#!/bin/sh

if test $(uci get autoupdater.settings.enabled) != 1; then
  echo "autoupdater is disabled"
  exit 0
fi

BRANCH=$(uci get autoupdater.settings.branch)

PROBABILITY=$(uci get autoupdater.${BRANCH}.probability)

if test "a$1" != "a-f"; then
  echo | awk "END{srand();exit rand() > $PROBABILITY}"
  if test $? -ne 0; then
    echo "No autoupdate this time. Use -f to override"
    exit 0
  fi
fi

BASE=$(uci get autoupdater.${BRANCH}.url)
PUBKEYS=$(uci get autoupdater.${BRANCH}.pubkey)
GOOD_SIGNATURES=$(uci get autoupdater.${BRANCH}.good_signatures)

VERSION_FILE=/lib/gluon/release

newer_than() {
  local old="$(printf '%s\n%s\n' "$1" "$2" | sort -n | head -n 1)"
  test "$1" != "$old"
}

cleanup() {
  rm -f $manifest
  rm -f $fw_image
  rm -f $manifest_upper
  rm -f $manifest_lower
}

trap cleanup INT TERM EXIT PIPE

. /lib/gluon/functions/model.sh
my_model="$(get_model | tr '[A-Z]' '[a-z]' | sed -r 's/[^a-z0-9]+/-/g;s/-$//')"

if [ ! -f "$VERSION_FILE" ]; then
  echo "Couldn't determine firmware version!" >&2
  exit 1
fi

my_version="$(cat "$VERSION_FILE")"

fw_image=$(mktemp)
manifest=$(mktemp)
manifest_upper=$(mktemp)
manifest_lower=$(mktemp)

wget -O$manifest "$BASE"/manifest

if test $? -ne 0; then
  echo "Couldn't fetch manifest" >&2
  exit 1
fi

seperator_line=$(cat $manifest|grep -n "^---$"|cut -d: -f1|head -n1)

if test -z "$seperator_line"; then
  echo "Couldn't find --- marker!" >&2
  exit 1
fi

head -n$(($seperator_line-1)) $manifest > $manifest_upper
tail -n+$(($seperator_line+1)) $manifest > $manifest_lower

signatures=""
while read sig; do
  echo "$sig" | grep -q "^[0-9a-f]\{128\}$"
  if test $? -ne 0; then
    continue
  fi
  signatures="$signatures -s $sig"
done < $manifest_lower

pubkeys=""
for key in $PUBKEYS; do
  pubkeys="$pubkeys -p $key"
done

ecdsaverify -n $GOOD_SIGNATURES $pubkeys $signatures $manifest_upper

if test $? -ne 0; then
  echo "Not enough valid signatures!" >&2
  exit 1
fi

grep -q "^BRANCH=${BRANCH}$" $manifest_upper

if test $? -ne 0; then
  echo "Wrong branch. We'are on ${BRANCH}" >&2
  exit 1
fi

my_firmware=$(grep "^${my_model} " $manifest_upper)

if test $? -ne 0; then
  echo "No matching firmware found (model ${my_model})" >&2
  exit 1
fi

fw_version=$(echo "${my_firmware}"|cut -d' ' -f2)
fw_md5=$(echo "${my_firmware}"|cut -d' ' -f3)
fw_file=$(echo "${my_firmware}"|cut -d' ' -f4)

if newer_than "$fw_version" "$my_version"; then
  echo "New version available"
  wget -O$fw_image "${BASE}/${fw_file}"
  if test $? -ne 0; then
    echo "Error downloading image" >&2
    exit 1
  fi

  image_md5=$(md5sum "$fw_image"|cut -b-32)
  if test "$image_md5" != "$fw_md5"; then
    echo "Invalid image checksum" >&2
    exit 1
  fi

  echo "Upgrading firmware."

  sysupgrade "${fw_image}"
else
  echo "No new firmware available"
fi

exit 0