oracle.rb

# frozen_string_literal: true

ActiveSupport.on_load(:active_record) do
  if System::Database.oracle?
    require 'arel/visitors/oracle12_hack'

    ENV['SCHEMA'] = 'db/oracle_schema.rb'
    Rails.configuration.active_record.schema_format = ActiveRecord.schema_format = :ruby

    ActiveRecord::ConnectionAdapters::TableDefinition.prepend(Module.new do
      def column(name, type, **options)
        # length parameter is not compatible with rails mysql/pg adapters:
        # rails expects it is limit in bytes, but oracle adapter expects it in number of characters
        # TODO: probably would be better to convert the byte limit to character limit
        if type == :integer
          super(name, type, **options.except(:limit))
        else
          super
        end
      end
    end)

    ENV['NLS_LANG'] ||= 'AMERICAN_AMERICA.UTF8'

    ActiveRecord::ConnectionAdapters::OracleEnhancedAdapter.class_eval do
      prepend(Module.new do
        # TODO: is this needed after
        # https://github.com/rsim/oracle-enhanced/commit/f76b6ef4edda72bddabab252177cb7f28d4418e2
        def add_column(table_name, column_name, type, **options)
          if type == :integer
            super(table_name, column_name, type, **options.except(:limit))
          else
            super
          end
        end

        # We need to patch Oracle Adapter quoting to actually serialize CLOB columns.
        # https://github.com/rsim/oracle-enhanced/issues/1588#issue-272289146
        # The default behaviour is to serialize them to 'empty_clob()' basically wiping out the data.
        # The team behind it believes `Table.update_all(column: 'text')`
        # should wipe all your data in that column: https://github.com/rsim/oracle-enhanced/issues/1588#issuecomment-343353756
        # So we try to convert the text to using `to_clob` function.
        def _quote(value)
          case value
          when ActiveModel::Type::Binary::Data
            # I know this looks ugly, but that just modified copy paste of what the adapter does (minus the rescue).
            # It is a bit improved in next version due to ActiveRecord Attributes API.
            %{to_blob(#{quote(value.to_s)})}
          when ActiveRecord::Type::OracleEnhanced::Text::Data
            %{to_clob(#{quote(value.to_s)})}
          else
            super
          end
        end
      end)
    end

    ActiveRecord::Relation.prepend(Module.new do
      # ar_object.with_lock doesn't work OOB on oracle, see https://github.com/rsim/oracle-enhanced/issues/2237
      # A workaround is to avoid using FETCH FIRST when reloading an object by primary key.
      # https://github.com/rails/rails/blob/v6.1.7.7/activerecord/lib/active_record/relation/finder_methods.rb#L465
      def find_one(id)
        if ActiveRecord::Base === id
          raise ArgumentError, <<-MSG.squish
            You are passing an instance of ActiveRecord::Base to `find`.
            Please pass the id of the object by calling `.id`.
          MSG
        end

        relation = where(primary_key => id)
        record = relation.to_a.first # this is the only change from the original method

        raise_record_not_found_exception!(id, 0, 1) unless record

        record
      end
    end)

    BabySqueel::Nodes::Attribute.prepend(Module.new do
      # those relations are used in subqueries and oracle does not support ORDER in subqueries
      private def sanitize_relation(rel)
        super rel.unscope(:order)
      end
    end)

    ThinkingSphinx::ActiveRecord::SQLSource.prepend(Module.new do
      # If the Adapter is Oracle then we forcibly use ODBC client
      def type
        @type ||= case adapter
                  when ThinkingSphinx::ActiveRecord::DatabaseAdapters::OracleAdapter
                    'odbc'
                  else
                    super
                  end
      end
    end)

    ThinkingSphinx::ActiveRecord::DatabaseAdapters.module_eval do
      class << self
        prepend(Module.new do
          # https://github.com/pat/thinking-sphinx/blob/v3.2.0/lib/thinking_sphinx/active_record/database_adapters.rb#L35-L45
          # Adding a new DatabaseAdapters for ThinkingSphinx
          # This adds support for Oracle. OracleAdapter is responsible of query generation for Sphinx
          def adapter_for(model)
            return default.new(model) if default

            adapter = adapter_type_for(model)
            klass   = case adapter
                      when :oracle
                        ThinkingSphinx::ActiveRecord::DatabaseAdapters::OracleAdapter
                      else
                        super
                      end
            klass.new model
          end

          # https://github.com/pat/thinking-sphinx/blob/v3.2.0/lib/thinking_sphinx/active_record/database_adapters.rb#L21-L33
          # This method is only needed for `adapter_for`
          # Part of freedom patch for ThinkingSphinx handling with Oracle
          def adapter_type_for(model)
            class_name = model.connection.class.name
            case class_name.split('::').last
            when /oracle/i
              :oracle
            else
              super
            end
          end
        end
        )
      end
    end

    ThinkingSphinx::Deltas::DatetimeDelta.prepend(Module.new do
      # https://github.com/pat/ts-datetime-delta/blob/v2.0.2/lib/thinking_sphinx/deltas/datetime_delta.rb#L167
      # A SQL condition (as part of the WHERE clause) that limits the result set to
      # just the delta data, or all data, depending on whether the toggled argument
      # is true or not. For datetime deltas, the former value is a check on the
      # delta column being within the threshold. In the latter's case, no condition
      # is needed, so nil is returned.
      def clause(*args)
        model    = (args.length >= 2 ? args[0] : nil)
        is_delta = (args.length >= 2 ? args[1] : args[0]) || false

        table_name  = (model.nil? ? adapter.quoted_table_name   : model.quoted_table_name)
        column_name = (model.nil? ? adapter.quote(@column.to_s) : model.connection.quote_column_name(@column.to_s))

        if is_delta
          if adapter.class.name.downcase[/oracle/]
            "EXTRACT( day from ((#{table_name}.#{column_name} - SYSDATE) * 60 * 60 * 24)) + #{@threshold} > 0"
          else
            super
          end
        else
          nil
        end
      end
    end)

    ThinkingSphinx::ActiveRecord::SQLSource.prepend(Module.new do
      # This autogenerate the odbc_dsn string based on database.yml
      # For now it is only particular to our project, later we could extract it and make a PR to the upstream project
      def set_database_settings(settings)
        super
        conf = System::Database.database_config.configuration_hash
        if type == 'odbc'
          @odbc_dsn ||= "DSN=oracle;Driver={Oracle-Driver};Dbq=#{conf[:host]}:#{conf[:port] || 1521}/#{conf[:database]};Uid=#{conf[:username]};Pwd=#{conf[:password]}"
        end
      end
    end)

    ActiveRecord::ConnectionAdapters::OracleEnhanced::SchemaStatements.module_eval do
      def add_index(table_name, column_name, **options) #:nodoc:
        # All this code is exactly the same as the original except the line of the ALTER TABLE, which adds an additional USING INDEX #{quote_column_name(index_name)}
        # The reason of this is otherwise it picks the first index that finds that contains that column name, even if it is shared with other columns and it is not unique.
        # upstreamed: https://github.com/rsim/oracle-enhanced/pull/2293
        index_name, index_type, quoted_column_names, tablespace, index_options = add_index_options(table_name, column_name, **options)
        quoted_table_name = quote_table_name(table_name)
        quoted_column_name = quote_column_name(index_name)
        execute "CREATE #{index_type} INDEX #{quoted_column_name} ON #{quoted_table_name} (#{quoted_column_names})#{tablespace} #{index_options}"
        if index_type == 'UNIQUE' && quoted_column_names !~ /\(.*\)/
          execute "ALTER TABLE #{quoted_table_name} ADD CONSTRAINT #{quoted_column_name} #{index_type} (#{quoted_column_names}) USING INDEX #{quoted_column_name}"
        end
      end
    end

    # see https://github.com/rsim/oracle-enhanced/issues/2276
    module OracleEnhancedAdapterSchemaIssue2276
      def column_definitions(table_name)
        deleted_object_id = prepared_statements_disabled_cache.delete(object_id)
        super
      ensure
        prepared_statements_disabled_cache.add(deleted_object_id) if deleted_object_id
      end
    end

    ActiveRecord::ConnectionAdapters::OracleEnhancedAdapter.prepend OracleEnhancedAdapterSchemaIssue2276
  end
end