#!/usr/bin/env bash
set -e

USAGE="Usage: migrate <up|down|new|init>"

# http://www.postgresql.org/docs/9.5/static/libpq-envars.html
export PGDATABASE=${PGDATABASE:-meetspace}

cd `dirname $0`/../migrations

if [[ $(psql -A -t -c "SELECT * FROM information_schema.tables WHERE table_name='migrations'") ]]
then
  versions=`psql -A -t -c "SELECT version FROM migrations;" || true`
fi

case $1 in
  up)
    upversions=`comm -23 <(ls *.up.sql | xargs basename -s .up.sql) <(echo "$versions")`
    for v in $upversions; do
      echo $v
      PAGER= psql --set=ON_ERROR_STOP=true -a -f $v.up.sql
    done
    ;;
  down)
    downversions=`comm -12 <(ls *.down.sql | xargs basename -s .down.sql) <(echo "$versions") | sort -r`
    for v in $downversions; do
      echo $v
      PAGER= psql --set=ON_ERROR_STOP=true -a -f $v.down.sql
    done
    ;;
  new)
    date=`date +%Y%m%d%H%M%S`
    name=$date-$2
    echo $name.up.sql
    tee  $name.up.sql <<SQL
BEGIN;
/* Your up migration code here */

INSERT INTO migrations (version) VALUES ('$name');
COMMIT;
SQL
    echo $name.down.sql
    tee  $name.down.sql <<SQL
BEGIN;
/* Your down migration code here */

DELETE FROM migrations WHERE version='$name';
COMMIT;
SQL
    ;;
  init)
    date=`date +%Y%m%d%H%M%S`
    name=$date-create-migrations
    echo $name.up.sql
    tee  $name.up.sql <<SQL
BEGIN;
CREATE TABLE migrations (
  version text not null unique,
  ran_at timestamp without time zone default now() not null
);

INSERT INTO migrations (version) VALUES ('$name');
COMMIT;
SQL
    echo $name.down.sql
    tee  $name.down.sql <<SQL
BEGIN;
DROP TABLE migrations;
COMMIT;
SQL
    ;;
  *)
    echo $USAGE
    exit 1
    ;;
esac