#!/bin/sh -e
APP_NAME=$1
PIPELINE_APP_NAME=$APP_NAME-slug
HEROKU_APP_REMOTE=git@heroku.com:$APP_NAME.git
HEROKU_PIPELINE_REMOTE=git@heroku.com:$PIPELINE_APP_NAME.git
WORKERS_COUNT=$(heroku ps --app $APP_NAME | grep "^worker." | wc -l | tr -d ' ')

# configure pipeline deploy https://devcenter.heroku.com/articles/labs-pipelines
heroku plugins:install git://github.com/heroku/heroku-pipeline.git
if test $(heroku apps | grep $PIPELINE_APP_NAME -c) -gt 0; then
  echo "Using existing pipeline $PIPELINE_APP_NAME"
  git remote add pipeline $HEROKU_PIPELINE_REMOTE
  DIFF_REMOTE=pipeline
else
  heroku apps:create $PIPELINE_APP_NAME --remote pipeline
  heroku labs:enable pipelines --app $PIPELINE_APP_NAME
  heroku pipeline:add $APP_NAME --app $PIPELINE_APP_NAME
  heroku pipeline --app $PIPELINE_APP_NAME

  git remote add heroku $HEROKU_APP_REMOTE
  DIFF_REMOTE=heroku
fi

# configure app and check for db changes
git fetch $DIFF_REMOTE
MIGRATION_CHANGES=$(git diff $CIRCLE_SHA1 $DIFF_REMOTE/master --name-only -- db | wc -l)
echo "$MIGRATION_CHANGES db changes since last deploy."

# use pipeline to prepare a slug to deploy
git push pipeline $CIRCLE_SHA1:refs/heads/master

DEPLOY_START=`date +%s`

# migrations require downtime so enter maintenance mode
if test $MIGRATION_CHANGES -gt 0; then
  heroku maintenance:on --app $APP_NAME

  # Make sure workers are not running during a migration
  heroku scale worker=0 --app $APP_NAME
fi

# Run our migrations in a subprocess so that failed db migrations
# don't immediately abort our deploy script.
(
  # promote the compiled slug
  heroku pipeline:promote --app $PIPELINE_APP_NAME

  # run database migrations if needed and restart background workers once finished
  if test $MIGRATION_CHANGES -gt 0; then
    heroku run rake db:migrate --app $APP_NAME
    heroku run rake db:seed --app $APP_NAME
  fi
)
MIGRATION_EXIT=$? # store the exit code

# Always scale our workers back up, regardless of whether the migration failed
if test $MIGRATION_CHANGES -gt 0; then
  heroku scale worker=$WORKERS_COUNT --app $APP_NAME
fi

# If the migration failed, now we can exit with that exit code
if test $MIGRATION_EXIT -ne 0; then
  exit $MIGRATION_EXIT
fi

heroku run rake cache:flush --app $APP_NAME
heroku maintenance:off --app $APP_NAME

DEPLOY_END=`date +%s`
ELAPSED=$(( $DEPLOY_END - $DEPLOY_START ))

echo "Deploy completed!"
if test $MIGRATION_CHANGES -gt 0; then
  echo "  $ELAPSED seconds in maintenance mode."
else
  echo "  $ELAPSED seconds, without maintenance mode."
fi

exit 0