source: trunk/gsdl3/src/java/org/greenstone/gsdl3/gs3build/metadata/OrderedNamespace.java@ 5945

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;
  }

  /**
   *  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", this.name);
      if (this.id != null) {
    tag = XMLTools.addAttribute(tag, "ID", this.id);
      }
      writer.println(tag);

      Iterator items = this.metadataList.iterator();
      
      while (items.hasNext())
      { NamespaceItem item = (NamespaceItem) items.next();
        this.writeItem(writer, item);
      }
      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);
      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(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);
  }
}