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.beam.sdk.extensions.sql.meta.provider.bigtable;
  
  import static java.util.stream.Collectors.toList;
  import static org.apache.beam.sdk.io.gcp.bigtable.RowUtils.KEY;
  import static org.apache.beam.sdk.io.gcp.bigtable.RowUtils.byteStringUtf8;
  import static org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.sql.SqlKind.LIKE;
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkArgument;
  
  import com.google.bigtable.v2.RowFilter;
  import java.util.List;
  import java.util.stream.Collectors;
  import org.apache.beam.sdk.extensions.sql.meta.BeamSqlTableFilter;
  import org.apache.beam.sdk.schemas.Schema;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexCall;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexInputRef;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexLiteral;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexNode;
  
  /**
   * BigtableFilter for queries with WHERE clause.
   *
   * <p>Currently only queries with a single LIKE statement by key field with <a
   * href=https://github.com/google/re2/wiki/Syntax>RE2 Syntax</a> regex type are supported, e.g.
   * `SELECT * FROM table WHERE key LIKE '^key\d'`
   */
  class BigtableFilter implements BeamSqlTableFilter {
    private final List<RexNode> supported;
    private final List<RexNode> unsupported;
    private final Schema schema;
  
    BigtableFilter(List<RexNode> predicateCNF, Schema schema) {
      supported = predicateCNF.stream().filter(BigtableFilter::isSupported).collect(toList());
      unsupported =
          predicateCNF.stream().filter(predicate -> !isSupported(predicate)).collect(toList());
      this.schema = schema;
    }
  
    @Override
    public List<RexNode> getNotSupported() {
      return unsupported;
    }
  
    @Override
    public int numSupported() {
      return BeamSqlTableFilter.expressionsInFilter(supported);
    }
  
    public List<RexNode> getSupported() {
      return supported;
    }
  
    @Override
    public String toString() {
      String supStr = supported.stream().map(RexNode::toString).collect(Collectors.joining());
      String unsupStr = unsupported.stream().map(RexNode::toString).collect(Collectors.joining());
      return String.format("[supported{%s}, unsupported{%s}]", supStr, unsupStr);
    }
  
    RowFilter getFilters() {
      checkArgument(
          supported.size() == 1,
          String.format("Only one LIKE operation is allowed. Got %s operations", supported.size()));
      return translateRexNodeToRowFilter(supported.get(0));
    }
  
    private RowFilter translateRexNodeToRowFilter(RexNode node) {
      checkNodeIsCoposite(node);
      checkArgument(LIKE.equals(node.getKind()), "Only LIKE operation is supported.");
  
      List<RexLiteral> literals = filterOperands((RexCall) node, RexLiteral.class);
      List<RexInputRef> inputRefs = filterOperands((RexCall) node, RexInputRef.class);
  
      checkArgument(literals.size() == 1);
      checkArgument(inputRefs.size() == 1);
  
      checkFieldIsKey(inputRefs.get(0));
      String literal = literals.get(0).getValueAs(String.class);
  
      if (literal == null) {
        throw new IllegalArgumentException("Expected non-null String literal");
      }
  
      return RowFilter.newBuilder().setRowKeyRegexFilter(byteStringUtf8(literal)).build();
    }
  
    private void checkFieldIsKey(RexInputRef inputRef) {
      String inputFieldName = schema.getField(inputRef.getIndex()).getName();
      checkArgument(
          KEY.equals(inputFieldName),
          "Only 'key' queries are supported. Got field " + inputFieldName);
    }
  
    private static boolean isSupported(RexNode node) {
      checkNodeIsCoposite(node);
      if (!LIKE.equals(node.getKind())) {
        return false;
      }
  
      long literalsCount = countOperands((RexCall) node, RexLiteral.class);
      long fieldsCount = countOperands((RexCall) node, RexInputRef.class);
  
      return literalsCount == 1 && fieldsCount == 1;
    }
  
    private <T extends RexNode> List<T> filterOperands(RexCall compositeNode, Class<T> clazz) {
      return compositeNode.getOperands().stream()
          .filter(clazz::isInstance)
          .map(clazz::cast)
          .collect(toList());
    }
  
    private static <T extends RexNode> long countOperands(RexCall compositeNode, Class<T> clazz) {
      return compositeNode.getOperands().stream().filter(clazz::isInstance).count();
    }
  
    private static void checkNodeIsCoposite(RexNode node) {
      checkArgument(
          node instanceof RexCall,
          String.format(
              "Encountered an unexpected node type: %s. Should be %s",
              node.getClass().getSimpleName(), RexCall.class.getSimpleName()));
    }
  }
  