content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to you under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.calcite.adapter.file;
  
  import org.apache.calcite.adapter.enumerable.EnumerableConvention;
  import org.apache.calcite.adapter.enumerable.EnumerableTableScan;
  import org.apache.calcite.adapter.java.AbstractQueryableTable;
  import org.apache.calcite.adapter.java.JavaTypeFactory;
  import org.apache.calcite.linq4j.AbstractEnumerable;
  import org.apache.calcite.linq4j.Enumerable;
  import org.apache.calcite.linq4j.Enumerator;
  import org.apache.calcite.linq4j.QueryProvider;
  import org.apache.calcite.linq4j.Queryable;
  import org.apache.calcite.plan.RelOptTable;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rel.type.RelDataTypeFactory;
  import org.apache.calcite.rel.type.RelProtoDataType;
  import org.apache.calcite.schema.SchemaPlus;
  import org.apache.calcite.schema.Statistic;
  import org.apache.calcite.schema.Statistics;
  import org.apache.calcite.schema.TranslatableTable;
  import org.apache.calcite.schema.impl.AbstractTableQueryable;
  import org.apache.calcite.util.Source;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  import java.util.Map;
  
  /**
   * Table implementation wrapping a URL / HTML table.
   */
  class FileTable extends AbstractQueryableTable
      implements TranslatableTable {
  
    private final @Nullable RelProtoDataType protoRowType;
    private final FileReader reader;
    private final FileRowConverter converter;
  
    /** Creates a FileTable. */
    private FileTable(Source source, String selector, Integer index,
        @Nullable RelProtoDataType protoRowType,
        List<Map<String, Object>> fieldConfigs) {
      super(Object[].class);
  
      this.protoRowType = protoRowType;
      this.reader = new FileReader(source, selector, index);
      this.converter = new FileRowConverter(this.reader, fieldConfigs);
    }
  
    /** Creates a FileTable. */
    static FileTable create(Source source, Map<String, Object> tableDef) {
      @SuppressWarnings("unchecked") List<Map<String, Object>> fieldConfigs =
          (List<Map<String, Object>>) tableDef.get("fields");
      String selector = (String) tableDef.get("selector");
      Integer index = (Integer) tableDef.get("index");
      return new FileTable(source, selector, index, null, fieldConfigs);
    }
  
    @Override public String toString() {
      return "FileTable";
    }
  
    @Override public Statistic getStatistic() {
      return Statistics.UNKNOWN;
    }
  
    @Override public RelDataType getRowType(RelDataTypeFactory typeFactory) {
      if (protoRowType != null) {
        return protoRowType.apply(typeFactory);
      }
      return this.converter.getRowType((JavaTypeFactory) typeFactory);
    }
  
    @Override public <T> Queryable<T> asQueryable(QueryProvider queryProvider,
        SchemaPlus schema, String tableName) {
      return new AbstractTableQueryable<T>(queryProvider, schema, this,
          tableName) {
        @Override public Enumerator<T> enumerator() {
          try {
            FileEnumerator enumerator =
                new FileEnumerator(reader.iterator(), converter);
            //noinspection unchecked
            return (Enumerator<T>) enumerator;
          } catch (Exception e) {
            throw new RuntimeException(e);
          }
        }
      };
    }
  
    /** Returns an enumerable over a given projection of the fields. */
    public Enumerable<Object> project(final int[] fields) {
      return new AbstractEnumerable<Object>() {
        @Override public Enumerator<Object> enumerator() {
          try {
            return new FileEnumerator(reader.iterator(), converter, fields);
          } catch (Exception e) {
            throw new RuntimeException(e);
          }
        }
      };
    }
  
    @Override public RelNode toRel(RelOptTable.ToRelContext context,
        RelOptTable relOptTable) {
      return new EnumerableTableScan(context.getCluster(),
          context.getCluster().traitSetOf(EnumerableConvention.INSTANCE),
          relOptTable, (Class) getElementType());
    }
  }
  