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.os;
  
  import org.apache.calcite.DataContext;
  import org.apache.calcite.linq4j.AbstractEnumerable;
  import org.apache.calcite.linq4j.Enumerable;
  import org.apache.calcite.linq4j.Enumerator;
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rel.type.RelDataTypeFactory;
  import org.apache.calcite.schema.ScannableTable;
  import org.apache.calcite.sql.type.SqlTypeName;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.NoSuchElementException;
  
  import static java.lang.Long.parseLong;
  
  /**
   * Table function that executes the OS "git log" command
   * to discover git commits.
   */
  public class GitCommitsTableFunction {
  
    /** An example of the timestamp + offset at the end of author and committer
     * fields. */
    private static final String TS_OFF = "1500769547 -0700";
  
    /** An example of the offset at the end of author and committer fields. */
    private static final String OFF = "-0700";
  
    private GitCommitsTableFunction() {}
  
    public static ScannableTable eval(boolean b) {
      return new AbstractBaseScannableTable() {
        @Override public Enumerable<@Nullable Object[]> scan(DataContext root) {
          final Enumerable<String> enumerable =
              Processes.processLines("git", "log", "--pretty=raw");
          return new AbstractEnumerable<@Nullable Object[]>() {
            @Override public Enumerator<@Nullable Object[]> enumerator() {
              final Enumerator<String> e = enumerable.enumerator();
              return new Enumerator<@Nullable Object[]>() {
                private @Nullable Object @Nullable [] objects;
                private final StringBuilder b = new StringBuilder();
  
                @Override public @Nullable Object[] current() {
                  if (objects == null) {
                    throw new NoSuchElementException();
                  }
                  return objects;
                }
  
                @Override public boolean moveNext() {
                  if (!e.moveNext()) {
                    objects = null;
                    return false;
                  }
                  objects = new Object[9];
                  for (;;) {
                    final String line = e.current();
                    if (line.isEmpty()) {
                      break; // next line will be start of comments
                    }
                    if (line.startsWith("commit ")) {
                      objects[0] = line.substring("commit ".length());
                    } else if (line.startsWith("tree ")) {
                      objects[1] = line.substring("tree ".length());
                    } else if (line.startsWith("parent ")) {
                      if (objects[2] == null) {
                        objects[2] = line.substring("parent ".length());
                      } else {
                        objects[3] = line.substring("parent ".length());
                      }
                    } else if (line.startsWith("author ")) {
                      objects[4] =
                          line.substring("author ".length(),
                              line.length() - TS_OFF.length() - 1);
                      objects[5] =
                          parseLong(
                              line.substring(line.length() - TS_OFF.length(),
                              line.length() - OFF.length() - 1)) * 1000;
                    } else if (line.startsWith("committer ")) {
                      objects[6] =
                          line.substring("committer ".length(),
                              line.length() - TS_OFF.length() - 1);
                      objects[7] =
                          parseLong(
                              line.substring(line.length() - TS_OFF.length(),
                              line.length() - OFF.length() - 1)) * 1000;
                    }
                    if (!e.moveNext()) {
                      // We have a row, and it's the last because input is empty
                      return true;
                    }
                  }
                  for (;;) {
                    if (!e.moveNext()) {
                      // We have a row, and it's the last because input is empty
                      objects[8] = b.toString();
                      b.setLength(0);
                      return true;
                    }
                    final String line = e.current();
                    if (line.isEmpty()) {
                      // We're seeing the empty line at the end of message
                      objects[8] = b.toString();
                      b.setLength(0);
                      return true;
                    }
                    b.append(line.substring("    ".length())).append("\n");
                  }
                }
  
                @Override public void reset() {
                  throw new UnsupportedOperationException();
                }
  
                @Override public void close() {
                  e.close();
                }
              };
            }
          };
        }
  
        @Override public RelDataType getRowType(RelDataTypeFactory typeFactory) {
          return typeFactory.builder()
              .add("commit", SqlTypeName.CHAR, 40)
              .add("tree", SqlTypeName.CHAR, 40)
              .add("parent", SqlTypeName.CHAR, 40)
              .add("parent2", SqlTypeName.CHAR, 40)
              .add("author", SqlTypeName.VARCHAR)
              .add("author_timestamp", SqlTypeName.TIMESTAMP)
              .add("committer", SqlTypeName.VARCHAR)
              .add("commit_timestamp", SqlTypeName.TIMESTAMP)
              .add("message", SqlTypeName.VARCHAR)
              .build();
        }
      };
    }
  }
  