#!/bin/bash
set -euo pipefail
DIRECTORY=$1
FORCE=${2-false}
JUST_DO_IT=${3-x}
I_MEAN_IT=${4-x}
LIMIT=10000000000 # 10GB
ACTION=print #delete
#LIMIT=13000000 # 13MB
#ACTION=print
MB1=1000000

estimate(){
	find "$1" -type f -"$2" +"$3" ${4-} -print0 | du -cb --files0-from=- | grep total | cut -d'	' -f1
}

cleanup(){
	filter="$1"
	unit="${2-}"
	tmin="${3-}"
	echo "Deleting files greater than ${WEIGHT}${unit} ($filter)$(if [ -n "$tmin" ]; then echo " where $tmin"; fi) ..."
	find "$DIRECTORY" -type f -"$filter" +"${WEIGHT}${unit}" ${tmin} -"$ACTION"
}

search(){
	upper="$3"
	lower="$2"
	filter="$1"
	unit="${4-}"
	tmin="${5-}"
	if [ "$unit" = "c" ]; then
		res=500000
	elif [ "$filter" = "mmin" ]; then
		res=3
	else
		res=0
	fi
	WEIGHT="$lower"
	while (( upper - lower > res)); do
		echo "Finding files greater than ${WEIGHT}${unit} ($filter)$(if [ -n "$tmin" ]; then echo " where $tmin"; fi) ..."
		RECLAIM=$(estimate "$DIRECTORY" "$filter" "${WEIGHT}${unit}" "${tmin}")
		if (( SIZE - RECLAIM > LIMIT ));
	       	then
			upper="$WEIGHT"
			WEIGHT=$(((WEIGHT + lower)/2))
			if (( WEIGHT == upper )); then break; fi
			if (( WEIGHT == lower )) && [ "$lower" != "$2" ]; then break; fi
		else
			lower="$WEIGHT"
			WEIGHT=$(((upper + WEIGHT)/2))
			if (( WEIGHT == lower )) || (( WEIGHT == upper )); then break; fi
		fi
	done
}

summary() {
	SIZE=$(find "$DIRECTORY" -type f -print0 | du -cb --files0-from=- | grep total | cut -d'	' -f1)
	echo "Current size is : $((SIZE/MB1)) MB"
}

RECLAIM=0
declare WEIGHT SIZE

summary
echo "Size limit is   : $((LIMIT/MB1)) MB"

# nothing to do
if (( SIZE < LIMIT )); then exit 0; fi

trap 'summary' EXIT

echo "Need to reclaim : $(( (SIZE - LIMIT)/MB1 )) MB"

search mtime 30 365
if (( WEIGHT > 30 )); then cleanup mtime && exit 0; fi

echo "Looking for big fat blobs older than 7 days and bigger than $((LIMIT/10/MB1))M ..."
search size $((LIMIT/10/MB1)) $((LIMIT/MB1)) M "-mtime +7"
if (( WEIGHT > LIMIT/10/MB1 )); then cleanup size M "-mtime +7" && exit 0; fi

# avoid deleting young files
if ! "$FORCE"; then echo "Refusing to cleanup files smaller than $((LIMIT/10/MB1))M and younger than 30 days";  exit 1; fi

search mtime 7 30
if (( WEIGHT > 7 )); then cleanup mtime && exit 0; fi

echo "Looking for big blobs older than 1 day and bigger than $((LIMIT/100/MB1))M ..."
search size $((LIMIT/100/MB1)) $((LIMIT/MB1)) M "-mtime +1"
if (( WEIGHT > LIMIT/100/MB1 )); then cleanup size M "-mtime +1" && exit 0; fi

# avoid deleting very young files
if [ "$JUST_DO_IT" != "JUST_DO_IT" ]; then echo "Refusing to cleanup files smaller than $((LIMIT/100/MB1))M and younger than 7 days";  exit 1; fi

search mtime 0 7
if (( WEIGHT > 0 )); then cleanup mtime && exit 0; fi

search mmin $((60*24)) $((60*24*2))
if (( WEIGHT > 60*24 )); then cleanup mmin && exit 0; fi

echo "Looking for blobs older than 12 hours and bigger than $((LIMIT/1000/MB1))M ..."
search size $((LIMIT/1000/MB1)) $((LIMIT/MB1)) M "-mmin +$((60*12))"
if (( WEIGHT > LIMIT/1000/MB1 )); then cleanup size M "-mmin +$((60*12))" && exit 0; fi

# avoid deleting ultra young files
if [ "$I_MEAN_IT" != "I_MEAN_IT" ]; then echo "Refusing to cleanup files smaller than $((LIMIT/1000/MB1))M and younger than 1 day";  exit 1; fi

search mmin 1 $((60*24))

cleanup mmin