#!/bin/bash

set -e

# This script should be run at the root of the repository.

# This script is used to, when a pull request changes the generation

# configuration (generation_config.yaml by default):

# 1. Find whether the last commit in this pull request contains changes to

# the generation configuration and exit early if it doesn't have such a change

# since the generation result would be the same.

# 2. Compare generation configurations in the current branch (with which the

# pull request associated) and target branch (into which the pull request is

# merged);

# 3. Generate changed libraries using library_generation image;

# 4. Commit the changes to the pull request, if any.

# 5. Edit the PR body with generated pull request description, if applicable.

# The following commands need to be installed before running the script:

# 1. git

# 2. gh

# 3. docker

# The parameters of this script is:

# 1. target_branch, the branch into which the pull request is merged.

# 2. current_branch, the branch with which the pull request is associated.

# 3. [optional] generation_config, the path to the generation configuration,

# the default value is generation_config.yaml in the repository root.

while [[ $# -gt 0 ]]; do

key="$1"

case "${key}" in

--target_branch)

target_branch="$2"

shift

;;

--current_branch)

current_branch="$2"

shift

;;

--generation_config)

generation_config="$2"

shift

;;

*)

echo "Invalid option: [$1]"

exit 1

;;

esac

shift

done

if [ -z "${target_branch}" ]; then

echo "missing required argument --target_branch"

exit 1

fi

if [ -z "${current_branch}" ]; then

echo "missing required argument --current_branch"

exit 1

fi

if [ -z "${generation_config}" ]; then

generation_config=generation_config.yaml

echo "Using default generation config: ${generation_config}"

fi

workspace_name="/workspace"

baseline_generation_config="baseline_generation_config.yaml"

message="chore: generate libraries at $(date)"

git checkout "${target_branch}"

git checkout "${current_branch}"

# if the last commit doesn't contain changes to generation configuration,

# do not generate again as the result will be the same.

change_of_last_commit="$(git diff-tree --no-commit-id --name-only HEAD~1..HEAD -r)"

if [[ ! ("${change_of_last_commit}" == *"${generation_config}"*) ]]; then

echo "The last commit doesn't contain any changes to the generation_config.yaml, skipping the whole generation process." || true

exit 0

fi

# copy generation configuration from target branch to current branch.

git show "${target_branch}":"${generation_config}" > "${baseline_generation_config}"

config_diff=$(diff "${generation_config}" "${baseline_generation_config}" || true)

# parse image tag from the generation configuration.

image_tag=$(grep "gapic_generator_version" "${generation_config}" | cut -d ':' -f 2 | xargs)

# run hermetic code generation docker image.

docker run \

--rm \

-u "$(id -u):$(id -g)" \

-v "$(pwd):${workspace_name}" \

gcr.io/cloud-devrel-public-resources/java-library-generation:"${image_tag}" \

--baseline-generation-config-path="${workspace_name}/${baseline_generation_config}" \

--current-generation-config-path="${workspace_name}/${generation_config}"

# commit the change to the pull request.

if [[ $(basename $(pwd)) == "google-cloud-java" ]]; then

git add java-* pom.xml gapic-libraries-bom/pom.xml versions.txt

else

# The image leaves intermediate folders and files it works with. Here we remove them

rm -rdf output googleapis "${baseline_generation_config}"

git add --all -- ':!pr_description.txt'

fi

changed_files=$(git diff --cached --name-only)

if [[ "${changed_files}" == "" ]]; then

echo "There is no generated code change with the generation config change ${config_diff}."

echo "Skip committing to the pull request."

exit 0

fi

echo "Configuration diff:"

echo "${config_diff}"

git commit -m "${message}"

git push

# set pr body if pr_description.txt is generated.

if [[ -f "pr_description.txt" ]]; then

pr_num=$(gh pr list -s open -H "${current_branch}" -q . --json number | jq ".[] | .number")

gh pr edit "${pr_num}" --body "$(cat pr_description.txt)"

fi