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.avro.schemas.utils;
  
  import com.pholser.junit.quickcheck.generator.GenerationStatus;
  import com.pholser.junit.quickcheck.generator.Generator;
  import com.pholser.junit.quickcheck.random.SourceOfRandomness;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  import java.util.function.Function;
  import java.util.stream.Collectors;
  import java.util.stream.IntStream;
  import org.apache.avro.Schema;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Joiner;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ObjectArrays;
  
  /** QuickCheck generators for AVRO. */
  class AvroGenerators {
  
    /** Generates arbitrary AVRO schemas. */
    public static class SchemaGenerator extends BaseSchemaGenerator {
  
      public static final SchemaGenerator INSTANCE = new SchemaGenerator();
  
      private static final ImmutableList<Schema.Type> PRIMITIVE_TYPES =
          ImmutableList.of(
              Schema.Type.STRING,
              Schema.Type.BYTES,
              Schema.Type.INT,
              Schema.Type.LONG,
              Schema.Type.FLOAT,
              Schema.Type.DOUBLE,
              Schema.Type.BOOLEAN);
  
      private static final ImmutableList<Schema.Type> ALL_TYPES =
          ImmutableList.<Schema.Type>builder()
              .addAll(PRIMITIVE_TYPES)
              .add(Schema.Type.FIXED)
              .add(Schema.Type.ENUM)
              .add(Schema.Type.RECORD)
              .add(Schema.Type.ARRAY)
              .add(Schema.Type.MAP)
              .add(Schema.Type.UNION)
              .add(Schema.Type.ARRAY)
              .build();
  
      private static final int MAX_NESTING = 10;
  
      @Override
      public Schema generate(SourceOfRandomness random, GenerationStatus status) {
        Schema.Type type;
  
        if (nesting(status) >= MAX_NESTING) {
          type = random.choose(PRIMITIVE_TYPES);
        } else {
          type = random.choose(ALL_TYPES);
        }
  
        if (PRIMITIVE_TYPES.contains(type)) {
          return Schema.create(type);
        } else {
          nestingInc(status);
  
          if (type == Schema.Type.FIXED) {
            int size = random.choose(Arrays.asList(1, 5, 12));
            return Schema.createFixed("fixed_" + branch(status), "", "", size);
          } else if (type == Schema.Type.UNION) {
            // only nullable fields, everything else isn't supported in row conversion code
            return UnionSchemaGenerator.INSTANCE.generate(random, status);
          } else if (type == Schema.Type.ENUM) {
            return EnumSchemaGenerator.INSTANCE.generate(random, status);
          } else if (type == Schema.Type.RECORD) {
            return RecordSchemaGenerator.INSTANCE.generate(random, status);
          } else if (type == Schema.Type.MAP) {
            return Schema.createMap(generate(random, status));
          } else if (type == Schema.Type.ARRAY) {
            return Schema.createArray(generate(random, status));
          } else {
            throw new AssertionError("Unexpected AVRO type: " + type);
          }
        }
      }
    }
  
    public static class RecordSchemaGenerator extends BaseSchemaGenerator {
  
      public static final RecordSchemaGenerator INSTANCE = new RecordSchemaGenerator();
  
      @Override
      public Schema generate(SourceOfRandomness random, GenerationStatus status) {
        List<Schema.Field> fields =
            IntStream.range(0, random.nextInt(0, status.size()) + 1)
                .mapToObj(
                    i -> {
                      // deterministically avoid collisions in record names
                      branchPush(status, String.valueOf(i));
                      Schema.Field field =
                          createField(i, SchemaGenerator.INSTANCE.generate(random, status));
                      branchPop(status);
                      return field;
                    })
                .collect(Collectors.toList());
  
        return Schema.createRecord("record_" + branch(status), "", "example", false, fields);
      }
  
      private Schema.Field createField(int i, Schema schema) {
        return new Schema.Field("field_" + i, schema, null, (Object) null);
      }
    }
  
    static class UnionSchemaGenerator extends BaseSchemaGenerator {
  
      public static final UnionSchemaGenerator INSTANCE = new UnionSchemaGenerator();
  
      @Override
      public Schema generate(SourceOfRandomness random, GenerationStatus status) {
        Map<String, Schema> schemaMap =
            IntStream.range(0, random.nextInt(0, status.size()) + 1)
                .mapToObj(
                    i -> {
                      // deterministically avoid collisions in record names
                      branchPush(status, String.valueOf(i));
                      Schema schema =
                          SchemaGenerator.INSTANCE
                              // nested unions aren't supported in AVRO
                              .filter(x -> x.getType() != Schema.Type.UNION)
                              .generate(random, status);
                      branchPop(status);
                      return schema;
                    })
                // AVRO requires uniqueness by full name
                .collect(Collectors.toMap(Schema::getFullName, Function.identity(), (x, y) -> x));
  
        List<Schema> schemas = new ArrayList<>(schemaMap.values());
  
        if (random.nextBoolean()) {
          Schema nullSchema = Schema.create(Schema.Type.NULL);
          schemas.add(nullSchema);
          Collections.shuffle(schemas, random.toJDKRandom());
        }
  
        return Schema.createUnion(schemas);
      }
    }
  
    static class EnumSchemaGenerator extends BaseSchemaGenerator {
  
      public static final EnumSchemaGenerator INSTANCE = new EnumSchemaGenerator();
  
      private static final Schema FRUITS =
          Schema.createEnum("Fruit", "", "example", Arrays.asList("banana", "apple", "pear"));
  
      private static final Schema STATUS =
          Schema.createEnum("Status", "", "example", Arrays.asList("OK", "ERROR", "WARNING"));
  
      @Override
      public Schema generate(final SourceOfRandomness random, final GenerationStatus status) {
        return random.choose(Arrays.asList(FRUITS, STATUS));
      }
    }
  
    abstract static class BaseSchemaGenerator extends Generator<Schema> {
  
      private static final GenerationStatus.Key<Integer> NESTING_KEY =
          new GenerationStatus.Key<>("nesting", Integer.class);
  
      private static final GenerationStatus.Key<String[]> BRANCH_KEY =
          new GenerationStatus.Key<>("branch", String[].class);
  
      BaseSchemaGenerator() {
        super(Schema.class);
      }
  
      void branchPush(GenerationStatus status, String value) {
        String[] current = status.valueOf(BRANCH_KEY).orElse(new String[0]);
        String[] next = ObjectArrays.concat(current, value);
  
        status.setValue(BRANCH_KEY, next);
      }
  
      void branchPop(GenerationStatus status) {
        String[] current = status.valueOf(BRANCH_KEY).orElse(new String[0]);
        String[] next = Arrays.copyOf(current, current.length - 1);
  
        status.setValue(BRANCH_KEY, next);
      }
  
      String branch(GenerationStatus status) {
        return Joiner.on("_").join(status.valueOf(BRANCH_KEY).orElse(new String[0]));
      }
  
      int nesting(GenerationStatus status) {
        return status.valueOf(NESTING_KEY).orElse(0);
      }
  
      void nestingInc(GenerationStatus status) {
        status.setValue(NESTING_KEY, nesting(status) + 1);
      }
    }
  }
  