# ImageExt.java

    /*
    ** Module   : ImageExts.java
    ** Abstract : Enumerates default image files' extensions
    **
    ** Copyright (c) 2016-2017, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ---------------------------------Description----------------------------------
    ** 001 IAS 20160112 Created initial version.
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program is distributed in the hope that it will be useful,
    ** but WITHOUT ANY WARRANTY; without even the implied warranty of
    ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ** GNU Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
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    **
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    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
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    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
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    **     attribution required in this license.
    */

    package com.goldencode.p2j.util;

    import java.util.*;
    import java.util.function.*;
    import java.util.stream.*;

    /** Default image files' extensions */
    public enum ImageExt
    {
       BMP("bmp", "image/bmp"),

       ICO("ico", "image/ico"),

       CUR("cur", "application/cur"),

       NONE("", "application/octet-stream");

       /** list of extensions with dot */
       public final static List<String> EXT_BASES = Collections.unmodifiableList(
                Arrays.stream(values()).map(e -> e.base).collect(Collectors.toList())
             );

       /** list of extension variants with dot */
       public final static List<String> EXT_VARIANTS = Collections.unmodifiableList(
                Arrays.stream(values()).map(e -> e.variants).
                      flatMap(List::stream).collect(Collectors.toList())
             );

       /** mime type */
       public final String mimeType;

       /** extension with dot */
       public final String base;

       /** extension variants with dot */
       public final List<String> variants;

       /** map of ImageExt by  extension*/
       private final static Map<String, ImageExt> EXTS = Collections.unmodifiableMap(
                Arrays.stream(values()).
                   collect(Collectors.toMap((ImageExt e) -> e.ext, Function.identity()))
             );

       /** extension */
       private final String ext;

       /**
        * Constructor
        *
        * @param ext
        *        extension
        */
       private ImageExt(String ext, String mimeType)
       {
          this.ext = ext;
          this.mimeType = mimeType;
          this.base = "." + ext.toLowerCase();
          this.variants = generateVariants(ext.toLowerCase());
       }

       /**
        * Retrieve ImageExt by extension string
        *
        * @param ext
        *        string extension string
        *
        * @return ImageExt instance or <code>null</code>
        */
       public static ImageExt fromExt(String ext)
       {
          return ext == null ? NONE : EXTS.getOrDefault(ext.toLowerCase(), NONE);
       }

       /**
        * Generate extension variants
        *
        * @param ext
        *        extension
        *
        * @return list of extension variants with dot
        *
        */
       private static List<String> generateVariants(String ext)
       {
          char[] extChars = ext.toCharArray();
          int le = extChars.length;
          int nv = 1 << le;
          List<String> list = new ArrayList<>(nv);
          char[] extVariant = new char[le];
          for (int i = 0; i < nv; i++)
          {
             for (int nc = 0; nc < le; nc++)
             {
                char c = extChars[nc];
                extVariant[nc] = (i & (1 << nc)) == 0 ? c : Character.toUpperCase(c);
             }
             list.add("." + String.valueOf(extVariant));
          }

          return Collections.unmodifiableList(list);
       }
    }