content: /*
   * Copyright 2010 Proofpoint, Inc.
   *
   * Licensed 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 io.airlift.json;
  
  import com.fasterxml.jackson.core.JsonParser;
  import com.fasterxml.jackson.databind.JavaType;
  import com.fasterxml.jackson.databind.ObjectMapper;
  import com.google.common.base.Suppliers;
  import com.google.common.reflect.TypeParameter;
  import com.google.common.reflect.TypeToken;
  import io.airlift.json.LengthLimitedWriter.LengthLimitExceededException;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.Reader;
  import java.io.StringWriter;
  import java.lang.reflect.Type;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  import java.util.function.Supplier;
  
  import static com.fasterxml.jackson.databind.SerializationFeature.INDENT_OUTPUT;
  import static com.google.common.base.Preconditions.checkArgument;
  import static java.lang.String.format;
  import static java.util.Objects.requireNonNull;
  
  public class JsonCodec<T>
  {
      private static final Supplier<ObjectMapper> OBJECT_MAPPER_SUPPLIER = Suppliers.memoize(
              () -> new ObjectMapperProvider().get().enable(INDENT_OUTPUT));
  
      public static <T> JsonCodec<T> jsonCodec(Class<T> type)
      {
          requireNonNull(type, "type is null");
  
          return new JsonCodec<>(OBJECT_MAPPER_SUPPLIER.get(), type);
      }
  
      public static <T> JsonCodec<T> jsonCodec(TypeToken<T> type)
      {
          requireNonNull(type, "type is null");
  
          return new JsonCodec<>(OBJECT_MAPPER_SUPPLIER.get(), type.getType());
      }
  
      public static <T> JsonCodec<List<T>> listJsonCodec(Class<T> type)
      {
          requireNonNull(type, "type is null");
  
          Type listType = new TypeToken<List<T>>() {}
                  .where(new TypeParameter<T>() {}, type)
                  .getType();
  
          return new JsonCodec<>(OBJECT_MAPPER_SUPPLIER.get(), listType);
      }
  
      public static <T> JsonCodec<List<T>> listJsonCodec(JsonCodec<T> type)
      {
          requireNonNull(type, "type is null");
  
          Type listType = new TypeToken<List<T>>() {}
                  .where(new TypeParameter<T>() {}, type.getTypeToken())
                  .getType();
  
          return new JsonCodec<>(OBJECT_MAPPER_SUPPLIER.get(), listType);
      }
  
      public static <K, V> JsonCodec<Map<K, V>> mapJsonCodec(Class<K> keyType, Class<V> valueType)
      {
          requireNonNull(keyType, "keyType is null");
          requireNonNull(valueType, "valueType is null");
  
          Type mapType = new TypeToken<Map<K, V>>() {}
                  .where(new TypeParameter<K>() {}, keyType)
                  .where(new TypeParameter<V>() {}, valueType)
                  .getType();
  
          return new JsonCodec<>(OBJECT_MAPPER_SUPPLIER.get(), mapType);
      }
  
      public static <K, V> JsonCodec<Map<K, V>> mapJsonCodec(Class<K> keyType, JsonCodec<V> valueType)
      {
          requireNonNull(keyType, "keyType is null");
          requireNonNull(valueType, "valueType is null");
  
          Type mapType = new TypeToken<Map<K, V>>() {}
                  .where(new TypeParameter<K>() {}, keyType)
                  .where(new TypeParameter<V>() {}, valueType.getTypeToken())
                  .getType();
  
          return new JsonCodec<>(OBJECT_MAPPER_SUPPLIER.get(), mapType);
      }
  
      private final ObjectMapper mapper;
      private final Type type;
      private final JavaType javaType;
  
      JsonCodec(ObjectMapper mapper, Type type)
      {
          this.mapper = mapper;
          this.type = type;
          this.javaType = mapper.getTypeFactory().constructType(type);
      }
  
      /**
       * Gets the type this codec supports.
       */
      public Type getType()
      {
          return type;
      }
  
      /**
       * Converts the specified json string into an instance of type T.
       *
       * @param json the json string to parse
       * @return parsed response; never null
       * @throws IllegalArgumentException if the json string can not be converted to the type T
       */
      public T fromJson(String json)
              throws IllegalArgumentException
      {
          try (JsonParser parser = mapper.createParser(json)) {
              T value = mapper.readerFor(javaType).readValue(parser);
              checkArgument(parser.nextToken() == null, "Found characters after the expected end of input");
              return value;
          }
          catch (IOException e) {
              throw new IllegalArgumentException(format("Invalid JSON string for %s", javaType), e);
          }
      }
  
      /**
       * Converts the specified instance to json.
       *
       * @param instance the instance to convert to json
       * @return json string
       * @throws IllegalArgumentException if the specified instance can not be converted to json
       */
      public String toJson(T instance)
              throws IllegalArgumentException
      {
          try {
              return mapper.writerFor(javaType).writeValueAsString(instance);
          }
          catch (IOException e) {
              throw new IllegalArgumentException(format("%s could not be converted to JSON", instance.getClass().getName()), e);
          }
      }
  
      /**
       * Converts the specified instance to optional json string with a length limit. Returns Optional.empty() if length limit is exceeded.
       *
       * @param instance the instance to convert to json
       * @param lengthLimit the maximum length of the serialized string in characters
       * @return json string
       * @throws IllegalArgumentException if the specified instance can not be converted to json
       */
      public Optional<String> toJsonWithLengthLimit(T instance, int lengthLimit)
      {
          try (StringWriter stringWriter = new StringWriter();
                  LengthLimitedWriter lengthLimitedWriter = new LengthLimitedWriter(stringWriter, lengthLimit)) {
              mapper.writeValue(lengthLimitedWriter, instance);
              return Optional.of(stringWriter.getBuffer().toString());
          }
          catch (LengthLimitExceededException e) {
              return Optional.empty();
          }
          catch (IOException e) {
              throw new IllegalArgumentException(format("%s could not be converted to JSON", instance.getClass().getName()), e);
          }
      }
  
      /**
       * Coverts the specified json bytes (UTF-8) into an instance of type T.
       *
       * @param json the json bytes (UTF-8) to parse
       * @return parsed response; never null
       * @throws IllegalArgumentException if the json bytes can not be converted to the type T
       */
      public T fromJson(byte[] json)
              throws IllegalArgumentException
      {
          try (JsonParser parser = mapper.createParser(json)) {
              T value = mapper.readerFor(javaType).readValue(parser);
              checkArgument(parser.nextToken() == null, "Found characters after the expected end of input");
              return value;
          }
          catch (IOException e) {
              throw new IllegalArgumentException(format("Invalid JSON bytes for %s", javaType), e);
          }
      }
  
      /**
       * Converts the specified instance to json.
       *
       * @param instance the instance to convert to json
       * @return json bytes (UTF-8)
       * @throws IllegalArgumentException if the specified instance can not be converted to json
       */
      public byte[] toJsonBytes(T instance)
              throws IllegalArgumentException
      {
          try {
              return mapper.writerFor(javaType).writeValueAsBytes(instance);
          }
          catch (IOException e) {
              throw new IllegalArgumentException(format("%s could not be converted to JSON", instance.getClass().getName()), e);
          }
      }
  
      /**
       * Coverts the specified {@link InputStream} (UTF-8) into an instance of type T.
       *
       * @param json the json stream (UTF-8) to parse
       * @return parsed response; never null
       * @throws IllegalArgumentException if the json bytes can not be converted to the type T
       */
      public T fromJson(InputStream json)
              throws IllegalArgumentException
      {
          try (JsonParser parser = mapper.createParser(json)) {
              T value = mapper.readerFor(javaType).readValue(parser);
              checkArgument(parser.nextToken() == null, "Found characters after the expected end of input");
              return value;
          }
          catch (IOException e) {
              throw new IllegalArgumentException(format("Invalid JSON bytes for %s", javaType), e);
          }
      }
  
      /**
       * Coverts the specified {@link Reader} into an instance of type T.
       *
       * @param json the json character stream to parse
       * @return parsed response; never null
       * @throws IllegalArgumentException if the json characters can not be converted to the type T
       */
      public T fromJson(Reader json)
              throws IllegalArgumentException
      {
          try (JsonParser parser = mapper.createParser(json)) {
              T value = mapper.readerFor(javaType).readValue(parser);
              checkArgument(parser.nextToken() == null, "Found characters after the expected end of input");
              return value;
          }
          catch (IOException e) {
              throw new IllegalArgumentException(format("Invalid JSON characters for %s", javaType), e);
          }
      }
  
      @SuppressWarnings("unchecked")
      TypeToken<T> getTypeToken()
      {
          return (TypeToken<T>) TypeToken.of(type);
      }
  }
  