#!/bin/sh

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

UPDATE_README_COMMIT_AUTHOR_NAME='Travis 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/travisci-update-readme'

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


echo 'Checking environment'
if test -z "${TRAVIS_BUILD_DIR:-}" || test -z "${TRAVIS_BRANCH:-}" || test -z "${TRAVIS_EVENT_TYPE:-}" || test -z "${TRAVIS_REPO_SLUG:-}"
then
	echo 'Not in a TravisCI environment' >&2
	exit 1
fi
if test -z "${GUTHUB_ACCESS_TOKEN:-}"
then
	
	echo 'GitHub access token not set' >&2
	# To create it:
	#  - go to https://github.com/settings/tokens/new?scopes=repo
	#  - create a new token
	#  - sudo apt install -y build-essential ruby ruby-dev
	#  - sudo gem install travis
	#  - travis encrypt -r <owner>/<repo> GUTHUB_ACCESS_TOKEN=<TOKEN>
	#  - Add to .travis.yml:
	#    env:
	#      global:
	#        - secure: "encrypted string"
	exit 1
fi
if test "${TRAVIS_EVENT_TYPE}" != 'push'
then
	echo 'This script should only be run in push builds' >&2
	exit 1
fi

printf 'Checking-out branch %s\n' "${TRAVIS_BRANCH}"
git checkout --force "${TRAVIS_BRANCH}"

LAST_AUTO_UPDATED_IN="$(git -C "${TRAVIS_BUILD_DIR}" rev-list --max-count 1 --author "<${UPDATE_README_COMMIT_AUTHOR_EMAIL}>" --grep "${UPDATE_README_COMMIT_MESSAGE}" "${TRAVIS_BRANCH}")"
if test -z "${LAST_AUTO_UPDATED_IN}"
then
	printf 'Rebuild of README.md enabled (no previous automatic refresh of it in branch %s)\n' "${TRAVIS_BRANCH}"
else
	MODIFIED_FILES_SINCE="$(git -C "${TRAVIS_BUILD_DIR}" diff --name-only "${LAST_AUTO_UPDATED_IN}...${TRAVIS_BRANCH}")"
	if test -z "$(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' "${TRAVIS_BRANCH}" "${LAST_AUTO_UPDATED_IN}"
		exit 0
	fi
	printf 'Rebuild of README.md enabled (relevant files changed in branch %s since commit %s)\n' "${TRAVIS_BRANCH}" "${LAST_AUTO_UPDATED_IN}"
fi

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

printf 'Adding %s remote\n' "${TRAVIS_REPO_SLUG}"
git remote add deploy "https://${GUTHUB_ACCESS_TOKEN}@github.com/${TRAVIS_REPO_SLUG}.git"

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

printf 'Pushing to %s\n' "${TRAVIS_REPO_SLUG}"
git push deploy "${TRAVIS_BRANCH}"

echo 'Done.'