elements.each(function () {
        let title = $(this).attr("title");

        if (!title) {
            $(this).attr("title", $(this).text());
        }

        let rel = reltime($(this).attr("datetime"));

        $(this).text(rel);
    });
}

const MINUTE = 60000,
    HOUR = 3600000,
    DAY = 86400000,
    WEEK = 604800000,
    MONTH = 2592000000,
    YEAR = 31536000000;

function reltime(date) {
    let delta = Date.now() - Date.parse(date);
    let fut = false;

    if (delta < 0) {
        delta = Math.abs(delta);
        fut = true;
    }

    let minutes = Math.floor(delta / MINUTE);
    let hours = Math.floor(delta / HOUR);
    let days = Math.floor(delta / DAY);
    let weeks = Math.floor(delta / WEEK);
    let months = Math.floor(delta / MONTH);
    let years = Math.floor(delta / YEAR);

    let rt = "Teď";

    if (minutes > 0) {
        if (fut) {
            rt = `za ${minutes} ${plural("minutu|minuty|minut", minutes)}`;
        } else {
            rt = `před ${minutes} ${plural("minutou|minutami|minutami", minutes)}`;
        }
    }

    if (hours > 0) {
        if (fut) {
            rt = `za ${hours} ${plural("hodinu|hodiny|hodin", hours)}`;
        } else {
            rt = `před ${hours} ${plural("hodinou|hodinami|hodinami", hours)}`;
        }
    }

    if (days > 0) {
        if (fut) {
            rt = `za ${days} ${plural("den|dny|dnů", days)}`;
        } else {
            rt = `před ${days} ${plural("dnem|dny|dny", days)}`;
        }
    }

    if (weeks > 0) {
        if (fut) {
            rt = `za ${weeks} ${plural("týden|týdny", weeks)}`;
        } else {
            rt = `před ${weeks} ${plural("týdnem|týdny", weeks)}`;
        }
    }

    if (months > 0) {
        if (fut) {
            rt = `za ${months} ${plural("měsíc|měsíce|měsíců", months)}`;
        } else {
            rt = `před ${months} ${plural("měsícem|měsíci|měsíci", months)}`;
        }
    }

    if (years > 0) {
        if (fut) {
            rt = `za ${years} ${plural("rok|roky|let", years)}`;
        } else {
            rt = `před ${years} ${plural("rokem|lety|lety", years)}`;
        }
    }

    return rt;
}

function plural(plurals, count) {
    let plurals_arr = plurals.split("|");
    let one = plurals_arr[0];
    let few = plurals_arr[1];
    let other = plurals_arr[2];

    if (count === 1) {
        return one;
    } else if (count < 5 && count !== 0) {
        return few;
    } else {
        return other;
    }
}