package ca.uhn.hl7v2.conf.store;

 import java.io.IOException;

 import java.net.URL;

 import java.util.ArrayList;

 import java.util.HashMap;

 import java.util.List;

 import java.util.Map;

 import org.xml.sax.Attributes;

 import org.xml.sax.SAXException;

 import org.xml.sax.XMLReader;

 import org.xml.sax.helpers.DefaultHandler;

 import org.xml.sax.helpers.XMLReaderFactory;

 import ca.uhn.hl7v2.conf.ProfileException;

 /**

  * 

  * This particular implementation of CodeStore retrieves valid codes and validates codeSystems using

  * tables found in 'spec xml tables only' docs generated from the HL7 Messaging Workbench tool.

  * 

  * Note: The codeSystem parameter value used in the following methods must be a concatenation of a

  * coding authority and coding table number that is 4 digits long.

  * 

  * Note: The current implementation only accepts a coding authority of HL7

  * 

  * @author Neal Acharya

  * @author Christian Ohr

  */

 public class ProfileCodeStore extends AbstractCodeStore {

     private Map<String, List<String>> codes = new HashMap<String, List<String>>();

     /**

      * Creates a ProfileCodeStore object that uses tables found in an 'spec xml tables only' xml doc

      * specified by the input URI. The private field member tableDoc is created with content from

      * the xml doc specified by the URI.

      * 

      * @param uri the location of the specification XML file

      * 

      * @throws ProfileException

      * @throws IOException

      * 

      */

     public ProfileCodeStore(String uri) throws ProfileException, IOException {

         try {

             if (uri == null) {

                 throw new ProfileException("The input url parameter cannot be null");

             }

             XMLReader reader = XMLReaderFactory.createXMLReader();

             reader.setContentHandler(new ProfileCodeStoreHandler());

             reader.parse(uri);

         } catch (IOException e) {

             throw e;

         } catch (Exception e) {

             throw new ProfileException(e.toString(), e);

         }

     }

     /** As string constructor but accepts a URL object */

     public ProfileCodeStore(URL url) throws ProfileException, IOException {

         this(url.toExternalForm());

     }

     /**

      * Retrieves all codes for a given conformance profile and codeSystem. Note: The codeSystem

      * parameter value must be a concatenation of a coding authority and coding table number that is

      * 4 digits long.

      * 

      * Note: The current implementation only accepts a coding authority of HL7

      * 

      * @param codeSystem

      * @return String[]

      * @throws ProfileException

      * @see ca.uhn.hl7v2.conf.store.CodeStore#getValidCodes(java.lang.String, java.lang.String)

      * 

      */

     public String[] getValidCodes(String codeSystem) throws ProfileException {

         List<String> result = getCodeTable(codeSystem);

         if (result == null)

             throw new ProfileException("Unknown code system: " + codeSystem);

         return result.toArray(new String[result.size()]);

     }

     /**

      * Validates the codeSystem against the input conformance profile. If valid then output is

      * 'true' else 'false'. Note: The codeSystem parameter value must be a concatenation of a coding

      * authority and coding table number that is 4 digits long.

      * 

      * Note: The current implementation only accepts a coding authority of HL7

      * 

      * @param codeSystem

      * 

      * @return boolean

      * @see ca.uhn.hl7v2.conf.store.CodeStore#knowsCodes(java.lang.String, java.lang.String)

      * 

      */

     public boolean knowsCodes(String codeSystem) {

         try {

             return getCodeTable(codeSystem) != null;

         } catch (ProfileException e) {

             return false;

         }

     }

     /**

      * Retrieves the hl7Table Element from the tableDoc object defined by the table number in the

      * input codeSystem.

      * 

      * @param profileId

      * 

      * @param codeSystem

      * @return Element

      * @throws ProfileException Element

      */

     private List<String> getCodeTable(String codeSystem) throws ProfileException {

         if (codeSystem == null) {

             throw new ProfileException("The input codeSystem parameter cannot be null");

         }

         if (codeSystem.length() < 4) {

             throw new ProfileException("The input codeSystem parameter cannot be less than 4 characters long");

         }

         // Extract the last 4 characters from the codeSystem param

         String tableId = codeSystem.substring(codeSystem.length() - 4);

         return codes.get(tableId);

     }

     private class ProfileCodeStoreHandler extends DefaultHandler {

         private String currentTable;

         private static final String HL7_TABLE_QNAME = "hl7table";

         private static final String TABLE_ELEMENT_QNAME = "tableElement";

         @Override

         public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {

             if (HL7_TABLE_QNAME.equals(qName)) {

                 currentTable = attributes.getValue("id");

                 codes.put(currentTable, new ArrayList<String>());

             } else if (TABLE_ELEMENT_QNAME.equals(qName)) {

                 codes.get(currentTable).add(attributes.getValue("code"));

             }

         }

     }

 }