com.theoryinpractise.halbuilder.json.JsonRepresentationReader Maven / Gradle / Ivy

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HAL+JSON serializer/deserializer extension to the HalBuilder Library
There is a newer version: 4.1.4
package com.theoryinpractise.halbuilder.json;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.collect.ImmutableMap;
import com.google.common.io.CharStreams;
import com.theoryinpractise.halbuilder.AbstractRepresentationFactory;
import com.theoryinpractise.halbuilder.api.ContentRepresentation;
import com.theoryinpractise.halbuilder.api.RepresentationException;
import com.theoryinpractise.halbuilder.api.RepresentationReader;
import com.theoryinpractise.halbuilder.impl.api.Support;
import com.theoryinpractise.halbuilder.impl.representations.ContentBasedRepresentation;
import com.theoryinpractise.halbuilder.impl.representations.MutableRepresentation;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import static com.theoryinpractise.halbuilder.impl.api.Support.CURIES;
import static com.theoryinpractise.halbuilder.impl.api.Support.EMBEDDED;
import static com.theoryinpractise.halbuilder.impl.api.Support.HREF;
import static com.theoryinpractise.halbuilder.impl.api.Support.HREFLANG;
import static com.theoryinpractise.halbuilder.impl.api.Support.LINKS;
import static com.theoryinpractise.halbuilder.impl.api.Support.NAME;
import static com.theoryinpractise.halbuilder.impl.api.Support.PROFILE;
import static com.theoryinpractise.halbuilder.impl.api.Support.TITLE;

public class JsonRepresentationReader implements RepresentationReader {
  private final ObjectMapper mapper;

  private final AbstractRepresentationFactory representationFactory;

  public JsonRepresentationReader(AbstractRepresentationFactory representationFactory) {
    this.representationFactory = representationFactory;
    this.mapper = new ObjectMapper();
  }

  public ContentRepresentation read(Reader reader) {
    try {
      String source = CharStreams.toString(reader);

      JsonNode rootNode = mapper.readValue(new StringReader(source), JsonNode.class);

      return readResource(rootNode);
    } catch (Exception e) {
      throw new RepresentationException(e);
    }

  }

  private ContentRepresentation readResource(JsonNode rootNode) throws IOException {

    ContentBasedRepresentation resource = new ContentBasedRepresentation(representationFactory, rootNode.toString());

    readNamespaces(resource, rootNode);
    readLinks(resource, rootNode);
    readProperties(resource, rootNode);
    readResources(resource, rootNode);
    return resource;
  }

  private void readNamespaces(MutableRepresentation resource, JsonNode rootNode) {
    if (rootNode.has(LINKS)) {
      JsonNode linksNode = rootNode.get(LINKS);
      if (linksNode.has(CURIES)) {
        JsonNode curieNode = linksNode.get(CURIES);

        if (curieNode.isArray()) {
          Iterator values = curieNode.elements();
          while (values.hasNext()) {
            JsonNode valueNode = values.next();
            resource.withNamespace(valueNode.get(NAME).asText(), valueNode.get(HREF).asText());
          }
        } else {
          resource.withNamespace(curieNode.get(NAME).asText(), curieNode.get(HREF).asText());
        }
      }
    }
  }

  private void readLinks(MutableRepresentation resource, JsonNode rootNode) {
    if (rootNode.has(LINKS)) {
      Iterator> fields = rootNode.get(LINKS).fields();
      while (fields.hasNext()) {
        Map.Entry keyNode = fields.next();
        if (!CURIES.equals((keyNode.getKey()))) {
          if (keyNode.getValue().isArray()) {
            Iterator values = keyNode.getValue().elements();
            while (values.hasNext()) {
              JsonNode valueNode = values.next();
              withJsonLink(resource, keyNode, valueNode);
            }
          } else {
            withJsonLink(resource, keyNode, keyNode.getValue());
          }
        }
      }
    }
  }

  private void withJsonLink(MutableRepresentation resource, Map.Entry keyNode, JsonNode valueNode) {
    String rel = keyNode.getKey();
    String href = valueNode.get(HREF).asText();
    String name = optionalNodeValueAsText(valueNode, NAME);
    String title = optionalNodeValueAsText(valueNode, TITLE);
    String hreflang = optionalNodeValueAsText(valueNode, HREFLANG);
    String profile = optionalNodeValueAsText(valueNode, PROFILE);

    resource.withLink(rel, href, name, title, hreflang, profile);
  }

  String optionalNodeValueAsText(JsonNode node, String key) {
    JsonNode value = node.get(key);
    return value != null ? value.asText() : null;
  }

  private void readProperties(MutableRepresentation resource, JsonNode rootNode) throws IOException {
    Iterator fieldNames = rootNode.fieldNames();
    while (fieldNames.hasNext()) {
      String fieldName = fieldNames.next();
      if (!Support.RESERVED_JSON_PROPERTIES.contains(fieldName)) {
        JsonNode field = rootNode.get(fieldName);
        if(field.isArray()) {
            List