/*
    * 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.internal.util;
  
  import javax.faces.convert.ConverterException;
  import javax.faces.convert.DateTimeConverter;
  import java.text.DateFormat;
  import java.text.SimpleDateFormat;
  import java.util.Locale;
  
  /**
   * This code is taken from myfaces core.
   * TODO: Should be sharable (e.g. myfaces-commons).
   */
  public final class DateFormatUtils {
  
    private static final String TYPE_DATE = "date";
    private static final String TYPE_TIME = "time";
    private static final String TYPE_BOTH = "both";
    private static final String STYLE_DEFAULT = "default";
    private static final String STYLE_MEDIUM = "medium";
    private static final String STYLE_SHORT = "short";
    private static final String STYLE_LONG = "long";
    private static final String STYLE_FULL = "full";
  
    private DateFormatUtils() {
    }
  
    /**
     * Find a pattern for the converter.
     * Returns the pattern inside the converter, if any.
     * Otherwise compute the pattern.
     *
     * @return the patter or null, if DateFormat.getDateInstance() returns no SimpleDateFormat.
     */
    public static String findPattern(final DateTimeConverter converter) {
      String pattern = converter.getPattern();
  
      if (pattern == null) {
        final DateFormat dateFormat = getDateFormat(
            converter.getType(), converter.getDateStyle(),
            converter.getTimeStyle(), converter.getLocale());
        if (dateFormat instanceof SimpleDateFormat) {
          final SimpleDateFormat format = (SimpleDateFormat) dateFormat;
          pattern = format.toPattern();
        }
      }
  
      return pattern;
    }
  
    private static DateFormat getDateFormat(
        final String type, final String dateStyle, final String timeStyle, final Locale locale) {
      final DateFormat format;
      if (type.equals(TYPE_DATE)) {
        format = DateFormat.getDateInstance(calcStyle(dateStyle), locale);
      } else if (type.equals(TYPE_TIME)) {
        format = DateFormat.getTimeInstance(calcStyle(timeStyle), locale);
      } else if (type.equals(TYPE_BOTH)) {
        format = DateFormat.getDateTimeInstance(calcStyle(dateStyle),
            calcStyle(timeStyle),
            locale);
      } else {
        throw new ConverterException("invalid type '" + type + "'");
      }
  
      // format cannot be lenient (JSR-127)
      format.setLenient(false);
      return format;
    }
  
    private static int calcStyle(final String name) {
      if (name.equals(STYLE_DEFAULT)) {
        return DateFormat.DEFAULT;
      }
      if (name.equals(STYLE_MEDIUM)) {
        return DateFormat.MEDIUM;
      }
      if (name.equals(STYLE_SHORT)) {
        return DateFormat.SHORT;
      }
      if (name.equals(STYLE_LONG)) {
       return DateFormat.LONG;
     }
     if (name.equals(STYLE_FULL)) {
       return DateFormat.FULL;
     }
 
     throw new ConverterException("invalid style '" + name + "'");
   }
 
 }