package org.greenstone.gsdl3.gs3build.metadata;

import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.ArrayList;
import java.util.HashMap;

import org.greenstone.gsdl3.gs3build.util.MultiMap;
import org.greenstone.gsdl3.gs3build.util.XMLTools;

/**
 *  Implement a generic, ordered namespace in METS.
 *
 *  @see: org.greenstone.gsdl3.gs3build.metadata.METSNamespace
 */

public class OrderedNamespace extends METSNamespace
{
    List metadataList;
    
    public OrderedNamespace(String name)
    { 
	super(name);
	this.metadataList = new ArrayList();
    }
    
    public OrderedNamespace(String name, METSLocation location)
    { 
	super(name, location);
	this.metadataList = new ArrayList();
    }
    
    public boolean validate(String field, String value)
    { 
	return true;
    }
    
    /**
     *  Add a metadata item.  Whether the field and value validate for this
     *  schema will also be tested.
     *
     *  @param <code>String</code> the name of the field to be given the value
     *  @param <code>String</code> the value to be assigned
     *
     *  @return <code>boolean</code> whether the field value was added.  This
     *          would return <code>false</code> if the values did not validate,
     *          for example.
     */
    public boolean addMetadata(String label, String value)
    { 
	if (!this.validate(label, value)) {
	    return false;
	}
	
	this.metadataList.add(new NamespaceItem(label, value));
	return true;
    }
    
    /**
     *  Assign a metadata item.  Whether the field and value validate for this
     *  schema will also be tested.  Any existing metadata for that field will
     *  be destroyed if the new value validates.
     *
     *  @param <code>String</code> the name of the field to be given the value
     *  @param <code>String</code> the value to be assigned
     *
     *  @return <code>boolean</code> whether the field value was added.  This
     *          would return <code>false</code> if the values did not validate,
     *          for example.
     */
    public boolean setMetadata(String label, String value)
    { 
	if (!this.validate(label, value)){
	    return false;
	}
	
	// TODO:		this.metadataMap.setOnly(label, value);
	int itemNo = this.findItem(label);
	if (itemNo >= 0){
	    this.metadataList.set(itemNo, new NamespaceItem(label, value));
	    return true;
	}
	return false;
    }
    
    /**
     *  Remove all metadata values for a given field name
     *
     *  @param <code>String</code> the field to delete
     *
     *  @return <code>boolean</code> whether the field was actually deleted; 
     *          will return <code>true</code> if the field was already empty.
     */
    public boolean removeMetadata(String label)
    { 
	int itemNo;
	
	itemNo = this.findItem(label);
	while (itemNo >= 0){
	    this.metadataList.remove(itemNo);
	    itemNo = this.findItem(label);
	}
	return true;
    }
    
    /**
     *  Remove a particular incidence of a given metadata field for a document.
     *  If an exact match for the given value is not found, nothing changes.
     *  N.B. if a value occurs twice, only the first incidence of it will be
     *  deleted from the list.
     *
     *  @param <code>String</code> the field to have the value removed
     *  @param <code>String</code> the value to be removed from a given field
     *
     *  @return <code>boolean</code> <code>true</code> if an actual metadata text
     *          is matched against the given value and is thus deleted.
     */
    public boolean removeMetadata(String label, String value)
    { 
	int itemNo;
	
	itemNo = this.findItem(label);
	if (itemNo >= 0) {
	    this.metadataList.remove(itemNo);
	    return true;
	}
	return false;
    }
    
    /**
     *  Get the metadata items for a particular label
     *
     *  @param <code>String</code> the label to fetch values for - must be devoid
     *                             of namespace prologue (i.e. "title" rather than
     *                             e.g. "dc:title").
     *  
     *  @return <code>List</code> the list of corresponding values.  May be
     *          <code>null</code> if no values are found for the metadata
     */
    public List getMetadata(String label)
    { 
	List resultList = new ArrayList();
	
	for (int i = 0; i < this.metadataList.size(); i ++) {
	    NamespaceItem item = (NamespaceItem) this.metadataList.get(i);
	    
	    if (item.getLabel().equals(label)){
		resultList.add(item.getValue());
	    }
	}
	if (resultList.size() > 0){
	    return resultList;
	}
	return null;
    }
    
    private int findItem(String label)
    { 
	for (int i = 0; i < this.metadataList.size(); i ++) {
	    if (((NamespaceItem) this.metadataList.get(i)).getLabel().equals(label)){
		return i;
	    }
	}
	return -1;
    }
    
    private int findItem(String label, String value)
    { 
	for (int i = 0; i < this.metadataList.size(); i ++){
	    NamespaceItem item = (NamespaceItem) this.metadataList.get(i);
	    if (item.getLabel().equals(label) && item.getValue().equals(value)){
		return i;
	    }
	}
	return -1;
    }
    
    public Iterator getMetadataNames() 
    {
 	return this.metadataList.iterator();
    }
    
    
    /**
     *  Write out the metadata to an XML file through a <code>PrintWriter</code>.
     *
     *  @param <code>PrintWriter</code> the writer to use.
     */
    public boolean write(PrintWriter writer)
    { 
	// if this is a non-file block of metadata, write it out in long hand
	if (this.location == null){
	    String tag = XMLTools.getOpenTag("mets", "mdWrap");
	    tag = XMLTools.addAttribute(tag, "MDTYPE", "OTHER");
	    tag = XMLTools.addAttribute(tag, "OTHERMDTYPE", this.name);
	    if (this.id != null) {
		this.id = "gsdl"+this.id;
		tag = XMLTools.addAttribute(tag, "ID", this.id);
	    }
	    writer.print("   ");  //indentation
	    writer.println(tag);
	    
	    Iterator items = this.metadataList.iterator();
	    
	    while (items.hasNext()){
		NamespaceItem item = (NamespaceItem) items.next();
		this.writeItem(writer, item);
	    }
	    writer.print("   ");  //indentation
	    writer.println("</mets:mdWrap>");
	}
	// otherwise, drop the metadata out in a simplified file-reference
	// form only
	else
	    { 
		String tag = XMLTools.getOpenTag("mets", "mdRef");
		tag = XMLTools.addAttribute(tag, "LOCTYPE", this.location.getType());
		tag = XMLTools.addAttribute(tag, "xlink:href", this.location.getLocation().toString());
		tag = XMLTools.addAttribute(tag, "MDTYPE", this.name);
		//tag = XMLTools.addAttribute (tag, "MDTYPE", "OTHER");
		//tag = XMLTools.addAttribute(tag, "OTHERMDTYPE", this.name); 
		if (this.id != null) {
		    tag = XMLTools.addAttribute(tag, "ID", this.id);
		}
		tag = XMLTools.makeSingleton(tag);
	    }
	return true;
    }
    
    /**
     *  Write out a single element - this may be overloaded to provide for the
     *  appropriate formatting for this metadata.
     */
    protected boolean writeItem(PrintWriter writer, NamespaceItem item)
    { 
	// Do some default sillinesses
	//writer.write("         "); 
	writer.write(XMLTools.getOpenTag(this.name, item.getLabel()));
	
	writer.write(item.getValue());
	
	writer.write(XMLTools.getCloseTag(this.name, item.getLabel()));
	return true;
    }
    
    /**
     *  <p>Indicate whether this metadata is open to being changed or not.</p>
     *  <p>Metadata which is created from a distinct file cannot be changed,
     *  only those which have no associated file can be modified.
     *
     *	@return <code>boolean</code> whether this namespace can be altered.
     */
    public boolean isEditable()
    { 
	return (this.location == null);
    }
}