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+/*
+ * 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.math.complex;
+
+import java.text.FieldPosition;
+import java.text.NumberFormat;
+import java.text.ParseException;
+import java.text.ParsePosition;
+import java.util.Locale;
+
+import org.apache.commons.math.MathRuntimeException;
+import org.apache.commons.math.exception.util.LocalizedFormats;
+import org.apache.commons.math.util.CompositeFormat;
+import org.apache.commons.math.exception.NullArgumentException;
+
+/**
+ * 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.
+ *
+ * @version $Revision: 983921 $ $Date: 2010-08-10 12:46:06 +0200 (mar. 10 août 2010) $
+ */
+public class ComplexFormat extends CompositeFormat {
+
+    /** Serializable version identifier */
+    private static final long serialVersionUID = -3343698360149467646L;
+
+     /** 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 String imaginaryCharacter;
+
+    /** The format used for the imaginary part. */
+    private NumberFormat imaginaryFormat;
+
+    /** The format used for the real part. */
+    private 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(DEFAULT_IMAGINARY_CHARACTER, getDefaultNumberFormat());
+    }
+
+    /**
+     * 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.
+     */
+    public ComplexFormat(NumberFormat format) {
+        this(DEFAULT_IMAGINARY_CHARACTER, 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.
+     */
+    public ComplexFormat(NumberFormat realFormat, NumberFormat imaginaryFormat) {
+        this(DEFAULT_IMAGINARY_CHARACTER, realFormat, imaginaryFormat);
+    }
+
+    /**
+     * 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.
+     */
+    public ComplexFormat(String imaginaryCharacter) {
+        this(imaginaryCharacter, 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.
+     */
+    public ComplexFormat(String imaginaryCharacter, NumberFormat format) {
+        this(imaginaryCharacter, format, (NumberFormat)format.clone());
+    }
+
+    /**
+     * 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.
+     */
+    public ComplexFormat(String imaginaryCharacter, NumberFormat realFormat,
+            NumberFormat imaginaryFormat) {
+        super();
+        setImaginaryCharacter(imaginaryCharacter);
+        setImaginaryFormat(imaginaryFormat);
+        setRealFormat(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 static method calls {@link #format(Object)} on a default instance of
+     * ComplexFormat.
+     *
+     * @param c Complex object to format
+     * @return A formatted number in the form "Re(c) + Im(c)i"
+     */
+    public static String formatComplex(Complex c) {
+        return getInstance().format(c);
+    }
+
+    /**
+     * 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();
+        formatDouble(re, getRealFormat(), toAppendTo, pos);
+
+        // format sign and imaginary
+        double im = complex.getImaginary();
+        if (im < 0.0) {
+            toAppendTo.append(" - ");
+            formatDouble(-im, getImaginaryFormat(), toAppendTo, pos);
+            toAppendTo.append(getImaginaryCharacter());
+        } else if (im > 0.0 || Double.isNaN(im)) {
+            toAppendTo.append(" + ");
+            formatDouble(im, getImaginaryFormat(), toAppendTo, pos);
+            toAppendTo.append(getImaginaryCharacter());
+        }
+
+        return toAppendTo;
+    }
+
+    /**
+     * Formats a object to produce a string.  <code>obj</code> 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 IllegalArgumentException is <code>obj</code> is not a valid type.
+     */
+    @Override
+    public StringBuffer format(Object obj, StringBuffer toAppendTo,
+            FieldPosition pos) {
+
+        StringBuffer ret = null;
+
+        if (obj instanceof Complex) {
+            ret = format( (Complex)obj, toAppendTo, pos);
+        } else if (obj instanceof Number) {
+            ret = format( new Complex(((Number)obj).doubleValue(), 0.0),
+                toAppendTo, pos);
+        } else {
+            throw MathRuntimeException.createIllegalArgumentException(
+                  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 = getDefaultNumberFormat(locale);
+        return new ComplexFormat(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.
+     * @exception ParseException if the beginning of the specified string
+     *            cannot be parsed.
+     */
+    public Complex parse(String source) throws ParseException {
+        ParsePosition parsePosition = new ParsePosition(0);
+        Complex result = parse(source, parsePosition);
+        if (parsePosition.getIndex() == 0) {
+            throw MathRuntimeException.createParseException(
+                    parsePosition.getErrorIndex(),
+                    LocalizedFormats.UNPARSEABLE_COMPLEX_NUMBER, source);
+        }
+        return result;
+    }
+
+    /**
+     * Parses a string to produce a {@link Complex} object.
+     *
+     * @param source the string to parse
+     * @param pos input/ouput parsing parameter.
+     * @return the parsed {@link Complex} object.
+     */
+    public Complex parse(String source, ParsePosition pos) {
+        int initialIndex = pos.getIndex();
+
+        // parse whitespace
+        parseAndIgnoreWhitespace(source, pos);
+
+        // parse real
+        Number re = 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 = parseNextCharacter(source, pos);
+        int sign = 0;
+        switch (c) {
+        case 0 :
+            // no sign
+            // return real only complex number
+            return new Complex(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
+        parseAndIgnoreWhitespace(source, pos);
+
+        // parse imaginary
+        Number im = 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 (!parseFixedstring(source, getImaginaryCharacter(), pos)) {
+            return null;
+        }
+
+        return new Complex(re.doubleValue(), im.doubleValue() * sign);
+
+    }
+
+    /**
+     * Parses a string to produce a object.
+     *
+     * @param source the string to parse
+     * @param pos input/ouput parsing parameter.
+     * @return the parsed object.
+     * @see java.text.Format#parseObject(java.lang.String, java.text.ParsePosition)
+     */
+    @Override
+    public Object parseObject(String source, ParsePosition pos) {
+        return parse(source, pos);
+    }
+
+    /**
+     * Modify the imaginaryCharacter.
+     * @param imaginaryCharacter The new imaginaryCharacter value.
+     * @throws IllegalArgumentException if <code>imaginaryCharacter</code> is
+     *         <code>null</code> or an empty string.
+     */
+    public void setImaginaryCharacter(String imaginaryCharacter) {
+        if (imaginaryCharacter == null || imaginaryCharacter.length() == 0) {
+            throw MathRuntimeException.createIllegalArgumentException(
+                  LocalizedFormats.EMPTY_STRING_FOR_IMAGINARY_CHARACTER);
+        }
+        this.imaginaryCharacter = imaginaryCharacter;
+    }
+
+    /**
+     * Modify the imaginaryFormat.
+     * @param imaginaryFormat The new imaginaryFormat value.
+     * @throws NullArgumentException if {@code imaginaryFormat} is {@code null}.
+     */
+    public void setImaginaryFormat(NumberFormat imaginaryFormat) {
+        if (imaginaryFormat == null) {
+            throw new NullArgumentException(LocalizedFormats.IMAGINARY_FORMAT);
+        }
+        this.imaginaryFormat = imaginaryFormat;
+    }
+
+    /**
+     * Modify the realFormat.
+     * @param realFormat The new realFormat value.
+     * @throws NullArgumentException if {@code realFormat} is {@code null}.
+     */
+    public void setRealFormat(NumberFormat realFormat) {
+        if (realFormat == null) {
+            throw new NullArgumentException(LocalizedFormats.REAL_FORMAT);
+        }
+        this.realFormat = realFormat;
+    }
+
+}