module DatabaseConnection
  def self.db_name
    ENV.fetch('DB', 'mysql2')
  end

  def self.setup
    db_config = ENV['DATABASE_URL'] || DEFAULT_CONFIG[db_name]
    begin
      ActiveRecord::Base.establish_connection(db_config)
      ActiveRecord::Base.connection
    rescue
      raise unless db_config.is_a?(Hash)
      ActiveRecord::Base.establish_connection(db_config.merge('database' => nil))
      ActiveRecord::Base.connection.create_database(db_config['database'])
      ActiveRecord::Base.establish_connection(db_config)
    end
  end

  def self.drop_tables
    TABLES.keys.each do |table|
      ActiveRecord::Base.connection.drop_table(table) if ActiveRecord::Base.connection.table_exists?(table)
    end
  end

  def self.create_tables
    TABLES.each do |table, fields|
      fields = fields.dup
      options = fields.last.is_a?(Hash) ? fields.pop : {}
      ActiveRecord::Base.connection.create_table(table, options) do |t|
        fields.each do |column_type, *args|
          t.send(column_type, *args)
        end
      end
    end
  end

  TABLES = {
    :polymorphic_records           => [[:string, :owner_type], [:integer, :owner_id], [:timestamps, null: true]],
    :deeply_associated_records     => [[:string, :name], [:integer, :associated_record_id], [:integer, :item_id], [:timestamps, null: true]],
    :associated_records            => [[:string, :name], [:integer, :item_id], [:integer, :item_two_id]],
    :normalized_associated_records => [[:string, :name], [:integer, :item_id], [:timestamps, null: true]],
    :not_cached_records            => [[:string, :name], [:integer, :item_id], [:timestamps, null: true]],
    :items                         => [[:integer, :item_id], [:string, :title], [:timestamps, null: true]],
    :items2                        => [[:integer, :item_id], [:string, :title], [:timestamps, null: true]],
    :keyed_records                 => [[:string, :value], :primary_key => "hashed_key"],
    :sti_records                   => [[:string, :type], [:string, :name]],
  }

  DEFAULT_CONFIG = {
    'mysql2' => {
      'adapter'  => 'mysql2',
      'database' => 'identity_cache_test',
      'host'     => ENV['MYSQL_HOST'] || '127.0.0.1',
      'username' => 'root'
    },
    'postgresql' => {
      'adapter'  => 'postgresql',
      'database' => 'identity_cache_test',
      'host'     => ENV['POSTGRES_HOST'] || '127.0.0.1',
      'username' => 'postgres',
      'prepared_statements' => false,
    }
  }
end