#!/bin/sh

. /lib/partman/lib/base.sh
. /lib/partman/lib/resize.sh
. /lib/partman/lib/auto-shared.sh

ARCH="$(archdetect)"
case $ARCH in
    armel/*)
	# Dual-booting on ARM is difficult for casual users
	exit 0
	;;
esac

bestfree=0
bestpart=none
bestpath=none

tmpfile="$(mktemp /tmp/partman-auto.XXXXXX)"
trap "rm -f $tmpfile" EXIT HUP INT QUIT TERM

# Count the number of primary and logical partitions.
count_primary_logical () {
	local primaries=0
	local logicals=0
	while { read num oldid size type fs path name; [ "$oldid" ]; }; do
		case $fs in
		    free)
			;;
		    *)
			case $type in
			    primary)
				primaries="$(($primaries + 1))"
				;;
			    logical)
				logicals="$(($logicals + 1))"
				;;
			esac
			;;
		esac
		echo "$primaries $logicals"
	done | tail -n1
}

# Filter a partition list to include only those entries which are already
# part of an extended partition or which can be resized to provide
# additional space in an extended partition.
can_be_extended () {
	local previous=
	while { read num oldid size type fs path name; [ "$oldid" ]; }; do
		case $type in
		    logical|pri/log)
			if [ "$previous" ]; then
				# If the previous partition can be resized, that will
				# create additional space at the end adjacent to this
				# partition.
				echo "$previous"
				previous=
			fi
			echo "$num $oldid $size $type $fs $path $name"
			;;
		    *)
			previous="$num $oldid $size $type $fs $path $name"
			;;
		esac
	done
}

scan_disk () {
	local partitions uses_extended max_primary
	local primary_logical primaries logicals

	totalfree=0
	diskfree=0
	diskpart=none
	diskpath=none

	open_dialog PARTITIONS
	partitions="$(read_paragraph)"
	close_dialog

	open_dialog USES_EXTENDED
	read_line uses_extended
	close_dialog

	open_dialog GET_MAX_PRIMARY
	read_line max_primary
	close_dialog
	if [ -z "$max_primary" ]; then
		log "Unable to get maximum primary partition count on $dev"
		return
	fi

	# TODO: This should all be checked later to take account of recipes
	# other than the defaults for the supported Ubuntu architectures.
	if [ "$uses_extended" = yes ]; then
		primary_logical="$(echo "$partitions" | count_primary_logical)"
		if [ "$primary_logical" ]; then
			primaries="${primary_logical% *}"
			logicals="${primary_logical#* }"
			log "$primaries primary partitions, $logicals logical partitions"

			# If there are no logical partitions, then we will need a
			# primary partition slot to create an extended partition.
			if [ "$logicals" -eq 0 ] && \
			   [ "$primaries" -ge "$max_primary" ]; then
				log "Too many primary partitions already exist on $dev without an extended partition"
				return
			fi

			# If there is already an extended partition, then only consider
			# those partitions in which (after resizing) partitions can be
			# created sufficiently freely.
			if [ "$logicals" -ne 0 ]; then
				partitions="$(echo "$partitions" | can_be_extended)"
				log "filtered partition list:"
				log "$partitions"
			fi
		fi
	fi

	# Parts of the body of this while loop may use debconf, so we must not
	# interfere with stdin, hence the temporary file.
	echo "$partitions" >"$tmpfile"
	while { read num oldid size type fs path name <&9; [ "$oldid" ]; }; do
		case $fs in
		    free)
			totalfree="$(expr "$totalfree" + "$size")"
			;;

		    linux-swap|fat32)
			get_resize_range
			if [ "$cursize" ] && [ "$minsize" ]; then
				thisfree="$(expr "$cursize" - "$minsize")"
				if longint_le $diskfree $thisfree; then
					diskfree=$thisfree
					diskpart=$dev//$oldid
					diskpath=$path
				fi
			fi
			;;

		    ext2|ext3|ext4)
			if ! type tune2fs >/dev/null 2>&1 || ! type resize2fs >/dev/null 2>&1; then
				continue
			fi
			check_virtual
			if [ "$virtual" = yes ]; then
				get_resize_range
			else
				get_real_resize_range "$oldid" "$fs" || continue
			fi
			if [ "$cursize" ] && [ "$minsize" ]; then
				thisfree="$(expr "$cursize" - "$minsize")"
				if longint_le $diskfree $thisfree; then
					diskfree=$thisfree
					diskpart=$dev//$oldid
					diskpath=$path
				fi
			fi
			;;

		    ntfs)
			if ! type ntfsresize >/dev/null 2>&1; then
				continue
			fi
			check_virtual
			if [ "$virtual" = yes ]; then
				get_resize_range
			else
				get_real_resize_range "$oldid" "$fs" || continue
			fi
			if [ "$cursize" ] && [ "$minsize" ]; then
				thisfree="$(expr "$cursize" - "$minsize")"
				if longint_le $diskfree $thisfree; then
					diskfree=$thisfree
					diskpart=$dev//$oldid
					diskpath=$path
				fi
			fi
			;;
		esac
	done 9<"$tmpfile"
}

get_resize_use_free_on_dev() {
	cd $dev

	scan_disk
	log "dev: '$dev', totalfree: '$totalfree', diskfree: '$diskfree', diskpart: '$diskpart', diskpath: '$diskpath'"
	if longint_le "$bestfree" "$diskfree"; then
		bestfree="$diskfree"
		bestpart="$diskpart"
		bestpath="$diskpath"
	fi
}

dev="$1"

if [ -z "$dev" ]; then
	DEVS="$(get_auto_disks)"
	IFS="$NL"
	for dev in $DEVS; do
		restore_ifs
		dev="${dev%$TAB*}"
		get_resize_use_free_on_dev
		IFS="$NL"
	done
	restore_ifs
else
	get_resize_use_free_on_dev
fi

if [ -z "$bestpart" ] || [ "$bestpart" = none ]; then
	log "Found no resizable partitions"
elif longint_le "$(expr 3 \* 1024 \* 1024 \* 1024)" $bestfree; then
	log "Found resizable partition '$bestpart' ($bestpath) with $bestfree bytes free"
	db_subst partman-auto/text/resize_use_free PARTITION "$(humandev "$bestpath")"
	db_metaget partman-auto/text/resize_use_free description
	printf "%s\t%s" "$bestpart" "$RET"
else
	log "Found resizable partition '$bestpart' ($bestpath), but not offering because only $bestfree bytes free"
fi