#!/bin/sh

# HAHAHAH Bro it finally works. It fucking works. It finally fucking works.

# It just needs to monitor IO with iotop and start killing firefox processes
# from the bottom (least memory usage) up. This allows any one tab access to the
# full memory available to Firefox! And integrate it into the your-fired.sh
# script. And it's truly fixed. And integrate the firefox updater.

IO_ROOT_DIR=$HOME/.cache/mozilla/firefox/

[ -d "$IO_ROOT_DIR" ] || exit

get_age()
{
    local mtime now
    mtime=$(stat --format=%Y "$1") || return
    now=$(date +%s) || return
    echo $(( now - mtime ))
}

get_filesystem()
{
    echo /
}

get_total_memory()
{
    free -b | {
        read _
        read _ total _
        echo $total
    }
}

math()
{
    printf '%s\n' "$*" | bc -lq
}

get_total_io()
{
    results=$IO_ROOT_DIR/io.test.result
    zeroes=$IO_ROOT_DIR/io.test
    if [ -e "$results" ]
    then
        age=$(get_age "$results") || return
        if [ "$age" -gt $((60 * 60 * 24 * 7)) ]
        then
            rm "$results"
        fi
    fi

    if ! [ -e "$results" ]
    then
        MEGS=128
        then=$(date +%s.%N) || return
        dd if=/dev/zero of="$zeroes" bs=${MEGS}M count=1 || return
        now=$(date +%s.%N) || return
        rm "$zeroes"
        speed=$(math $now - $then / $((MEGS * 1024 * 1024))) || return
        echo $speed > "$results"
    fi
    read total < "$results" || return
    echo ${total%.*}
}

join_group()
{
    GROUP_DIR=/sys/fs/cgroup/firefox~$id
    [ -d "$GROUP_DIR" ] || sudo mkdir "$GROUP_DIR"
    echo $$ | sudo tee "$GROUP_DIR"/cgroup.procs
}

add_subtree_controller()
{
    search="\\b$1\\b"
    grep -q "$search" /sys/fs/cgroup/cgroup.controllers || return
    grep "$search" /sys/fs/cgroup/cgroup.subtree_control || echo +"$1" | $AS_ROOT tee /sys/fs/cgroup/cgroup.subtree_control
}

set_max()
{
    add_subtree_controller "$1"
    [ -e "$GROUP_DIR"/"$1".max ] || return
    printf '%s\n' "$2" | $AS_ROOT tee "$GROUP_DIR"/"$1".max
}

set_max_ratio()
{
    local controller="$1" ratio="$2" limit
    total=$(get_total_$controller)
    n=${ratio%%/*}
    d=${ratio#$n/}
    [ "$d" = "${d%/*}" ] || return
    limit=$(( total * n / d ))
    [ "$limit" ] || return
    [ "$limit" -gt 0 ] || return
    case "$controller" in
        io)
            fsroot=$(get_filesystem "$IO_ROOT_DIR") || return
            majmin=$(lsblk -o 'MOUNTPOINT,MAJ:MIN' | sed -ne "s?^$fsroot  *??p") || return
            case "$majmin" in
                *:*) ;;
                *) return 1 ;;
            esac
            set_max "$controller" "$majmin wbps=$limit rbps=$limit"
        ;;
        *) set_max "$controller" "$limit"
    esac
}

set -ex

[ "$(id -un)" = 0 ] && AS_ROOT= || AS_ROOT='sudo --'

id=$(id -u)

join_group firefox~"$id"
set_max_ratio memory 1/2
set_max_ratio io 9/10

exec firefox "$@"