package org.greenstone.gsdl3.gs3build.classifier;

import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;

import java.sql.ResultSet;
import java.sql.SQLException;

import org.greenstone.gsdl3.gs3build.doctypes.DocumentID;

import org.greenstone.gsdl3.gs3build.util.GS3SQLConnection;
import org.greenstone.gsdl3.gs3build.database.*;

public abstract class AbstractHierarchyNode
{
  String prefix;        // a basic prefix used in this hierarchy
  String descriptor;    // the textual descriptor used on screen or long-hand
  String name;          // the index number, letter assignment or other item
                        //   used to identify the position of the item in the
                        //   hierarchy
  String id;            // an identifier used by the GLI for maintenance
                        //   purposes; this plays no active role in the
                        //   rebuilding process (at the moment)
  List childNodes;      // the child classification nodes of this node
  List childDocs;       // the child documents of this node
  List matches;         // the other metadata values that may be matched
                        //   against the classifier
  AbstractHierarchyNode parent; // the parent of the node

  class AbstractHierarchyDocument
  { DocumentID documentId;
    String     sortKey;

    public AbstractHierarchyDocument(DocumentID documentId, String sortKey)
    { this.documentId = documentId;
      this.sortKey    = sortKey;
    }

    public DocumentID getID()
    { return this.documentId;
    }

    public String toString()
    { return this.sortKey;
    }
  } 

  /**
   *  Simple node
   */
  public AbstractHierarchyNode()
  { this.descriptor = "";
    this.name       = "";
    this.id         = "";
    this.prefix     = "";
    this.childNodes = new ArrayList();
    this.childDocs  = new ArrayList();
    this.parent     = null;
    this.matches    = new ArrayList();
  }
    
  public AbstractHierarchyNode(String prefix, String name, String id, String descriptor)
  { this.descriptor = descriptor;
    this.name       = name;
    this.id         = id;
    this.prefix     = prefix;
    this.childNodes = new ArrayList();
    this.childDocs  = new ArrayList();
    this.parent     = null;
    this.matches    = new ArrayList();
    this.matches.add(this.id);
    this.matches.add(this.name);
  }
    
  public void addChild(AbstractHierarchyNode child)
  { this.childNodes.add(child);
    child.setParent(this);

    /**
    if (this.id == null) {
      System.out.println(child.id.toString() + " added to root");
    }
    else {
      System.out.println(child.id.toString() + " added to " + this.id);
    }
    */
  }

  public boolean add(AbstractHierarchyNode child)
  { if (this.id != null && this.id.length() > 0 &&
        !child.id.startsWith(this.id + "."))
    { return false;
    }

    Iterator subNodes = this.childNodes.iterator();
    while (subNodes.hasNext()) {
      AbstractHierarchyNode subNode = (AbstractHierarchyNode) subNodes.next();
      
      if (subNode.add(child)) {
	return true;
      }
    }
    
    this.addChild(child);
    return true;
  }

  public void addDocument(DocumentID document, String sortKey)
  { this.childDocs.add(new AbstractHierarchyDocument(document, sortKey));

    if (sortKey != null) {
      int first = 0;
      int last  = this.childDocs.size() - 1;

      while (first != last) {
	int at = (first + last) / 2;
	
	if (this.childDocs.get(at) == null) {
	  last = at;
	  continue;
	}

	if (this.childDocs.get(at).toString().compareTo(sortKey) > 0) {
	  last = at;
	}
	else {
	  first = at + 1;
	}
      }

      Object newItem = this.childDocs.get(this.childDocs.size() - 1);
      last = this.childDocs.size() - 1;
      while (last > first) {
	this.childDocs.set(last, this.childDocs.get(last-1));
	last --;
      }
      this.childDocs.set(first, newItem);
    }
  }

  public void setParent(AbstractHierarchyNode parent)
  { this.parent = parent;
  }
    
  public AbstractHierarchyNode getParent()
  { return this.parent;
  }

  public String getParentId()
  { 
    if (this.id == null) {
      return "";
    }

    int dotAt = this.id.lastIndexOf('.');
    if (dotAt < 0) {
      return "";
    }
    return this.id.substring(0, dotAt);
  }  

  public void setDescriptor(String descriptor)
  { this.descriptor = descriptor;
  }

  public void setID(String id)
  { this.id = id;
    this.matches.add(id);
  }

  public String getID()
  { return this.id;
  }

  public int noOfChildDocs()
  { return this.childDocs.size();
  }

  public int noOfLeafDocs()
  { int total = this.childDocs.size();

    Iterator iterator = this.childNodes.iterator();
    while (iterator.hasNext()) {
      AbstractHierarchyNode childNode = (AbstractHierarchyNode) iterator.next();

      total += childNode.noOfLeafDocs();
    }

    return total;
  }

  /**
   *  Set the name for this hierarchy node - i.e. its brief description
   *
   *  @param <code>String</code> the new node name.
   */
  public void setName(String name)
  { this.name = name;
  }

  /**
   *  Get the name for this hierarchy node - i.e. its brief description
   *
   *  @return <code>String</code> the node's name.
   */
  public String getName()
  { return this.name;
  }

  /**
   *  Add another string which can be used to describe this hierarchy node - i.e. one which if
   *  found in a document would indicate that that document belongs to this hierarchy node.
   *
   *  @param <code>String</code> the string to match.
   */
  public void addMatch(String match)
  { this.matches.add(match);
  }

  /**
   *  Check if a given string matches any of the values given for this hierarchy node...
   *
   *  @param <code>String</code> the descriptive string to be compared against the hierarchy
   *  @return <code>boolean</code> <code>true</code> whether the string matches this hierarchy
   */
  public boolean isMatch (String toMatch)
  { Iterator thisMatch = this.matches.iterator();
			
    while (thisMatch.hasNext())
    { String thisMatchText = thisMatch.next().toString();
      
      if (thisMatchText.equals(toMatch))
      { return true;
      }
    }
    return false;
  }

  /**
   *  Take a document, and find the classifications that it matches against in
   *  the current hierarchy.  
   *
   *  @param <code>DocumentID</code> the id of the document being classified
   *  @param <code>List</code> the values against which the classifier should
   *         test for the document being a match - i.e. the pertinent document
   *         property values.
   *  @param <code>ClassifierObserverInterface</code>
   *         object modifies the document with information about the
   *         classifications that it fell within.
   */
  abstract public void getClassifications(DocumentID documentID, List values, String sortKey,
					  ClassifierObserverInterface observer);

  public boolean writeSQL(GS3SQLConnection connection)
  {
    int classifyRef;
    GS3SQLAction action = null;
    GS3SQLSelect select;
    GS3SQLInsert insert;

    // Get own full id
    String fullId = this.id.length() > 0 ? this.prefix+"."+this.id : this.prefix;

    // check for an existing instance of this classifier
    select = new GS3SQLSelect("classifiers");
    select.addField("ClassifyRef");
    GS3SQLWhereItem whereItem = new GS3SQLWhereItem("ClassifyID", "=", fullId);
    GS3SQLWhere where = new GS3SQLWhere(whereItem);
    select.setWhere(where);

    connection.execute(select.toString());

    // update or insert the classifier as required
    try {
      ResultSet results = connection.getResultSet();
      if (results != null && results.first()) {
	GS3SQLUpdate update = new GS3SQLUpdate("classifiers");
	update.setWhere(where);
	action = update;
 
	classifyRef = results.getInt("ClassifyRef");
      }
      else {
	insert = new GS3SQLInsert("classifiers");

	if (this.id == null || this.id.length() == 0) {
	  insert.addValue("ParentID", "");
	}
	else {
	  String parentId = this.getParentId();

	  if (parentId.length() > 0) {
	    insert.addValue("ParentID", this.prefix+"."+this.getParentId());
	  }
	  else {
	    insert.addValue("ParentID", this.prefix);
	  }
	}

	action = insert;
      }
      action.addValue("ClassifyID", fullId);
      action.addValue("Name", this.name);
      action.addValue("Description", this.descriptor);

      String tailId = "0";
      if (this.id.length() > 0) {
	int lastDot = this.id.lastIndexOf('.');
	if (lastDot >= 0) {
	  tailId = this.id.substring(lastDot+1);
	}
	else {
	  tailId = this.id;
	}
      }
      action.addValue("ClassifyOrder", tailId, GS3SQLField.INTEGER_TYPE);
      action.addValue("NumLeafDocs", Integer.toString(this.noOfLeafDocs()), GS3SQLField.INTEGER_TYPE);

      connection.execute(action.toString());
      classifyRef = -1;
    }
    catch (SQLException sqlEx) {
      if (action == null) {
	System.err.println(sqlEx);
      }
      else {
	System.err.println(sqlEx + " " + action.toString());
      }
      return false;
    }

    // get the ClassifyRef if we don't already have it (have done a
    // insert action above)...
    if (classifyRef == -1) {
      connection.execute(select.toString());
      
      try {
	ResultSet results = connection.getResultSet();
	if (results == null || !results.first()) {
	  return false;
	}
	
	classifyRef = results.getInt("ClassifyRef");
      }
      catch (SQLException sqlEx) {
	System.err.println(sqlEx);
	return false;
      }
    }
    else {
      // TODO: clear 'dead' child classifications

      // delete child documents
      GS3SQLDelete delete = new GS3SQLDelete("classdocuments");
      delete.setWhere(where);

      connection.execute(delete.toString());
    }

    // post the child nodes...
    Iterator iterator = this.childNodes.iterator();
    while (iterator.hasNext()) {
      AbstractHierarchyNode childNode = (AbstractHierarchyNode) iterator.next();

      if (!childNode.writeSQL(connection)) {
	  System.out.println("Failed to write " );
	return false;
      }
    }

    // note the child documents...
    iterator = this.childDocs.iterator();
    int order = 1;
    while (iterator.hasNext()) {
      AbstractHierarchyDocument hierarchyDoc = (AbstractHierarchyDocument) iterator.next();
      DocumentID docId = hierarchyDoc.getID();

      insert = new GS3SQLInsert("classdocuments");
      insert.addValue("ClassifyRef", Integer.toString(classifyRef), GS3SQLField.INTEGER_TYPE);
      insert.addValue("DocID", docId.toString());
      insert.addValue("DocOrder", Integer.toString(order), GS3SQLField.INTEGER_TYPE);

      connection.execute(insert.toString());

      order ++;
    }
    return true;
  }
}