/*
    * 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.linear;
  
  import java.text.FieldPosition;
  import java.text.NumberFormat;
  import java.text.ParsePosition;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Locale;
  
  import org.apache.commons.math4.legacy.exception.MathParseException;
  import org.apache.commons.math4.legacy.util.CompositeFormat;
  
  /**
   * Formats a vector in components list format "{v0; v1; ...; vk-1}".
   * <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>
   *
   * @since 2.0
   */
  public class RealVectorFormat {
  
      /** The default prefix: "{". */
      private static final String DEFAULT_PREFIX = "{";
      /** The default suffix: "}". */
      private static final String DEFAULT_SUFFIX = "}";
      /** The default separator: ", ". */
      private static final String DEFAULT_SEPARATOR = "; ";
      /** Prefix. */
      private final String prefix;
      /** Suffix. */
      private final String suffix;
      /** Separator. */
      private final String separator;
      /** Trimmed prefix. */
      private final String trimmedPrefix;
      /** Trimmed suffix. */
      private final String trimmedSuffix;
      /** Trimmed separator. */
      private final String trimmedSeparator;
      /** The format used for components. */
      private final NumberFormat format;
  
      /**
       * 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>
       */
      public RealVectorFormat() {
          this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR,
               CompositeFormat.getDefaultNumberFormat());
      }
  
      /**
       * Create an instance with a custom number format for components.
       * @param format the custom format for components.
       */
      public RealVectorFormat(final NumberFormat format) {
          this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR, format);
      }
  
      /**
       * 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 "; "
       */
      public RealVectorFormat(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.
       * @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.
      */
     public RealVectorFormat(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 real vectors formats are available.
      * <p>This is the same set as the {@link NumberFormat} set.</p>
      * @return available real vector format locales.
      */
     public static Locale[] getAvailableLocales() {
         return NumberFormat.getAvailableLocales();
     }
 
     /**
      * Get the format prefix.
      * @return format prefix.
      */
     public String getPrefix() {
         return prefix;
     }
 
     /**
      * Get the format suffix.
      * @return format suffix.
      */
     public String getSuffix() {
         return suffix;
     }
 
     /**
      * Get the format separator between components.
      * @return format separator.
      */
     public String getSeparator() {
         return separator;
     }
 
     /**
      * Get the components format.
      * @return components format.
      */
     public NumberFormat getFormat() {
         return format;
     }
 
     /**
      * Returns the default real vector format for the current locale.
      * @return the default real vector format.
      */
     public static RealVectorFormat getInstance() {
         return getInstance(Locale.getDefault());
     }
 
     /**
      * Returns the default real vector format for the given locale.
      * @param locale the specific locale used by the format.
      * @return the real vector format specific to the given locale.
      */
     public static RealVectorFormat getInstance(final Locale locale) {
         return new RealVectorFormat(CompositeFormat.getDefaultNumberFormat(locale));
     }
 
     /**
      * This method calls {@link #format(RealVector,StringBuffer,FieldPosition)}.
      *
      * @param v RealVector object to format.
      * @return a formatted vector.
      */
     public String format(RealVector v) {
         return format(v, new StringBuffer(), new FieldPosition(0)).toString();
     }
 
     /**
      * Formats a {@link RealVector} 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 StringBuffer format(RealVector vector, StringBuffer toAppendTo,
                                FieldPosition pos) {
 
         pos.setBeginIndex(0);
         pos.setEndIndex(0);
 
         // format prefix
         toAppendTo.append(prefix);
 
         // format components
         for (int i = 0; i < vector.getDimension(); ++i) {
             if (i > 0) {
                 toAppendTo.append(separator);
             }
             CompositeFormat.formatDouble(vector.getEntry(i), format, toAppendTo, pos);
         }
 
         // format suffix
         toAppendTo.append(suffix);
 
         return toAppendTo;
     }
 
     /**
      * Parse a string to produce a {@link RealVector} object.
      *
      * @param source String to parse.
      * @return the parsed {@link RealVector} object.
      * @throws MathParseException if the beginning of the specified string
      * cannot be parsed.
      */
     public ArrayRealVector parse(String source) {
         final ParsePosition parsePosition = new ParsePosition(0);
         final ArrayRealVector result = parse(source, parsePosition);
         if (parsePosition.getIndex() == 0) {
             throw new MathParseException(source,
                                          parsePosition.getErrorIndex(),
                                          ArrayRealVector.class);
         }
         return result;
     }
 
     /**
      * Parse a string to produce a {@link RealVector} object.
      *
      * @param source String to parse.
      * @param pos input/output parsing parameter.
      * @return the parsed {@link RealVector} object.
      */
     public ArrayRealVector parse(String source, ParsePosition pos) {
         int initialIndex = pos.getIndex();
 
         // parse prefix
         CompositeFormat.parseAndIgnoreWhitespace(source, pos);
         if (!CompositeFormat.parseFixedstring(source, trimmedPrefix, pos)) {
             return null;
         }
 
         // parse components
         List<Number> components = new ArrayList<>();
         for (boolean loop = true; loop;){
 
             if (!components.isEmpty()) {
                 CompositeFormat.parseAndIgnoreWhitespace(source, pos);
                 if (!CompositeFormat.parseFixedstring(source, trimmedSeparator, pos)) {
                     loop = false;
                 }
             }
 
             if (loop) {
                 CompositeFormat.parseAndIgnoreWhitespace(source, pos);
                 Number component = CompositeFormat.parseNumber(source, format, pos);
                 if (component != null) {
                     components.add(component);
                 } else {
                     // invalid component
                     // set index back to initial, error index should already be set
                     pos.setIndex(initialIndex);
                     return null;
                 }
             }
         }
 
         // parse suffix
         CompositeFormat.parseAndIgnoreWhitespace(source, pos);
         if (!CompositeFormat.parseFixedstring(source, trimmedSuffix, pos)) {
             return null;
         }
 
         // build vector
         double[] data = new double[components.size()];
         for (int i = 0; i < data.length; ++i) {
             data[i] = components.get(i).doubleValue();
         }
         return new ArrayRealVector(data, false);
     }
 }