#!/bin/bash

if [ "$UID" != 0 ]
then
    sudo -- "$0" "$@"
    exit
fi

while [ $# -gt 0 ]
do
    case "$1" in
        -q | --quiet )
            exec 2>/dev/null
            shift
            ;;
        -a | --all )
            IOSLAY_KILL_ALL=y
            shift
            ;;
        -- )
            shift
            break
            ;;
        -* )
            exit 1
            ;;
        * )
            break
            ;;
    esac
done

if [ $# -gt 0 ]
then
    echo "$0: Error: usage" >&2
    exit 1
fi

web_content_pids()
{
    top -w512 -b -o '%MEM' | {
        unset PIDS
        while read line
        do
            case "$line" in
                top*)
                    if [ "${PIDS+is_set}" ]
                    then
                        echo $PIDS
                    fi
                    while [ "$line" ]
                    do read line
                    done
                    PIDS=
                    ;;
                *)
                    set -- $line
                    [ "${12} ${13}" = "Web Content" ] || continue
                    PIDS="$PIDS $1"
                    ;;
                esac
        done
    }
}

sum()
{
    local total=0 n
    for n in $*
    do
        total=$((total + n))
    done
    echo $total
}

keep()
{
    local n=$1
    shift
    set -- $*
    while [ $# -ge "$n" ]
    do
        shift
    done
    printf '%s\n' "$*"
}

new_pids()
{
    # This is not correct because the correct code is not implemented yet.
    # But this is OK for testing the other parts.  Fixing this is only an
    # optimization.
    [ "$1" != "$2" ]
}

unset IOTOP_PID
relaunch_iotop()
{
    if [ "$IOTOP_PID" ]
    then
        kill "$IOTOP_PID"
    fi

    web_content_pids | (
        while read pids
        do
            set -- $pids
            if [ $# = 0 ]
            then
                kill_iotop
            elif new_pids "$pids" "$oldpids"
            then
                kill_iotop
                IOTOP_PID=$(launch_iotop $pids)
            fi
            sleep 1
            oldpids=$pids
        done
    )
}

kill_iotop()
{
    if [ "$IOTOP_PID" ]
    then
        (
            set -x
            kill "$IOTOP_PID"
        )
    fi
}

launch_iotop()
{
    set -- $(printf '%s\n' "$@" | tac | sed 's/^/--pid=/')
    (set -x; iotop -qq -b "$@") | iotop_reader &
    echo $!
}

iotop_reader()
{
    log=
    pct_log=
    while read line
    do
        case "$line" in
            "Total DISK"*)
                pct=$(sum $pct_log)
                [ "$pct" -ge 85 ] && over=y || over=
                pct_log=
                log=$(keep 9 $log)
                if [ "$over" ]
                then
                    log="$log 1"
                    over=
                    if [ "$(sum $log)" -ge 3 ]
                    then
                        (
                            set -x
                            fireslay -y
                        )
                    fi
                else
                    log="$log 0"
                fi
                case "$log" in
                    *1* )
                        (
                            set -x
                            : $log
                        )
                        ;;
                esac
                ;;
            "Current DISK"*) continue ;;
            *)
                set -- $line
                pct=${10%.*}
                pct_log="$pct_log $pct"
                ;;
        esac
    done
}

relaunch_iotop