/**
 * Copyright (c) 2008, SnakeYAML
 *
 * Licensed 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.yaml.snakeyaml;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.regex.Pattern;
import org.yaml.snakeyaml.DumperOptions.FlowStyle;
import org.yaml.snakeyaml.composer.Composer;
import org.yaml.snakeyaml.constructor.BaseConstructor;
import org.yaml.snakeyaml.constructor.Constructor;
import org.yaml.snakeyaml.emitter.Emitable;
import org.yaml.snakeyaml.emitter.Emitter;
import org.yaml.snakeyaml.error.YAMLException;
import org.yaml.snakeyaml.events.Event;
import org.yaml.snakeyaml.introspector.BeanAccess;
import org.yaml.snakeyaml.nodes.Node;
import org.yaml.snakeyaml.nodes.Tag;
import org.yaml.snakeyaml.parser.Parser;
import org.yaml.snakeyaml.parser.ParserImpl;
import org.yaml.snakeyaml.reader.StreamReader;
import org.yaml.snakeyaml.reader.UnicodeReader;
import org.yaml.snakeyaml.representer.Representer;
import org.yaml.snakeyaml.resolver.Resolver;
import org.yaml.snakeyaml.serializer.Serializer;

/**
 * Public YAML interface. This class is not thread-safe. Which means that all the methods of the
 * same instance can be called only by one thread. It is better to create an instance for every YAML
 * stream.
 */
public class Yaml {

  protected final Resolver resolver;
  private String name;
  protected BaseConstructor constructor;
  protected Representer representer;
  protected DumperOptions dumperOptions;
  protected LoaderOptions loadingConfig;

  /**
   * Create Yaml instance.
   */
  public Yaml() {
    this(new Constructor(new LoaderOptions()), new Representer(new DumperOptions()));
  }

  /**
   * Create Yaml instance.
   *
   * @param dumperOptions DumperOptions to configure outgoing objects
   */
  public Yaml(DumperOptions dumperOptions) {
    this(new Constructor(new LoaderOptions()), new Representer(dumperOptions), dumperOptions);
  }

  /**
   * Create Yaml instance.
   *
   * @param loadingConfig LoadingConfig to control load behavior
   */
  public Yaml(LoaderOptions loadingConfig) {
    this(new Constructor(loadingConfig), new Representer(new DumperOptions()), new DumperOptions(),
        loadingConfig);
  }

  /**
   * Create Yaml instance.
   *
   * @param representer Representer to emit outgoing objects
   */
  public Yaml(Representer representer) {
    this(new Constructor(new LoaderOptions()), representer);
  }

  /**
   * Create Yaml instance.
   *
   * @param constructor BaseConstructor to construct incoming documents
   */
  public Yaml(BaseConstructor constructor) {
    this(constructor, new Representer(new DumperOptions()));
  }

  /**
   * Create Yaml instance.
   *
   * @param constructor BaseConstructor to construct incoming documents
   * @param representer Representer to emit outgoing objects
   */
  public Yaml(BaseConstructor constructor, Representer representer) {
    this(constructor, representer, initDumperOptions(representer));
  }

  private static DumperOptions initDumperOptions(Representer representer) {
    DumperOptions dumperOptions = new DumperOptions();
    dumperOptions.setDefaultFlowStyle(representer.getDefaultFlowStyle());
    dumperOptions.setDefaultScalarStyle(representer.getDefaultScalarStyle());
    dumperOptions
        .setAllowReadOnlyProperties(representer.getPropertyUtils().isAllowReadOnlyProperties());
    dumperOptions.setTimeZone(representer.getTimeZone());
    return dumperOptions;
  }

  /**
   * Create Yaml instance. It is safe to create a few instances and use them in different Threads.
   *
   * @param representer Representer to emit outgoing objects
   * @param dumperOptions DumperOptions to configure outgoing objects
   */
  public Yaml(Representer representer, DumperOptions dumperOptions) {
    this(new Constructor(new LoaderOptions()), representer, dumperOptions);
  }

  /**
   * Create Yaml instance. It is safe to create a few instances and use them in different Threads.
   *
   * @param constructor BaseConstructor to construct incoming documents
   * @param representer Representer to emit outgoing objects
   * @param dumperOptions DumperOptions to configure outgoing objects
   */
  public Yaml(BaseConstructor constructor, Representer representer, DumperOptions dumperOptions) {
    this(constructor, representer, dumperOptions, new LoaderOptions(), new Resolver());
  }

  /**
   * Create Yaml instance. It is safe to create a few instances and use them in different Threads.
   *
   * @param constructor BaseConstructor to construct incoming documents
   * @param representer Representer to emit outgoing objects
   * @param dumperOptions DumperOptions to configure outgoing objects
   * @param loadingConfig LoadingConfig to control load behavior
   */
  public Yaml(BaseConstructor constructor, Representer representer, DumperOptions dumperOptions,
      LoaderOptions loadingConfig) {
    this(constructor, representer, dumperOptions, loadingConfig, new Resolver());
  }

  /**
   * Create Yaml instance. It is safe to create a few instances and use them in different Threads.
   *
   * @param constructor BaseConstructor to construct incoming documents
   * @param representer Representer to emit outgoing objects
   * @param dumperOptions DumperOptions to configure outgoing objects
   * @param resolver Resolver to detect implicit type
   */
  public Yaml(BaseConstructor constructor, Representer representer, DumperOptions dumperOptions,
      Resolver resolver) {
    this(constructor, representer, dumperOptions, new LoaderOptions(), resolver);
  }

  /**
   * Create Yaml instance. It is safe to create a few instances and use them in different Threads.
   *
   * @param constructor BaseConstructor to construct incoming documents
   * @param representer Representer to emit outgoing objects
   * @param dumperOptions DumperOptions to configure outgoing objects
   * @param loadingConfig LoadingConfig to control load behavior
   * @param resolver Resolver to detect implicit type
   */
  public Yaml(BaseConstructor constructor, Representer representer, DumperOptions dumperOptions,
      LoaderOptions loadingConfig, Resolver resolver) {
    if (!constructor.isExplicitPropertyUtils()) {
      constructor.setPropertyUtils(representer.getPropertyUtils());
    } else if (!representer.isExplicitPropertyUtils()) {
      representer.setPropertyUtils(constructor.getPropertyUtils());
    }
    this.constructor = constructor;
    this.constructor.setAllowDuplicateKeys(loadingConfig.isAllowDuplicateKeys());
    this.constructor.setWrappedToRootException(loadingConfig.isWrappedToRootException());
    if (!dumperOptions.getIndentWithIndicator()
        && dumperOptions.getIndent() <= dumperOptions.getIndicatorIndent()) {
      throw new YAMLException("Indicator indent must be smaller then indent.");
    }
    representer.setDefaultFlowStyle(dumperOptions.getDefaultFlowStyle());
    representer.setDefaultScalarStyle(dumperOptions.getDefaultScalarStyle());
    representer.getPropertyUtils()
        .setAllowReadOnlyProperties(dumperOptions.isAllowReadOnlyProperties());
    representer.setTimeZone(dumperOptions.getTimeZone());
    this.representer = representer;
    this.dumperOptions = dumperOptions;
    this.loadingConfig = loadingConfig;
    this.resolver = resolver;
    this.name = "Yaml:" + System.identityHashCode(this);
  }

  /**
   * Serialize a Java object into a YAML String.
   *
   * @param data Java object to be Serialized to YAML
   * @return YAML String
   */
  public String dump(Object data) {
    List<Object> list = new ArrayList<Object>(1);
    list.add(data);
    return dumpAll(list.iterator());
  }

  /**
   * Produce the corresponding representation tree for a given Object.
   *
   * @param data instance to build the representation tree for
   * @return representation tree
   * @see <a href="http://yaml.org/spec/1.1/#id859333">Figure 3.1. Processing Overview</a>
   */
  public Node represent(Object data) {
    return representer.represent(data);
  }

  /**
   * Serialize a sequence of Java objects into a YAML String.
   *
   * @param data Iterator with Objects
   * @return YAML String with all the objects in proper sequence
   */
  public String dumpAll(Iterator<? extends Object> data) {
    StringWriter buffer = new StringWriter();
    dumpAll(data, buffer, null);
    return buffer.toString();
  }

  /**
   * Serialize a Java object into a YAML stream.
   *
   * @param data Java object to be serialized to YAML
   * @param output stream to write to
   */
  public void dump(Object data, Writer output) {
    List<Object> list = new ArrayList<Object>(1);
    list.add(data);
    dumpAll(list.iterator(), output, null);
  }

  /**
   * Serialize a sequence of Java objects into a YAML stream.
   *
   * @param data Iterator with Objects
   * @param output stream to write to
   */
  public void dumpAll(Iterator<? extends Object> data, Writer output) {
    dumpAll(data, output, null);
  }

  private void dumpAll(Iterator<? extends Object> data, Writer output, Tag rootTag) {
    Serializer serializer =
        new Serializer(new Emitter(output, dumperOptions), resolver, dumperOptions, rootTag);
    try {
      serializer.open();
      while (data.hasNext()) {
        Node node = representer.represent(data.next());
        serializer.serialize(node);
      }
      serializer.close();
    } catch (IOException e) {
      throw new YAMLException(e);
    }
  }

  /**
   * <p>
   * Serialize a Java object into a YAML string. Override the default root tag with
   * <code>rootTag</code>.
   * </p>
   *
   * <p>
   * This method is similar to <code>Yaml.dump(data)</code> except that the root tag for the whole
   * document is replaced with the given tag. This has two main uses.
   * </p>
   *
   * <p>
   * First, if the root tag is replaced with a standard YAML tag, such as <code>Tag.MAP</code>, then
   * the object will be dumped as a map. The root tag will appear as <code>!!map</code>, or blank
   * (implicit !!map).
   * </p>
   *
   * <p>
   * Second, if the root tag is replaced by a different custom tag, then the document appears to be
   * a different type when loaded. For example, if an instance of MyClass is dumped with the tag
   * !!YourClass, then it will be handled as an instance of YourClass when loaded.
   * </p>
   *
   * @param data Java object to be serialized to YAML
   * @param rootTag the tag for the whole YAML document. The tag should be Tag.MAP for a JavaBean to
   *        make the tag disappear (to use implicit tag !!map). If <code>null</code> is provided
   *        then the standard tag with the full class name is used.
   * @param flowStyle flow style for the whole document. See Chapter 10. Collection Styles
   *        http://yaml.org/spec/1.1/#id930798. If <code>null</code> is provided then the flow style
   *        from DumperOptions is used.
   * @return YAML String
   */
  public String dumpAs(Object data, Tag rootTag, FlowStyle flowStyle) {
    FlowStyle oldStyle = representer.getDefaultFlowStyle();
    if (flowStyle != null) {
      representer.setDefaultFlowStyle(flowStyle);
    }
    List<Object> list = new ArrayList<Object>(1);
    list.add(data);
    StringWriter buffer = new StringWriter();
    dumpAll(list.iterator(), buffer, rootTag);
    representer.setDefaultFlowStyle(oldStyle);
    return buffer.toString();
  }

  /**
   * <p>
   * Serialize a Java object into a YAML string. Override the default root tag with
   * <code>Tag.MAP</code>.
   * </p>
   * <p>
   * This method is similar to <code>Yaml.dump(data)</code> except that the root tag for the whole
   * document is replaced with <code>Tag.MAP</code> tag (implicit !!map).
   * </p>
   * <p>
   * Block Mapping is used as the collection style. See 10.2.2. Block Mappings
   * (http://yaml.org/spec/1.1/#id934537)
   * </p>
   *
   * @param data Java object to be serialized to YAML
   * @return YAML String
   */
  public String dumpAsMap(Object data) {
    return dumpAs(data, Tag.MAP, FlowStyle.BLOCK);
  }

  /**
   * Serialize (dump) a YAML node into a YAML stream.
   *
   * @param node YAML node to be serialized to YAML
   * @param output stream to write to
   */
  public void serialize(Node node, Writer output) {
    Serializer serializer =
        new Serializer(new Emitter(output, dumperOptions), resolver, dumperOptions, null);
    try {
      serializer.open();
      serializer.serialize(node);
      serializer.close();
    } catch (IOException e) {
      throw new YAMLException(e);
    }
  }

  /**
   * Serialize the representation tree into Events.
   *
   * @param data representation tree
   * @return Event list
   * @see <a href="http://yaml.org/spec/1.1/#id859333">Processing Overview</a>
   */
  public List<Event> serialize(Node data) {
    SilentEmitter emitter = new SilentEmitter();
    Serializer serializer = new Serializer(emitter, resolver, dumperOptions, null);
    try {
      serializer.open();
      serializer.serialize(data);
      serializer.close();
    } catch (IOException e) {
      throw new YAMLException(e);
    }
    return emitter.getEvents();
  }

  private static class SilentEmitter implements Emitable {

    private final List<Event> events = new ArrayList<Event>(100);

    public List<Event> getEvents() {
      return events;
    }

    @Override
    public void emit(Event event) throws IOException {
      events.add(event);
    }
  }

  /**
   * Parse the only YAML document in a String and produce the corresponding Java object. (Because
   * the encoding in known BOM is not respected.)
   *
   * @param yaml YAML data to load from (BOM must not be present)
   * @param <T> the class of the instance to be created
   * @return parsed object
   */
  @SuppressWarnings("unchecked")
  public <T> T load(String yaml) {
    return (T) loadFromReader(new StreamReader(yaml), Object.class);
  }

  /**
   * Parse the only YAML document in a stream and produce the corresponding Java object.
   *
   * @param io data to load from (BOM is respected to detect encoding and removed from the data)
   * @param <T> the class of the instance to be created
   * @return parsed object
   */
  @SuppressWarnings("unchecked")
  public <T> T load(InputStream io) {
    return (T) loadFromReader(new StreamReader(new UnicodeReader(io)), Object.class);
  }

  /**
   * Parse the only YAML document in a stream and produce the corresponding Java object.
   *
   * @param io data to load from (BOM must not be present)
   * @param <T> the class of the instance to be created
   * @return parsed object
   */
  @SuppressWarnings("unchecked")
  public <T> T load(Reader io) {
    return (T) loadFromReader(new StreamReader(io), Object.class);
  }

  /**
   * Parse the only YAML document in a stream and produce the corresponding Java object.
   *
   * @param <T> Class is defined by the second argument
   * @param io data to load from (BOM must not be present)
   * @param type Class of the object to be created
   * @return parsed object
   */
  @SuppressWarnings("unchecked")
  public <T> T loadAs(Reader io, Class<T> type) {
    return (T) loadFromReader(new StreamReader(io), type);
  }

  /**
   * Parse the only YAML document in a String and produce the corresponding Java object. (Because
   * the encoding in known BOM is not respected.)
   *
   * @param <T> Class is defined by the second argument
   * @param yaml YAML data to load from (BOM must not be present)
   * @param type Class of the object to be created
   * @return parsed object
   */
  @SuppressWarnings("unchecked")
  public <T> T loadAs(String yaml, Class<T> type) {
    return (T) loadFromReader(new StreamReader(yaml), type);
  }

  /**
   * Parse the only YAML document in a stream and produce the corresponding Java object.
   *
   * @param <T> Class is defined by the second argument
   * @param input data to load from (BOM is respected to detect encoding and removed from the data)
   * @param type Class of the object to be created
   * @return parsed object
   */
  @SuppressWarnings("unchecked")
  public <T> T loadAs(InputStream input, Class<T> type) {
    return (T) loadFromReader(new StreamReader(new UnicodeReader(input)), type);
  }

  private Object loadFromReader(StreamReader sreader, Class<?> type) {
    Composer composer =
        new Composer(new ParserImpl(sreader, loadingConfig), resolver, loadingConfig);
    constructor.setComposer(composer);
    return constructor.getSingleData(type);
  }

  /**
   * Parse all YAML documents in the Reader and produce corresponding Java objects. The documents
   * are parsed only when the iterator is invoked.
   *
   * @param yaml YAML data to load from (BOM must not be present)
   * @return an Iterable over the parsed Java objects in this String in proper sequence
   */
  public Iterable<Object> loadAll(Reader yaml) {
    Composer composer = new Composer(new ParserImpl(new StreamReader(yaml), loadingConfig),
        resolver, loadingConfig);
    constructor.setComposer(composer);
    Iterator<Object> result = new Iterator<Object>() {
      @Override
      public boolean hasNext() {
        return constructor.checkData();
      }

      @Override
      public Object next() {
        return constructor.getData();
      }

      @Override
      public void remove() {
        throw new UnsupportedOperationException();
      }
    };
    return new YamlIterable(result);
  }

  private static class YamlIterable implements Iterable<Object> {

    private final Iterator<Object> iterator;

    public YamlIterable(Iterator<Object> iterator) {
      this.iterator = iterator;
    }

    @Override
    public Iterator<Object> iterator() {
      return iterator;
    }
  }

  /**
   * Parse all YAML documents in a String and produce corresponding Java objects. (Because the
   * encoding in known BOM is not respected.) The documents are parsed only when the iterator is
   * invoked.
   *
   * @param yaml YAML data to load from (BOM must not be present)
   * @return an Iterable over the parsed Java objects in this String in proper sequence
   */
  public Iterable<Object> loadAll(String yaml) {
    return loadAll(new StringReader(yaml));
  }

  /**
   * Parse all YAML documents in a stream and produce corresponding Java objects. The documents are
   * parsed only when the iterator is invoked.
   *
   * @param yaml YAML data to load from (BOM is respected to detect encoding and removed from the
   *        data)
   * @return an Iterable over the parsed Java objects in this stream in proper sequence
   */
  public Iterable<Object> loadAll(InputStream yaml) {
    return loadAll(new UnicodeReader(yaml));
  }

  /**
   * Parse the first YAML document in a stream and produce the corresponding representation tree.
   * (This is the opposite of the represent() method)
   *
   * @param yaml YAML document
   * @return parsed root Node for the specified YAML document
   * @see <a href="http://yaml.org/spec/1.1/#id859333">Figure 3.1. Processing Overview</a>
   */
  public Node compose(Reader yaml) {
    Composer composer = new Composer(new ParserImpl(new StreamReader(yaml), loadingConfig),
        resolver, loadingConfig);
    return composer.getSingleNode();
  }

  /**
   * Parse all YAML documents in a stream and produce corresponding representation trees.
   *
   * @param yaml stream of YAML documents
   * @return parsed root Nodes for all the specified YAML documents
   * @see <a href="http://yaml.org/spec/1.1/#id859333">Processing Overview</a>
   */
  public Iterable<Node> composeAll(Reader yaml) {
    final Composer composer = new Composer(new ParserImpl(new StreamReader(yaml), loadingConfig),
        resolver, loadingConfig);
    Iterator<Node> result = new Iterator<Node>() {
      @Override
      public boolean hasNext() {
        return composer.checkNode();
      }

      @Override
      public Node next() {
        Node node = composer.getNode();
        if (node != null) {
          return node;
        } else {
          throw new NoSuchElementException("No Node is available.");
        }
      }

      @Override
      public void remove() {
        throw new UnsupportedOperationException();
      }
    };
    return new NodeIterable(result);
  }

  private static class NodeIterable implements Iterable<Node> {

    private final Iterator<Node> iterator;

    public NodeIterable(Iterator<Node> iterator) {
      this.iterator = iterator;
    }

    @Override
    public Iterator<Node> iterator() {
      return iterator;
    }
  }

  /**
   * Add an implicit scalar detector. If an implicit scalar value matches the given regexp, the
   * corresponding tag is assigned to the scalar.
   *
   * @param tag tag to assign to the node
   * @param regexp regular expression to match against
   * @param first a sequence of possible initial characters or null (which means any).
   */
  public void addImplicitResolver(Tag tag, Pattern regexp, String first) {
    resolver.addImplicitResolver(tag, regexp, first);
  }

  /**
   * Add an implicit scalar detector. If an implicit scalar value matches the given regexp, the
   * corresponding tag is assigned to the scalar.
   *
   * @param tag tag to assign to the node
   * @param regexp regular expression to match against
   * @param first a sequence of possible initial characters or null (which means any).
   * @param limit the max length of the value which may match the regular expression
   */
  public void addImplicitResolver(Tag tag, Pattern regexp, String first, int limit) {
    resolver.addImplicitResolver(tag, regexp, first, limit);
  }

  @Override
  public String toString() {
    return name;
  }

  /**
   * Get a meaningful name. It simplifies debugging in a multi-threaded environment. If nothing is
   * set explicitly the address of the instance is returned.
   *
   * @return human readable name
   */
  public String getName() {
    return name;
  }

  /**
   * Set a meaningful name to be shown in toString()
   *
   * @param name human readable name
   */
  public void setName(String name) {
    this.name = name;
  }

  /**
   * Parse a YAML stream and produce parsing events.
   *
   * @param yaml YAML document(s)
   * @return parsed events
   * @see <a href="http://yaml.org/spec/1.1/#id859333">Processing Overview</a>
   */
  public Iterable<Event> parse(Reader yaml) {
    final Parser parser = new ParserImpl(new StreamReader(yaml), loadingConfig);
    Iterator<Event> result = new Iterator<Event>() {
      @Override
      public boolean hasNext() {
        return parser.peekEvent() != null;
      }

      @Override
      public Event next() {
        Event event = parser.getEvent();
        if (event != null) {
          return event;
        } else {
          throw new NoSuchElementException("No Event is available.");
        }
      }

      @Override
      public void remove() {
        throw new UnsupportedOperationException();
      }
    };
    return new EventIterable(result);
  }

  private static class EventIterable implements Iterable<Event> {

    private final Iterator<Event> iterator;

    public EventIterable(Iterator<Event> iterator) {
      this.iterator = iterator;
    }

    @Override
    public Iterator<Event> iterator() {
      return iterator;
    }
  }

  public void setBeanAccess(BeanAccess beanAccess) {
    constructor.getPropertyUtils().setBeanAccess(beanAccess);
    representer.getPropertyUtils().setBeanAccess(beanAccess);
  }

  public void addTypeDescription(TypeDescription td) {
    constructor.addTypeDescription(td);
    representer.addTypeDescription(td);
  }
}
