package com.drew.metadata.iptc;

import java.nio.ByteBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;

public final class Iso2022Converter
{

    private Iso2022Converter() 
    {
    }
    
    private static final String ISO_8859_1 = "ISO-8859-1";
    private static final String UTF_8 = "UTF-8";
    private static final int LATIN_CAPITAL_A = 0x41;
    private static final int DOT = 0xe280a2;
    private static final int LATIN_CAPITAL_G = 0x47;
    private static final int PERCENT_SIGN = 0x25;
    private static final int ESC = 0x1B;

    /**
     * Converts the given ISO2022 char set to a java char set.
     *
     * @param bytes the ISO2022 char set
     * @return the java char set name as a string or null if the converting was not possible
     */
    public static String convertISO2022CharsetToJavaCharset(byte[] bytes)
    {
        if (bytes[0] == ESC && bytes[1] == PERCENT_SIGN && bytes[2] == LATIN_CAPITAL_G)
            return UTF_8;
        if (bytes[0] == ESC && (bytes[3] & 0xFF | ((bytes[2] & 0xFF) << 8) | ((bytes[1] & 0xFF ) <<16)) == DOT && bytes[4] == LATIN_CAPITAL_A)
            return ISO_8859_1;

        return null;
    }

    /**
     * This method tries to guess if the encoding is UTF-8, System.getProperty("file.encoding") or ISO-8859-1.
     * It's only purpose is to guess the encoding if and only if iptc tag coded character set is not set. If the
     * encoding is not UTF-8, the tag should be set. Otherwise it is bad practice. This method tries to
     * workaround this issue since some metadata manipulating tools do not prevent such bad practice.
     *
     * About the reliability of this method: The check if some bytes are UTF-8 or not has a very high reliability.
     * The two other checks are less reliable.
     *
     * @param bytes some text as bytes
     * @return the name of the encoding or null if none could be guessed
     */
    static String guessEncoding(byte[] bytes) {
        CharsetDecoder cs = Charset.forName(UTF_8).newDecoder();

        try {
            cs.decode(ByteBuffer.wrap(bytes));
            return UTF_8;
        } catch (CharacterCodingException e) {
        }

        cs = Charset.forName(System.getProperty("file.encoding")).newDecoder();
        try 
        {
            cs.decode(ByteBuffer.wrap(bytes));
            return System.getProperty("file.encoding");
        } catch (CharacterCodingException e) 
        {
        }

        cs = Charset.forName(ISO_8859_1).newDecoder();
        try 
        {
            cs.decode(ByteBuffer.wrap(bytes));
            return ISO_8859_1;
        } catch (CharacterCodingException e) 
        {
        }

        return null;
    }
    
    
}

@@ -2212,24 +2212,55 @@
 eption e) %7B%0A
+            // fall through...%0A
         %7D%0A%0A 
@@ -2249,32 +2249,32 @@
 gh...%0A        %7D%0A
-
 %0A        cs = Ch
@@ -2341,33 +2341,32 @@
 r();%0A        try
- 
 %0A        %7B%0A     
@@ -2500,32 +2500,33 @@
 ingException e) 
+%7B
 %0A        %7B%0A     
@@ -2510,33 +2510,54 @@
 on e) %7B%0A        
-%7B
+    // fall through...
 %0A        %7D%0A%0A    
@@ -2618,17 +2618,16 @@
      try
- 
 %0A       
@@ -2752,16 +2752,17 @@
 tion e) 
+%7B
 %0A       
@@ -2754,33 +2754,54 @@
 on e) %7B%0A        
-%7B
+    // fall through...
 %0A        %7D%0A%0A    

Document fall-through of empty catch blocks.