# lib/tasks/db_import.rake
namespace :db do
  namespace :import do
    desc 'Import Heroku Staging database locally'
    task :staging do
      import_db('staging', 'YOUR_STAGING_HEROKU_APP_HERE')
    end

    desc 'Import Heroku Production database locally'
    task :production do
      import_db('production', 'YOUR_PRODUCTION_HEROKU_APP_HERE')
    end

    # Creates a unique database dump based on the current time and specified environment.
    def import_db(environment, heroku_app_name)
      puts("Importing #{environment} database locally...")
      file = "tmp/#{environment}-#{date}.dump"
      dump_local
      capture_and_download_heroku_db(heroku_app_name)
      `mv latest.dump #{file}`
      import_locally(file)
      run_migrations
      puts("#{environment} database successfully imported")
    end

    # Returns the readable date in YYYY-MM-DD with an
    # appended integer time to make the filename unique.
    def date
      "#{Time.now.to_date.to_s}-#{Time.now.to_i}"
    end

    # Returns the current machine's user for use with PG commands
    def user
      `whoami`.strip
    end

    # Creates and downloads a Heroku database back-up.
    # Requires the Heroku toolchain to be installed and setup.
    def capture_and_download_heroku_db(app)
      `heroku pg:backups:capture --app #{app}`
      `heroku pg:backups:download --app #{app}`
    end

    # Creates a back-up of your current local development
    # database in case you want to restore it.
    def dump_local
      `pg_dump -Fc --no-acl --no-owner -h localhost -U #{user} YOUR_LOCAL_DB_NAME_HERE > tmp/development-#{date}.dump`
    end

    # Imports the downloaded database dump into your local development database.
    def import_locally(file)
      `pg_restore --verbose --clean --no-acl --no-owner -h localhost -U #{user} -d YOUR_LOCAL_DB_NAME_HERE #{file}`
    end

    # Runs migrations against the just imported database dump from Heroku.
    def run_migrations
      `bin/rake db:migrate`
    end
  end
end