// ***************************************************************************************************************************
// * 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.juneau.json;

import static org.apache.juneau.internal.ClassUtils.*;

import java.util.*;

import org.apache.juneau.*;
import org.apache.juneau.serializer.*;
import org.apache.juneau.transform.*;

/**
 * Session object that lives for the duration of a single use of {@link JsonSchemaSerializer}.
 * 
 * <p>
 * This class is NOT thread safe.
 * It is typically discarded after one-time use although it can be reused within the same thread.
 */
public class JsonSchemaSerializerSession extends JsonSerializerSession {

   /**
    * Create a new session using properties specified in the context.
    * 
    * @param ctx
    *    The context creating this session object.
    *    The context contains all the configuration settings for this object.
    * @param args
    *    Runtime arguments.
    *    These specify session-level information such as locale and URI context.
    *    It also include session-level properties that override the properties defined on the bean and
    *    serializer contexts.
    */
   protected JsonSchemaSerializerSession(JsonSerializer ctx, SerializerSessionArgs args) {
      super(ctx, args);
   }

   @Override /* SerializerSession */
   protected void doSerialize(SerializerPipe out, Object o) throws Exception {
      ObjectMap schema = getSchema(getClassMetaForObject(o), "root", null);
      serializeAnything(getJsonWriter(out), schema, getExpectedRootType(o), "root", null);
   }

   /*
    * Creates a schema representation of the specified class type.
    * 
    * @param eType The class type to get the schema of.
    * @param ctx Serialize context used to prevent infinite loops.
    * @param attrName The name of the current attribute.
    * @return A schema representation of the specified class.
    * @throws SerializeException If a problem occurred trying to convert the output.
    */
   @SuppressWarnings({ "unchecked", "rawtypes" })
   private ObjectMap getSchema(ClassMeta<?> eType, String attrName, String[] pNames) throws Exception {
      ObjectMap out = new ObjectMap();

      if (eType == null)
         eType = object();

      ClassMeta<?> aType;        // The actual type (will be null if recursion occurs)
      ClassMeta<?> sType;        // The serialized type

      aType = push(attrName, eType, null);

      sType = eType.getSerializedClassMeta(this);
      String type = null;

      if (sType.isEnum() || sType.isCharSequence() || sType.isChar())
         type = "string";
      else if (sType.isNumber())
         type = "number";
      else if (sType.isBoolean())
         type = "boolean";
      else if (sType.isMapOrBean())
         type = "object";
      else if (sType.isCollectionOrArray())
         type = "array";
      else
         type = "any";

      out.put("type", type);
      out.put("description", eType.toString());
      PojoSwap f = eType.getPojoSwap(this);
      if (f != null)
         out.put("transform", f);

      if (aType != null) {
         if (sType.isEnum())
            out.put("enum", getEnumStrings((Class<Enum<?>>)sType.getInnerClass()));
         else if (sType.isCollectionOrArray()) {
            ClassMeta componentType = sType.getElementType();
            if (sType.isCollection() && isParentClass(Set.class, sType.getInnerClass()))
               out.put("uniqueItems", true);
            out.put("items", getSchema(componentType, "items", pNames));
         } else if (sType.isBean()) {
            ObjectMap properties = new ObjectMap();
            BeanMeta bm = getBeanMeta(sType.getInnerClass());
            if (pNames != null)
               bm = new BeanMetaFiltered(bm, pNames);
            for (Iterator<BeanPropertyMeta> i = bm.getPropertyMetas().iterator(); i.hasNext();) {
               BeanPropertyMeta p = i.next();
               if (p.canRead())
                  properties.put(p.getName(), getSchema(p.getClassMeta(), p.getName(), p.getProperties()));
            }
            out.put("properties", properties);
         }
      }
      pop();
      return out;
   }

   @SuppressWarnings({ "unchecked", "rawtypes" })
   private static List<String> getEnumStrings(Class<? extends Enum> c) {
      List<String> l = new LinkedList<>();
      for (Object e : EnumSet.allOf(c))
         l.add(e.toString());
      return l;
   }
}