michael@0: /**
michael@0:  * Copyright (c) 2012, Ben Fortuna
michael@0:  * All rights reserved.
michael@0:  *
michael@0:  * Redistribution and use in source and binary forms, with or without
michael@0:  * modification, are permitted provided that the following conditions
michael@0:  * are met:
michael@0:  *
michael@0:  *  o Redistributions of source code must retain the above copyright
michael@0:  * notice, this list of conditions and the following disclaimer.
michael@0:  *
michael@0:  *  o Redistributions in binary form must reproduce the above copyright
michael@0:  * notice, this list of conditions and the following disclaimer in the
michael@0:  * documentation and/or other materials provided with the distribution.
michael@0:  *
michael@0:  *  o Neither the name of Ben Fortuna nor the names of any other contributors
michael@0:  * may be used to endorse or promote products derived from this software
michael@0:  * without specific prior written permission.
michael@0:  *
michael@0:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0:  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0:  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
michael@0:  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
michael@0:  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
michael@0:  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
michael@0:  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
michael@0:  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
michael@0:  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
michael@0:  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
michael@0:  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0:  */
michael@0: package net.fortuna.ical4j.data;
michael@0: 
michael@0: import java.io.IOException;
michael@0: import java.io.PushbackReader;
michael@0: import java.io.Reader;
michael@0: import java.util.Arrays;
michael@0: 
michael@0: import net.fortuna.ical4j.util.CompatibilityHints;
michael@0: 
michael@0: import org.apache.commons.logging.Log;
michael@0: import org.apache.commons.logging.LogFactory;
michael@0: 
michael@0: /**
michael@0:  * <pre>
michael@0:  * $Id$ [06-Apr-2004]
michael@0:  * </pre>
michael@0:  *
michael@0:  * A reader which performs iCalendar unfolding as it reads. Note that unfolding rules may be "relaxed" to allow
michael@0:  * unfolding of non-conformant *.ics files. By specifying the system property "ical4j.unfolding.relaxed=true" iCalendar
michael@0:  * files created with Mozilla Calendar/Sunbird may be correctly unfolded.
michael@0:  * 
michael@0:  * To wrap this reader with a {@link java.io.BufferedReader} you must ensure you specify an identical buffer size
michael@0:  * to that used in the {@link java.io.BufferedReader}.
michael@0:  * 
michael@0:  * @author Ben Fortuna
michael@0:  */
michael@0: public class UnfoldingReader extends PushbackReader {
michael@0: 
michael@0:     private Log log = LogFactory.getLog(UnfoldingReader.class);
michael@0: 
michael@0:     /**
michael@0:      * The pattern used to identify a fold in an iCalendar data stream.
michael@0:      */
michael@0:     private static final char[] DEFAULT_FOLD_PATTERN_1 = { '\r', '\n', ' ' };
michael@0:     
michael@0:     /** 
michael@0:      * The pattern used to identify a fold in Microsoft Outlook 2007. 
michael@0:      */ 
michael@0:     private static final char[] DEFAULT_FOLD_PATTERN_2 = { '\r', '\n', '\t' };
michael@0: 
michael@0:     /**
michael@0:      * The pattern used to identify a fold in Mozilla Calendar/Sunbird and KOrganizer.
michael@0:      */
michael@0:     private static final char[] RELAXED_FOLD_PATTERN_1 = { '\n', ' ' };
michael@0:     
michael@0:     /** 
michael@0:      * The pattern used to identify a fold in Microsoft Outlook 2007. 
michael@0:      */ 
michael@0:     private static final char[] RELAXED_FOLD_PATTERN_2 = { '\n', '\t' };
michael@0:     
michael@0:     private char[][] patterns;
michael@0: 
michael@0:     private char[][] buffers;
michael@0: 
michael@0:     private int linesUnfolded;
michael@0:     
michael@0:     private int maxPatternLength = 0;
michael@0: 
michael@0:     /**
michael@0:      * Creates a new unfolding reader instance. Relaxed unfolding flag is read from system property.
michael@0:      * @param in the reader to unfold from
michael@0:      */
michael@0:     public UnfoldingReader(final Reader in) {
michael@0:         this(in, DEFAULT_FOLD_PATTERN_1.length, CompatibilityHints
michael@0:                 .isHintEnabled(CompatibilityHints.KEY_RELAXED_UNFOLDING));
michael@0:     }
michael@0:     
michael@0:     /**
michael@0:      * @param in reader source for data
michael@0:      * @param size the buffer size
michael@0:      */
michael@0:     public UnfoldingReader(final Reader in, int size) {
michael@0:         this(in, size, CompatibilityHints.isHintEnabled(CompatibilityHints.KEY_RELAXED_UNFOLDING));
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * @param in reader source for data
michael@0:      * @param relaxed indicates whether relaxed unfolding is enabled
michael@0:      */
michael@0:     public UnfoldingReader(final Reader in, boolean relaxed) {
michael@0:         this(in, DEFAULT_FOLD_PATTERN_1.length, relaxed); 
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Creates a new unfolding reader instance.
michael@0:      * @param in a reader to read from
michael@0:      * @param size the buffer size
michael@0:      * @param relaxed specifies whether unfolding is relaxed
michael@0:      */
michael@0:     public UnfoldingReader(final Reader in, int size, final boolean relaxed) {
michael@0:         super(in, size);
michael@0:         if (relaxed) {
michael@0:             patterns = new char[4][];
michael@0:             patterns[0] = DEFAULT_FOLD_PATTERN_1;
michael@0:             patterns[1] = DEFAULT_FOLD_PATTERN_2;
michael@0:             patterns[2] = RELAXED_FOLD_PATTERN_1;
michael@0:             patterns[3] = RELAXED_FOLD_PATTERN_2;
michael@0:         }
michael@0:         else {
michael@0:             patterns = new char[2][];
michael@0:             patterns[0] = DEFAULT_FOLD_PATTERN_1;
michael@0:             patterns[1] = DEFAULT_FOLD_PATTERN_2;
michael@0:         }
michael@0:         buffers = new char[patterns.length][];
michael@0:         for (int i = 0; i < patterns.length; i++) {
michael@0:             buffers[i] = new char[patterns[i].length];
michael@0:             maxPatternLength = Math.max(maxPatternLength, patterns[i].length);
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * @return number of lines unfolded so far while reading
michael@0:      */
michael@0:     public final int getLinesUnfolded() {
michael@0:         return linesUnfolded;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * {@inheritDoc}
michael@0:      */
michael@0:     public final int read() throws IOException {
michael@0:         final int c = super.read();
michael@0:         boolean doUnfold = false;
michael@0:         for (int i = 0; i < patterns.length; i++) {
michael@0:             if (c == patterns[i][0]) {
michael@0:                 doUnfold = true;
michael@0:                 break;
michael@0:             }
michael@0:         }
michael@0:         if (!doUnfold) {
michael@0:             return c;
michael@0:         }
michael@0:         else {
michael@0:             unread(c);
michael@0:         }
michael@0: 
michael@0:         unfold();
michael@0: 
michael@0:         return super.read();
michael@0:     }
michael@0:     
michael@0:     /**
michael@0:      * {@inheritDoc}
michael@0:      */
michael@0:     public int read(final char[] cbuf, final int off, final int len) throws IOException {
michael@0:         final int read = super.read(cbuf, off, len);
michael@0:         boolean doUnfold = false;
michael@0:         for (int i = 0; i < patterns.length; i++) {
michael@0:             if (read > 0 && cbuf[0] == patterns[i][0]) {
michael@0:                 doUnfold = true;
michael@0:                 break;
michael@0:             }
michael@0:             else {
michael@0:                 for (int j = 0; j < read; j++) {
michael@0:                     if (cbuf[j] == patterns[i][0]) {
michael@0:                         unread(cbuf, j, read - j);
michael@0:                         return j;
michael@0:                     }
michael@0:                 }
michael@0:             }
michael@0:         }
michael@0:         if (!doUnfold) {
michael@0:             return read;
michael@0:         }
michael@0:         else {
michael@0:             unread(cbuf, off, read);
michael@0:         }
michael@0: 
michael@0:         unfold();
michael@0: 
michael@0:         return super.read(cbuf, off, maxPatternLength);
michael@0:     }
michael@0:     
michael@0:     private void unfold() throws IOException {
michael@0:         // need to loop since one line fold might be directly followed by another
michael@0:         boolean didUnfold;
michael@0:         do {
michael@0:             didUnfold = false;
michael@0: 
michael@0:             for (int i = 0; i < buffers.length; i++) {
michael@0:                 int read = 0;             
michael@0:                 while (read < buffers[i].length) {
michael@0:                     final int partialRead = super.read(buffers[i], read, buffers[i].length - read);
michael@0:                     if (partialRead < 0) {
michael@0:                         break;
michael@0:                     }
michael@0:                     read += partialRead;
michael@0:                 }
michael@0:                 if (read > 0) {
michael@0:                     if (!Arrays.equals(patterns[i], buffers[i])) {
michael@0:                         unread(buffers[i], 0, read);
michael@0:                     }
michael@0:                     else {
michael@0:                         if (log.isTraceEnabled()) {
michael@0:                             log.trace("Unfolding...");
michael@0:                         }
michael@0:                         linesUnfolded++;
michael@0:                         didUnfold = true;
michael@0:                     }
michael@0:                 }
michael@0: //                else {
michael@0: //                    return read;
michael@0: //                }
michael@0:             }
michael@0:         }
michael@0:         while (didUnfold);
michael@0:     }
michael@0: }