/*
    * 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
    *
    *      https://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.commons.beanutils2.converters;
  
  import java.math.BigDecimal;
  import java.math.BigInteger;
  import java.text.DecimalFormat;
  import java.text.DecimalFormatSymbols;
  import java.text.NumberFormat;
  import java.text.ParsePosition;
  import java.util.Calendar;
  import java.util.Date;
  import java.util.Locale;
  
  import org.apache.commons.beanutils2.ConversionException;
  
  /**
   * {@link org.apache.commons.beanutils2.Converter} implementation that handles conversion to and from <strong>java.lang.Number</strong> objects.
   * <p>
   * This implementation handles conversion for the following {@link Number} types.
   * <ul>
   * <li>{@link Byte}</li>
   * <li>{@link Short}</li>
   * <li>{@link Integer}</li>
   * <li>{@link Long}</li>
   * <li>{@link Float}</li>
   * <li>{@link Double}</li>
   * <li>{@link java.math.BigDecimal}</li>
   * <li>{@link java.math.BigInteger}</li>
   * </ul>
   *
   * <h2>String Conversions (to and from)</h2> This class provides a number of ways in which number conversions to/from Strings can be achieved:
   * <ul>
   * <li>Using the default format for the default Locale, configure using:
   * <ul>
   * <li>{@code setUseLocaleFormat(true)}</li>
   * </ul>
   * </li>
   * <li>Using the default format for a specified Locale, configure using:
   * <ul>
   * <li>{@code setLocale(Locale)}</li>
   * </ul>
   * </li>
   * <li>Using a specified pattern for the default Locale, configure using:
   * <ul>
   * <li>{@code setPattern(String)}</li>
   * </ul>
   * </li>
   * <li>Using a specified pattern for a specified Locale, configure using:
   * <ul>
   * <li>{@code setPattern(String)}</li>
   * <li>{@code setLocale(Locale)}</li>
   * </ul>
   * </li>
   * <li>If none of the above are configured the {@code toNumber(String)} method is used to convert from String to Number and the Number's {@code toString()}
   * method used to convert from Number to String.</li>
   * </ul>
   *
   * <p>
   * <strong>N.B.</strong>Patterns can only be specified using the <em>standard</em> pattern characters and NOT in <em>localized</em> form (see
   * {@link java.text.DecimalFormat}). For example to cater for number styles used in Germany such as {@code 0.000,00} the pattern is specified in the normal form
   * {@code 0,000.00</code> and the locale set to <code>Locale.GERMANY}
   *
   * @param <N> The default value type.
   * @since 1.8.0
   */
  public abstract class NumberConverter<N extends Number> extends AbstractConverter<N> {
  
      private static final Integer ZERO = Integer.valueOf(0);
      private static final Integer ONE = Integer.valueOf(1);
  
      private String pattern;
      private final boolean allowDecimals;
      private boolean useLocaleFormat;
      private Locale locale;
  
      /**
       * Constructs a <strong>java.lang.Number</strong> <em>Converter</em> that throws a {@code ConversionException} if a error occurs.
       *
       * @param allowDecimals Indicates whether decimals are allowed
       */
      public NumberConverter(final boolean allowDecimals) {
          this.allowDecimals = allowDecimals;
      }
  
     /**
      * Constructs a {@link Number} <em>Converter</em> that returns a default value if an error occurs.
      *
      * @param allowDecimals Indicates whether decimals are allowed
      * @param defaultValue  The default value to be returned
      */
     public NumberConverter(final boolean allowDecimals, final N defaultValue) {
         this.allowDecimals = allowDecimals;
         setDefaultValue(defaultValue);
     }
 
     /**
      * Convert an input Number object into a String.
      *
      * @param value The input value to be converted
      * @return the converted String value.
      * @throws IllegalArgumentException if an error occurs converting to a String
      */
     @Override
     protected String convertToString(final Object value) {
 
         String result = null;
         if (useLocaleFormat && value instanceof Number) {
             final NumberFormat format = getFormat();
             format.setGroupingUsed(false);
             result = format.format(value);
             if (log().isDebugEnabled()) {
                 log().debug("    Converted  to String using format '" + result + "'");
             }
 
         } else {
             result = value.toString();
             if (log().isDebugEnabled()) {
                 log().debug("    Converted  to String using toString() '" + result + "'");
             }
         }
         return result;
 
     }
 
     /**
      * Convert the input object into a Number object of the specified type.
      *
      * @param <T>        Target type of the conversion.
      * @param targetType Data type to which this value should be converted.
      * @param value      The input value to be converted.
      * @return The converted value.
      * @throws Throwable if an error occurs converting to the specified type
      */
     @Override
     protected <T> T convertToType(final Class<T> targetType, final Object value) throws Throwable {
         final Class<?> sourceType = value.getClass();
         // Handle Number
         if (value instanceof Number) {
             return toNumber(sourceType, targetType, (Number) value);
         }
 
         // Handle Boolean
         if (value instanceof Boolean) {
             return toNumber(sourceType, targetType, ((Boolean) value).booleanValue() ? ONE : ZERO);
         }
 
         // Handle Date --> Long
         if (value instanceof Date && Long.class.equals(targetType)) {
             return targetType.cast(Long.valueOf(((Date) value).getTime()));
         }
 
         // Handle Calendar --> Long
         if (value instanceof Calendar && Long.class.equals(targetType)) {
             return targetType.cast(Long.valueOf(((Calendar) value).getTime().getTime()));
         }
 
         // Convert all other types to String & handle
         final String stringValue = toTrim(value);
         if (stringValue.isEmpty()) {
             return handleMissing(targetType);
         }
 
         // Convert/Parse a String
         Number number = null;
         if (useLocaleFormat) {
             final NumberFormat format = getFormat();
             number = parse(sourceType, targetType, stringValue, format);
         } else {
             if (log().isDebugEnabled()) {
                 log().debug("    No NumberFormat, using default conversion");
             }
             number = toNumber(sourceType, targetType, stringValue);
         }
 
         // Ensure the correct number type is returned
         return toNumber(sourceType, targetType, number);
     }
 
     /**
      * Gets a NumberFormat to use for Conversion.
      *
      * @return The NumberFormat.
      */
     private NumberFormat getFormat() {
         NumberFormat format = null;
         if (pattern != null) {
             if (locale == null) {
                 if (log().isDebugEnabled()) {
                     log().debug("    Using pattern '" + pattern + "'");
                 }
                 format = new DecimalFormat(pattern);
             } else {
                 if (log().isDebugEnabled()) {
                     log().debug("    Using pattern '" + pattern + "'" + " with Locale[" + locale + "]");
                 }
                 final DecimalFormatSymbols symbols = new DecimalFormatSymbols(locale);
                 format = new DecimalFormat(pattern, symbols);
             }
         } else if (locale == null) {
             if (log().isDebugEnabled()) {
                 log().debug("    Using default Locale format");
             }
             format = NumberFormat.getInstance();
         } else {
             if (log().isDebugEnabled()) {
                 log().debug("    Using Locale[" + locale + "] format");
             }
             format = NumberFormat.getInstance(locale);
         }
         if (!allowDecimals) {
             format.setParseIntegerOnly(true);
         }
         return format;
     }
 
     /**
      * Gets the Locale for the <em>Converter</em> (or {@code null} if none specified).
      *
      * @return The locale to use for conversion
      */
     public Locale getLocale() {
         return locale;
     }
 
     /**
      * Gets the number format pattern used to convert Numbers to/from a {@link String} (or {@code null} if none specified).
      * <p>
      * See {@link java.text.DecimalFormat} for details of how to specify the pattern.
      *
      * @return The format pattern.
      */
     public String getPattern() {
         return pattern;
     }
 
     /**
      * Gets whether decimals are allowed in the number.
      *
      * @return Whether decimals are allowed in the number
      */
     public boolean isAllowDecimals() {
         return allowDecimals;
     }
 
     /**
      * Convert a String into a {@code Number} object.
      *
      * @param sourceType the source type of the conversion
      * @param targetType The type to convert the value to
      * @param value      The String date value.
      * @param format     The NumberFormat to parse the String value.
      * @return The converted Number object.
      * @throws ConversionException if the String cannot be converted.
      */
     private Number parse(final Class<?> sourceType, final Class<?> targetType, final String value, final NumberFormat format) {
         final ParsePosition pos = new ParsePosition(0);
         final Number parsedNumber = format.parse(value, pos);
         if (pos.getErrorIndex() >= 0 || pos.getIndex() != value.length() || parsedNumber == null) {
             String msg = "Error converting from '" + toString(sourceType) + "' to '" + toString(targetType) + "'";
             if (format instanceof DecimalFormat) {
                 msg += " using pattern '" + ((DecimalFormat) format).toPattern() + "'";
             }
             if (locale != null) {
                 msg += " for locale=[" + locale + "]";
             }
             if (log().isDebugEnabled()) {
                 log().debug("    " + msg);
             }
             throw new ConversionException(msg);
         }
         return parsedNumber;
     }
 
     /**
      * Sets the Locale for the <em>Converter</em>.
      *
      * @param locale The locale to use for conversion
      */
     public void setLocale(final Locale locale) {
         this.locale = locale;
         setUseLocaleFormat(true);
     }
 
     /**
      * Sets a number format pattern to use to convert Numbers to/from a {@link String}.
      * <p>
      * See {@link java.text.DecimalFormat} for details of how to specify the pattern.
      *
      * @param pattern The format pattern.
      */
     public void setPattern(final String pattern) {
         this.pattern = pattern;
         setUseLocaleFormat(true);
     }
 
     /**
      * Sets whether a format should be used to convert the Number.
      *
      * @param useLocaleFormat {@code true} if a number format should be used.
      */
     public void setUseLocaleFormat(final boolean useLocaleFormat) {
         this.useLocaleFormat = useLocaleFormat;
     }
 
     /**
      * Default String to Number conversion.
      * <p>
      * This method handles conversion from a String to the following types:
      * <ul>
      * <li>{@link Byte}</li>
      * <li>{@link Short}</li>
      * <li>{@link Integer}</li>
      * <li>{@link Long}</li>
      * <li>{@link Float}</li>
      * <li>{@link Double}</li>
      * <li>{@link java.math.BigDecimal}</li>
      * <li>{@link java.math.BigInteger}</li>
      * </ul>
      *
      * @param sourceType The type being converted from
      * @param targetType The Number type to convert to
      * @param value      The String value to convert.
      * @return The converted Number value.
      */
     private Number toNumber(final Class<?> sourceType, final Class<?> targetType, final String value) {
         // Byte
         if (targetType.equals(Byte.class)) {
             return Byte.valueOf(value);
         }
 
         // Short
         if (targetType.equals(Short.class)) {
             return Short.valueOf(value);
         }
 
         // Integer
         if (targetType.equals(Integer.class)) {
             return Integer.valueOf(value);
         }
 
         // Long
         if (targetType.equals(Long.class)) {
             return Long.valueOf(value);
         }
 
         // Float
         if (targetType.equals(Float.class)) {
             return Float.valueOf(value);
         }
 
         // Double
         if (targetType.equals(Double.class)) {
             return Double.valueOf(value);
         }
 
         // BigDecimal
         if (targetType.equals(BigDecimal.class)) {
             return new BigDecimal(value);
         }
 
         // BigInteger
         if (targetType.equals(BigInteger.class)) {
             return new BigInteger(value);
         }
 
         final String msg = toString(getClass()) + " cannot handle conversion from '" + toString(sourceType) + "' to '" + toString(targetType) + "'";
         if (log().isWarnEnabled()) {
             log().warn("    " + msg);
         }
         throw new ConversionException(msg);
     }
 
     /**
      * Convert any Number object to the specified type for this <em>Converter</em>.
      * <p>
      * This method handles conversion to the following types:
      * <ul>
      * <li>{@link Byte}</li>
      * <li>{@link Short}</li>
      * <li>{@link Integer}</li>
      * <li>{@link Long}</li>
      * <li>{@link Float}</li>
      * <li>{@link Double}</li>
      * <li>{@link java.math.BigDecimal}</li>
      * <li>{@link java.math.BigInteger}</li>
      * </ul>
      *
      * @param sourceType The type being converted from
      * @param targetType The Number type to convert to
      * @param value      The Number to convert.
      * @return The converted value.
      */
     private <T> T toNumber(final Class<?> sourceType, final Class<T> targetType, final Number value) {
         // Correct Number type already
         if (targetType.equals(value.getClass())) {
             return targetType.cast(value);
         }
 
         // Byte
         if (targetType.equals(Byte.class)) {
             final long longValue = value.longValue();
             if (longValue > Byte.MAX_VALUE) {
                 throw ConversionException.format("%s value '%s' is too large for %s", toString(sourceType), value, toString(targetType));
             }
             if (longValue < Byte.MIN_VALUE) {
                 throw ConversionException.format("%s value '%s' is too small %s", toString(sourceType), value, toString(targetType));
             }
             return targetType.cast(Byte.valueOf(value.byteValue()));
         }
 
         // Short
         if (targetType.equals(Short.class)) {
             final long longValue = value.longValue();
             if (longValue > Short.MAX_VALUE) {
                 throw ConversionException.format("%s value '%s' is too large for %s", toString(sourceType), value, toString(targetType));
             }
             if (longValue < Short.MIN_VALUE) {
                 throw ConversionException.format("%s value '%s' is too small %s", toString(sourceType), value, toString(targetType));
             }
             return targetType.cast(Short.valueOf(value.shortValue()));
         }
 
         // Integer
         if (targetType.equals(Integer.class)) {
             final long longValue = value.longValue();
             if (longValue > Integer.MAX_VALUE) {
                 throw ConversionException.format("%s value '%s' is too large for %s", toString(sourceType), value, toString(targetType));
             }
             if (longValue < Integer.MIN_VALUE) {
                 throw ConversionException.format("%s value '%s' is too small %s", toString(sourceType), value, toString(targetType));
             }
             return targetType.cast(Integer.valueOf(value.intValue()));
         }
 
         // Long
         if (targetType.equals(Long.class)) {
             return targetType.cast(Long.valueOf(value.longValue()));
         }
 
         // Float
         if (targetType.equals(Float.class)) {
             if (value.doubleValue() > Float.MAX_VALUE) {
                 throw ConversionException.format("%s value '%s' is too large for %s", toString(sourceType), value, toString(targetType));
             }
             return targetType.cast(Float.valueOf(value.floatValue()));
         }
 
         // Double
         if (targetType.equals(Double.class)) {
             return targetType.cast(Double.valueOf(value.doubleValue()));
         }
 
         // BigDecimal
         if (targetType.equals(BigDecimal.class)) {
             if (value instanceof Float || value instanceof Double) {
                 return targetType.cast(new BigDecimal(value.toString()));
             }
             if (value instanceof BigInteger) {
                 return targetType.cast(new BigDecimal((BigInteger) value));
             }
             if (value instanceof BigDecimal) {
                 return targetType.cast(new BigDecimal(value.toString()));
             }
             return targetType.cast(BigDecimal.valueOf(value.longValue()));
         }
 
         // BigInteger
         if (targetType.equals(BigInteger.class)) {
             if (value instanceof BigDecimal) {
                 return targetType.cast(((BigDecimal) value).toBigInteger());
             }
             return targetType.cast(BigInteger.valueOf(value.longValue()));
         }
 
         final String msg = toString(getClass()) + " cannot handle conversion to '" + toString(targetType) + "'";
         if (log().isWarnEnabled()) {
             log().warn("    " + msg);
         }
         throw new ConversionException(msg);
     }
 
     /**
      * Provide a String representation of this number converter.
      *
      * @return A String representation of this number converter
      */
     @Override
     public String toString() {
         final StringBuilder buffer = new StringBuilder();
         buffer.append(toString(getClass()));
         buffer.append("[UseDefault=");
         buffer.append(isUseDefault());
         buffer.append(", UseLocaleFormat=");
         buffer.append(useLocaleFormat);
         if (pattern != null) {
             buffer.append(", Pattern=");
             buffer.append(pattern);
         }
         if (locale != null) {
             buffer.append(", Locale=");
             buffer.append(locale);
         }
         buffer.append(']');
         return buffer.toString();
     }
 
 }