package org.davidmoten.kool.json;
   
   import java.io.IOException;
   import java.io.UncheckedIOException;
   import java.util.function.Supplier;
   
   import org.davidmoten.kool.Stream;
   
   import com.fasterxml.jackson.core.JsonParser;
  import com.fasterxml.jackson.core.JsonToken;
  import com.fasterxml.jackson.core.TreeNode;
  import com.fasterxml.jackson.databind.JsonNode;
  import com.fasterxml.jackson.databind.ObjectMapper;
  import com.fasterxml.jackson.databind.node.ArrayNode;
  
  public final class LazyArrayNode implements Supplier<ArrayNode> {
  
      private final JsonParser parser;
      private final ObjectMapper mapper;
  
      LazyArrayNode(JsonParser parser, ObjectMapper mapper) {
          this.parser = parser;
          this.mapper = mapper;
      }
  
      @Override
      public ArrayNode get() {
          try {
              return (ArrayNode) mapper.readTree(parser);
          } catch (IOException e) {
              throw new UncheckedIOException(e);
          }
      }
  
      public Stream<JsonNode> values() {
          return Stream.<JsonNode>defer(() -> //
          Stream.generate(emitter -> {
              JsonToken token = parser.nextToken();
              if (token.equals(JsonToken.END_ARRAY)) {
                  emitter.onComplete();
              } else {
                  TreeNode v = mapper.readTree(parser);
                  emitter.onNext((JsonNode) v);
              }
          })).doOnDispose(() -> parser.close());
      }
  
      public <T> Stream<T> values(Class<T> cls) {
          return Stream.<T>defer(() -> {
              // skip array start
              parser.nextToken();
              return Stream.generate(emitter -> {
                  if (parser.isClosed()) {
                      emitter.onComplete();
                  } else {
                      T v = mapper.readValue(parser, cls);
                      if (v == null) {
                          emitter.onComplete();
                      } else {
                          emitter.onNext(v);
                      }
                  }
              });
          }).doOnDispose(() -> parser.close());
      }
  
  }