package com.github.mygreen.supercsv.cellprocessor.constraint;
   
   import java.util.HashMap;
   import java.util.Map;
   
   import org.supercsv.cellprocessor.ift.CellProcessor;
   import org.supercsv.util.CsvContext;
   
   import com.github.mygreen.supercsv.cellprocessor.ValidationCellProcessor;
  import com.github.mygreen.supercsv.cellprocessor.format.TextPrinter;
  
  /**
   * 値がユニークかハッシュコードを元にチェックするCellProcessor.
   * 
   * @since 2.0
   * @author T.TSUCHIE
   *
   */
  public class UniqueHashCode<T> extends ValidationCellProcessor {
      
      private final Map<Integer, ValueObject> encounteredElements = new HashMap<>();
      
      private final TextPrinter<T> printer;
      
      public UniqueHashCode(final TextPrinter<T> printer) {
          super();
          checkPreconditions(printer);
          this.printer = printer;
      }
      
      public UniqueHashCode(final TextPrinter<T> printer, final CellProcessor next) {
          super(next);
          checkPreconditions(printer);
          this.printer = printer;
      }
      
      private static <T> void checkPreconditions(final TextPrinter<T> printer) {
          if(printer == null) {
              throw new NullPointerException("printer should not be null.");
          }
      }
      
      @SuppressWarnings("unchecked")
      @Override
      public Object execute(final Object value, final CsvContext context) {
          
          if(value == null) {
              return next.execute(value, context);
          }
          
          final T result = (T)value;
          final int hashCode = value.hashCode();
          
          if(encounteredElements.containsKey(hashCode)) {
              
              final ValueObject duplicatedObject = encounteredElements.get(result);
              throw createValidationException(context)
                  .messageFormat("duplicate hashCode '%s' encountered.", hashCode)
                  .rejectedValue(result)
                  .messageVariables("hashCode", hashCode)
                  .messageVariables("duplicatedRowNumber", duplicatedObject.rowNumber)
                  .messageVariables("duplicatedLineNumber", duplicatedObject.lineNumber)
                  .messageVariables("printer", getPrinter())
                  .build();
              
          } else {
              final ValueObject object = new ValueObject(hashCode, context.getRowNumber(), context.getLineNumber());
              encounteredElements.put(object.hashCode, object);
          }
          
          return next.execute(value, context);
      }
      
      private static class ValueObject {
          
          final int hashCode;
          
          final int rowNumber;
          
          final int lineNumber;
          
          ValueObject(final int hashCode, final int rowNumber, final int lineNumber) {
              this.hashCode = hashCode;
              this.rowNumber = rowNumber;
              this.lineNumber = lineNumber;
          }
          
      }
      
      /**
       * 
       * @return 値のフォーマッタを取得する。
       */
      public TextPrinter<T> getPrinter() {
          return printer;
      }
      
  }