apt-clean

#!/bin/bash
# Simplify and clean up redundant or incorrect APT package state.
# TODO: add commands to query the database, and display sorted based
# on name/status/component/section etc.

abort() { local x="$1"; shift; echo >&2 "$@"; exit "$x"; }

NATIVE="$(dpkg --print-architecture)"

# Save to $STATE.new - we can't save to $STATE directly because dialog provides
# no way to distinguish between empty output vs operation cancelled.
save_state() {
	if grep -q '^\['"$1"'\]' "$STATE"; then
		# blank between "[$1]" and "[!$1]||<EOF>"
		awk '(/\[/ && !/\['"$1"'\]/ || 0){f=0} !f; /\['"$1"'\]/{f=1}' "$STATE" > "$STATE.tmp"
		sed -i -e '/\['"$1"'\]/r'<(cat; echo;) "$STATE.tmp"
	else
		cat "$STATE" <(echo "[$1]"; cat; echo;) >> "$STATE.tmp"
	fi
	mv "$STATE.tmp" "$STATE.new"
}

commit_state() {
	cat <"$STATE.new" >"$STATE" && rm -f "$STATE.new"
}

read_state() {
	# output between "[$1]" and "[!$1]||<EOF>"
	awk '/\['"$1"'\]/{f=1} (/\[/ && !/\['"$1"'\]/ || 0){f=0} f' "$STATE"
}

# Either output &1, or (if the first item is "_") $1 \ &1.
maybe_invert() {
	read x
	if [ "$x" = "_" ]; then
		comm -13 <(sort) "$1"
	else
		{ echo "$x"; cat; } | sort
	fi
}

# Execute a query and ask the user to select a subset to "keep" i.e. do nothing
# with. This selection is saved to STATE, and everything else is output for
# further processing.
#
# old stdout (tty) must be saved to fd 3 before calling, e.g. with `exec 3>&1`
user_select() {
	local tag="$1" query="$2" filter="$3" title="$4" sel="$5" sweep="$6"
	aptitude search --disable-columns -F '%p %d' "!~v $query" | sort -k1 | {
	local argsY=()
	local argsN=()
	local pkgsf=$(mktemp --tmpdir=/dev/shm apt-clean.XXXXXXXXXX)
	trap 'excode=$?; '"rm $pkgsf"'; trap - EXIT; exit $excode' EXIT HUP INT QUIT PIPE TERM
	while read pkg desc; do
		if ! eval "$filter" >/dev/null 2>/dev/null; then
			continue
		fi
		if read_state "$tag" | grep -qxF "$pkg"; then
			argsY+=( "$pkg" "$desc" "on" )
		else
			argsN+=( "$pkg" "$desc" "off" )
		fi
		echo "$pkg" >> "$pkgsf"
	done
	sort "$pkgsf" -o "$pkgsf"
	if ! [ -s "$pkgsf" ]; then return; fi

	# skip dialog if everything already selected
	if $SKIP_FULL && [ "${#argsN[@]}" -eq 0 ]; then
		# discard previously-selected entries that are no longer valid i.e.
		# didn't show up in the query. the `git diff` will reveal them anyway.
		comm -12 "$pkgsf" <(read_state "$tag" | sort) | save_state "$tag"
		commit_state
		return
	fi

	rm -f "$STATE.tmp"
	if dialog --output-fd 4 --separate-output \
	  --title "$title" --checklist "Select items that you would like to $sel.\n\nEverything else will be $sweep." \
	  43 132 40 "_" "INVERT SELECTION" "" "${argsN[@]}" "${argsY[@]}" 4> >(maybe_invert "$pkgsf" | save_state "$tag") >&3; then
		# sleep because save_state happens in bg
		while [ -f "$STATE.tmp" ]; do sleep 0.1; done
		commit_state
		# aptitude sorts differently
		comm -23 "$pkgsf" <(read_state "$tag" | sort)
	fi
	}
}

user_run() {
	exec 3>&1 # save stdout for user_select
	xargs --verbose -r -a <(user_select "${@:1:6}" | tee "$STATE.round") "${@:7}"
	local X=$?
	if $AUTO_NEXT; then
		echo "step \"$1\" complete."
	else
		read -p "step \"$1\" complete; examine in sub-shell? [y/N] " x
		if [ "$x" = "y" ]; then "$SHELL"; fi
	fi
	if [ "$X" = 0 -a -s "$STATE.round" ]; then
		return 119 # a code that xargs does not use
	else
		return $X
	fi
}

git_commit_state() {
	local q="$1"
	local msg="$2"
	shift 2
	read -p "$q [y/N] " x
	if [ "$x" = "y" ]; then
		"$@"
		git add "$STATE"
		git commit -m "apt-clean: $msg"
	fi
}

ESSENTIAL='~prequired|~pimportant|~E'
TOP_LEVEL='!~Rpredepends:~i !~Rdepends:~i !~Rrecommends:~i'
ABS_TOP_LEVEL="$TOP_LEVEL"' !~Rsuggests:~i'
CUR_ARCH='~rnative'

LOCALITY_CAVEAT="This shouldn't affect other packages not listed here - i.e. the aptitude prompt that follows should not contain any non-trivial {a} entries. If it does, then you should have selected extra packages - abort the command by selecting NO, and we will schedule another round for you to fix the problem"

USAGE="Usage: $0 [-a|-s|-h] <STATE>"

# runtime vars
SKIP_FULL=false
AUTO_NEXT=false
USING_GIT=false

while getopts ash o; do
	case $o in
	a ) AUTO_NEXT=true;;
	s ) SKIP_FULL=true;;
	h )
		cat <<-EOF
		$USAGE

		Simplify and clean up redundant or incorrect APT package state.

		Arguments:
		-a                  Auto mode; don't ask to drop to shell after each step.
		-s                  Skip the selection dialog if all available entries are
		                    already selected.
		-h                  Show this help.
		EOF
		exit 1
		;;
	esac
done
shift `expr $OPTIND - 1`

STATE=${1:-apt-clean.txt}
touch "$STATE" "$STATE.tmp" "$STATE.round" || abort 3 "cannot write to one of $STATE{,.tmp,.round}"
cleanup() { rm -f "$STATE.tmp" "$STATE.round" 2>/dev/null; exit; }
trap 'excode=$?; cleanup; trap - EXIT; exit $excode' EXIT HUP INT QUIT PIPE TERM

test -z "$(aptitude search "(~prequired|~E) $CUR_ARCH !~i")" || abort 4 "Your system appears to be FUBAR, try \`aptitude install '(~prequired|~E) $CUR_ARCH'\`."
test -n "$(git ls-tree HEAD -- "$STATE")" && USING_GIT=true

if ! $USING_GIT; then
	echo >&2 "warning: $STATE is not controlled by git"
	git_commit_state "automatically add to existing (or else new) git repo?" "initialise" git init
	read -p "press any key to continue" x
	test -n "$(git ls-tree HEAD -- "$STATE")" && USING_GIT=true
fi

while $imperfect; do
imperfect=false

user_run 'block-rec' '~RBrecommends:~i !~i' true 'broken recommends' \
  "keep uninstalled, even if recommended by another installed package.\n  - You might do this if e.g. it takes up too much space, or it conflicts with another installed package" \
  "installed" \
  aptitude --prompt install \
  || imperfect=true

user_run 'block-imp' "~pimportant $CUR_ARCH !~i" true 'uninstalled important packages' \
  "keep uninstalled, which should only be packages where a functional alternative (e.g. a different version or flavour) is already installed" \
  "installed" \
  aptitude --prompt install \
  || imperfect=true

user_run 'manual-sub' "~i !($ESSENTIAL) !($TOP_LEVEL) !~M" true 'not top-level, non-automatic' \
  "keep installed, even if (theoretically, in the future) nothing else depends on it" \
  "marked automatic, which means it will be removed if no longer required, but otherwise kept" \
  aptitude --prompt markauto \
  || imperfect=true

user_run 'auto-abstop' "~i !($ESSENTIAL) $ABS_TOP_LEVEL ~M" true 'abs-top-level, automatic' \
  "be automatically removed. They will no longer show up here next time, which is what you want" \
  "marked manual, which means it will be retained even if nothing else depends on it" \
  aptitude --prompt unmarkauto \
  || imperfect=true

user_run 'manual-top' "~i !($ESSENTIAL) $TOP_LEVEL !~M" true 'top-level, non-automatic' \
  "keep installed, even if nothing else depends on it" \
  "removed, which may benignly cause other autoremovals and another round to be executed" \
  aptitude --prompt remove \
  || imperfect=true

user_run 'auto-top' "~i !($ESSENTIAL) $TOP_LEVEL ~M" true 'top-level, automatic' \
  "keep automatically installed as a result of a suggestion.\n  - If you want to make these unconditionally manually installed, you should 'aptitude unmarkauto' these later, and re-run this script" \
  "uninstalled.\n  - $LOCALITY_CAVEAT" \
  aptitude --prompt remove \
  || imperfect=true

user_run 'foreign-arch' '~rforeign ~i' '! dpkg-query -W "${pkg%:*}:$NATIVE"' 'installed-foreign without installed-native' \
  "keep installed, even if the corresponding native package isn't installed" \
  "removed, which might trigger aptitude to try to install the native package" \
  aptitude --prompt remove \
  || imperfect=true

user_run 'keep-config' '~c' true 'uninstalled but with configuration' \
  "keep config files for" \
  "purged" \
  aptitude --prompt purge \
  || imperfect=true

user_run 'maybe-dummy' "~i !($ESSENTIAL) $TOP_LEVEL (~ddummy|~dtransitional|~d\"safely removed\")" true 'possibly transitional or dummy packages' \
  "keep installed, i.e. for which the heuristic (simple regex) we use here is incorrect" \
  "purged, since it is simply a dummy or transitional package.\n  - $LOCALITY_CAVEAT" \
  aptitude --prompt purge \
  || imperfect=true

if $imperfect; then
	echo "This round caused some changes and/or exposed some problems; running one final cleanup."
	echo "It should not do anything unexpected; if it does, then abort and re-run this script."
	aptitude --prompt install
	echo "Running another round to iron out newly-uncovered issues and/or to fix those problems."
fi

done

echo "apt-clean done."

if $USING_GIT && ! git diff --quiet; then
	git diff
	git_commit_state "commit changes?" "$STATE: update package state"
fi