/*
 * 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.common.utils.IOUtils.*;

import java.io.*;
import java.lang.reflect.*;
import java.nio.charset.*;
import java.util.*;
import java.util.function.*;

import org.apache.juneau.*;
import org.apache.juneau.httppart.*;
import org.apache.juneau.internal.*;
import org.apache.juneau.serializer.*;
import org.apache.juneau.svl.*;
import org.apache.juneau.swap.*;

/**
 * Session object that lives for the duration of a single use of {@link JsonSerializer}.
 *
 * <h5 class='section'>Notes:</h5><ul>
 *    <li class='warn'>This class is not thread safe and is typically discarded after one use.
 * </ul>
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JsonBasics">JSON Basics</a>
 * </ul>
 */
public class JsonSerializerSession extends WriterSerializerSession {

   //-----------------------------------------------------------------------------------------------------------------
   // Static
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Creates a new builder for this object.
    *
    * @param ctx The context creating this session.
    * @return A new builder.
    */
   public static Builder create(JsonSerializer ctx) {
      return new Builder(ctx);
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Builder
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Builder class.
    */
   public static class Builder extends WriterSerializerSession.Builder {

      JsonSerializer ctx;

      /**
       * Constructor
       *
       * @param ctx The context creating this session.
       */
      protected Builder(JsonSerializer ctx) {
         super(ctx);
         this.ctx = ctx;
      }

      @Override
      public JsonSerializerSession build() {
         return new JsonSerializerSession(this);
      }
      @Override /* Overridden from Builder */
      public <T> Builder apply(Class<T> type, Consumer<T> apply) {
         super.apply(type, apply);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder debug(Boolean value) {
         super.debug(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder properties(Map<String,Object> value) {
         super.properties(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder property(String key, Object value) {
         super.property(key, value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder unmodifiable() {
         super.unmodifiable();
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder locale(Locale value) {
         super.locale(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder localeDefault(Locale value) {
         super.localeDefault(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder mediaType(MediaType value) {
         super.mediaType(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder mediaTypeDefault(MediaType value) {
         super.mediaTypeDefault(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder timeZone(TimeZone value) {
         super.timeZone(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder timeZoneDefault(TimeZone value) {
         super.timeZoneDefault(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder javaMethod(Method value) {
         super.javaMethod(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder resolver(VarResolverSession value) {
         super.resolver(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder schema(HttpPartSchema value) {
         super.schema(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder schemaDefault(HttpPartSchema value) {
         super.schemaDefault(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder uriContext(UriContext value) {
         super.uriContext(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder fileCharset(Charset value) {
         super.fileCharset(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder streamCharset(Charset value) {
         super.streamCharset(value);
         return this;
      }

      @Override /* Overridden from Builder */
      public Builder useWhitespace(Boolean value) {
         super.useWhitespace(value);
         return this;
      }
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Instance
   //-----------------------------------------------------------------------------------------------------------------

   private final JsonSerializer ctx;

   /**
    * Constructor.
    *
    * @param builder The builder for this object.
    */
   protected JsonSerializerSession(Builder builder) {
      super(builder);
      this.ctx = builder.ctx;
   }

   @Override /* SerializerSesssion */
   protected void doSerialize(SerializerPipe out, Object o) throws IOException, SerializeException {
      serializeAnything(getJsonWriter(out).i(getInitialDepth()), o, getExpectedRootType(o), "root", null);
   }

   /**
    * Method that can be called from subclasses to serialize an object to JSON.
    *
    * <p>
    * Used by {@link JsonSchemaSerializerSession} for serializing examples to JSON.
    *
    * @param o The object to serialize.
    * @return The serialized object.
    * @throws Exception Error occurred.
    */
   protected String serializeJson(Object o) throws Exception {
      StringWriter sw = new StringWriter();
      serializeAnything(getJsonWriter(createPipe(sw)).i(getInitialDepth()), o, getExpectedRootType(o), "root", null);
      return sw.toString();
   }

   /**
    * Workhorse method.
    * Determines the type of object, and then calls the appropriate type-specific serialization method.
    *
    * @param out The output writer.
    * @param o The object to serialize.
    * @param eType The expected type.
    * @param attrName The attribute name.
    * @param pMeta The bean property currently being parsed.
    * @return The same writer passed in.
    * @throws SerializeException General serialization error occurred.
    */
   @SuppressWarnings({ "rawtypes" })
   protected JsonWriter serializeAnything(JsonWriter out, Object o, ClassMeta<?> eType, String attrName, BeanPropertyMeta pMeta) throws SerializeException {

      if (o == null) {
         out.append("null");
         return out;
      }

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

      ClassMeta<?> aType;        // The actual type
      ClassMeta<?> sType;        // The serialized type

      aType = push2(attrName, o, eType);
      boolean isRecursion = aType == null;

      // Handle recursion
      if (aType == null) {
         o = null;
         aType = object();
      }

      // Handle Optional<X>
      if (isOptional(aType)) {
         o = getOptionalValue(o);
         eType = getOptionalType(eType);
         aType = getClassMetaForObject(o, object());
      }

      sType = aType;
      String typeName = getBeanTypeName(this, eType, aType, pMeta);

      // Swap if necessary
      ObjectSwap swap = aType.getSwap(this);
      if (swap != null) {
         o = swap(swap, o);
         sType = swap.getSwapClassMeta(this);

         // If the getSwapClass() method returns Object, we need to figure out
         // the actual type now.
         if (sType.isObject())
            sType = getClassMetaForObject(o);
      }

      String wrapperAttr = getJsonClassMeta(sType).getWrapperAttr();
      if (wrapperAttr != null) {
         out.w('{').cr(indent).attr(wrapperAttr).w(':').s(indent);
         indent++;
      }

      // '\0' characters are considered null.
      if (o == null || (sType.isChar() && ((Character)o).charValue() == 0)) {
         out.append("null");
      } else if (sType.isNumber() || sType.isBoolean()) {
         out.append(o);
      } else if (sType.isBean()) {
         serializeBeanMap(out, toBeanMap(o), typeName);
      } else if (sType.isUri() || (pMeta != null && pMeta.isUri())) {
         out.uriValue(o);
      } else if (sType.isMap()) {
         if (o instanceof BeanMap)
            serializeBeanMap(out, (BeanMap)o, typeName);
         else
            serializeMap(out, (Map)o, eType);
      } else if (sType.isCollection()) {
         serializeCollection(out, (Collection) o, eType);
      } else if (sType.isArray()) {
         serializeCollection(out, toList(sType.getInnerClass(), o), eType);
      } else if (sType.isReader()) {
         pipe((Reader)o, out, SerializerSession::handleThrown);
      } else if (sType.isInputStream()) {
         pipe((InputStream)o, out, SerializerSession::handleThrown);
      } else {
         out.stringValue(toString(o));
      }

      if (wrapperAttr != null) {
         indent--;
         out.cre(indent-1).w('}');
      }

      if (! isRecursion)
         pop();
      return out;
   }

   @SuppressWarnings({ "rawtypes", "unchecked" })
   private SerializerWriter serializeMap(JsonWriter out, Map m, ClassMeta<?> type) throws SerializeException {

      ClassMeta<?> keyType = type.getKeyType(), valueType = type.getValueType();

      int i = indent;
      out.w('{');

      Flag addComma = Flag.create();
      forEachEntry(m, x -> {
         addComma.ifSet(()->out.w(',').smi(i)).set();
         Object value = x.getValue();
         Object key = generalize(x.getKey(), keyType);
         out.cr(i).attr(toString(key)).w(':').s(i);
         serializeAnything(out, value, valueType, (key == null ? null : toString(key)), null);
      });

      out.cre(i-1).w('}');

      return out;
   }

   private SerializerWriter serializeBeanMap(JsonWriter out, BeanMap<?> m, String typeName) throws SerializeException {
      int i = indent;
      out.w('{');

      Flag addComma = Flag.create();
      Predicate<Object> checkNull = x -> isKeepNullProperties() || x != null;

      if (typeName != null) {
         BeanPropertyMeta pm = m.getMeta().getTypeProperty();
         out.cr(i).attr(pm.getName()).w(':').s(i).stringValue(typeName);
         addComma.set();
      }

      m.forEachValue(checkNull, (pMeta,key,value,thrown) -> {
         ClassMeta<?> cMeta = pMeta.getClassMeta();
         if (thrown != null)
            onBeanGetterException(pMeta, thrown);

         if (canIgnoreValue(cMeta, key, value))
            return;

         addComma.ifSet(()->out.append(',').smi(i)).set();

         out.cr(i).attr(key).w(':').s(i);

         serializeAnything(out, value, cMeta, key, pMeta);
      });

      out.cre(i-1).w('}');
      return out;
   }

   @SuppressWarnings({"rawtypes", "unchecked"})
   private SerializerWriter serializeCollection(JsonWriter out, Collection c, ClassMeta<?> type) throws SerializeException {

      ClassMeta<?> elementType = type.getElementType();

      out.w('[');
      Flag addComma = Flag.create();
      forEachEntry(c, x -> {
         addComma.ifSet(()->out.w(',').smi(indent)).set();
         out.cr(indent);
         serializeAnything(out, x, elementType, "<iterator>", null);
      });

      out.cre(indent-1).w(']');
      return out;
   }

   /**
    * Converts the specified output target object to an {@link JsonWriter}.
    *
    * @param out The output target object.
    * @return The output target object wrapped in an {@link JsonWriter}.
    * @throws IOException Thrown by underlying stream.
    */
   protected final JsonWriter getJsonWriter(SerializerPipe out) throws IOException {
      Object output = out.getRawOutput();
      if (output instanceof JsonWriter)
         return (JsonWriter)output;
      JsonWriter w = new JsonWriter(out.getWriter(), isUseWhitespace(), getMaxIndent(), isEscapeSolidus(), getQuoteChar(),
         isSimpleAttrs(), isTrimStrings(), getUriResolver());
      out.setWriter(w);
      return w;
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Properties
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Add <js>"_type"</js> properties when needed.
    *
    * @see JsonSerializer.Builder#addBeanTypesJson()
    * @return
    *    <jk>true</jk> if <js>"_type"</js> properties will be added to beans if their type cannot be inferred
    *    through reflection.
    */
   @Override
   protected final boolean isAddBeanTypes() {
      return ctx.isAddBeanTypes();
   }

   /**
    * Prefix solidus <js>'/'</js> characters with escapes.
    *
    * @see JsonSerializer.Builder#escapeSolidus()
    * @return
    *    <jk>true</jk> if solidus (e.g. slash) characters should be escaped.
    */
   protected final boolean isEscapeSolidus() {
      return ctx.isEscapeSolidus();
   }

   /**
    * Simple JSON attributes.
    *
    * @see JsonSerializer.Builder#simpleAttrs()
    * @return
    *    <jk>true</jk> if JSON attribute names will only be quoted when necessary.
    *    <br>Otherwise, they are always quoted.
    */
   protected final boolean isSimpleAttrs() {
      return ctx.isSimpleAttrs();
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Extended metadata
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Returns the language-specific metadata on the specified class.
    *
    * @param cm The class to return the metadata on.
    * @return The metadata.
    */
   protected JsonClassMeta getJsonClassMeta(ClassMeta<?> cm) {
      return ctx.getJsonClassMeta(cm);
   }
}