/*
 * 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.runners.core.construction;

import com.fasterxml.jackson.core.TreeNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.base.CaseFormat;
import com.google.common.collect.ImmutableMap;
import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.util.common.ReflectHelpers;
import org.apache.beam.vendor.protobuf.v3.com.google.protobuf.Struct;
import org.apache.beam.vendor.protobuf.v3.com.google.protobuf.util.JsonFormat;

/**
 * Utilities for going to/from Runner API pipeline options.
 *
 * <p>TODO: Make this the default to/from translation for PipelineOptions.
 */
public class PipelineOptionsTranslation {
  private static final ObjectMapper MAPPER =
      new ObjectMapper()
          .registerModules(ObjectMapper.findModules(ReflectHelpers.findClassLoader()));

  /** Converts the provided {@link PipelineOptions} to a {@link Struct}. */
  public static Struct toProto(PipelineOptions options) {
    Struct.Builder builder = Struct.newBuilder();

    try {
      // TODO: Officially define URNs for options and their scheme.
      TreeNode treeNode = MAPPER.valueToTree(options);
      TreeNode rootOptions = treeNode.get("options");
      Iterator<String> optionsKeys = rootOptions.fieldNames();
      Map<String, TreeNode> optionsUsingUrns = new HashMap<>();
      while (optionsKeys.hasNext()) {
        String optionKey = optionsKeys.next();
        TreeNode optionValue = rootOptions.get(optionKey);
        optionsUsingUrns.put(
            "beam:option:"
                + CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, optionKey)
                + ":v1",
            optionValue);
      }

      // The JSON format of a Protobuf Struct is the JSON object that is equivalent to that struct
      // (with values encoded in a standard json-codeable manner). See Beam PR 3719 for more.
      JsonFormat.parser().merge(MAPPER.writeValueAsString(optionsUsingUrns), builder);
      return builder.build();
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }

  /** Converts the provided {@link Struct} into {@link PipelineOptions}. */
  public static PipelineOptions fromProto(Struct protoOptions) throws IOException {
    Map<String, TreeNode> mapWithoutUrns = new HashMap<>();
    TreeNode rootOptions = MAPPER.readTree(JsonFormat.printer().print(protoOptions));
    Iterator<String> optionsKeys = rootOptions.fieldNames();
    while (optionsKeys.hasNext()) {
      String optionKey = optionsKeys.next();
      TreeNode optionValue = rootOptions.get(optionKey);
      mapWithoutUrns.put(
          CaseFormat.LOWER_UNDERSCORE.to(
              CaseFormat.LOWER_CAMEL,
              optionKey.substring("beam:option:".length(), optionKey.length() - ":v1".length())),
          optionValue);
    }
    return MAPPER.readValue(
        MAPPER.writeValueAsString(ImmutableMap.of("options", mapWithoutUrns)),
        PipelineOptions.class);
  }
}
