#!/bin/sh

# Let's set a sane environment
set -o errexit
set -o nounset

UPDATE_README_COMMIT_AUTHOR_NAME='CI'
UPDATE_README_COMMIT_AUTHOR_EMAIL='michele@locati.it'
UPDATE_README_COMMIT_MESSAGE='[skip ci] Automatically update README.md'
WATCHED_FILES='data/special-requirements data/supported-extensions scripts/common scripts/update-readme scripts/ci-update-readme'
UPDATE_BRANCH='master'

echo 'Checking environment'
if test -z "${GITHUB_WORKSPACE:-}" || test -z "${GITHUB_REF:-}" || test -z "${GITHUB_EVENT_NAME:-}" || test -z "${GITHUB_REPOSITORY:-}"; then
	echo 'Not in a GitHub Actions environment' >&2
	exit 1
fi
if test "$GITHUB_EVENT_NAME" != 'push' || test "$GITHUB_REF" != "refs/heads/$UPDATE_BRANCH"; then
	echo 'This script should only be run in push builds to %s' "$UPDATE_BRANCH" >&2
	exit 1
fi
if test -z "${DEPLOY_KEY:-}"; then
	echo 'GitHub deploy key not set' >&2
	exit 1
fi

SCRIPTS_DIR="$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)"
. "$SCRIPTS_DIR/common"

cd "$GITHUB_WORKSPACE"

printf 'Checking-out branch %s\n' "$UPDATE_BRANCH"
git checkout --force "$UPDATE_BRANCH"

LAST_AUTO_UPDATED_IN="$(git rev-list --max-count 1 --author "<$UPDATE_README_COMMIT_AUTHOR_EMAIL>" --grep "$UPDATE_README_COMMIT_MESSAGE" "$UPDATE_BRANCH")"
if test -z "$LAST_AUTO_UPDATED_IN"; then
	printf 'Rebuild of README.md enabled (no previous automatic refresh of it in branch %s)\n' "$UPDATE_BRANCH"
else
	MODIFIED_FILES_SINCE="$(git diff --name-only "$LAST_AUTO_UPDATED_IN...$UPDATE_BRANCH")"
	if test -z "$(commonElements "$WATCHED_FILES" "$MODIFIED_FILES_SINCE")"; then
		printf 'Rebuild of README.md not needed (no relevant files changed in branch %s since commit %s)\n' "$UPDATE_BRANCH" "$LAST_AUTO_UPDATED_IN"
		exit 0
	fi
	printf 'Rebuild of README.md enabled (relevant files changed in branch %s since commit %s)\n' "$UPDATE_BRANCH" "$LAST_AUTO_UPDATED_IN"
fi

echo 'Updating README.md'
"$SCRIPTS_DIR/update-readme"
if test -z "$(git ls-files -m | grep -E '^README\.md$')"; then
	echo 'README.md has not been changed'
	exit 0
fi

printf 'Initializing SSH'
eval "$(ssh-agent)"
printf '%s' "$DEPLOY_KEY" | tr -d '\r' | ssh-add - >/dev/null

printf 'Adding %s remote\n' "$GITHUB_REPOSITORY"
git remote add deploy "git@github.com:$GITHUB_REPOSITORY.git"

echo 'Committing changes to README.md'
git config user.name "$UPDATE_README_COMMIT_AUTHOR_NAME"
git config user.email "$UPDATE_README_COMMIT_AUTHOR_EMAIL"
git add README.md
git commit -m "$UPDATE_README_COMMIT_MESSAGE"

printf 'Pushing to %s\n' "$GITHUB_REPOSITORY"
git push deploy "$UPDATE_BRANCH:$UPDATE_BRANCH"

echo 'Done.'