#!/bin/bash
#
# This script is designed to be run inside the container
#

# fail hard and fast even on pipelines
set -eo pipefail

# set debug based on envvar
[[ $DEBUG ]] && set -x

# configure etcd
export ETCD_PORT=${ETCD_PORT:-4001}
export ETCD="$HOST:$ETCD_PORT"
export ETCD_PATH=${ETCD_PATH:-/deis/database}
export ETCD_TTL=${ETCD_TTL:-10}

export BUCKET_NAME=${BUCKET_NAME:-db_wal}
export BACKUPS_TO_RETAIN=${BACKUPS_TO_RETAIN:-5}

# how many TTL/2 sleeps between backups -- 2160 is 3 hours
export BACKUP_FREQUENCY=${BACKUP_FREQUENCY:-2160}

# wait for etcd to be available
until etcdctl --no-sync -C $ETCD ls >/dev/null 2>&1; do
	echo "database: waiting for etcd at $ETCD..."
	sleep $(($ETCD_TTL/2))  # sleep for half the TTL
done

# wait until etcd has discarded potentially stale values
sleep $(($ETCD_TTL+1))

function etcd_set_default {
  set +e
  etcdctl --no-sync -C $ETCD mk $ETCD_PATH/$1 $2 >/dev/null 2>&1
  if [[ $? -ne 0 && $? -ne 4 ]]; then
    echo "etcd_set_default: an etcd error occurred. aborting..."
    exit 1
  fi
  set -e
}

etcd_set_default engine postgresql_psycopg2
etcd_set_default adminUser ${PG_ADMIN_USER:-postgres}
etcd_set_default adminPass ${PG_ADMIN_PASS:-changeme123}
etcd_set_default user ${PG_USER_NAME:-deis}
etcd_set_default password ${PG_USER_PASS:-changeme123}
etcd_set_default name ${PG_USER_DB:-deis}
etcd_set_default bucketName ${BUCKET_NAME}

# wait for confd to run once and install initial templates
until confd -onetime -node $ETCD -config-file /app/confd.toml; do
	echo "database: waiting for confd to write initial templates..."
	sleep $(($ETCD_TTL/2))  # sleep for half the TTL
done

# initialize database if one doesn't already exist
# for example, in the case of a data container
if [[ ! -d /var/lib/postgresql/9.3/main ]]; then
	chown -R postgres:postgres /var/lib/postgresql
	sudo -u postgres /usr/lib/postgresql/9.3/bin/initdb -D /var/lib/postgresql/9.3/main
fi

# ensure WAL log bucket exists
envdir /etc/wal-e.d/env /app/bin/create_bucket ${BUCKET_NAME}

initial_backup=0
if [[ ! -f /var/lib/postgresql/9.3/main/initialized ]]; then
  echo "database: no existing database found."
  # check if there are any backups -- if so, let's restore
  # we could probably do better than just testing number of lines -- one line is just a heading, meaning no backups
  if [[ `envdir /etc/wal-e.d/env wal-e --terse backup-list | wc -l` -gt "1" ]]; then
    echo "database: restoring from backup..."
    rm -rf /var/lib/postgresql/9.3/main
    sudo -u postgres envdir /etc/wal-e.d/env wal-e backup-fetch /var/lib/postgresql/9.3/main LATEST
    chown -R postgres:postgres /var/lib/postgresql/9.3/main
    chmod 0700 /var/lib/postgresql/9.3/main
    echo "restore_command = 'envdir /etc/wal-e.d/env wal-e wal-fetch \"%f\" \"%p\"'" | sudo -u postgres tee /var/lib/postgresql/9.3/main/recovery.conf >/dev/null
  else
    echo "database: no backups found. Initializing a new database..."
    initial_backup=1
  fi
  # either way, we mark the database as initialized
  touch /var/lib/postgresql/9.3/main/initialized
else
  echo "database: existing data directory found. Starting postgres..."
fi

# run the service in the background
sudo -i -u postgres /usr/lib/postgresql/9.3/bin/postgres \
                    -c config-file=${PG_CONFIG:-/etc/postgresql/9.3/main/postgresql.conf} \
                    -c listen-addresses=${PG_LISTEN:-*} &

SERVICE_PID=$!

# smart shutdown on SIGINT and SIGTERM
function on_exit() {
    kill -TERM $SERVICE_PID
    wait $SERVICE_PID 2>/dev/null
    exit 0
}
trap on_exit INT TERM

# spawn confd in the background to update services based on etcd changes
confd -node $ETCD -config-file /app/confd.toml &
CONFD_PID=$!

# wait for the service to become available
sleep 1 && while [[ -z $(netstat -lnt | awk "\$6 == \"LISTEN\" && \$4 ~ \".5432\" && \$1 ~ \"tcp.?\"") ]] ; do sleep 1; done

# perform a one-time reload to populate database entries
/usr/local/bin/reload

if [[ "${initial_backup}" == "1" ]] ; then
  echo "database: performing an initial backup..."
  # perform an initial backup
  sudo -u postgres envdir /etc/wal-e.d/env wal-e backup-push /var/lib/postgresql/9.3/main
fi

echo "database: postgres is running..."

count=1
# publish the service to etcd using the injected HOST and EXTERNAL_PORT
if [[ ! -z $EXTERNAL_PORT ]]; then
	# configure service discovery
	PORT=${PORT:-5432}
	PROTO=${PROTO:-tcp}

	set +e

	# wait for the service to become available on PORT
	sleep 1 && while [[ -z $(netstat -lnt | awk "\$6 == \"LISTEN\" && \$4 ~ \".$PORT\" && \$1 ~ \"$PROTO.?\"") ]] ; do sleep 1; done

	# while the port is listening, publish to etcd
	while [[ ! -z $(netstat -lnt | awk "\$6 == \"LISTEN\" && \$4 ~ \".$PORT\" && \$1 ~ \"$PROTO.?\"") ]] ; do
		etcdctl --no-sync -C $ETCD set $ETCD_PATH/host $HOST --ttl $ETCD_TTL >/dev/null
		etcdctl --no-sync -C $ETCD set $ETCD_PATH/port $EXTERNAL_PORT --ttl $ETCD_TTL >/dev/null

    # perform a backup whenever we hit BACKUP_FREQUENCY
    # we really need cron :(
    if [[ "${count}" -ge "${BACKUP_FREQUENCY}" ]] ; then
      echo "database: performing a backup..."
      if [[ -f /var/lib/postgresql/9.3/main/recovery.conf ]] ; then
        echo "database: database is currently recovering from a backup. Will try again next loop..."
      else
        # perform a backup
        sudo -u postgres envdir /etc/wal-e.d/env wal-e backup-push /var/lib/postgresql/9.3/main
        # only retain the latest BACKUPS_TO_RETAIN backups
        sudo -u postgres envdir /etc/wal-e.d/env wal-e delete --confirm retain ${BACKUPS_TO_RETAIN}
        count=0
      fi
    fi
    ((count++))
		sleep $(($ETCD_TTL/2)) # sleep for half the TTL
	done

	# if the loop quits, something went wrong
	exit 1

fi

wait