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.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 final Map<String, List<String>> codes = new HashMap<>();
  
      /**
       * 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
       * 
       */
      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[0]);
      }
  
      /**
       * 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
       * 
       */
      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 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) {
             if (HL7_TABLE_QNAME.equals(qName)) {
                 currentTable = attributes.getValue("id");
                 codes.put(currentTable, new ArrayList<>());
             } else if (TABLE_ELEMENT_QNAME.equals(qName)) {
                 codes.get(currentTable).add(attributes.getValue("code"));
             }
         }
 
     }
 }