/*
 * 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.marshall;

import static org.apache.juneau.commons.utils.SystemUtils.*;

import org.apache.juneau.commons.collections.*;

/**
 * Parent class for all classes that traverse POJOs.
 *
 * <h5 class='topic'>Description</h5>
 * <p>
 * Base class that serves as the parent class for all serializers and other classes that traverse POJOs.
 *
 * <h5 class='section'>Notes:</h5><ul>
 *    <li class='note'>This class is thread safe and reusable.
 * </ul>
 *
 */
@SuppressWarnings({
   "java:S1192", // Duplicated literals (argument/property names) read more clearly inline than as constants
   "rawtypes" // The protected constructor takes the raw Builder type, shared by subclasses that have different self-type parameters
})
public abstract class MarshallingTraverseContext extends MarshallingContextable {

   /**
    * Builder class.
    */
   @SuppressWarnings({
      "java:S119" // 'SELF' (CRTP self-type) is intentional and clearer than a single-letter name.
   })
   public abstract static class Builder<SELF extends Builder<SELF>> extends MarshallingContextable.Builder<SELF> {

      private boolean detectRecursions;
      private boolean ignoreRecursions;
      private int initialDepth;
      private int maxDepth;

      /**
       * Constructor, default settings.
       */
      protected Builder() {
         detectRecursions = env("MarshallingTraverseContext.detectRecursions", false);
         ignoreRecursions = env("MarshallingTraverseContext.ignoreRecursions", false);
         initialDepth = env("MarshallingTraverseContext.initialDepth", 0);
         maxDepth = env("MarshallingTraverseContext.maxDepth", 100);
      }

      /**
       * Copy constructor.
       *
       * @param copyFrom The bean to copy from.  Cannot be <jk>null</jk>.
       */
      protected Builder(MarshallingTraverseContext copyFrom) {
         super(copyFrom);
         detectRecursions = copyFrom.getDetectRecursions();
         ignoreRecursions = copyFrom.getIgnoreRecursions();
         initialDepth = copyFrom.getInitialDepth();
         maxDepth = copyFrom.getMaxDepth();
      }

      /**
       * Copy constructor.
       *
       * @param copyFrom The builder to copy from.  Cannot be <jk>null</jk>.
       */
      protected Builder(Builder<?> copyFrom) {
         super(copyFrom);
         detectRecursions = copyFrom.detectRecursions;
         ignoreRecursions = copyFrom.ignoreRecursions;
         initialDepth = copyFrom.initialDepth;
         maxDepth = copyFrom.maxDepth;
      }

      /**
       * Automatically detect POJO recursions.
       *
       * <p>
       * When enabled, specifies that recursions should be checked for during traversal.
       *
       * <p>
       * Recursions can occur when traversing models that aren't true trees but rather contain loops.
       * <br>When recursion detection is disabled, such loops are instead bounded by {@link #maxDepth(int) maxDepth}
       *    (default <c>100</c>): the over-depth branch is silently truncated, producing finite but semantically-incomplete output.
       * <br>If the stack is exhausted before <c>maxDepth</c> is reached, the resulting {@link StackOverflowError} is
       *    converted to a {@link MarshallingRecursionException MarshallingRecursionException} with the message <js>"Depth too deep.  Stack overflow occurred."</js>.
       *
       * <h5 class='section'>Notes:</h5><ul>
       *    <li class='note'>
       *       Checking for recursion can cause a small performance penalty.
       *    <li class='note'>
       *       This is the recommended way to fail-fast on cyclic bean graphs such as parent/child
       *       {@link ParentProperty @ParentProperty} references.  Under the default config such cycles are instead
       *       silently truncated at {@link #maxDepth(int) maxDepth} (see the {@link ParentProperty} Javadoc).
       * </ul>
       *
       * <h5 class='section'>Example:</h5>
       * <p class='bjava'>
       *    <jc>// Create a serializer that automatically checks for recursions.</jc>
       *    WriterSerializer <jv>serializer</jv> = JsonSerializer
       *       .<jsm>create</jsm>()
       *       .detectRecursions()
       *       .build();
       *
       *    <jc>// Create a POJO model with a recursive loop.</jc>
       *    <jk>public class</jk> MyBean {
       *       <jk>public</jk> Object <jf>f</jf>;
       *    }
       *    MyBean <jv>bean</jv> = <jk>new</jk> MyBean();
       *    <jv>bean</jv>.<jf>f</jf> = <jv>bean</jv>;
       *
       *    <jc>// Throws a SerializeException and not a StackOverflowError</jc>
       *    String <jv>json</jv> = <jv>serializer</jv>.write(<jv>bean</jv>);
       * </p>
       *
       * @return This object.
       */
      public SELF detectRecursions() {
         return detectRecursions(true);
      }

      /**
       * Same as {@link #detectRecursions()} but allows you to explicitly specify the value.
       *
       * @param value The value for this setting.
       * @return This object.
       */
      public SELF detectRecursions(boolean value) {
         detectRecursions = value;
         return self();
      }

      @Override /* Overridden from Context.Builder<?> */
      public HashKey hashKey() {
         // @formatter:off
         return HashKey.of(
            super.hashKey(),
            detectRecursions,
            ignoreRecursions,
            initialDepth,
            maxDepth
         );
         // @formatter:on
      }

      /**
       * Ignore recursion errors.
       *
       * <p>
       * When enabled, when we encounter the same object when traversing a tree, we set the value to <jk>null</jk>.
       *
       * <p>
       * For example, if a model contains the links A-&gt;B-&gt;C-&gt;A, then the JSON generated will look like
       *    the following when this setting is <jk>true</jk>...
       *
       * <p class='bjson'>
       *    {A:{B:{C:<jk>null</jk>}}}
       * </p>
       *
       * <h5 class='section'>Notes:</h5><ul>
       *    <li class='note'>
       *       Checking for recursion can cause a small performance penalty.
       *    <li class='note'>
       *       Use this to serialize cyclic bean graphs (such as parent/child {@link ParentProperty @ParentProperty}
       *       references) by emitting the repeated node as <jk>null</jk> so the output round-trips cleanly.
       * </ul>
       *
       * <h5 class='section'>Example:</h5>
       * <p class='bjava'>
       *    <jc>// Create a serializer ignores recursions.</jc>
       *    WriterSerializer <jv>serializer</jv> = JsonSerializer
       *       .<jsm>create</jsm>()
       *       .ignoreRecursions()
       *       .build();
       *
       *    <jc>// Create a POJO model with a recursive loop.</jc>
       *    <jk>public class</jk> MyBean {
       *       <jk>public</jk> Object <jf>f</jf>;
       *    }
       *    MyBean <jv>bean</jv> = <jk>new</jk> MyBean();
       *    <jv>bean</jv>.<jf>f</jf> = <jv>bean</jv>;
       *
       *    <jc>// Produces "{f:null}"</jc>
       *    String <jv>json</jv> = <jv>serializer</jv>.write(<jv>bean</jv>);
       * </p>
       *
       * @return This object.
       */
      public SELF ignoreRecursions() {
         return ignoreRecursions(true);
      }

      /**
       * Same as {@link #ignoreRecursions()} but allows you to explicitly specify the value.
       *
       * @param value The value for this setting.
       * @return This object.
       */
      public SELF ignoreRecursions(boolean value) {
         ignoreRecursions = value;
         return self();
      }

      /**
       * Initial depth.
       *
       * <p>
       * The initial indentation level at the root.
       *
       * <p>
       * Useful when constructing document fragments that need to be indented at a certain level when whitespace is enabled.
       *
       * <h5 class='section'>Example:</h5>
       * <p class='bjava'>
       *    <jc>// Create a serializer with whitespace enabled and an initial depth of 2.</jc>
       *    WriterSerializer <jv>serializer</jv> = JsonSerializer
       *       .<jsm>create</jsm>()
       *       .ws()
       *       .initialDepth(2)
       *       .build();
       *
       *    <jc>// Produces "\t\t{\n\t\t\t'foo':'bar'\n\t\t}\n"</jc>
       *    String <jv>json</jv> = <jv>serializer</jv>.write(<jk>new</jk> MyBean());
       * </p>
       *
       * @param value
       *    The new value for this setting.
       *    <br>The default is <c>0</c>.
       * @return This object.
       */
      public SELF initialDepth(int value) {
         initialDepth = value;
         return self();
      }

      /**
       * Max traversal depth.
       *
       * <p>
       * Specifies the maximum depth traversed in the POJO tree.
       *
       * <p>
       * When this depth is exceeded, the over-depth nodes are silently dropped (truncated) from the output — no
       * exception is thrown.  This is a size guard that bounds the output of deeply-nested (or cyclic) models; it is
       * <b>not</b> a cycle detector.  For genuine recursive references, enable {@link #detectRecursions()} to fail-fast
       * with a {@link MarshallingRecursionException}, or {@link #ignoreRecursions()} to emit repeated nodes as
       * <jk>null</jk> so the output round-trips cleanly.
       *
       * <h5 class='section'>Example:</h5>
       * <p class='bjava'>
       *    <jc>// Create a serializer that truncates output beyond a depth of 20.</jc>
       *    WriterSerializer <jv>serializer</jv> = JsonSerializer
       *       .<jsm>create</jsm>()
       *       .maxDepth(20)
       *       .build();
       * </p>
       *
       * <h5 class='section'>See Also:</h5><ul>
       *    <li class='jm'>{@link Builder#maxDepth(int)}
       * </ul>
       *
       * @param value
       *    The new value for this setting.
       *    <br>The default is <c>100</c>.
       * @return This object.
       */
      public SELF maxDepth(int value) {
         maxDepth = value;
         return self();
      }


   }

   private final boolean detectRecursions;
   private final boolean ignoreRecursions;
   private final int initialDepth;
   private final int maxDepth;
   private final boolean actualDetectRecursions;

   /**
    * Constructor
    *
    * @param builder The builder for this object.  Cannot be <jk>null</jk>.
    */
   protected MarshallingTraverseContext(Builder builder) {
      super(builder);

      detectRecursions = builder.detectRecursions;
      ignoreRecursions = builder.ignoreRecursions;
      initialDepth = builder.initialDepth;
      maxDepth = builder.maxDepth;

      actualDetectRecursions = detectRecursions || ignoreRecursions || super.isDebug();
   }

   @Override /* Overridden from Context */
   public abstract Builder<?> copy();

   /**
    * Initial depth.
    *
    * @see Builder#initialDepth(int)
    * @return
    *    The initial indentation level at the root.
    */
   public final int getInitialDepth() { return initialDepth; }

   /**
    * Max traversal depth.
    *
    * @see Builder#maxDepth(int)
    * @return
    *    The depth beyond which nodes in the POJO tree are dropped (truncated) from the output.
    * <br>Values deeper than this limit are silently omitted rather than causing an exception to be thrown.
    * <br>This is a size guard, not a cycle detector.
    */
   public final int getMaxDepth() { return maxDepth; }

   /**
    * Automatically detect POJO recursions.
    *
    * @see Builder#detectRecursions()
    * @return
    *    <jk>true</jk> if recursions should be checked for during traversal.
    */
   public final boolean isDetectRecursions() { return detectRecursions; }

   /**
    * Whether recursion detection is effectively enabled during traversal.
    * This is {@link #isDetectRecursions()} OR {@link #isIgnoreRecursions()} OR {@link #isDebug()}.
    */
   protected final boolean shouldDetectRecursions() { return actualDetectRecursions; }

   /**
    * Ignore recursion errors.
    *
    * @see Builder#ignoreRecursions()
    * @return
    *    <jk>true</jk> if when we encounter the same object when traversing a tree, we set the value to <jk>null</jk>.
    *    <br>Otherwise, an exception is thrown with the message <js>"Recursion occurred, stack=..."</js>.
    */
   public final boolean isIgnoreRecursions() { return ignoreRecursions; }

   /**
    * Detect recursions flag (raw value).
    *
    * @return The detect recursions flag.
    */
   protected final boolean getDetectRecursions() { return detectRecursions; }

   /**
    * Ignore recursions flag (raw value).
    *
    * @return The ignore recursions flag.
    */
   protected final boolean getIgnoreRecursions() { return ignoreRecursions; }

   @Override /* Overridden from MarshallingContextable */
   protected FluentMap<String,Object> properties() {
      return super.properties()
         .a("detectRecursions", detectRecursions)
         .a("ignoreRecursions", ignoreRecursions)
         .a("initialDepth", initialDepth)
         .a("maxDepth", maxDepth);
   }
}