content: # Copyright Contributors to the Amundsen project.
  # SPDX-License-Identifier: Apache-2.0
  
  import logging
  from collections import namedtuple
  from itertools import groupby
  from typing import (
      Any, Dict, Iterator, Union,
  )
  
  from pyhocon import ConfigFactory, ConfigTree
  
  from databuilder.extractor import sql_alchemy_extractor
  from databuilder.extractor.base_extractor import Extractor
  from databuilder.models.table_metadata import ColumnMetadata, TableMetadata
  
  TableKey = namedtuple('TableKey', ['schema', 'table_name'])
  
  LOGGER = logging.getLogger(__name__)
  
  
  class AthenaMetadataExtractor(Extractor):
      """
      Extracts Athena table and column metadata from underlying meta store database using SQLAlchemyExtractor
      """
  
      SQL_STATEMENT = """
      SELECT
          {catalog_source} as cluster, table_schema as schema, table_name as name, column_name as col_name,
          data_type as col_type,ordinal_position as col_sort_order,
          comment as col_description, extra_info as extras from information_schema.columns
          {where_clause_suffix}
          ORDER by cluster, schema, name, col_sort_order ;
      """
  
      # CONFIG KEYS
      WHERE_CLAUSE_SUFFIX_KEY = 'where_clause_suffix'
      CATALOG_KEY = 'catalog_source'
  
      # Default values
      DEFAULT_CLUSTER_NAME = 'master'
  
      DEFAULT_CONFIG = ConfigFactory.from_dict(
          {WHERE_CLAUSE_SUFFIX_KEY: ' ', CATALOG_KEY: DEFAULT_CLUSTER_NAME}
      )
  
      def init(self, conf: ConfigTree) -> None:
          conf = conf.with_fallback(AthenaMetadataExtractor.DEFAULT_CONFIG)
          self._cluster = conf.get_string(AthenaMetadataExtractor.CATALOG_KEY)
  
          self.sql_stmt = AthenaMetadataExtractor.SQL_STATEMENT.format(
              where_clause_suffix=conf.get_string(AthenaMetadataExtractor.WHERE_CLAUSE_SUFFIX_KEY),
              catalog_source=self._cluster
          )
  
          LOGGER.info('SQL for Athena metadata: %s', self.sql_stmt)
  
          self._alchemy_extractor = sql_alchemy_extractor.from_surrounding_config(conf, self.sql_stmt)
          self._extract_iter: Union[None, Iterator] = None
  
      def close(self) -> None:
          if getattr(self, '_alchemy_extractor', None) is not None:
              self._alchemy_extractor.close()
  
      def extract(self) -> Union[TableMetadata, None]:
          if not self._extract_iter:
              self._extract_iter = self._get_extract_iter()
          try:
              return next(self._extract_iter)
          except StopIteration:
              return None
  
      def get_scope(self) -> str:
          return 'extractor.athena_metadata'
  
      def _get_extract_iter(self) -> Iterator[TableMetadata]:
          """
          Using itertools.groupby and raw level iterator, it groups to table and yields TableMetadata
          :return:
          """
  
          for key, group in groupby(self._get_raw_extract_iter(), self._get_table_key):
              columns = []
  
              for row in group:
                  last_row = row
                  columns.append(ColumnMetadata(row['col_name'],
                                                row['extras'] if row['extras'] is not None else row['col_description'],
                                                row['col_type'], row['col_sort_order']))
  
              yield TableMetadata('athena', last_row['cluster'],
                                  last_row['schema'],
                                  last_row['name'],
                                  '',
                                  columns)
  
      def _get_raw_extract_iter(self) -> Iterator[Dict[str, Any]]:
          """
          Provides iterator of result row from SQLAlchemy extractor
          :return:
          """
          row = self._alchemy_extractor.extract()
          while row:
              yield row
              row = self._alchemy_extractor.extract()
  
      def _get_table_key(self, row: Dict[str, Any]) -> Union[TableKey, None]:
          """
          Table key consists of schema and table name
          :param row:
          :return:
          """
          if row:
              return TableKey(schema=row['schema'], table_name=row['name'])
  
          return None
  