function prettify_seconds(seconds) {
    return (seconds / 60).toFixed(1) + "min";
}

function compute_statistics_for_user(user) {
    user.large_pauses = [];
    user.max_pause = 0;

    last_active = user.posts[0];
    total_pause_time = 0;
    total_accounted_pauses = 1;
    user.posts.slice(1).forEach(function(post_time) {
        pause = post_time.getTime() - last_active.getTime();
        pause = pause / 1000; // from milliseconds to seconds
        user.max_pause = Math.max(user.max_pause, pause);
        if (pause <= 1 * 60 * 60) {
            total_pause_time += pause;
            total_accounted_pauses += 1;
        } else {
            user.large_pauses.push({
                begin: last_active,
                end: post_time,
                duration: prettify_seconds(pause)
            });
        }
        last_active = post_time;
    });

    user.average_pause = prettify_seconds(total_pause_time / total_accounted_pauses);
    user.max_pause = prettify_seconds(user.max_pause);
    user.posts = user.posts.length;

    return user;
}

function compute_statistics_for_all() {
    var regex_pattern = /(\d\d)\/(\d\d)\/(\d\d) [А-Яа-я]{2,4} (\d\d)\:(\d\d)\:(\d\d)/;
    users_by_name = {}
    posts = Array.from(document.querySelectorAll('.post'))
    .map(value => {
        var result = new Object();
        result.name = value.querySelector("[id^=id_tag_]");
        result.name = (result.name != null) ? result.name.innerText : "# OP"
        result.date = value.querySelector("[class^=post__time]").innerText;
        return result;
    })
    .map( post => {
        match = regex_pattern.exec(post.date);
        post.date = (new Date(Date.UTC("20" + match[3], match[2], match[1], parseInt(match[4]), match[5], match[6])));
        return post;
    })
    .forEach(post => {
        user = users_by_name[post.name] || {name: post.name, posts: []};
        user.posts.push(post.date);
        users_by_name[post.name] = user;
    })

    users = Object.entries(users_by_name)
        .map(entry => entry[1])
        .map(compute_statistics_for_user)
        .sort((a, b) => b.posts - a.posts);

    return users;
}

compute_statistics_for_all();