require 'cassandra'

module CassandraObject
  class Schemaless

    class << self
      DEFAULT_CREATE_KEYSPACE = {
        'strategy_class' => 'SimpleStrategy',
        'strategy_options' => 'replication_factor:1'
      }

      def create_keyspace(keyspace, options = nil)
        stmt = "CREATE KEYSPACE #{keyspace} WITH REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };"

        options ||= {} #DEFAULT_CREATE_KEYSPACE

        system_execute stmt #adapter.statement_with_options(stmt, options)
      end

      def drop_keyspace(keyspace, confirm = false)
        if adapter.cassandra_version < 3
          count = (system_execute "SELECT count(*) FROM schema_columnfamilies where keyspace_name = '#{keyspace}' ALLOW FILTERING;").rows.first['count']
        else
          count = (system_schema_execute "SELECT count(*) FROM tables where keyspace_name = '#{keyspace}';").rows.first['count']
        end
        if confirm || count == 0
          system_execute "DROP KEYSPACE #{keyspace}"
        else
          raise "Cannot drop keyspace #{keyspace}. You must delete all tables before"
        end
      end

      def create_column_family(column_family, options = {})
        create_table column_family, options
      end

      def create_table(table_name, options = {})
        adapter.create_table table_name, options
      end

      def alter_column_family(column_family, instruction, options = {})
        stmt = "ALTER TABLE #{column_family} #{instruction}"
        keyspace_execute adapter.statement_with_options(stmt, options)
      end

      def drop_column_family(column_family)
        drop_table column_family
      end

      def drop_table(table_name, confirm = false)
        adapter.drop_table table_name, confirm
      end

      def add_index(column_family, column, index_name = nil)
        stmt = "CREATE INDEX #{index_name.nil? ? '' : index_name} ON #{column_family} (#{column})"
        keyspace_execute stmt
      end

      # If the index was not given a name during creation, the index name is <columnfamily_name>_<column_name>_idx.
      def drop_index(index_name)
        keyspace_execute "DROP INDEX #{index_name}"
      end

      private

        def adapter
          @adapter ||= CassandraObject::Adapters::CassandraSchemalessAdapter.new(CassandraObject::Base.config)
        end

        def keyspace_execute(cql)
          adapter.schema_execute cql, CassandraObject::Base.config[:keyspace]
        end

        def system_schema_execute(cql)
          adapter.schema_execute cql, 'system_schema'
        end

        def system_execute(cql)
          adapter.schema_execute cql, 'system'
        end
    end
  end
end