/*
 * 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.util.CompositeFormat;

/**
 * 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.
 *
 * @author Apache Software Foundation
 * @version $Revision$ $Date$
 */
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(
					"cannot format a {0} instance as a complex number", 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(),
					"unparseable complex number: \"{0}\"", 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("empty string for imaginary character");
		}
		this.imaginaryCharacter = imaginaryCharacter;
	}

	/**
	 * Modify the imaginaryFormat.
	 * 
	 * @param imaginaryFormat
	 *            The new imaginaryFormat value.
	 * @throws IllegalArgumentException
	 *             if <code>imaginaryFormat</code> is <code>null</code>.
	 */
	public void setImaginaryFormat(NumberFormat imaginaryFormat) {
		if (imaginaryFormat == null) {
			throw MathRuntimeException.createIllegalArgumentException("null imaginary format");
		}
		this.imaginaryFormat = imaginaryFormat;
	}

	/**
	 * Modify the realFormat.
	 * 
	 * @param realFormat
	 *            The new realFormat value.
	 * @throws IllegalArgumentException
	 *             if <code>realFormat</code> is <code>null</code>.
	 */
	public void setRealFormat(NumberFormat realFormat) {
		if (realFormat == null) {
			throw MathRuntimeException.createIllegalArgumentException("null real format");
		}
		this.realFormat = realFormat;
	}

}
