#!/bin/sh

[ -e /etc/.userdata_ready ] && exit 0
[ -b /dev/mmcblk0 ] || exit 0
command -v parted >/dev/null 2>&1 || exit 0

DISK=/dev/mmcblk0
LABEL=UserData

# already present? (by GPT name, not by partition number)
NUM=$(parted -s "$DISK" print 2>/dev/null | awk -v n="$LABEL" '$0 ~ n {print $1; exit}')
if [ -n "$NUM" ]; then
	touch /etc/.userdata_ready
	exit 0
fi

# start of the biggest free gap
START=$(parted -s "$DISK" unit MB print free 2>/dev/null |
	awk '/Free Space/ {v = $1} END {print v}')
[ -n "$START" ] || exit 0

# needs at least 64 MiB to be worth it
FREE_MB=$(parted -s "$DISK" unit MB print free 2>/dev/null |
	awk '/Free Space/ {if ($3 > m) m = $3} END {printf "%d", m}')
[ "${FREE_MB:-0}" -ge 64 ] || {
	touch /etc/.userdata_ready
	exit 0
}

logger -t userdata "fitting GPT to disk end, creating $LABEL from ${START}MB"

printf 'print\nOK\nFix\nmkpart %s ext4 %s 100%%\nquit\n' "$LABEL" "$START" |
	parted ---pretend-input-tty "$DISK" >/dev/null 2>&1

NUM=$(parted -s "$DISK" print 2>/dev/null | awk -v n="$LABEL" '$0 ~ n {print $1; exit}')
[ -n "$NUM" ] || {
	logger -t userdata "partition was not created, giving up"
	exit 0
}

DEV="/dev/mmcblk0p$NUM"
[ -b "$DEV" ] || {
	logger -t userdata "$DEV missing, giving up"
	exit 0
}

if ! blkid -s TYPE -o value "$DEV" 2>/dev/null | grep -q .; then
	mkfs.ext4 -F -L "$LABEL" "$DEV" >/dev/null 2>&1
	logger -t userdata "formatted $DEV as ext4"
else
	logger -t userdata "$DEV already has a filesystem, left untouched"
fi

mkdir -p /mnt/UserData
mountpoint -q /mnt/UserData || mount "$DEV" /mnt/UserData 2>/dev/null

uci -q delete fstab.mnt_userdata 2>/dev/null
uci set fstab.mnt_userdata=mount
uci set fstab.mnt_userdata.target='/mnt/UserData'
uci set fstab.mnt_userdata.device="$DEV"
uci set fstab.mnt_userdata.fstype='ext4'
uci set fstab.mnt_userdata.options='rw,noatime'
uci set fstab.mnt_userdata.enabled='1'
uci commit fstab

logger -t userdata "mounted $DEV on /mnt/UserData (persisted in fstab)"

sync
touch /etc/.userdata_ready
exit 0