module ActiveRecord::Import::SQLite3Adapter
  include ActiveRecord::Import::ImportSupport

  MIN_VERSION_FOR_IMPORT = "3.7.11"
  SQLITE_LIMIT_COMPOUND_SELECT = 500

  # Override our conformance to ActiveRecord::Import::ImportSupport interface
  # to ensure that we only support import in supported version of SQLite.
  # Which INSERT statements with multiple value sets was introduced in 3.7.11.
  def supports_import?(current_version=self.sqlite_version)
    if current_version >= MIN_VERSION_FOR_IMPORT
      true
    else
      false
    end
  end

  # +sql+ can be a single string or an array. If it is an array all
  # elements that are in position >= 1 will be appended to the final SQL.
  def insert_many(sql, values, *args) # :nodoc:
    number_of_inserts = 0
    base_sql,post_sql = if sql.is_a?( String )
      [ sql, '' ]
    elsif sql.is_a?( Array )
      [ sql.shift, sql.join( ' ' ) ]
    end

    value_sets = ::ActiveRecord::Import::ValueSetsRecordsParser.parse(values,
      :max_records => SQLITE_LIMIT_COMPOUND_SELECT)

    value_sets.each do |values|
      number_of_inserts += 1
      sql2insert = base_sql + values.join( ',' ) + post_sql
      insert( sql2insert, *args )
    end

    [number_of_inserts,[]]
  end

  def next_value_for_sequence(sequence_name)
    %{nextval('#{sequence_name}')}
  end
end