/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  package org.apache.myfaces.tobago.convert;
  
  import org.apache.myfaces.tobago.component.Attributes;
  import org.apache.myfaces.tobago.util.ComponentUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import javax.faces.component.UIComponent;
  import javax.faces.context.FacesContext;
  import javax.faces.convert.Converter;
  import javax.faces.convert.ConverterException;
  import java.lang.invoke.MethodHandles;
  import java.text.DecimalFormat;
  import java.text.NumberFormat;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.StringTokenizer;
  
  /**
   * Converts durations. The duration value in the model is of type long.
   * The string format must have one of this patterns:
   * <ul>
   * <li>hh:MM:ss</li>
   * <li>MM:ss</li>
   * <li>ss</li>
   * </ul>
   * There may be an optional attribute "unit" in the component, which allows to set the unit of the model.
   * The default unit is "millis".
   * <table>
   *   <caption>Examples</caption>
   *   <tr><th>input string</th><th>unit</th><th>resulting long in model</th><th>Remark</th></tr>
   *   <tr><td>1:15</td><td>milli</td><td>75000</td><td></td></tr>
   *   <tr><td>1:15:00</td><td>hour</td><td>1</td><td>Loosing 15 Minutes!</td></tr>
   *   <tr><td>1:15:00</td><td>null</td><td>4500000</td><td></td></tr>
   * </table>
   */
  @org.apache.myfaces.tobago.apt.annotation.Converter(id = DurationConverter.CONVERTER_ID)
  public class DurationConverter implements Converter {
  
    private static final Logger LOG = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
  
    public static final String CONVERTER_ID = "org.apache.myfaces.tobago.Duration";
  
    private enum Unit {
      nano, milli, second, minute, hour, day, year
    }
  
    @Override
    public String getAsString(
        final FacesContext facesContext, final UIComponent component, final Object object)
        throws ConverterException {
      if (object == null || object instanceof String) {
        return (String) object;
      }
      double aDouble = ((Number) object).doubleValue();
      boolean negative = false;
      if (aDouble < 0) {
        negative = true;
        aDouble = -aDouble;
      }
      final double factor = getUnitFactor(component);
      aDouble = aDouble * factor;
  
      final NumberFormat format = new DecimalFormat("00");
      long value = Double.valueOf(aDouble).longValue();
      final int seconds = (int) (value % 60);
      value = value / 60;
      final int minutes = (int) (value % 60);
      value = value / 60;
      final String string;
      if (value > 0) {
        string = (negative ? "-" : "") + value + ":"
            + format.format(minutes) + ":"
            + format.format(seconds);
      } else {
        string = (negative ? "-" : "") + minutes + ":"
            + format.format(seconds);
      }
      LOG.debug("string = '{}'", string);
      return string;
   }
 
   @Override
   public Object getAsObject(
       final FacesContext facesContext, final UIComponent component, final String string)
       throws ConverterException {
     final boolean negative = string.indexOf('-') > -1;
     final StringTokenizer tokenizer = new StringTokenizer(string, " :-");
     final List<String> elements = new ArrayList<>();
     while (tokenizer.hasMoreTokens()) {
       elements.add(tokenizer.nextToken());
     }
     final int hours;
     final int minutes;
     final int seconds;
     switch (elements.size()) {
       case 3:
         hours = Integer.parseInt(elements.get(0));
         minutes = Integer.parseInt(elements.get(1));
         seconds = Integer.parseInt(elements.get(2));
         break;
       case 2:
         hours = 0;
         minutes = Integer.parseInt(elements.get(0));
         seconds = Integer.parseInt(elements.get(1));
         break;
       case 1:
         hours = 0;
         minutes = 0;
         seconds = Integer.parseInt(elements.get(0));
         break;
       default:
         throw new ConverterException("Cannot parse string='" + string + "'");
     }
     final double factor = getUnitFactor(component);
     final long value = (long) (((hours * 60L + minutes) * 60L + seconds) / factor);
     if (negative) {
       return -value;
     } else {
       return value;
     }
   }
 
   private static double getUnitFactor(final UIComponent component) {
     final String unitString = ComponentUtils.getStringAttribute(component, Attributes.unit);
     Unit unit;
     if (unitString != null) {
       try {
         unit = Unit.valueOf(unitString);
       } catch (final Exception e) {
         LOG.warn("Unsupported unit: '{}'", unitString);
         unit = Unit.milli;
       }
     } else {
       unit = Unit.milli;
     }
     switch (unit) {
       case nano:
         return 0.000_000_001;
       default:
       case milli:
         return 0.001;
       case second:
         return 1.0;
       case minute:
         return 60.0;
       case hour:
         return 3_600.0;
       case day:
         return 86_400.0;
       case year:
         return 31_556_736.0;
     }
   }
 
 }