/*******************************************************************************
 * Copyright (c) 2007 - 2012 Red Hat, Inc.
 * Distributed under license by Red Hat, Inc. All rights reserved.
 * This program is made available under the terms of the
 * Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributor:
 *     Red Hat, Inc. - initial API and implementation
 ******************************************************************************/
package org.jboss.tools.common.model.loaders.impl;

import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.util.Date;
import java.util.Enumeration;
import java.util.Properties;

import org.jboss.tools.common.CommonPlugin;
import org.jboss.tools.common.util.FileUtil;

public class EncodedProperties extends Properties {
     private static final long serialVersionUID = 4112578634029123456L;

    /**
     * V.K.
     */
    private String encoding = "8859_1"; //$NON-NLS-1$

    /**
     * Creates an empty property list with no default values.
     */
    public EncodedProperties() {
    	this(null);
    }

    /**
     * Creates an empty property list with the specified defaults.
     *
     * @param   defaults   the defaults.
     */
    public EncodedProperties(EncodedProperties defaults) {
    	super(defaults);
    }

    /**
     * V.K
     * @param encoding
     */
    public void setEncoding(String encoding) {
    	this.encoding = encoding;
    }

    /**
     *
     * @param      inStream   the input stream.
     * @exception  IOException  if an error occurred when reading from the
     *               input stream.
     * @throws	   IllegalArgumentException if the input stream contains a
     * 		   malformed Unicode escape sequence.
     */
    public synchronized void load(InputStream inStream) throws IOException {
        char[] convtBuf = new char[1024];
        LineReader lr = new LineReader(inStream);

        int limit;
        int keyLen;
        int valueStart;
        char c;
        boolean hasSep;
        boolean precedingBackslash;

        while ((limit = lr.readLine()) >= 0) {
            c = 0;
            keyLen = 0;
            valueStart = limit;
            hasSep = false;

            precedingBackslash = false;
            while (keyLen < limit) {
                c = lr.lineBuf[keyLen];
                //need check if escaped.
                if ((c == '=' ||  c == ':') && !precedingBackslash) {
                    valueStart = keyLen + 1;
                    hasSep = true;
                    break;
                } else if ((c == ' ' || c == '\t' ||  c == '\f') && !precedingBackslash) {
                    valueStart = keyLen + 1;
                    break;
                } 
                if (c == '\\') {
                    precedingBackslash = !precedingBackslash;
                } else {
                    precedingBackslash = false;
                }
                keyLen++;
            }
            while (valueStart < limit) {
                c = lr.lineBuf[valueStart];
                if (c != ' ' && c != '\t' &&  c != '\f') {
                    if (!hasSep && (c == '=' ||  c == ':')) {
                        hasSep = true;
                    } else {
                        break;
                    }
                }
                valueStart++;
            }
        try {
            String key = loadConvert(lr.lineBuf, 0, keyLen, convtBuf);
            String value = loadConvert(lr.lineBuf, valueStart, limit - valueStart, convtBuf);
	    put(key, value);
        } catch (IllegalArgumentException e) {
        	//TODO create object for error marker
        }
	}
    }

    /* read in a "logical line" from input stream, skip all comment and
     * blank lines and filter out those leading whitespace characters 
     * (\u0020, \u0009 and \u000c) from the beginning of a "natural line". 
     * Method returns the char length of the "logical line" and stores 
     * the line in "lineBuf". 
     */
	class LineReader {
		char[] lineBuf = new char[1024];
		int inOff = 0;
		int inLimit = 0;
		String source = null;

		public LineReader(InputStream inStream) {
			source = FileUtil.readStream(inStream, encoding);
			inLimit = source.length();
		}

		int readLine() throws IOException {
			int len = 0;
			char c = 0;

			boolean skipWhiteSpace = true;
			boolean isCommentLine = false;
			boolean isNewLine = true;
			boolean appendedLineBegin = false;
			boolean precedingBackslash = false;
			boolean skipLF = false;

			while (true) {
				if (inOff >= inLimit) {
					if (len == 0 || isCommentLine) { 
						return -1; 
					}
					return len;
				}     

				//V.K.
				c = source.charAt(inOff++);

				if (skipLF) {
					skipLF = false;
					if (c == '\n') {
						continue;
					}
				}
				if (skipWhiteSpace) {
					if (c == ' ' || c == '\t' || c == '\f') {
						continue;
					}
					if (!appendedLineBegin && (c == '\r' || c == '\n')) {
						continue;
					}
					skipWhiteSpace = false;
					appendedLineBegin = false;
				}
				if (isNewLine) {
					isNewLine = false;
					if (c == '#' || c == '!') {
						isCommentLine = true;
						continue;
					}
				}

				if (c != '\n' && c != '\r') {
					lineBuf[len++] = c;
					if (len == lineBuf.length) {
						int newLength = lineBuf.length * 2;
						if (newLength < 0) {
							newLength = Integer.MAX_VALUE;
						}
						char[] buf = new char[newLength];
						System.arraycopy(lineBuf, 0, buf, 0, lineBuf.length);
						lineBuf = buf;
					}
					//flip the preceding backslash flag
					if (c == '\\') {
						precedingBackslash = !precedingBackslash;
					} else {
						precedingBackslash = false;
					}
				} else {
					// reached EOL
					if (isCommentLine || len == 0) {
						isCommentLine = false;
						isNewLine = true;
						skipWhiteSpace = true;
						len = 0;
						continue;
					}
					if (inOff >= inLimit) {
						return len;
					}
					if (precedingBackslash) {
						len -= 1;
						//skip the leading whitespace characters in following line
						skipWhiteSpace = true;
						appendedLineBegin = true;
						precedingBackslash = false;
						if (c == '\r') {
							skipLF = true;
						}
					} else {
						return len;
					}
				}
			}
	    }
    }    
    
    /*
     * Converts encoded &#92;uxxxx to unicode chars
     * and changes special saved chars to their original forms
     */
    private String loadConvert (char[] in, int off, int len, char[] convtBuf) {
        if (convtBuf.length < len) {
            int newLen = len * 2;
            if (newLen < 0) {
	        newLen = Integer.MAX_VALUE;
	    } 
	    convtBuf = new char[newLen];
        }
        char aChar;
        char[] out = convtBuf; 
        int outLen = 0;
        int end = off + len;

        while (off < end) {
            aChar = in[off++];
            if (aChar == '\\') {
                aChar = in[off++];   
                if(aChar == 'u') {
                    // Read the xxxx
                    int value=0;
		    for (int i=0; i<4; i++) {
		        aChar = in[off++];  
		        switch (aChar) {
		          case '0': case '1': case '2': case '3': case '4':
		          case '5': case '6': case '7': case '8': case '9':
		             value = (value << 4) + aChar - '0';
			     break;
			  case 'a': case 'b': case 'c':
                          case 'd': case 'e': case 'f':
			     value = (value << 4) + 10 + aChar - 'a';
			     break;
			  case 'A': case 'B': case 'C':
                          case 'D': case 'E': case 'F':
			     value = (value << 4) + 10 + aChar - 'A';
			     break;
			  default:
				  //TODO create object for error marker
                              throw new IllegalArgumentException(
                                           "Malformed \\uxxxx encoding."); //$NON-NLS-1$
                        }
                     }
                    out[outLen++] = (char)value;
                } else {
                    if (aChar == 't') aChar = '\t'; 
                    else if (aChar == 'r') aChar = '\r';
                    else if (aChar == 'n') aChar = '\n';
                    else if (aChar == 'f') aChar = '\f'; 
                    out[outLen++] = aChar;
                }
            } else {
	        out[outLen++] = (char)aChar;
            }
        }
        return new String (out, 0, outLen);
    }

    /*
     * Converts unicodes to encoded &#92;uxxxx and escapes
     * special characters with a preceding slash
     */
    public static String saveConvert(String theString, boolean escapeSpace) {
        int len = theString.length();
        int bufLen = len * 2;
        if (bufLen < 0) {
            bufLen = Integer.MAX_VALUE;
        }
        StringBuffer outBuffer = new StringBuffer(bufLen);

        for(int x=0; x<len; x++) {
            char aChar = theString.charAt(x);
            // Handle common case first, selecting largest block that
            // avoids the specials below
            if ((aChar > 61) && (aChar < 127)) {
                if (aChar == '\\') {
                    outBuffer.append('\\'); outBuffer.append('\\');
                    continue;
                }
                outBuffer.append(aChar);
                continue;
            }
            switch(aChar) {
		case ' ':
		    if (x == 0 || escapeSpace) 
			outBuffer.append('\\');
		    outBuffer.append(' ');
		    break;
                case '\t':outBuffer.append('\\'); outBuffer.append('t');
                          break;
                case '\n':outBuffer.append('\\'); outBuffer.append('n');
                          break;
                case '\r':outBuffer.append('\\'); outBuffer.append('r');
                          break;
                case '\f':outBuffer.append('\\'); outBuffer.append('f');
                          break;
                case '=': // Fall through
                case ':': // Fall through
                case '#': // Fall through
                case '!':
                    outBuffer.append('\\'); outBuffer.append(aChar);
                    break;
                default:
                    if ((aChar < 0x0020) || (aChar > 0x007e)) {
                        outBuffer.append('\\');
                        outBuffer.append('u');
                        outBuffer.append(toHex((aChar >> 12) & 0xF));
                        outBuffer.append(toHex((aChar >>  8) & 0xF));
                        outBuffer.append(toHex((aChar >>  4) & 0xF));
                        outBuffer.append(toHex( aChar        & 0xF));
                    } else {
                        outBuffer.append(aChar);
                    }
            }
        }
        return outBuffer.toString();
    }

    public synchronized void store(OutputStream out, String comments)
    throws IOException
    {
        BufferedWriter awriter;
        awriter = new BufferedWriter(new OutputStreamWriter(out, encoding));
        if (comments != null)
            writeln(awriter, "#" + comments); //$NON-NLS-1$
        writeln(awriter, "#" + new Date().toString()); //$NON-NLS-1$
        for (Enumeration e = keys(); e.hasMoreElements();) {
            String key = (String)e.nextElement();
            String val = (String)get(key);
            key = saveConvert(key, true);

	    /* No need to escape embedded and trailing spaces for value, hence
	     * pass false to flag.
	     */
            val = saveConvert(val, false);
            writeln(awriter, key + "=" + val); //$NON-NLS-1$
        }
        awriter.flush();
    }

    private static void writeln(BufferedWriter bw, String s) throws IOException {
        bw.write(s);
        bw.newLine();
    }

    /**
     * Convert a nibble to a hex character
     * @param	nibble	the nibble to convert.
     */
    private static char toHex(int nibble) {
	return hexDigit[(nibble & 0xF)];
    }

    /** A table of hex digits */
    private static final char[] hexDigit = {
	'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'
    };

    public static void main(String[] args) {
    	String ps = "p1:v1 \\\n  hh \\\n gg\n\np2=v2\\u0034\\u0055"; //$NON-NLS-1$
    	EncodedProperties p = new EncodedProperties();
    	ByteArrayInputStream s = new ByteArrayInputStream(ps.getBytes());
    	try {
    		p.load(s);
    	} catch (IOException e) {
    		e.printStackTrace();
    	}
    	p.list(System.out);
    }

}
