/*
 * $Id: JBIG2SegmentReader.java 4784 2011-03-15 08:33:00Z blowagie $
 *
 * This file is part of the iText (R) project.
 * Copyright (c) 1998-2011 1T3XT BVBA
 * Authors: Bruno Lowagie, Paulo Soares, et al.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3
 * as published by the Free Software Foundation with the addition of the
 * following permission added to Section 15 as permitted in Section 7(a):
 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY 1T3XT,
 * 1T3XT DISCLAIMS THE WARRANTY OF NON INFRINGEMENT OF THIRD PARTY RIGHTS.
 *
 * 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 should have received a copy of the GNU Affero General Public License
 * along with this program; if not, see http://www.gnu.org/licenses or write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA, 02110-1301 USA, or download the license from the following URL:
 * http://itextpdf.com/terms-of-use/
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License.
 *
 * In accordance with Section 7(b) of the GNU Affero General Public License,
 * a covered work must retain the producer line in every PDF that is created
 * or manipulated using iText.
 *
 * You can be released from the requirements of the license by purchasing
 * a commercial license. Buying such a license is mandatory as soon as you
 * develop commercial activities involving the iText software without
 * disclosing the source code of your own applications.
 * These activities include: offering paid services to customers as an ASP,
 * serving PDFs on the fly in a web application, shipping iText with a closed
 * source product.
 *
 * For more information, please contact iText Software Corp. at this
 * address: sales@itextpdf.com
 */
package com.itextpdf.text.pdf.codec;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;

import com.itextpdf.text.error_messages.MessageLocalization;
import com.itextpdf.text.pdf.RandomAccessFileOrArray;

/**
 * Class to read a JBIG2 file at a basic level: understand all the segments,
 * understand what segments belong to which pages, how many pages there are,
 * what the width and height of each page is, and global segments if there
 * are any.  Or: the minimum required to be able to take a normal sequential
 * or random-access organized file, and be able to embed JBIG2 pages as images
 * in a PDF.
 *
 * TODO: the indeterminate-segment-size value of dataLength, else?
 *
 * @since 2.1.5
 */

public class JBIG2SegmentReader {

        public static final int SYMBOL_DICTIONARY = 0; //see 7.4.2.

        public static final int INTERMEDIATE_TEXT_REGION = 4; //see 7.4.3.
        public static final int IMMEDIATE_TEXT_REGION = 6; //see 7.4.3.
        public static final int IMMEDIATE_LOSSLESS_TEXT_REGION = 7; //see 7.4.3.
        public static final int PATTERN_DICTIONARY = 16; //see 7.4.4.
        public static final int INTERMEDIATE_HALFTONE_REGION = 20; //see 7.4.5.
        public static final int IMMEDIATE_HALFTONE_REGION = 22; //see 7.4.5.
        public static final int IMMEDIATE_LOSSLESS_HALFTONE_REGION = 23; //see 7.4.5.
        public static final int INTERMEDIATE_GENERIC_REGION = 36; //see 7.4.6.
        public static final int IMMEDIATE_GENERIC_REGION = 38; //see 7.4.6.
        public static final int IMMEDIATE_LOSSLESS_GENERIC_REGION = 39; //see 7.4.6.
        public static final int INTERMEDIATE_GENERIC_REFINEMENT_REGION = 40; //see 7.4.7.
        public static final int IMMEDIATE_GENERIC_REFINEMENT_REGION = 42; //see 7.4.7.
        public static final int IMMEDIATE_LOSSLESS_GENERIC_REFINEMENT_REGION = 43; //see 7.4.7.

        public static final int PAGE_INFORMATION = 48; //see 7.4.8.
        public static final int END_OF_PAGE = 49; //see 7.4.9.
        public static final int END_OF_STRIPE = 50; //see 7.4.10.
        public static final int END_OF_FILE = 51; //see 7.4.11.
        public static final int PROFILES = 52; //see 7.4.12.
        public static final int TABLES = 53; //see 7.4.13.
        public static final int EXTENSION = 62; //see 7.4.14.

        private final SortedMap<Integer, JBIG2Segment> segments = new TreeMap<Integer, JBIG2Segment>();
        private final SortedMap<Integer, JBIG2Page> pages = new TreeMap<Integer, JBIG2Page>();
        private final SortedSet<JBIG2Segment> globals = new TreeSet<JBIG2Segment>();
        private RandomAccessFileOrArray ra;
        private boolean sequential;
        private boolean number_of_pages_known;
        private int number_of_pages = -1;
        private boolean read = false;

        /**
         * Inner class that holds information about a JBIG2 segment.
         * @since       2.1.5
         */
        public static class JBIG2Segment implements Comparable<JBIG2Segment> {

                public final int segmentNumber;
                public long dataLength = -1;
                public int page = -1;
                public int[] referredToSegmentNumbers = null;
                public boolean[] segmentRetentionFlags = null;
                public int type = -1;
                public boolean deferredNonRetain = false;
                public int countOfReferredToSegments = -1;
                public byte[] data = null;
                public byte[] headerData = null;
                public boolean page_association_size = false;
                public int page_association_offset = -1;

                public JBIG2Segment(int segment_number) {
                        this.segmentNumber = segment_number;
                }

                public int compareTo(JBIG2Segment s) {
                        return this.segmentNumber - s.segmentNumber;
                }


        }
        /**
         * Inner class that holds information about a JBIG2 page.
         * @since       2.1.5
         */
        public static class JBIG2Page {
                public final int page;
                private final JBIG2SegmentReader sr;
                private final SortedMap<Integer, JBIG2Segment> segs = new TreeMap<Integer, JBIG2Segment>();
                public int pageBitmapWidth = -1;
                public int pageBitmapHeight = -1;
                public JBIG2Page(int page, JBIG2SegmentReader sr) {
                        this.page = page;
                        this.sr = sr;
                }
                /**
                 * return as a single byte array the header-data for each segment in segment number
                 * order, EMBEDDED organization, but i am putting the needed segments in SEQUENTIAL organization.
                 * if for_embedding, skip the segment types that are known to be not for acrobat.
                 * @param for_embedding
                 * @return      a byte array
                 * @throws IOException
                 */
                public byte[] getData(boolean for_embedding) throws IOException {
                        ByteArrayOutputStream os = new ByteArrayOutputStream();
                        for (Integer sn : segs.keySet()) {
                                JBIG2Segment s = segs.get(sn);

                                // pdf reference 1.4, section 3.3.6 JBIG2Decode Filter
                                // D.3 Embedded organisation
                                if ( for_embedding &&
                                                ( s.type == END_OF_FILE || s.type == END_OF_PAGE ) ) {
                                        continue;
                                }

                                if ( for_embedding ) {
                                        // change the page association to page 1
                                        byte[] headerData_emb = copyByteArray(s.headerData);
                                        if ( s.page_association_size ) {
                                                headerData_emb[s.page_association_offset] = 0x0;
                                                headerData_emb[s.page_association_offset+1] = 0x0;
                                                headerData_emb[s.page_association_offset+2] = 0x0;
                                                headerData_emb[s.page_association_offset+3] = 0x1;
                                        } else {
                                                headerData_emb[s.page_association_offset] = 0x1;
                                        }
                                        os.write(headerData_emb);
                                } else {
                                        os.write(s.headerData);
                                }
                                os.write(s.data);
                        }
                        os.close();
                        return os.toByteArray();
                }
                public void addSegment(JBIG2Segment s) {
                        segs.put(Integer.valueOf(s.segmentNumber), s);
                }

        }

        public JBIG2SegmentReader(RandomAccessFileOrArray ra ) throws IOException {
                this.ra = ra;
        }

        public static byte[] copyByteArray(byte[] b) {
                byte[] bc = new byte[b.length];
                System.arraycopy(b, 0, bc, 0, b.length);
                return bc;
        }

        public void read() throws IOException {
                if ( this.read ) {
                        throw new IllegalStateException(MessageLocalization.getComposedMessage("already.attempted.a.read.on.this.jbig2.file"));
                }
                this.read = true;

                readFileHeader();
                // Annex D
                if ( this.sequential ) {
                        // D.1
                        do {
                                JBIG2Segment tmp = readHeader();
                                readSegment(tmp);
                                segments.put(Integer.valueOf(tmp.segmentNumber), tmp);
                        } while ( this.ra.getFilePointer() < this.ra.length() );
                } else {
                        // D.2
                        JBIG2Segment tmp;
                        do {
                                tmp = readHeader();
                                segments.put(Integer.valueOf(tmp.segmentNumber), tmp);
                        } while ( tmp.type != END_OF_FILE );
                        Iterator<Integer> segs = segments.keySet().iterator();
                        while ( segs.hasNext() ) {
                                readSegment(segments.get(segs.next()));
                        }
                }
        }

        void readSegment(JBIG2Segment s) throws IOException {
                int ptr = ra.getFilePointer();

                if ( s.dataLength == 0xffffffffl ) {
                        // TODO figure this bit out, 7.2.7
                        return;
                }

                byte[] data = new byte[(int)s.dataLength];
                ra.read(data);
                s.data = data;

                if ( s.type == PAGE_INFORMATION ) {
                        int last = ra.getFilePointer();
                        ra.seek(ptr);
                        int page_bitmap_width = ra.readInt();
                        int page_bitmap_height = ra.readInt();
                        ra.seek(last);
                        JBIG2Page p = pages.get(Integer.valueOf(s.page));
                        if ( p == null ) {
                                throw new IllegalStateException(MessageLocalization.getComposedMessage("referring.to.widht.height.of.page.we.havent.seen.yet.1", s.page));
                        }

                        p.pageBitmapWidth = page_bitmap_width;
                        p.pageBitmapHeight = page_bitmap_height;
                }
        }

        JBIG2Segment readHeader() throws IOException {
                int ptr = ra.getFilePointer();
                // 7.2.1
                int segment_number = ra.readInt();
                JBIG2Segment s = new JBIG2Segment(segment_number);

                // 7.2.3
                int segment_header_flags = ra.read();
                boolean deferred_non_retain = ( segment_header_flags & 0x80 ) == 0x80;
                s.deferredNonRetain = deferred_non_retain;
                boolean page_association_size = ( segment_header_flags & 0x40 ) == 0x40;
                int segment_type = segment_header_flags & 0x3f;
                s.type = segment_type;

                //7.2.4
                int referred_to_byte0 = ra.read();
                int count_of_referred_to_segments = (referred_to_byte0 & 0xE0) >> 5;
                int[] referred_to_segment_numbers = null;
                boolean[] segment_retention_flags = null;

                if ( count_of_referred_to_segments == 7 ) {
                        // at least five bytes
                        ra.seek(ra.getFilePointer() - 1);
                        count_of_referred_to_segments = ra.readInt() & 0x1fffffff;
                        segment_retention_flags = new boolean[count_of_referred_to_segments+1];
                        int i = 0;
                        int referred_to_current_byte = 0;
                        do {
                                int j = i % 8;
                                if ( j == 0) {
                                        referred_to_current_byte = ra.read();
                                }
                                segment_retention_flags[i] = (0x1 << j & referred_to_current_byte) >> j == 0x1;
                                i++;
                        } while ( i <= count_of_referred_to_segments );

                } else if ( count_of_referred_to_segments <= 4 ) {
                        // only one byte
                        segment_retention_flags = new boolean[count_of_referred_to_segments+1];
                        referred_to_byte0 &= 0x1f;
                        for ( int i = 0; i <= count_of_referred_to_segments; i++ ) {
                                segment_retention_flags[i] = (0x1 << i & referred_to_byte0) >> i == 0x1;
                        }

                } else if ( count_of_referred_to_segments == 5 || count_of_referred_to_segments == 6 ) {
                        throw new IllegalStateException(MessageLocalization.getComposedMessage("count.of.referred.to.segments.had.bad.value.in.header.for.segment.1.starting.at.2", String.valueOf(segment_number), String.valueOf(ptr)));
                }
                s.segmentRetentionFlags = segment_retention_flags;
                s.countOfReferredToSegments = count_of_referred_to_segments;

                // 7.2.5
                referred_to_segment_numbers = new int[count_of_referred_to_segments+1];
                for ( int i = 1; i <= count_of_referred_to_segments; i++ ) {
                        if ( segment_number <= 256 ) {
                                referred_to_segment_numbers[i] = ra.read();
                        } else if ( segment_number <= 65536 ) {
                                referred_to_segment_numbers[i] = ra.readUnsignedShort();
                        } else {
                                referred_to_segment_numbers[i] = (int)ra.readUnsignedInt(); // TODO wtf ack
                        }
                }
                s.referredToSegmentNumbers = referred_to_segment_numbers;

                // 7.2.6
                int segment_page_association;
                int page_association_offset = ra.getFilePointer() - ptr;
                if ( page_association_size ) {
                        segment_page_association = ra.readInt();
                } else {
                        segment_page_association = ra.read();
                }
                if ( segment_page_association < 0 ) {
                        throw new IllegalStateException(MessageLocalization.getComposedMessage("page.1.invalid.for.segment.2.starting.at.3", String.valueOf(segment_page_association), String.valueOf(segment_number), String.valueOf(ptr)));
                }
                s.page = segment_page_association;
                // so we can change the page association at embedding time.
                s.page_association_size = page_association_size;
                s.page_association_offset = page_association_offset;

                if ( segment_page_association > 0 && ! pages.containsKey(Integer.valueOf(segment_page_association)) ) {
                        pages.put(Integer.valueOf(segment_page_association), new JBIG2Page(segment_page_association, this));
                }
                if ( segment_page_association > 0 ) {
                        pages.get(Integer.valueOf(segment_page_association)).addSegment(s);
                } else {
                        globals.add(s);
                }

                // 7.2.7
                long segment_data_length = ra.readUnsignedInt();
                // TODO the 0xffffffff value that might be here, and how to understand those afflicted segments
                s.dataLength = segment_data_length;

                int end_ptr = ra.getFilePointer();
                ra.seek(ptr);
                byte[] header_data = new byte[end_ptr - ptr];
                ra.read(header_data);
                s.headerData  = header_data;

                return s;
        }

        void readFileHeader() throws IOException {
                ra.seek(0);
                byte[] idstring = new byte[8];
                ra.read(idstring);

                byte[] refidstring = {(byte)0x97, 0x4A, 0x42, 0x32, 0x0D, 0x0A, 0x1A, 0x0A};

                for ( int i = 0; i < idstring.length; i++ ) {
                        if ( idstring[i] != refidstring[i] ) {
                                throw new IllegalStateException(MessageLocalization.getComposedMessage("file.header.idstring.not.good.at.byte.1", i));
                        }
                }

                int fileheaderflags = ra.read();

                this.sequential = ( fileheaderflags & 0x1 ) == 0x1;
                this.number_of_pages_known = ( fileheaderflags & 0x2) == 0x0;

                if ( (fileheaderflags & 0xfc) != 0x0 ) {
                        throw new IllegalStateException(MessageLocalization.getComposedMessage("file.header.flags.bits.2.7.not.0"));
                }

                if ( this.number_of_pages_known ) {
                        this.number_of_pages = ra.readInt();
                }
        }

        public int numberOfPages() {
                return pages.size();
        }

        public int getPageHeight(int i) {
                return pages.get(Integer.valueOf(i)).pageBitmapHeight;
        }

        public int getPageWidth(int i) {
                return pages.get(Integer.valueOf(i)).pageBitmapWidth;
        }

        public JBIG2Page getPage(int page) {
                return pages.get(Integer.valueOf(page));
        }

        public byte[] getGlobal(boolean for_embedding) {
                ByteArrayOutputStream os = new ByteArrayOutputStream();
                try {
                        for (Object element : globals) {
                                JBIG2Segment s = (JBIG2Segment)element;
                                if ( for_embedding &&
                                                ( s.type == END_OF_FILE || s.type == END_OF_PAGE ) ) {
                                        continue;
                                }
                                os.write(s.headerData);
                                os.write(s.data);
                        }
                        os.close();
                } catch (IOException e) {
                        e.printStackTrace();
                }
                if ( os.size() <= 0 ) {
                        return null;
                }
                return os.toByteArray();
        }

        @Override
    public String toString() {
                if ( this.read ) {
                        return "Jbig2SegmentReader: number of pages: " + this.numberOfPages();
                } else {
                        return "Jbig2SegmentReader in indeterminate state.";
                }
        }
}