pre-commit

#!/bin/bash
set -e

RELEASE=1.6
JAR_NAME="google-java-format-${RELEASE}-all-deps.jar"
RELEASES_URL=https://github.com/google/google-java-format/releases/download
JAR_URL="${RELEASES_URL}/google-java-format-${RELEASE}/${JAR_NAME}"

CACHE_DIR="$HOME/.cache/google-java-format-git-pre-commit-hook"
JAR_FILE="$CACHE_DIR/$JAR_NAME"
JAR_PGP_ASC_FILE="${JAR_FILE}.asc"
PGP_SIGN_KEY_ID=E77417AC194160A3FABD04969A259C7EE636C5ED

if [[ ! -f "$JAR_FILE" ]]
then
    mkdir -p "$CACHE_DIR"
    curl -L "$JAR_URL" -o "$JAR_FILE"
    cat >"$JAR_PGP_ASC_FILE" <<EOF
-----BEGIN PGP SIGNATURE-----

iQIzBAABCgAdFiEE53QXrBlBYKP6vQSWmiWcfuY2xe0FAlsHZhoACgkQmiWcfuY2
xe3tgQ//ft5l8gtDAN5s9Tl+uvoykG/Kxq4UTi2+DsAQ4oGeHJg99SKAwrwDGduG
rUhB8CVlCyKBfBoNKK94JAOP/Q7wq88VOlriuN4o8QM5UwP+ZOCCRfY+xlHhuu1+
UyrD1N0oVdGa/omrf4IKWBDgIs6Zishn0ie15qUVNz9k8+hc0bP3+wB1tIGFnugR
66jV9vjL5N+2PakI6Hz4ASucTH6EUhmGYsSMGQlaxmJWWcuIO+y3ufwG+8DtrOuj
13bkn78s4PbCvfgC+b+uuqF3nB1J1H+ZDTTiqxTCFGgOI9+ksa6H1CA9BRwqxbBV
Jn6I4FB3LnP8xfaA+zRimaa7zFR7uI8/qJo+S55Y7nsT06TnaaSX6IodN5G9FCBp
POQSx++SB56DuRvwqA6U1cqvSBJEzekPRw/C3xFgbFHOjCYujhkCNEXq1CRd10Ng
FAnivzXoyEHzMgGy3R8jAlinxMYmUGm0NEtWbgFwNMlXUJIsE9ff+qzrFES8hfAH
MSBvPcPBdTUtvpMSjKWBLeOqrJtDWwv/RL8Aoq616W5DKWtZV9Iy8lVvEckwFlc8
SkTJMY70+4pDR1kRGg5rsxFfL3JQ2/EuncYGaNqpaSZkD7Uj4bCzDohYO5qvZcXj
aZ74ifXOYUKs3n18rveK1EVgxD/+iohpUt2JPccEQkRVsOoVTlY=
=uy69
-----END PGP SIGNATURE-----
EOF
fi

changed_java_files=$(git diff --cached --name-only --diff-filter=ACMR | grep ".*java$" || true)
if [[ -n "$changed_java_files" ]]
then
    if ! gpg --list-keys "$PGP_SIGN_KEY_ID" >/dev/null
    then
        gpg --keyserver hkp://pgp.mit.edu --recv-key "$PGP_SIGN_KEY_ID"
    fi
    if ! gpg --verify "$JAR_PGP_ASC_FILE" 2>/dev/null
    then
        echo "Failed to verify signature at: $JAR_PGP_ASC_FILE" >&2
        exit 1
    fi

    echo "Reformatting Java files: $changed_java_files"
    if ! java -jar "$JAR_FILE" --replace --set-exit-if-changed $changed_java_files
    then
        echo "Some files were changed, aborting commit!" >&2
        exit 1
    fi
else
    echo "No Java files changes found."
fi