/*
 * 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.xml;

import static javax.xml.stream.XMLStreamConstants.*;
import static org.apache.juneau.commons.utils.CollectionUtils.*;
import static org.apache.juneau.commons.utils.StringUtils.*;
import static org.apache.juneau.commons.utils.ThrowableUtils.*;
import static org.apache.juneau.commons.utils.Utils.*;
import static org.apache.juneau.xml.annotation.XmlFormat.*;

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

import javax.xml.stream.*;
import javax.xml.stream.util.*;

import org.apache.juneau.*;
import org.apache.juneau.collections.*;
import org.apache.juneau.commons.reflect.*;
import org.apache.juneau.httppart.*;
import org.apache.juneau.parser.*;
import org.apache.juneau.swap.*;

/**
 * Session object that lives for the duration of a single use of {@link XmlParser}.
 *
 * <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/XmlBasics">XML Basics</a>

 * </ul>
 */
@SuppressWarnings({ "unchecked", "rawtypes" })
public class XmlParserSession extends ReaderParserSession {
   /**
    * Builder class.
    */
   public static class Builder extends ReaderParserSession.Builder {

      private XmlParser ctx;

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

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

      @Override
      public XmlParserSession build() {
         return new XmlParserSession(this);
      }

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

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

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

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

   private static final int UNKNOWN = 0, OBJECT = 1, ARRAY = 2, STRING = 3, NUMBER = 4, BOOLEAN = 5, NULL = 6;

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

   private static int getJsonType(String s) {
      if (s == null)
         return UNKNOWN;
      var c = s.charAt(0);
      return switch (c) {
         case 'o' -> (s.equals("object") ? OBJECT : UNKNOWN);
         case 'a' -> (s.equals("array") ? ARRAY : UNKNOWN);
         case 's' -> (s.equals("string") ? STRING : UNKNOWN);
         case 'b' -> (s.equals("boolean") ? BOOLEAN : UNKNOWN);
         case 'n' -> {
            c = s.charAt(2);
            yield switch (c) {
               case 'm' -> (s.equals("number") ? NUMBER : UNKNOWN);
               case 'l' -> (s.equals("null") ? NULL : UNKNOWN);
               default -> NUMBER;
            };
         }
         default -> UNKNOWN;
      };
   }

   private final XmlParser ctx;

   private final StringBuilder rsb = new StringBuilder();  // Reusable string builder used in this class.

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

   /*
    * Returns the name of the specified attribute on the current XML element.
    * Any <js>'_x####_'</js> sequences in the string will be decoded.
    */
   private String getAttributeName(XmlReader r, int i) {
      return decodeString(r.getAttributeLocalName(i));
   }

   /*
    * Returns the value of the specified attribute on the current XML element.
    * Any <js>'_x####_'</js> sequences in the string will be decoded.
    */
   private String getAttributeValue(XmlReader r, int i) {
      return decodeString(r.getAttributeValue(i));
   }

   /*
    * Takes the element being read from the XML stream reader and reconstructs it as XML.
    * Used when reconstructing bean properties of type {@link XmlFormat#XMLTEXT}.
    */
   private String getElementAsString(XmlReader r) {
      int t = r.getEventType();
      if (t > 2)
         throw rex("Invalid event type on stream reader for elementToString() method: ''{0}''", XmlUtils.toReadableEvent(r));
      rsb.setLength(0);
      rsb.append("<").append(t == 1 ? "" : "/").append(r.getLocalName());
      if (t == 1)
         for (var i = 0; i < r.getAttributeCount(); i++)
            rsb.append(' ').append(r.getAttributeName(i)).append('=').append('\'').append(r.getAttributeValue(i)).append('\'');
      rsb.append('>');
      return rsb.toString();
   }

   /*
    * Returns the name of the current XML element.
    * Any <js>'_x####_'</js> sequences in the string will be decoded.
    */
   private String getElementName(XmlReader r) {
      return decodeString(r.getLocalName());
   }

   /*
    * Returns the _name attribute value.
    * Any <js>'_x####_'</js> sequences in the string will be decoded.
    */
   private String getNameProperty(XmlReader r) {
      return decodeString(r.getAttributeValue(null, getNamePropertyName()));
   }

   /*
    * Shortcut for calling <code>getText(r, <jk>true</jk>);</code>.
    */
   private String getText(XmlReader r) {
      return getText(r, true);
   }

   /*
    * Returns the content of the current CHARACTERS node.
    * Any <js>'_x####_'</js> sequences in the string will be decoded.
    * Leading and trailing whitespace (unencoded) will be trimmed from the result.
    */
   private String getText(XmlReader r, boolean trim) {
      var s = r.getText();
      if (trim)
         s = s.trim();
      if (s.isEmpty())
         return null;
      return decodeString(s);
   }

   @SuppressWarnings("null")
   private Object getUnknown(XmlReader r) throws IOException, ParseException, ExecutableException, XMLStreamException {
      if (r.getEventType() != START_ELEMENT) {
         throw new ParseException(this, "Parser must be on START_ELEMENT to read next text.");
      }
      var m = (JsonMap)null;

      // If this element has attributes, then it's always a JsonMap.
      if (r.getAttributeCount() > 0) {
         m = new JsonMap(this);
         for (var i = 0; i < r.getAttributeCount(); i++) {
            var key = getAttributeName(r, i);
            var val = r.getAttributeValue(i);
            if (! isSpecialAttr(key))
               m.put(key, val);
         }
      }
      int eventType = r.next();
      var sb = getStringBuilder();
      while (eventType != END_ELEMENT) {
         if (eventType == CHARACTERS || eventType == CDATA || eventType == XMLStreamConstants.SPACE || eventType == ENTITY_REFERENCE) {
            sb.append(r.getText());
         } else if (eventType == PROCESSING_INSTRUCTION || eventType == COMMENT) {
            // skipping
         } else if (eventType == END_DOCUMENT) {
            throw new ParseException(this, "Unexpected end of document when reading element text content");
         } else if (eventType == START_ELEMENT) {
            // Oops...this has an element in it.
            // Parse it as a map.
            if (m == null)
               m = new JsonMap(this);
            int depth = 0;
            do {
               int event = (eventType == -1 ? r.nextTag() : eventType);
               String currAttr;
               if (event == START_ELEMENT) {
                  depth++;
                  currAttr = getNameProperty(r);
                  if (currAttr == null)
                     currAttr = getElementName(r);
                  String key = convertAttrToType(null, currAttr, string());
                  var value = parseAnything(object(), currAttr, r, null, false, null);
                  if (m.containsKey(key)) {
                     var o = m.get(key);
                     if (o instanceof JsonList o2)
                        o2.add(value);
                     else
                        m.put(key, new JsonList(o, value).setBeanSession(this));
                  } else {
                     m.put(key, value);
                  }

               } else if (event == END_ELEMENT) {
                  depth--;
                  break;
               }
               eventType = -1;
            } while (depth > 0);
            break;
         } else {
            throw new ParseException(this, "Unexpected event type ''{0}''", eventType);
         }
         eventType = r.next();
      }
      var s = sb.toString().trim();
      returnStringBuilder(sb);
      s = decodeString(s);
      if (nn(m)) {
         if (! s.isEmpty())
            m.put("contents", s);
         return m;
      }
      return s;
   }

   private boolean isSpecialAttr(String key) {
      return key.equals(getBeanTypePropertyName(null)) || key.equals(getNamePropertyName());
   }

   @SuppressWarnings("null")
   private <T> BeanMap<T> parseIntoBean(XmlReader r, BeanMap<T> m, boolean isNil) throws IOException, ParseException, ExecutableException, XMLStreamException {
      var bMeta = m.getMeta();
      var xmlMeta = getXmlBeanMeta(bMeta);

      for (var i = 0; i < r.getAttributeCount(); i++) {
         String key = getAttributeName(r, i);
         if (! ("nil".equals(key) || isSpecialAttr(key))) {
            var val = r.getAttributeValue(i);
            var ns = r.getAttributeNamespace(i);
            var bpm = xmlMeta.getPropertyMeta(key);
            if (bpm == null) {
               if (nn(xmlMeta.getAttrsProperty())) {
                  xmlMeta.getAttrsProperty().add(m, key, key, val);
               } else if (ns == null) {
                  onUnknownProperty(key, m, val);
               }
            } else {
               try {
                  bpm.set(m, key, val);
               } catch (BeanRuntimeException e) {
                  onBeanSetterException(bpm, e);
                  throw e;
               }
            }
         }
      }

      var cp = xmlMeta.getContentProperty();
      var cpf = xmlMeta.getContentFormat();
      var trim = cp == null || ! cpf.isOneOf(MIXED_PWS, TEXT_PWS);
      var cpcm = (cp == null ? object() : cp.getClassMeta());
      var sb = (StringBuilder)null;
      var breg = cp == null ? null : cp.getBeanRegistry();
      var l = (LinkedList<Object>)null;

      int depth = 0;
      do {
         var event = r.next();
         String currAttr;
         // We only care about text in MIXED mode.
         // Ignore if in ELEMENTS mode.
         if (event == CHARACTERS) {
            if (nn(cp) && cpf.isOneOf(MIXED, MIXED_PWS)) {
               if (cpcm.isCollectionOrArray()) {
                  if (l == null)
                     l = new LinkedList<>();
                  l.add(getText(r, false));
               } else {
                  cp.set(m, null, getText(r, trim));
               }
            } else if (cpf != ELEMENTS) {
               var s = getText(r, trim);
               if (nn(s)) {
                  if (sb == null)
                     sb = getStringBuilder();
                  sb.append(s);
               }
            } else {
               // Do nothing...we're in ELEMENTS mode.
            }
         } else if (event == START_ELEMENT) {
            if (nn(cp) && cpf.isOneOf(TEXT, TEXT_PWS)) {
               var s = parseText(r);
               if (nn(s)) {
                  if (sb == null)
                     sb = getStringBuilder();
                  sb.append(s);
               }
               depth--;
            } else if (cpf == XMLTEXT) {
               if (sb == null)
                  sb = getStringBuilder();
               sb.append(getElementAsString(r));
               depth++;
            } else if (nn(cp) && cpf.isOneOf(MIXED, MIXED_PWS)) {
               if (isWhitespaceElement(r) && (breg == null || ! breg.hasName(r.getLocalName()))) {
                  if (cpcm.isCollectionOrArray()) {
                     if (l == null)
                        l = new LinkedList<>();
                     l.add(parseWhitespaceElement(r));
                  } else {
                     cp.set(m, null, parseWhitespaceElement(r));
                  }
               } else {
                  if (cpcm.isCollectionOrArray()) {
                     if (l == null)
                        l = new LinkedList<>();
                     l.add(parseAnything(cpcm.getElementType(), cp.getName(), r, m.getBean(false), false, cp));
                  } else {
                     cp.set(m, null, parseAnything(cpcm, cp.getName(), r, m.getBean(false), false, cp));
                  }
               }
            } else if (nn(cp) && cpf == ELEMENTS) {
               cp.add(m, null, parseAnything(cpcm.getElementType(), cp.getName(), r, m.getBean(false), false, cp));
            } else {
               currAttr = getNameProperty(r);
               if (currAttr == null)
                  currAttr = getElementName(r);
               var pMeta = xmlMeta.getPropertyMeta(currAttr);
               if (pMeta == null) {
                  var value = parseAnything(object(), currAttr, r, m.getBean(false), false, null);
                  onUnknownProperty(currAttr, m, value);
               } else {
                  setCurrentProperty(pMeta);
                  var xf = getXmlBeanPropertyMeta(pMeta).getXmlFormat();
                  if (xf == COLLAPSED) {
                     var et = pMeta.getClassMeta().getElementType();
                     var value = parseAnything(et, currAttr, r, m.getBean(false), false, pMeta);
                     setName(et, value, currAttr);
                     pMeta.add(m, currAttr, value);
                  } else if (xf == ATTR) {
                     pMeta.set(m, currAttr, getAttributeValue(r, 0));
                     r.nextTag();
                  } else {
                     var cm = pMeta.getClassMeta();
                     var value = parseAnything(cm, currAttr, r, m.getBean(false), false, pMeta);
                     setName(cm, value, currAttr);
                     pMeta.set(m, currAttr, value);
                  }
                  setCurrentProperty(null);
               }
            }
         } else if (event == END_ELEMENT) {
            if (depth > 0) {
               if (cpf == XMLTEXT) {
                  if (sb == null)
                     sb = getStringBuilder();
                  sb.append(getElementAsString(r));
               } else
                  throw new ParseException("End element found where one was not expected.  {0}", XmlUtils.toReadableEvent(r));
            }
            depth--;
         } else if (event == COMMENT) {
            // Ignore comments.
         } else {
            throw new ParseException("Unexpected event type: {0}", XmlUtils.toReadableEvent(r));
         }
      } while (depth >= 0);

      if (nn(cp) && ! isNil) {
         if (nn(sb))
            cp.set(m, null, sb.toString());
         else if (nn(l))
            cp.set(m, null, XmlUtils.collapseTextNodes(l));
         else if (cpcm.isCollectionOrArray()) {
            var o = cp.get(m, null);
            if (o == null)
               cp.set(m, cp.getName(), list());
         }
      }

      returnStringBuilder(sb);
      return m;
   }

   private <E> Collection<E> parseIntoCollection(XmlReader r, Collection<E> l, ClassMeta<?> type, BeanPropertyMeta pMeta) throws IOException, ParseException, ExecutableException, XMLStreamException {
      int depth = 0;
      int argIndex = 0;
      do {
         var event = r.nextTag();
         if (event == START_ELEMENT) {
            depth++;
            var elementType = type == null ? object() : type.isArgs() ? type.getArg(argIndex++) : type.getElementType();
            E value = (E)parseAnything(elementType, null, r, l, false, pMeta);
            l.add(value);
         } else if (event == END_ELEMENT) {
            depth--;
            return l;
         }
      } while (depth > 0);
      return l;
   }

   private <K,V> Map<K,V> parseIntoMap(XmlReader r, Map<K,V> m, ClassMeta<K> keyType, ClassMeta<V> valueType, BeanPropertyMeta pMeta)
      throws IOException, ParseException, ExecutableException, XMLStreamException {
      int depth = 0;
      for (var i = 0; i < r.getAttributeCount(); i++) {
         var a = r.getAttributeLocalName(i);
         // TODO - Need better handling of namespaces here.
         if (! isSpecialAttr(a)) {
            K key = trim(convertAttrToType(m, a, keyType));
            V value = trim(convertAttrToType(m, r.getAttributeValue(i), valueType));
            setName(valueType, value, key);
            m.put(key, value);
         }
      }
      do {
         var event = r.nextTag();
         String currAttr;
         if (event == START_ELEMENT) {
            depth++;
            currAttr = getNameProperty(r);
            if (currAttr == null)
               currAttr = getElementName(r);
            K key = convertAttrToType(m, currAttr, keyType);
            V value = parseAnything(valueType, currAttr, r, m, false, pMeta);
            setName(valueType, value, currAttr);
            if (valueType.isObject() && m.containsKey(key)) {
               var o = m.get(key);
               if (o instanceof List o2)
                  o2.add(value);
               else
                  m.put(key, (V)new JsonList(o, value).setBeanSession(this));
            } else {
               m.put(key, value);
            }
         } else if (event == END_ELEMENT) {
            depth--;
            return m;
         }
      } while (depth > 0);
      return m;
   }

   /**
    * Decodes and trims the specified string.
    *
    * <p>
    * Any <js>'_x####_'</js> sequences in the string will be decoded.
    *
    * @param s The string to be decoded.
    * @return The decoded string.
    */
   protected final String decodeString(String s) {
      if (s == null)
         return null;
      rsb.setLength(0);
      s = XmlUtils.decode(s, rsb);
      if (isTrimStrings())
         s = s.trim();
      return s;
   }

   @Override /* Overridden from ParserSession */
   protected <T> T doParse(ParserPipe pipe, ClassMeta<T> type) throws IOException, ParseException, ExecutableException {
      try {
         return parseAnything(type, null, getXmlReader(pipe), getOuter(), true, null);
      } catch (XMLStreamException e) {
         throw new ParseException(e);
      }
   }

   @Override /* Overridden from ReaderParserSession */
   protected <E> Collection<E> doParseIntoCollection(ParserPipe pipe, Collection<E> c, Type elementType) throws Exception {
      var cm = getClassMeta(c.getClass(), elementType);
      return parseIntoCollection(pipe, c, cm.getElementType());
   }

   @Override /* Overridden from ReaderParserSession */
   protected <K,V> Map<K,V> doParseIntoMap(ParserPipe pipe, Map<K,V> m, Type keyType, Type valueType) throws Exception {
      var cm = getClassMeta(m.getClass(), keyType, valueType);
      return parseIntoMap(pipe, m, cm.getKeyType(), cm.getValueType());
   }

   /**
    * Returns the text content of the current XML element.
    *
    * <p>
    * Any <js>'_x####_'</js> sequences in the string will be decoded.
    *
    * <p>
    * Leading and trailing whitespace (unencoded) will be trimmed from the result.
    *
    * @param r The reader to read the element text from.
    * @return The decoded text.  <jk>null</jk> if the text consists of the sequence <js>'_x0000_'</js>.
    * @throws XMLStreamException Thrown by underlying reader.
    * @throws IOException Thrown by underlying stream.
    * @throws ParseException Malformed input encountered.
    */
   protected String getElementText(XmlReader r) throws XMLStreamException, IOException, ParseException {
      return decodeString(r.getElementText().trim());
   }

   /**
    * XML event allocator.
    *
    * @see XmlParser.Builder#eventAllocator(Class)
    * @return
    *    The {@link XMLEventAllocator} associated with this parser, or <jk>null</jk> if there isn't one.
    */
   protected final XMLEventAllocator getEventAllocator() { return ctx.getEventAllocator(); }

   /**
    * XML reporter.
    *
    * @see XmlParser.Builder#reporter(Class)
    * @return
    *    The {@link XMLReporter} associated with this parser, or <jk>null</jk> if there isn't one.
    */
   protected final XMLReporter getReporter() { return ctx.getReporter(); }

   /**
    * XML resolver.
    *
    * @see XmlParser.Builder#resolver(Class)
    * @return
    *    The {@link XMLResolver} associated with this parser, or <jk>null</jk> if there isn't one.
    */
   protected final XMLResolver getResolver() { return ctx.getResolver(); }

   /**
    * Returns the language-specific metadata on the specified bean.
    *
    * @param bm The bean to return the metadata on.
    * @return The metadata.
    */
   protected XmlBeanMeta getXmlBeanMeta(BeanMeta<?> bm) {
      return ctx.getXmlBeanMeta(bm);
   }

   /**
    * Returns the language-specific metadata on the specified bean property.
    *
    * @param bpm The bean property to return the metadata on.
    * @return The metadata.
    */
   protected XmlBeanPropertyMeta getXmlBeanPropertyMeta(BeanPropertyMeta bpm) {
      return ctx.getXmlBeanPropertyMeta(bpm);
   }

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

   /**
    * Wrap the specified reader in a STAX reader based on settings in this context.
    *
    * @param pipe The parser input.
    * @return The new STAX reader.
    * @throws IOException Thrown by underlying stream.
    * @throws XMLStreamException Unexpected XML processing error.
    */
   protected final XmlReader getXmlReader(ParserPipe pipe) throws IOException, XMLStreamException {
      return new XmlReader(pipe, isValidating(), getReporter(), getResolver(), getEventAllocator());
   }

   /**
    * Preserve root element during generalized parsing.
    *
    * @see XmlParser.Builder#preserveRootElement()
    * @return
    *    <jk>true</jk> if when parsing into a generic {@link JsonMap}, the map will contain a single entry whose key
    *    is the root element name.
    */
   protected final boolean isPreserveRootElement() { return ctx.isPreserveRootElement(); }

   /**
    * Enable validation.
    *
    * @see XmlParser.Builder#validating()
    * @return
    *    <jk>true</jk> if XML document will be validated.
    */
   protected final boolean isValidating() { return ctx.isValidating(); }

   /**
    * Returns <jk>true</jk> if the current element is a whitespace element.
    *
    * <p>
    * For the XML parser, this always returns <jk>false</jk>.
    * However, the HTML parser defines various whitespace elements such as <js>"br"</js> and <js>"sp"</js>.
    *
    * @param r The XML stream reader to read the current event from.
    * @return <jk>true</jk> if the current element is a whitespace element.
    */
   protected boolean isWhitespaceElement(XmlReader r) {
      return false;
   }

   /**
    * Workhorse method.
    *
    * @param <T> The expected type of object.
    * @param eType The expected type of object.
    * @param currAttr The current bean property name.
    * @param r The reader.
    * @param outer The outer object.
    * @param isRoot If <jk>true</jk>, then we're serializing a root element in the document.
    * @param pMeta The bean property metadata.
    * @return The parsed object.
    * @throws IOException Thrown by underlying stream.
    * @throws ParseException Malformed input encountered.
    * @throws ExecutableException Exception occurred on invoked constructor/method/field.
    * @throws XMLStreamException Malformed XML encountered.
    */
   @SuppressWarnings("null")
   protected <T> T parseAnything(ClassMeta<T> eType, String currAttr, XmlReader r, Object outer, boolean isRoot, BeanPropertyMeta pMeta)
      throws IOException, ParseException, ExecutableException, XMLStreamException {

      if (eType == null)
         eType = (ClassMeta<T>)object();
      var swap = (ObjectSwap<T,Object>)eType.getSwap(this);
      var builder = (BuilderSwap<T,Object>)eType.getBuilderSwap(this);
      var sType = (ClassMeta<?>)null;
      if (nn(builder))
         sType = builder.getBuilderClassMeta(this);
      else if (nn(swap))
         sType = swap.getSwapClassMeta(this);
      else
         sType = eType;

      if (sType.isOptional())
         return (T)opt(parseAnything(eType.getElementType(), currAttr, r, outer, isRoot, pMeta));

      setCurrentClass(sType);

      var wrapperAttr = (isRoot && isPreserveRootElement()) ? r.getName().getLocalPart() : null;
      var typeAttr = r.getAttributeValue(null, getBeanTypePropertyName(eType));
      var isNil = "true".equals(r.getAttributeValue(null, "nil"));
      var jsonType = getJsonType(typeAttr);
      var elementName = getElementName(r);
      if (jsonType == 0) {
         if (elementName == null || elementName.equals(currAttr))
            jsonType = UNKNOWN;
         else {
            typeAttr = elementName;
            jsonType = getJsonType(elementName);
         }
      }

      ClassMeta tcm = getClassMeta(typeAttr, pMeta, eType);
      if (tcm == null && nn(elementName) && ! elementName.equals(currAttr))
         tcm = getClassMeta(elementName, pMeta, eType);
      if (nn(tcm))
         sType = eType = tcm;

      var o = (Object)null;

      if (jsonType == NULL) {
         r.nextTag();   // Discard end tag
         return null;
      }

      if (sType.isObject()) {
         if (jsonType == OBJECT) {
            var m = new JsonMap(this);
            parseIntoMap(r, m, string(), object(), pMeta);
            if (nn(wrapperAttr))
               m = new JsonMap(this).append(wrapperAttr, m);
            o = cast(m, pMeta, eType);
         } else if (jsonType == ARRAY)
            o = parseIntoCollection(r, new JsonList(this), null, pMeta);
         else if (jsonType == STRING) {
            o = getElementText(r);
            if (sType.isChar())
               o = parseCharacter(o);
         } else if (jsonType == NUMBER)
            o = parseNumber(getElementText(r), null);
         else if (jsonType == BOOLEAN)
            o = Boolean.parseBoolean(getElementText(r));
         else if (jsonType == UNKNOWN)
            o = getUnknown(r);
      } else if (sType.isBoolean()) {
         o = Boolean.parseBoolean(getElementText(r));
      } else if (sType.isCharSequence()) {
         o = getElementText(r);
      } else if (sType.isChar()) {
         o = parseCharacter(getElementText(r));
      } else if (sType.isMap()) {
         var m = (sType.canCreateNewInstance(outer) ? (Map)sType.newInstance(outer) : newGenericMap(sType));
         o = parseIntoMap(r, m, sType.getKeyType(), sType.getValueType(), pMeta);
         if (nn(wrapperAttr))
            o = new JsonMap(this).append(wrapperAttr, m);
      } else if (sType.isCollection()) {
         var l = (sType.canCreateNewInstance(outer) ? (Collection)sType.newInstance(outer) : new JsonList(this));
         o = parseIntoCollection(r, l, sType, pMeta);
      } else if (sType.isNumber()) {
         o = parseNumber(getElementText(r), (Class<? extends Number>)sType.inner());
      } else if (nn(builder) || sType.canCreateNewBean(outer)) {
         if (getXmlClassMeta(sType).getFormat() == COLLAPSED) {
            var fieldName = r.getLocalName();
            var m = nn(builder) ? toBeanMap(builder.create(this, eType)) : newBeanMap(outer, sType.inner());
            var bpm = getXmlBeanMeta(m.getMeta()).getPropertyMeta(fieldName);
            var cm = m.getMeta().getClassMeta();
            Object value = parseAnything(cm, currAttr, r, m.getBean(false), false, null);
            setName(cm, value, currAttr);
            bpm.set(m, currAttr, value);
            o = nn(builder) ? builder.build(this, m.getBean(), eType) : m.getBean();
         } else {
            var m = nn(builder) ? toBeanMap(builder.create(this, eType)) : newBeanMap(outer, sType.inner());
            m = parseIntoBean(r, m, isNil);
            o = nn(builder) ? builder.build(this, m.getBean(), eType) : m.getBean();
         }
      } else if (sType.isArray() || sType.isArgs()) {
         var l = (ArrayList)parseIntoCollection(r, list(), sType, pMeta);
         o = toArray(sType, l);
      } else if (sType.canCreateNewInstanceFromString(outer)) {
         o = sType.newInstanceFromString(outer, getElementText(r));
      } else if (nn(sType.getProxyInvocationHandler())) {
         var m = new JsonMap(this);
         parseIntoMap(r, m, string(), object(), pMeta);
         if (nn(wrapperAttr))
            m = new JsonMap(this).append(wrapperAttr, m);
         o = newBeanMap(outer, sType.inner()).load(m).getBean();
      } else {
         throw new ParseException(this, "Class ''{0}'' could not be instantiated.  Reason: ''{1}'', property: ''{2}''", cn(sType), sType.getNotABeanReason(),
            pMeta == null ? null : pMeta.getName());
      }

      if (nn(swap) && nn(o))
         o = unswap(swap, o, eType);

      if (nn(outer))
         setParent(eType, o, outer);

      return (T)o;
   }

   /**
    * Parses the current element as text.
    *
    * @param r The input reader.
    * @return The parsed text.
    * @throws XMLStreamException Thrown by underlying reader.
    * @throws IOException Thrown by underlying stream.
    * @throws ParseException Malformed input encountered.
    */
   protected String parseText(XmlReader r) throws IOException, XMLStreamException, ParseException {
      // Note that this is different than {@link #getText(XmlReader)} since it assumes that we're pointing to a
      // whitespace element.

      var sb2 = getStringBuilder();

      int depth = 0;
      while (true) {
         var et = r.getEventType();
         if (et == START_ELEMENT) {
            sb2.append(getElementAsString(r));
            depth++;
         } else if (et == CHARACTERS) {
            sb2.append(getText(r));
         } else if (et == END_ELEMENT) {
            sb2.append(getElementAsString(r));
            depth--;
            if (depth <= 0)
               break;
         }
         et = r.next();
      }
      var s = sb2.toString();
      returnStringBuilder(sb2);
      return s;
   }

   /**
    * Parses the current whitespace element.
    *
    * <p>
    * For the XML parser, this always returns <jk>null</jk> since there is no concept of a whitespace element.
    * However, the HTML parser defines various whitespace elements such as <js>"br"</js> and <js>"sp"</js>.
    *
    * @param r The XML stream reader to read the current event from.
    * @return The whitespace character or characters.
    * @throws XMLStreamException Thrown by underlying reader.
    * @throws IOException Thrown by underlying stream.
    * @throws ParseException Malformed input encountered.
    */
   protected String parseWhitespaceElement(XmlReader r) throws IOException, XMLStreamException, ParseException {
      return null;
   }
}