/*
    * 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.commons.math4.legacy.util;
  
  import java.text.FieldPosition;
  import java.text.NumberFormat;
  import java.text.ParsePosition;
  import java.util.Locale;
  
  import org.apache.commons.numbers.complex.Complex;
  import org.apache.commons.math4.legacy.exception.MathIllegalArgumentException;
  import org.apache.commons.math4.legacy.exception.MathParseException;
  import org.apache.commons.math4.legacy.exception.NoDataException;
  import org.apache.commons.math4.legacy.exception.NullArgumentException;
  import org.apache.commons.math4.legacy.exception.util.LocalizedFormats;
  
  /**
   * Formats a Complex number in cartesian format "Re(c) + Im(c)i".  'i' can
   * be replaced with 'j' (or anything else), and the number format for both real
   * and imaginary parts can be configured.
   *
   */
  public class ComplexFormat {
  
       /** The default imaginary character. */
      private static final String DEFAULT_IMAGINARY_CHARACTER = "i";
      /** The notation used to signify the imaginary part of the complex number. */
      private final String imaginaryCharacter;
      /** The format used for the imaginary part. */
      private final NumberFormat imaginaryFormat;
      /** The format used for the real part. */
      private final NumberFormat realFormat;
  
      /**
       * Create an instance with the default imaginary character, 'i', and the
       * default number format for both real and imaginary parts.
       */
      public ComplexFormat() {
          this.imaginaryCharacter = DEFAULT_IMAGINARY_CHARACTER;
          this.imaginaryFormat = CompositeFormat.getDefaultNumberFormat();
          this.realFormat = imaginaryFormat;
      }
  
      /**
       * Create an instance with a custom number format for both real and
       * imaginary parts.
       * @param format the custom format for both real and imaginary parts.
       * @throws NullArgumentException if {@code realFormat} is {@code null}.
       */
      public ComplexFormat(NumberFormat format) throws NullArgumentException {
          if (format == null) {
              throw new NullArgumentException(LocalizedFormats.IMAGINARY_FORMAT);
          }
          this.imaginaryCharacter = DEFAULT_IMAGINARY_CHARACTER;
          this.imaginaryFormat = format;
          this.realFormat = format;
      }
  
      /**
       * Create an instance with a custom number format for the real part and a
       * custom number format for the imaginary part.
       * @param realFormat the custom format for the real part.
       * @param imaginaryFormat the custom format for the imaginary part.
       * @throws NullArgumentException if {@code imaginaryFormat} is {@code null}.
       * @throws NullArgumentException if {@code realFormat} is {@code null}.
        */
      public ComplexFormat(NumberFormat realFormat, NumberFormat imaginaryFormat)
          throws NullArgumentException {
          if (imaginaryFormat == null) {
              throw new NullArgumentException(LocalizedFormats.IMAGINARY_FORMAT);
          }
          if (realFormat == null) {
              throw new NullArgumentException(LocalizedFormats.REAL_FORMAT);
          }
  
          this.imaginaryCharacter = DEFAULT_IMAGINARY_CHARACTER;
          this.imaginaryFormat = imaginaryFormat;
          this.realFormat = realFormat;
      }
  
      /**
       * Create an instance with a custom imaginary character, and the default
       * number format for both real and imaginary parts.
       * @param imaginaryCharacter The custom imaginary character.
      * @throws NullArgumentException if {@code imaginaryCharacter} is
      * {@code null}.
      * @throws NoDataException if {@code imaginaryCharacter} is an
      * empty string.
      */
     public ComplexFormat(String imaginaryCharacter)
         throws NullArgumentException, NoDataException {
         this(imaginaryCharacter, CompositeFormat.getDefaultNumberFormat());
     }
 
     /**
      * Create an instance with a custom imaginary character, and a custom number
      * format for both real and imaginary parts.
      * @param imaginaryCharacter The custom imaginary character.
      * @param format the custom format for both real and imaginary parts.
      * @throws NullArgumentException if {@code imaginaryCharacter} is
      * {@code null}.
      * @throws NoDataException if {@code imaginaryCharacter} is an
      * empty string.
      * @throws NullArgumentException if {@code format} is {@code null}.
      */
     public ComplexFormat(String imaginaryCharacter, NumberFormat format)
         throws NullArgumentException, NoDataException {
         this(imaginaryCharacter, format, format);
     }
 
     /**
      * Create an instance with a custom imaginary character, a custom number
      * format for the real part, and a custom number format for the imaginary
      * part.
      *
      * @param imaginaryCharacter The custom imaginary character.
      * @param realFormat the custom format for the real part.
      * @param imaginaryFormat the custom format for the imaginary part.
      * @throws NullArgumentException if {@code imaginaryCharacter} is
      * {@code null}.
      * @throws NoDataException if {@code imaginaryCharacter} is an
      * empty string.
      * @throws NullArgumentException if {@code imaginaryFormat} is {@code null}.
      * @throws NullArgumentException if {@code realFormat} is {@code null}.
      */
     public ComplexFormat(String imaginaryCharacter,
                          NumberFormat realFormat,
                          NumberFormat imaginaryFormat)
         throws NullArgumentException, NoDataException {
         if (imaginaryCharacter == null) {
             throw new NullArgumentException();
         }
         if (imaginaryCharacter.isEmpty()) {
             throw new NoDataException();
         }
         if (imaginaryFormat == null) {
             throw new NullArgumentException(LocalizedFormats.IMAGINARY_FORMAT);
         }
         if (realFormat == null) {
             throw new NullArgumentException(LocalizedFormats.REAL_FORMAT);
         }
 
         this.imaginaryCharacter = imaginaryCharacter;
         this.imaginaryFormat = imaginaryFormat;
         this.realFormat = realFormat;
     }
 
     /**
      * Get the set of locales for which complex formats are available.
      * <p>This is the same set as the {@link NumberFormat} set.</p>
      * @return available complex format locales.
      */
     public static Locale[] getAvailableLocales() {
         return NumberFormat.getAvailableLocales();
     }
 
     /**
      * This method calls {@link #format(Object,StringBuffer,FieldPosition)}.
      *
      * @param c Complex object to format.
      * @return A formatted number in the form "Re(c) + Im(c)i".
      */
     public String format(Complex c) {
         return format(c, new StringBuffer(), new FieldPosition(0)).toString();
     }
 
     /**
      * This method calls {@link #format(Object,StringBuffer,FieldPosition)}.
      *
      * @param c Double object to format.
      * @return A formatted number.
      */
     public String format(Double c) {
         return format(Complex.ofCartesian(c, 0), new StringBuffer(), new FieldPosition(0)).toString();
     }
 
     /**
      * Formats a {@link Complex} object to produce a string.
      *
      * @param complex the object to format.
      * @param toAppendTo where the text is to be appended
      * @param pos On input: an alignment field, if desired. On output: the
      *            offsets of the alignment field
      * @return the value passed in as toAppendTo.
      */
     public StringBuffer format(Complex complex, StringBuffer toAppendTo,
                                FieldPosition pos) {
         pos.setBeginIndex(0);
         pos.setEndIndex(0);
 
         // format real
         double re = complex.getReal();
         CompositeFormat.formatDouble(re, getRealFormat(), toAppendTo, pos);
 
         // format sign and imaginary
         double im = complex.getImaginary();
         StringBuffer imAppendTo;
         if (im < 0.0) {
             toAppendTo.append(" - ");
             imAppendTo = formatImaginary(-im, new StringBuffer(), pos);
             toAppendTo.append(imAppendTo);
             toAppendTo.append(getImaginaryCharacter());
         } else if (im > 0.0 || Double.isNaN(im)) {
             toAppendTo.append(" + ");
             imAppendTo = formatImaginary(im, new StringBuffer(), pos);
             toAppendTo.append(imAppendTo);
             toAppendTo.append(getImaginaryCharacter());
         }
 
         return toAppendTo;
     }
 
     /**
      * Format the absolute value of the imaginary part.
      *
      * @param absIm Absolute value of the imaginary part of a complex number.
      * @param toAppendTo where the text is to be appended.
      * @param pos On input: an alignment field, if desired. On output: the
      * offsets of the alignment field.
      * @return the value passed in as toAppendTo.
      */
     private StringBuffer formatImaginary(double absIm,
                                          StringBuffer toAppendTo,
                                          FieldPosition pos) {
         pos.setBeginIndex(0);
         pos.setEndIndex(0);
 
         CompositeFormat.formatDouble(absIm, getImaginaryFormat(), toAppendTo, pos);
         if (toAppendTo.toString().equals("1")) {
             // Remove the character "1" if it is the only one.
             toAppendTo.setLength(0);
         }
 
         return toAppendTo;
     }
 
     /**
      * Formats a object to produce a string.  {@code obj} must be either a
      * {@link Complex} object or a {@link Number} object.  Any other type of
      * object will result in an {@link IllegalArgumentException} being thrown.
      *
      * @param obj the object to format.
      * @param toAppendTo where the text is to be appended
      * @param pos On input: an alignment field, if desired. On output: the
      *            offsets of the alignment field
      * @return the value passed in as toAppendTo.
      * @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition)
      * @throws MathIllegalArgumentException is {@code obj} is not a valid type.
      */
     public StringBuffer format(Object obj, StringBuffer toAppendTo,
                                FieldPosition pos)
         throws MathIllegalArgumentException {
 
         StringBuffer ret = null;
 
         if (obj instanceof Complex) {
             ret = format( (Complex)obj, toAppendTo, pos);
         } else if (obj instanceof Number) {
             ret = format(Complex.ofCartesian(((Number)obj).doubleValue(), 0.0),
                          toAppendTo, pos);
         } else {
             throw new MathIllegalArgumentException(LocalizedFormats.CANNOT_FORMAT_INSTANCE_AS_COMPLEX,
                                                    obj.getClass().getName());
         }
 
         return ret;
     }
 
     /**
      * Access the imaginaryCharacter.
      * @return the imaginaryCharacter.
      */
     public String getImaginaryCharacter() {
         return imaginaryCharacter;
     }
 
     /**
      * Access the imaginaryFormat.
      * @return the imaginaryFormat.
      */
     public NumberFormat getImaginaryFormat() {
         return imaginaryFormat;
     }
 
     /**
      * Returns the default complex format for the current locale.
      * @return the default complex format.
      */
     public static ComplexFormat getInstance() {
         return getInstance(Locale.getDefault());
     }
 
     /**
      * Returns the default complex format for the given locale.
      * @param locale the specific locale used by the format.
      * @return the complex format specific to the given locale.
      */
     public static ComplexFormat getInstance(Locale locale) {
         NumberFormat f = CompositeFormat.getDefaultNumberFormat(locale);
         return new ComplexFormat(f);
     }
 
     /**
      * Returns the default complex format for the given locale.
      * @param locale the specific locale used by the format.
      * @param imaginaryCharacter Imaginary character.
      * @return the complex format specific to the given locale.
      * @throws NullArgumentException if {@code imaginaryCharacter} is
      * {@code null}.
      * @throws NoDataException if {@code imaginaryCharacter} is an
      * empty string.
      */
     public static ComplexFormat getInstance(String imaginaryCharacter, Locale locale)
         throws NullArgumentException, NoDataException {
         NumberFormat f = CompositeFormat.getDefaultNumberFormat(locale);
         return new ComplexFormat(imaginaryCharacter, f);
     }
 
     /**
      * Access the realFormat.
      * @return the realFormat.
      */
     public NumberFormat getRealFormat() {
         return realFormat;
     }
 
     /**
      * Parses a string to produce a {@link Complex} object.
      *
      * @param source the string to parse.
      * @return the parsed {@link Complex} object.
      * @throws MathParseException if the beginning of the specified string
      * cannot be parsed.
      */
     public Complex parse(String source) throws MathParseException {
         ParsePosition parsePosition = new ParsePosition(0);
         Complex result = parse(source, parsePosition);
         if (parsePosition.getIndex() == 0) {
             throw new MathParseException(source,
                                          parsePosition.getErrorIndex(),
                                          Complex.class);
         }
         return result;
     }
 
     /**
      * Parses a string to produce a {@link Complex} object.
      *
      * @param source the string to parse
      * @param pos input/output parsing parameter.
      * @return the parsed {@link Complex} object.
      */
     public Complex parse(String source, ParsePosition pos) {
         int initialIndex = pos.getIndex();
 
         // parse whitespace
         CompositeFormat.parseAndIgnoreWhitespace(source, pos);
 
         // parse real
         Number re = CompositeFormat.parseNumber(source, getRealFormat(), pos);
         if (re == null) {
             // invalid real number
             // set index back to initial, error index should already be set
             pos.setIndex(initialIndex);
             return null;
         }
 
         // parse sign
         int startIndex = pos.getIndex();
         char c = CompositeFormat.parseNextCharacter(source, pos);
         int sign = 0;
         switch (c) {
         case 0 :
             // no sign
             // return real only complex number
             return Complex.ofCartesian(re.doubleValue(), 0.0);
         case '-' :
             sign = -1;
             break;
         case '+' :
             sign = 1;
             break;
         default :
             // invalid sign
             // set index back to initial, error index should be the last
             // character examined.
             pos.setIndex(initialIndex);
             pos.setErrorIndex(startIndex);
             return null;
         }
 
         // parse whitespace
         CompositeFormat.parseAndIgnoreWhitespace(source, pos);
 
         // parse imaginary
         Number im = CompositeFormat.parseNumber(source, getRealFormat(), pos);
         if (im == null) {
             // invalid imaginary number
             // set index back to initial, error index should already be set
             pos.setIndex(initialIndex);
             return null;
         }
 
         // parse imaginary character
         if (!CompositeFormat.parseFixedstring(source, getImaginaryCharacter(), pos)) {
             return null;
         }
 
         return Complex.ofCartesian(re.doubleValue(), im.doubleValue() * sign);
     }
 }