#!/usr/bin/env bash

FILENAME='CHANGELOG.md'

# get the latest git tags
gittags="$(git tag --sort=-creatordate | grep -Ev '(alpha|beta|rc)')"
gittag_latest=$(printf '%s' "$gittags" | awk 'NR==1')
gittag_secondlatest=$(printf '%s' "$gittags" | awk 'NR==2')

echo "gittag_latest: ${gittag_latest}"
echo "gittag_secondlatest: ${gittag_secondlatest}"

# delete generated line (or it will be added multiple times)
sed -i '/This Changelog was automatically generated by/d' "$FILENAME"

# delete trailing empty lines
sed -i -e :a -e '/^\n*$/{$d;N;};/\n$/ba' "$FILENAME"

# determine correct tag to go back to
# @TODO
if [[ ! -z $TRAVIS_TAG ]]; then
  echo "release build"
  gittag=${gittag_secondlatest}
else
  echo "merge into master or develop"
  gittag=${gittag_latest}
fi
echo "gittag: ${gittag}"

# find the line the tag starts on, and subtract 1
tagline=$(grep -n "^## \[\?$gittag\]\?" CHANGELOG.md | awk '{print $1}' FS=':' | head -1)
echo "tagline: ${tagline}"
[[ ! -z $tagline ]] && sed -i "1,$(expr $tagline - 1)d" "$FILENAME"

# generate the changelog
docker run -it --rm -v "$(pwd)":/usr/local/src/your-app ferrarimarco/github-changelog-generator -t $CHANGELOG_GITHUB_TOKEN --since-tag $gittag

# @TODO commit changes, etc
git diff