/*
 * 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.math3.geometry;

import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;
import java.util.Locale;

import org.apache.commons.math3.util.CompositeFormat;
import org.apache.commons.math3.exception.MathParseException;

Formats a vector in components list format "{x; y; ...}".
The prefix and suffix "{" and "}" and the separator "; " can be replaced by
any user-defined strings. The number format for components can be configured.
White space is ignored at parse time, even if it is in the prefix, suffix
or separator specifications. So even if the default separator does include a space
character that is used at format time, both input string "{1;1;1}" and
" { 1 ; 1 ; 1 } " will be parsed without error and the same vector will be
returned. In the second case, however, the parse position after parsing will be
just after the closing curly brace, i.e. just before the trailing space.
Note: using "," as a separator may interfere with the grouping separator of the default NumberFormat for the current locale. Thus it is advised to use a NumberFormat instance with disabled grouping in such a case.
Type parameters:
<S> – Type of the space.
Since:
3.0/**
 * Formats a vector in components list format "{x; y; ...}".
 * <p>The prefix and suffix "{" and "}" and the separator "; " can be replaced by
 * any user-defined strings. The number format for components can be configured.</p>
 * <p>White space is ignored at parse time, even if it is in the prefix, suffix
 * or separator specifications. So even if the default separator does include a space
 * character that is used at format time, both input string "{1;1;1}" and
 * " { 1 ; 1 ; 1 } " will be parsed without error and the same vector will be
 * returned. In the second case, however, the parse position after parsing will be
 * just after the closing curly brace, i.e. just before the trailing space.</p>
 * <p><b>Note:</b> using "," as a separator may interfere with the grouping separator
 * of the default {@link NumberFormat} for the current locale. Thus it is advised
 * to use a {@link NumberFormat} instance with disabled grouping in such a case.</p>
 *
 * @param <S> Type of the space.
 * @since 3.0
 */
public abstract class VectorFormat<S extends Space> {

    
The default prefix: "{". /** The default prefix: "{". */
    public static final String DEFAULT_PREFIX = "{";

    
The default suffix: "}". /** The default suffix: "}". */
    public static final String DEFAULT_SUFFIX = "}";

    
The default separator: ", ". /** The default separator: ", ". */
    public static final String DEFAULT_SEPARATOR = "; ";

    
Prefix. /** Prefix. */
    private final String prefix;

    
Suffix. /** Suffix. */
    private final String suffix;

    
Separator. /** Separator. */
    private final String separator;

    
Trimmed prefix. /** Trimmed prefix. */
    private final String trimmedPrefix;

    
Trimmed suffix. /** Trimmed suffix. */
    private final String trimmedSuffix;

    
Trimmed separator. /** Trimmed separator. */
    private final String trimmedSeparator;

    
The format used for components. /** The format used for components. */
    private final NumberFormat format;

    
Create an instance with default settings.
The instance uses the default prefix, suffix and separator:
"{", "}", and "; " and the default number format for components.
/**
     * Create an instance with default settings.
     * <p>The instance uses the default prefix, suffix and separator:
     * "{", "}", and "; " and the default number format for components.</p>
     */
    protected VectorFormat() {
        this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR,
             CompositeFormat.getDefaultNumberFormat());
    }

    
Create an instance with a custom number format for components.
Params:
format – the custom format for components./**
     * Create an instance with a custom number format for components.
     * @param format the custom format for components.
     */
    protected VectorFormat(final NumberFormat format) {
        this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR, format);
    }

    
Create an instance with custom prefix, suffix and separator.
Params:
prefix – prefix to use instead of the default "{"
suffix – suffix to use instead of the default "}"
separator – separator to use instead of the default "; "/**
     * Create an instance with custom prefix, suffix and separator.
     * @param prefix prefix to use instead of the default "{"
     * @param suffix suffix to use instead of the default "}"
     * @param separator separator to use instead of the default "; "
     */
    protected VectorFormat(final String prefix, final String suffix,
                          final String separator) {
        this(prefix, suffix, separator, CompositeFormat.getDefaultNumberFormat());
    }

    
Create an instance with custom prefix, suffix, separator and format
for components.
Params:
prefix – prefix to use instead of the default "{"
suffix – suffix to use instead of the default "}"
separator – separator to use instead of the default "; "
format – the custom format for components./**
     * Create an instance with custom prefix, suffix, separator and format
     * for components.
     * @param prefix prefix to use instead of the default "{"
     * @param suffix suffix to use instead of the default "}"
     * @param separator separator to use instead of the default "; "
     * @param format the custom format for components.
     */
    protected VectorFormat(final String prefix, final String suffix,
                          final String separator, final NumberFormat format) {
        this.prefix      = prefix;
        this.suffix      = suffix;
        this.separator   = separator;
        trimmedPrefix    = prefix.trim();
        trimmedSuffix    = suffix.trim();
        trimmedSeparator = separator.trim();
        this.format      = format;
    }

    
Get the set of locales for which point/vector formats are available.
This is the same set as the NumberFormat set.
Returns:
available point/vector format locales./**
     * Get the set of locales for which point/vector formats are available.
     * <p>This is the same set as the {@link NumberFormat} set.</p>
     * @return available point/vector format locales.
     */
    public static Locale[] getAvailableLocales() {
        return NumberFormat.getAvailableLocales();
    }

    
Get the format prefix.
Returns:
format prefix./**
     * Get the format prefix.
     * @return format prefix.
     */
    public String getPrefix() {
        return prefix;
    }

    
Get the format suffix.
Returns:
format suffix./**
     * Get the format suffix.
     * @return format suffix.
     */
    public String getSuffix() {
        return suffix;
    }

    
Get the format separator between components.
Returns:
format separator./**
     * Get the format separator between components.
     * @return format separator.
     */
    public String getSeparator() {
        return separator;
    }

    
Get the components format.
Returns:
components format./**
     * Get the components format.
     * @return components format.
     */
    public NumberFormat getFormat() {
        return format;
    }

    
Formats a Vector object to produce a string. 
Params:
vector – the object to format.
Returns:
a formatted string./**
     * Formats a {@link Vector} object to produce a string.
     * @param vector the object to format.
     * @return a formatted string.
     */
    public String format(Vector<S> vector) {
        return format(vector, new StringBuffer(), new FieldPosition(0)).toString();
    }

    
Formats a Vector object to produce a string. 
Params:
vector – the object to format.
toAppendTo – where the text is to be appended
pos – On input: an alignment field, if desired. On output: the
           offsets of the alignment field
Returns:
the value passed in as toAppendTo./**
     * Formats a {@link Vector} object to produce a string.
     * @param vector 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 abstract StringBuffer format(Vector<S> vector,
                                        StringBuffer toAppendTo, FieldPosition pos);

    
Formats the coordinates of a Vector to produce a string. 
Params:
toAppendTo – where the text is to be appended
pos – On input: an alignment field, if desired. On output: the
           offsets of the alignment field
coordinates – coordinates of the object to format.
Returns:
the value passed in as toAppendTo./**
     * Formats the coordinates of a {@link Vector} to produce a string.
     * @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
     * @param coordinates coordinates of the object to format.
     * @return the value passed in as toAppendTo.
     */
    protected StringBuffer format(StringBuffer toAppendTo, FieldPosition pos,
                                  double ... coordinates) {

        pos.setBeginIndex(0);
        pos.setEndIndex(0);

        // format prefix
        toAppendTo.append(prefix);

        // format components
        for (int i = 0; i < coordinates.length; ++i) {
            if (i > 0) {
                toAppendTo.append(separator);
            }
            CompositeFormat.formatDouble(coordinates[i], format, toAppendTo, pos);
        }

        // format suffix
        toAppendTo.append(suffix);

        return toAppendTo;

    }

    
Parses a string to produce a Vector object. 
Params:
source – the string to parse
Throws:
MathParseException – if the beginning of the specified string
cannot be parsed.
Returns:
the parsed Vector object./**
     * Parses a string to produce a {@link Vector} object.
     * @param source the string to parse
     * @return the parsed {@link Vector} object.
     * @throws MathParseException if the beginning of the specified string
     * cannot be parsed.
     */
    public abstract Vector<S> parse(String source) throws MathParseException;

    
Parses a string to produce a Vector object. 
Params:
source – the string to parse
pos – input/output parsing parameter.
Returns:
the parsed Vector object./**
     * Parses a string to produce a {@link Vector} object.
     * @param source the string to parse
     * @param pos input/output parsing parameter.
     * @return the parsed {@link Vector} object.
     */
    public abstract Vector<S> parse(String source, ParsePosition pos);

    
Parses a string to produce an array of coordinates.
Params:
dimension – dimension of the space
source – the string to parse
pos – input/output parsing parameter.
Returns:
coordinates array./**
     * Parses a string to produce an array of coordinates.
     * @param dimension dimension of the space
     * @param source the string to parse
     * @param pos input/output parsing parameter.
     * @return coordinates array.
     */
    protected double[] parseCoordinates(int dimension, String source, ParsePosition pos) {

        int initialIndex = pos.getIndex();
        double[] coordinates = new double[dimension];

        // parse prefix
        CompositeFormat.parseAndIgnoreWhitespace(source, pos);
        if (!CompositeFormat.parseFixedstring(source, trimmedPrefix, pos)) {
            return null;
        }

        for (int i = 0; i < dimension; ++i) {

            // skip whitespace
            CompositeFormat.parseAndIgnoreWhitespace(source, pos);

            // parse separator
            if (i > 0 && !CompositeFormat.parseFixedstring(source, trimmedSeparator, pos)) {
                return null;
            }

            // skip whitespace
            CompositeFormat.parseAndIgnoreWhitespace(source, pos);

            // parse coordinate
            Number c = CompositeFormat.parseNumber(source, format, pos);
            if (c == null) {
                // invalid coordinate
                // set index back to initial, error index should already be set
                pos.setIndex(initialIndex);
                return null;
            }

            // store coordinate
            coordinates[i] = c.doubleValue();

        }

        // parse suffix
        CompositeFormat.parseAndIgnoreWhitespace(source, pos);
        if (!CompositeFormat.parseFixedstring(source, trimmedSuffix, pos)) {
            return null;
        }

        return coordinates;

    }

}