/**
 * 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 nokogiri.internals.c14n;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import org.w3c.dom.Attr;
import org.w3c.dom.Node;

/**
 * A stack based Symbol Table.
 *<br>For speed reasons all the symbols are introduced in the same map,
 * and at the same time in a list so it can be removed when the frame is pop back.
 * @author Raul Benito
 */
public class NameSpaceSymbTable
{

  private static final String XMLNS = "xmlns";
  private static final SymbMap initialMap = new SymbMap();

  static
  {
    NameSpaceSymbEntry ne = new NameSpaceSymbEntry("", null, true, XMLNS);
    ne.lastrendered = "";
    initialMap.put(XMLNS, ne);
  }

  /**The map betwen prefix-> entry table. */
  private SymbMap symb;

  /**The stacks for removing the definitions when doing pop.*/
  private List<SymbMap> level;
  private boolean cloned = true;

  /**
   * Default constractor
   **/
  public
  NameSpaceSymbTable()
  {
    level = new ArrayList<SymbMap>();
    //Insert the default binding for xmlns.
    symb = (SymbMap) initialMap.clone();
  }

  /**
   * Get all the unrendered nodes in the name space.
   * For Inclusive rendering
   * @param result the list where to fill the unrendered xmlns definitions.
   **/
  public void
  getUnrenderedNodes(Collection<Attr> result)
  {
    Iterator<NameSpaceSymbEntry> it = symb.entrySet().iterator();
    while (it.hasNext()) {
      NameSpaceSymbEntry n = it.next();
      //put them rendered?
      if ((!n.rendered) && (n.n != null)) {
        n = (NameSpaceSymbEntry) n.clone();
        needsClone();
        symb.put(n.prefix, n);
        n.lastrendered = n.uri;
        n.rendered = true;

        result.add(n.n);
      }
    }
  }

  /**
   * Push a frame for visible namespace.
   * For Inclusive rendering.
   **/
  public void
  outputNodePush()
  {
    push();
  }

  /**
   * Pop a frame for visible namespace.
   **/
  public void
  outputNodePop()
  {
    pop();
  }

  /**
   * Push a frame for a node.
   * Inclusive or Exclusive.
   **/
  public void
  push()
  {
    //Put the number of namespace definitions in the stack.
    level.add(null);
    cloned = false;
  }

  /**
   * Pop a frame.
   * Inclusive or Exclusive.
   **/
  public void
  pop()
  {
    int size = level.size() - 1;
    Object ob = level.remove(size);
    if (ob != null) {
      symb = (SymbMap)ob;
      if (size == 0) {
        cloned = false;
      } else {
        cloned = (level.get(size - 1) != symb);
      }
    } else {
      cloned = false;
    }
  }

  final void
  needsClone()
  {
    if (!cloned) {
      level.set(level.size() - 1, symb);
      symb = (SymbMap) symb.clone();
      cloned = true;
    }
  }


  /**
   * Gets the attribute node that defines the binding for the prefix.
   * @param prefix the prefix to obtain the attribute.
   * @return null if there is no need to render the prefix. Otherwise the node of
   * definition.
   **/
  public Attr
  getMapping(String prefix)
  {
    NameSpaceSymbEntry entry = symb.get(prefix);
    if (entry == null) {
      //There is no definition for the prefix(a bug?).
      return null;
    }
    if (entry.rendered) {
      //No need to render an entry already rendered.
      return null;
    }
    // Mark this entry as render.
    entry = (NameSpaceSymbEntry) entry.clone();
    needsClone();
    symb.put(prefix, entry);
    entry.rendered = true;
    entry.lastrendered = entry.uri;
    // Return the node for outputing.
    return entry.n;
  }

  /**
   * Gets a definition without mark it as render.
   * For render in exclusive c14n the namespaces in the include prefixes.
   * @param prefix The prefix whose definition is neaded.
   * @return the attr to render, null if there is no need to render
   **/
  public Attr
  getMappingWithoutRendered(String prefix)
  {
    NameSpaceSymbEntry entry = symb.get(prefix);
    if (entry == null) {
      return null;
    }
    if (entry.rendered) {
      return null;
    }
    return entry.n;
  }

  /**
   * Adds the mapping for a prefix.
   * @param prefix the prefix of definition
   * @param uri the Uri of the definition
   * @param n the attribute that have the definition
   * @return true if there is already defined.
   **/
  public boolean
  addMapping(String prefix, String uri, Attr n)
  {
    NameSpaceSymbEntry ob = symb.get(prefix);
    if ((ob != null) && uri.equals(ob.uri)) {
      //If we have it previously defined. Don't keep working.
      return false;
    }
    //Creates and entry in the table for this new definition.
    NameSpaceSymbEntry ne = new NameSpaceSymbEntry(uri, n, false, prefix);
    needsClone();
    symb.put(prefix, ne);
    if (ob != null) {
      //We have a previous definition store it for the pop.
      //Check if a previous definition(not the inmidiatly one) has been rendered.
      ne.lastrendered = ob.lastrendered;
      if ((ob.lastrendered != null) && (ob.lastrendered.equals(uri))) {
        //Yes it is. Mark as rendered.
        ne.rendered = true;
      }
    }
    return true;
  }

  /**
   * Adds a definition and mark it as render.
   * For inclusive c14n.
   * @param prefix the prefix of definition
   * @param uri the Uri of the definition
   * @param n the attribute that have the definition
   * @return the attr to render, null if there is no need to render
   **/
  public Node
  addMappingAndRender(String prefix, String uri, Attr n)
  {
    NameSpaceSymbEntry ob = symb.get(prefix);

    if ((ob != null) && uri.equals(ob.uri)) {
      if (!ob.rendered) {
        ob = (NameSpaceSymbEntry) ob.clone();
        needsClone();
        symb.put(prefix, ob);
        ob.lastrendered = uri;
        ob.rendered = true;
        return ob.n;
      }
      return null;
    }

    NameSpaceSymbEntry ne = new NameSpaceSymbEntry(uri, n, true, prefix);
    ne.lastrendered = uri;
    needsClone();
    symb.put(prefix, ne);
    if ((ob != null) && (ob.lastrendered != null) && (ob.lastrendered.equals(uri))) {
      ne.rendered = true;
      return null;
    }
    return ne.n;
  }

  public int
  getLevel()
  {
    return level.size();
  }

  public void
  removeMapping(String prefix)
  {
    NameSpaceSymbEntry ob = symb.get(prefix);

    if (ob != null) {
      needsClone();
      symb.put(prefix, null);
    }
  }

  public void
  removeMappingIfNotRender(String prefix)
  {
    NameSpaceSymbEntry ob = symb.get(prefix);

    if (ob != null && !ob.rendered) {
      needsClone();
      symb.put(prefix, null);
    }
  }

  public boolean
  removeMappingIfRender(String prefix)
  {
    NameSpaceSymbEntry ob = symb.get(prefix);

    if (ob != null && ob.rendered) {
      needsClone();
      symb.put(prefix, null);
    }
    return false;
  }
}

/**
 * The internal structure of NameSpaceSymbTable.
 **/
class NameSpaceSymbEntry implements Cloneable
{

  String prefix;

  /**The URI that the prefix defines */
  String uri;

  /**The last output in the URI for this prefix (This for speed reason).*/
  String lastrendered = null;

  /**This prefix-URI has been already render or not.*/
  boolean rendered = false;

  /**The attribute to include.*/
  Attr n;

  NameSpaceSymbEntry(String name, Attr n, boolean rendered, String prefix)
  {
    this.uri = name;
    this.rendered = rendered;
    this.n = n;
    this.prefix = prefix;
  }

  /** @inheritDoc */
  public Object
  clone()
  {
    try {
      return super.clone();
    } catch (CloneNotSupportedException e) {
      return null;
    }
  }
}

class SymbMap implements Cloneable
{
  int free = 23;
  NameSpaceSymbEntry[] entries;
  String[] keys;

  SymbMap()
  {
    entries = new NameSpaceSymbEntry[free];
    keys = new String[free];
  }

  void
  put(String key, NameSpaceSymbEntry value)
  {
    int index = index(key);
    Object oldKey = keys[index];
    keys[index] = key;
    entries[index] = value;
    if ((oldKey == null || !oldKey.equals(key)) && (--free == 0)) {
      free = entries.length;
      int newCapacity = free << 2;
      rehash(newCapacity);
    }
  }

  List<NameSpaceSymbEntry>
  entrySet()
  {
    List<NameSpaceSymbEntry> a = new ArrayList<NameSpaceSymbEntry>();
    for (int i = 0; i < entries.length; i++) {
      if ((entries[i] != null) && !("".equals(entries[i].uri))) {
        a.add(entries[i]);
      }
    }
    return a;
  }

  protected int
  index(Object obj)
  {
    Object[] set = keys;
    int length = set.length;
    //abs of index
    int index = (obj.hashCode() & 0x7fffffff) % length;
    Object cur = set[index];

    if (cur == null || (cur.equals(obj))) {
      return index;
    }
    length--;
    do {
      index = index == length ? 0 : ++index;
      cur = set[index];
    } while (cur != null && (!cur.equals(obj)));
    return index;
  }

  /**
   * rehashes the map to the new capacity.
   *
   * @param newCapacity an <code>int</code> value
   */
  protected void
  rehash(int newCapacity)
  {
    int oldCapacity = keys.length;
    String oldKeys[] = keys;
    NameSpaceSymbEntry oldVals[] = entries;

    keys = new String[newCapacity];
    entries = new NameSpaceSymbEntry[newCapacity];

    for (int i = oldCapacity; i-- > 0;) {
      if (oldKeys[i] != null) {
        String o = oldKeys[i];
        int index = index(o);
        keys[index] = o;
        entries[index] = oldVals[i];
      }
    }
  }

  NameSpaceSymbEntry
  get(String key)
  {
    return entries[index(key)];
  }

  protected Object
  clone()
  {
    try {
      SymbMap copy = (SymbMap) super.clone();
      copy.entries = new NameSpaceSymbEntry[entries.length];
      System.arraycopy(entries, 0, copy.entries, 0, entries.length);
      copy.keys = new String[keys.length];
      System.arraycopy(keys, 0, copy.keys, 0, keys.length);

      return copy;
    } catch (CloneNotSupportedException e) {
      e.printStackTrace();
    }
    return null;
  }
}
