#!/bin/bash
# purgeSwap v0.01 - run swapoff if enough available memory and monitor swap usage.
# (C) 2023 Felix Hauri - felix@f-hauri.ch
# Licensed under terms of GPL v3. www.gnu.org
#
# This script permit to monitor ``swapoff'' process.
# Without argument this script print amount of swapped and available memory,
# then offer a small timeout of 8 seconds before running "swapoff -a".
# Once timeout done or if `-y` switch on command line, the show a progress bar
# for displaying amount of swap freed.
# If `swapoff` is alwready running, just monitor progress until no swap used.
#
# This script don't use getopts (yet), so only 1 parameter could be used!
#
# Usage $0 [-q|-y|-n]
#  -q  quiet! Implie -y: Don't ask, and don't print anything
#  -y  Yes, don't ask, run monitor and doit.
#  -n  Don't do anything, just print if we CAN swap or NOT.
#
# Default variables, could be set by prendening script at run:
#  accurateTopSwapped=1 ./purgeSwap -y
:	${stopTimeout:=8} \
	${refreshBarRate:=.02} \
	${refreshSwapedListRate:=1} \
	${accurateTopSwapped:=0}


msgs=("NOT " "")
declare -i avail swaped
while read field val _; do
    case $field in
	MemAvailable:) avail=$val;;
	SwapTotal:) swaped=$val;;
	SwapFree:) swaped+=-$val;break;;
    esac
done < /proc/meminfo

if (( swaped == 0 )); then
   echo There is no swap used.
   exit 0
fi

if [[ $1 == -q ]]; then # Be quiet, implie `-y` "Yes, doit".
   if (( avail > swaped )); then
       /usr/sbin/swapoff -a
       /usr/sbin/swapon -a
   fi
   exit $?
fi

txtsize() { # Convert integer into readable string, store result in $2 varname
    local i=$(($1>=1<<50?5:$1>=1<<40?4:$1>=1<<30?3:$1>=1<<20?2:$1>1023?1:0))
    local a=(K M G T P)
    ((i>4?i+=-2:0)) && a=(${a[@]:2}) && set -- $(($1>>20)) $2
    local r=00$((1000*$1/(1024**i)))
    printf -v $2 %.2f%s ${r::-3}.${r: -3} ${a[i]}
}
percentBar() { # Compute percent+bar from ( $1 * 100 / $2 ) store is $3
    local _pB_percent _pB_lastChar _pB_blankString _pB_barString
    local -i _pB_totLen _pB_barLen _pB_blankLen _pB_prop _pB_strLen=${4:-80}
    _pB_prop=" $1 * 100000 / $2 " _pB_totLen=' 8 * _pB_strLen '
    _pB_percent=00$_pB_prop
    printf -v _pB_percent %.2f "${_pB_percent::-3}.${_pB_percent: -3}"
    _pB_prop="
	(10#${_pB_percent/.}>10000?10000:10#${_pB_percent/.})*_pB_totLen/10000"
    _pB_barLen=' _pB_prop%8 '
    (( _pB_barLen )) && _pB_strLen+=-1 &&
	printf -v _pB_lastChar '\\U258%X' $(( 16 - _pB_barLen )) ||
	    _pB_lastChar=''
    _pB_barLen=' _pB_prop / 8 '
    _pB_blankLen=' _pB_strLen - _pB_barLen '
    printf -v _pB_barString '%*s' "$_pB_barLen" ''
    printf -v _pB_barString '%b' "${_pB_barString// /\\U2588}$_pB_lastChar"
    printf -v _pB_blankString '%*s' "$_pB_blankLen" ''
    printf -v "${3:-renderedBar}" '%s %s%s' \
	   "$_pB_percent" "$_pB_barString" "$_pB_blankString"
}
displaySleep() {
    local -i refrBySeconds=50 _start=${EPOCHREALTIME/.} reqslp target \
	  crtslp crtp cols cpos dlen
    local strng percent prctbar tleft ostty="$(stty -g)" 
    [[ $COLUMNS ]] && cols=${COLUMNS} || read -r cols < <(tput cols)
    refrBySeconds=' 1000000 / refrBySeconds '
    printf -v strng %.6f $1
    stty -icanon -echo
    printf '\E[6n' && IFS=\; read -sdR _ cpos
    stty "$ostty"
    dlen=${#strng}-1  cols=' cols - dlen - cpos -1 '
    reqslp=10#${strng/.} target=reqslp+_start
    printf \\e7
    for ((;${EPOCHREALTIME/.}<target;)); do
        crtp=${EPOCHREALTIME/.}
        crtslp='( target - crtp ) > refrBySeconds? refrBySeconds: target - crtp'
        strng=00000$crtslp  crtp+=-_start
        printf -v strng %.6f ${strng::-6}.${strng: -6}
        percentBar $crtp $reqslp prctbar $cols
        tleft=00000$((reqslp-crtp))
        printf '\e8\e[36;48;5;23m%s\e[0m%*.4fs' "${prctbar#* }" \
	       "$dlen" ${tleft::-6}.${tleft: -6}
        IFS= read -d '' -rsn1 -t $strng ${2:-_} && { echo; return;}
    done
    percentBar 1 1 prctbar $cols
    printf '\e8\e[36;48;5;30m%s\e[0m%*.4fs\n' "${prctbar#* }" "$dlen" 0
    false
}
showProgress() { # Show progess bar with refresh: 50x/sec
    local -i tot=$1 used=$1 etime crtfrd endat penalty=25 lrftpids=0
    local htot freed bar
    txtsize $tot htot
    printf \\e7
    while (( used ? 1 : penaylty-->0 )); do
	read -t $refreshBarRate -u $dummy _  # pseudo builtin sleep
	used=0
	while read field val _; do case $field in
	      SwapTotal:) used=$val;; SwapFree:) used+=-$val; break;;
	esac; done < /proc/meminfo
        crtp=${EPOCHREALTIME/.}
	etime=" $crtp - startTime"
	crtfrd=" tot - used > 0 ? tot - used : 1 "
	endat=" etime * tot / crtfrd + startTime "
	printf -v endat %.0f ${endat::-6}.${endat: -6}
	txtsize $crtfrd freed
	percentBar $crtfrd $tot bar $((cols-35-${#htot}))
	if (( crtp-lrftpids > refreshSwapedListRate )); then
	    lrftpids=crtp
	    topSwapped swappedStr
	    printf '\e8\e[42;100;32;227m%s\e[0m %6.2f%% %8s/%s End:%(%a %T)T\n%s' \
		   "${bar#* }" ${bar// *} $freed $htot $endat "${swappedStr}"
	else
	    printf \
		'\e8\e[42;100;32;227m%s\e[0m %6.2f%% %8s/%s End:%(%a %T)T\e[%dB\r\e[32C' \
		"${bar#* }" ${bar// *} $freed $htot $endat 12
	fi
    done
}
topSwapped() {
    local -i total=0 cnt=${2:-10}
    local -a bypid=() bysize=() sizes=()
    local pid swaped cmd  output=""
    local -n result=${1:-topSwapped}
    if ((accurateTopSwapped)); then
	while read -r pid swaped cmd; do
	    rSwaped=$(($(sed -ne </proc/$pid/smaps 's/Swap: *\([1-9][0-9]\+\) kB/+\1/p')))
	    (( rSwaped )) &&bysize[$rSwaped]+="${pid} " bypid[$pid]=${cmd}
	done< <( sed -ne' /^Name:/h; /^Pid:/H; /^VmSwap:[[:space:]]*[1-9]/{
			s/.* \([0-9]\+\) \+kB/\1/; /^0/!{
			  H; x; s/^.*:\o11\(.*\)\n.*:\o11\(.*\)\n\(.*\)/\2 \3 \1/; p; }}'\
			      /proc/[1-9]*/status 2>/dev/null ) 2>/dev/null
    else
	while read -r pid swaped cmd; do  bysize[$swaped]+="${pid} " bypid[$pid]=${cmd}
	done< <( sed -ne' /^Name:/h; /^Pid:/H; /^VmSwap:/{ s/.* \([0-9]\+\) \+kB/\1/;
		   /^0/!{H; x; s/^.*:\o11\(.*\)\n.*:\o11\(.*\)\n\(.*\)/\2 \3 \1/; p; }}'\
		     /proc/[1-9]*/status 2>/dev/null )
    fi
    sizes=(${!bysize[@]})
    for ((i=${#sizes[@]};i--;)); do
	read -ra pids <<<${bysize[sizes[i]]}
	for pid in ${pids[@]}; do
	    total+=sizes[i]
	    if ((cnt-->0)); then
		txtsize ${sizes[i]} swaped
		printf -v swaped ' - %-20s %8s\e[K\n' "${bypid[pid]}" "$swaped"
		output+=${swaped}
	    fi
	done
    done
    txtsize $total swaped
    cnt=${#bypid[@]}
    printf -v swaped 'Total: %d pids %*s\e[K' "$cnt" $((19-${#cnt})) "$swaped"
    result="${output}${swaped}"
}
winSize() { cols=$(( $(tput cols) ));((cols))||cols=80 ;}
trap winSize WINCH
winSize

txtsize $avail havail
txtsize $swaped hswaped
printf 'Avail: %s (%d) swaped: (%s) %d Can %sunswap!\n' \
    "$havail" $avail "$hswaped" $swaped "${msgs[ avail > swaped ]}"

[[ $1 == -n ]] && exit 0

if ((UID)); then
    printf 'Run this as \47root\47 to be able to run \e[3mswapoff\e[0m!\n'
    exit 0
fi
if (( avail > swaped )); then
    if [[ $1 != -y ]] &&
	   printf 'Hit any key to stop now or "Y" to continue. Proceed in ' &&
	   displaySleep $stopTimeout chr &&
	   [[ ${chr//[yY]} ]]; then
	echo 'User abort.'
    	exit 0
    fi
    printf '\n\n\n\n\n\n\n\n\n\n\n\e[11A\e7'
    exec {dummy}<> <(:)  # pseudo builtin sleep using read -t
    export startTime=${EPOCHREALTIME/.}
    tput civis
    printf -v refreshSwapedListRate '%.6f' $refreshSwapedListRate
    refreshSwapedListRate=$((10#${refreshSwapedListRate/.}))
    showProgress $swaped &
    monPid=$!
    trap 'tput cnorm;[[ -d /proc/$monPid ]] && kill $monPid;echo;exit' 0 1 2 3 9 15
    /usr/sbin/swapoff -a ||
	if (($?==32)) && sofpid=$(ps -C swapoff ho pid); then
	    while [[ -d /proc/$sofpid ]]; do
	     	read -t .1 -u $dummy _
	    done
	    [[ -d /proc/$monPid ]] && kill $monPid
	    exit 0
	else
	    exit $?
	fi
	
    elapsedTime=00000$(( ${EPOCHREALTIME/.} - startTime ))
    [[ -d /proc/$monPid ]] && kill $monPid
    echo
    tput cnorm
    /usr/sbin/swapon -a
    elapsedMin=$(( 10#$elapsedTime / 60000000 ))
    elapsedSec=00000$(( 10#$elapsedTime % 60000000 ))
    printf 'Swap: %s purged in %d minutes and %.3f secs (%.4f").\n' \
	"$hswaped" "$elapsedMin" ${elapsedSec::-6}.${elapsedSec: -6} \
	${elapsedTime::-6}.${elapsedTime: -6}
fi