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 *
 * The contents of this file are subject to the Eclipse Public
 * License Version 2.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.eclipse.org/legal/epl-v20.html
 *
 * Software distributed under the License is distributed on an "AS
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 * rights and limitations under the License.
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package org.jruby.ext.zlib;

import com.jcraft.jzlib.GZIPException;
import com.jcraft.jzlib.GZIPInputStream;
import com.jcraft.jzlib.Inflater;
import org.jruby.Ruby;
import org.jruby.RubyClass;
import org.jruby.RubyEnumerator;
import org.jruby.RubyException;
import org.jruby.RubyInteger;
import org.jruby.RubyNumeric;
import org.jruby.RubyString;
import org.jruby.anno.FrameField;
import org.jruby.anno.JRubyClass;
import org.jruby.anno.JRubyMethod;
import org.jruby.exceptions.RaiseException;
import org.jruby.runtime.Block;
import org.jruby.runtime.Helpers;
import org.jruby.runtime.ObjectAllocator;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.util.ByteList;
import org.jruby.util.IOInputStream;
import org.jruby.util.StringSupport;
import org.jruby.util.TypeConverter;
import org.jruby.util.io.EncodingUtils;
import org.jruby.util.io.PosixShim;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.PushbackInputStream;
import java.util.ArrayList;
import java.util.List;

import static org.jruby.RubyIO.PARAGRAPH_SEPARATOR;
import static org.jruby.runtime.Visibility.PRIVATE;

Author:
enebo/**
 *
 * @author enebo
 */
@JRubyClass(name = "Zlib::GzipReader", parent = "Zlib::GzipFile", include = "Enumerable")
public class JZlibRubyGzipReader extends RubyGzipFile {
    @JRubyClass(name = "Zlib::GzipReader::Error", parent = "Zlib::GzipReader")
    public static class Error {}
    
    protected static final ObjectAllocator GZIPREADER_ALLOCATOR = new ObjectAllocator() {
        @Override
        public IRubyObject allocate(Ruby runtime, RubyClass klass) {
        return new JZlibRubyGzipReader(runtime, klass);
        }
    };

    @JRubyMethod(name = "new", rest = true, meta = true)
    public static IRubyObject newInstance(ThreadContext context, IRubyObject recv, IRubyObject[] args, Block block) {
        JZlibRubyGzipReader result = newInstance(recv, args);

        return RubyGzipFile.wrapBlock(context, result, block);
    }

    public static JZlibRubyGzipReader newInstance(IRubyObject recv, IRubyObject[] args) {
        RubyClass klass = (RubyClass) recv;
        JZlibRubyGzipReader result = (JZlibRubyGzipReader) klass.allocate();

        result.callInit(args, Block.NULL_BLOCK);

        return result;
    }

    @JRubyMethod(name = "open", required = 1, optional = 1, meta = true)
    public static IRubyObject open19(final ThreadContext context, IRubyObject recv, IRubyObject[] args, Block block) {
        Ruby runtime = recv.getRuntime();
        args[0] = Helpers.invoke(context, runtime.getFile(), "open", args[0], runtime.newString("rb"));

        JZlibRubyGzipReader gzio = newInstance(recv, args);

        return RubyGzipFile.wrapBlock(context, gzio, block);
    }

    public JZlibRubyGzipReader(Ruby runtime, RubyClass type) {
        super(runtime, type);
    }

    public IRubyObject initialize(ThreadContext context, IRubyObject stream) {
        Ruby runtime = context.runtime;

        realIo = stream;

        try {
            // don't close realIO
            ioInputStream = new IOInputStream(realIo);
            io = new GZIPInputStream(ioInputStream, 512, false);

            // JRUBY-4502
            // CRuby expects to parse gzip header in 'new'.
            io.readHeader();

        } catch (IOException e) {
            RaiseException re = RubyZlib.newGzipFileError(runtime, "not in gzip format");

            byte[] input = io.getAvailIn();
            if (input != null && input.length > 0) {
                RubyException rubye = re.getException();
                rubye.setInstanceVariable("@input", 
                        RubyString.newString(runtime, new ByteList(input, 0, input.length)));
            }

            throw re;
        }

        position = 0;
        line = 0;
        bufferedStream = new PushbackInputStream(new BufferedInputStream(io), 512);

        return this;
    }

    @JRubyMethod(name = "initialize", required = 1, optional = 1, visibility = PRIVATE)
    public IRubyObject initialize19(ThreadContext context, IRubyObject[] args) {
        Ruby runtime = context.runtime;
        IRubyObject obj = initialize(context, args[0]);
        IRubyObject opt = context.nil;
        
        if (args.length == 2) {
            opt = args[1];
            if (TypeConverter.checkHashType(runtime, opt).isNil()) {
                throw runtime.newArgumentError(2, 1);
            }
        }
        
        ecopts(context, opt);

        return obj;
    }

    
Get position within this stream including that has been read by users
calling read + what jzlib may have speculatively read in because of
buffering.
Returns:
number of bytes/**
     * Get position within this stream including that has been read by users
     * calling read + what jzlib may have speculatively read in because of
     * buffering.
     *
     * @return number of bytes
     */
    private long internalPosition() {
        Inflater inflater = io.getInflater();

        return inflater.getTotalIn() + inflater.getAvailIn();
    }

    @JRubyMethod
    public IRubyObject rewind(ThreadContext context) {
        Ruby runtime = context.runtime;

        // should invoke seek on realIo...
        realIo.callMethod(context, "seek",
                new IRubyObject[]{runtime.newFixnum(-internalPosition()), runtime.newFixnum(PosixShim.SEEK_CUR)});

        // ... and then reinitialize
        initialize(context, realIo);

        return getRuntime().getNil();
    }

    @JRubyMethod(name = "lineno")
    public IRubyObject lineno() {
        return getRuntime().newFixnum(line);
    }

    @JRubyMethod(name = "readline", writes = FrameField.LASTLINE)
    public IRubyObject readline(ThreadContext context) {
        IRubyObject dst = gets(context, IRubyObject.NULL_ARRAY);

        if (dst.isNil()) throw context.runtime.newEOFError();

        return dst;
    }

    private IRubyObject internalGets(IRubyObject[] args) throws IOException {
        ByteList sep = ((RubyString) getRuntime().getGlobalVariables().get("$/")).getByteList();
        int limit = -1;

        switch (args.length) {
            case 0:
                break;
            case 1:
                if (args[0].isNil()) {
                    return readAll();
                }
                IRubyObject tmp = args[0].checkStringType();
                if (tmp.isNil()) {
                    limit = RubyNumeric.fix2int(args[0]);
                } else {
                    sep = tmp.convertToString().getByteList();
                }
                break;
            case 2:
            default:
                limit = RubyNumeric.fix2int(args[1]);
                if (args[0].isNil()) {
                    return readAll(limit);
                }
                sep = args[0].convertToString().getByteList();
                break;
        }

        return internalSepGets(sep, limit);
    }

    private IRubyObject internalSepGets(ByteList sep) throws IOException {
        return internalSepGets(sep, -1);
    }

    private ByteList newReadByteList() {
        ByteList byteList = new ByteList();

        return byteList;
    }

    private ByteList newReadByteList(int size) {
        ByteList byteList = new ByteList(size);

        return byteList;
    }

    private IRubyObject internalSepGets(ByteList sep, int limit) throws IOException {
        ByteList result = newReadByteList();
        boolean stripNewlines = false;

        if (sep.getRealSize() == 0) {
            sep = PARAGRAPH_SEPARATOR;
            stripNewlines = true;
        }

        if (stripNewlines) skipNewlines();

        int ce = -1;
        
        while (limit <= 0 || result.length() < limit) {
            int sepOffset = result.length() - sep.getRealSize();
            if (sepOffset >= 0 && result.startsWith(sep, sepOffset)) break;

            ce = bufferedStream.read();

            if (ce == -1) break;

            result.append(ce);
        }
        
        fixBrokenTrailingCharacter(result);

        if (stripNewlines) skipNewlines();

        // io.available() only returns 0 after EOF is encountered
        // so we need to differentiate between the empty string and EOF
        if (0 == result.length() && -1 == ce) return getRuntime().getNil();

        line++;
        position += result.length();

        return newStr(getRuntime(), result);
    }

    private static final int NEWLINE = '\n';

    private void skipNewlines() throws IOException {
        while (true) {
            int b = bufferedStream.read();
            if (b == -1) break;

            if (b != NEWLINE) {
                bufferedStream.unread(b);
                break;
            }
        }
    }

    @Deprecated
    public IRubyObject gets_18(ThreadContext context, IRubyObject[] args) {
        return gets(context, args);
    }

    @JRubyMethod(name = "gets", optional = 2, writes = FrameField.LASTLINE)
    public IRubyObject gets(ThreadContext context, IRubyObject[] args) {
        try {
            IRubyObject result = internalGets(args);

            if (!result.isNil()) context.setLastLine(result);
            
            return result;
        } catch (IOException ioe) {
            throw getRuntime().newIOErrorFromException(ioe);
        }
    }
    private final static int BUFF_SIZE = 4096;

    @JRubyMethod(name = "read", optional = 1)
    public IRubyObject read(ThreadContext context, IRubyObject[] args) {
        Ruby runtime = context.runtime;

        try {
            if (args.length == 0 || args[0].isNil()) return readAll();

            int len = RubyNumeric.fix2int(args[0]);
            
            if (len < 0) throw runtime.newArgumentError("negative length " + len + " given");

            if (len > 0) {
                // rb_gzfile_read
                ByteList buf = readSize(len);
                
                if (buf == null) return runtime.getNil();
                
                return runtime.newString(buf);
            }

            return RubyString.newEmptyString(runtime);
        } catch (IOException ioe) {
            String m = ioe.getMessage();

            if (m.startsWith("Unexpected end of ZLIB input stream")) {
                throw RubyZlib.newGzipFileError(runtime, ioe.getMessage());
            } else if (m.startsWith("footer is not found")) {
                throw RubyZlib.newNoFooter(runtime, "footer is not found");
            } else if (m.startsWith("incorrect data check")) {
                throw RubyZlib.newCRCError(runtime, "invalid compressed data -- crc error");
            } else if (m.startsWith("incorrect length check")) {
                throw RubyZlib.newLengthError(runtime, "invalid compressed data -- length error");
            } else {
                throw RubyZlib.newDataError(runtime, ioe.getMessage());
            }
        }
    }

    @JRubyMethod(name = "readpartial", required = 1, optional = 1)
    public IRubyObject readpartial(IRubyObject[] args) {
        try {
            int len = RubyNumeric.fix2int(args[0]);

            if (len < 0) {
                throw getRuntime().newArgumentError("negative length " + len + " given");
            }

            if (args.length > 1 && !args[1].isNil()) {
                if (!(args[1] instanceof RubyString)) {
                    throw getRuntime().newTypeError(
                            "wrong argument type " + args[1].getMetaClass().getName()
                            + " (expected String)");
                }

                return readPartial(len, (RubyString) args[1]);
            }

            return readPartial(len, null);
        } catch (IOException ioe) {
            throw getRuntime().newIOErrorFromException(ioe);
        }
    }

    private IRubyObject readPartial(int len, RubyString outbuf) throws IOException {
        ByteList val = newReadByteList(10);
        byte[] buffer = new byte[len];
        int read = bufferedStream.read(buffer, 0, len);

        if (read == -1) {
            return getRuntime().getNil();
        }

        val.append(buffer, 0, read);
        this.position += val.length();

        if (outbuf != null) {
            outbuf.view(val);
        }

        return newStr(getRuntime(), val);
    }

    private IRubyObject readAll() throws IOException {
        return readAll(-1);
    }

    private IRubyObject readAll(int limit) throws IOException {
        ByteList val = newReadByteList(10);
        int rest = limit == -1 ? BUFF_SIZE : limit;
        byte[] buffer = new byte[rest];
        
        while (rest > 0) {
            int read = bufferedStream.read(buffer, 0, rest);
            if (read == -1) break;

            val.append(buffer, 0, read);
            if (limit != -1) rest -= read;
        }
        
        fixBrokenTrailingCharacter(val);
        
        this.position += val.length();
        return newStr(getRuntime(), val);
    }


    // FIXME: I think offset == 0 should return empty bytelist and not null
    // mri: gzfile_read
    // This returns a bucket of bytes trying to read length bytes.
    private ByteList readSize(int length) throws IOException {
        byte[] buffer = new byte[length];
        int toRead = length;
        int offset = 0;

        while (toRead > 0) {
            int read = bufferedStream.read(buffer, offset, toRead);
            
            if (read == -1) {
                if (offset == 0) return null; // we're at EOF right away
                break;
            }
            
            toRead -= read;
            offset += read;
        } // hmm...

        this.position += length - toRead;

        return new ByteList(buffer, 0, length - toRead, false);
    }

    @JRubyMethod(name = "lineno=", required = 1)
    public IRubyObject set_lineno(IRubyObject lineArg) {
        line = RubyNumeric.fix2int(lineArg);

        return lineArg;
    }

    @JRubyMethod(name = {"pos", "tell"})
    public IRubyObject pos() {
        return RubyNumeric.int2fix(getRuntime(), position);
    }

    @JRubyMethod(name = "readchar")
    public IRubyObject readchar() {
        try {
            int value = bufferedStream.read();
            if (value == -1) throw getRuntime().newEOFError();

            position++;
            
            return getRuntime().newFixnum(value);
        } catch (IOException ioe) {
            throw getRuntime().newIOErrorFromException(ioe);
        }
    }

    @JRubyMethod(name = "getbyte")
    public IRubyObject getc() {
        try {
            int value = bufferedStream.read();
            if (value == -1) return getRuntime().getNil();

            position++;

            return getRuntime().newFixnum(value);
        } catch (IOException ioe) {
            throw getRuntime().newIOErrorFromException(ioe);
        }
    }

    public IRubyObject getbyte() {
        return getc();
    }

    @JRubyMethod(name = "readbyte")
    public IRubyObject readbyte() {
        IRubyObject dst = getbyte();
        if (dst.isNil()) {
            throw getRuntime().newEOFError();
        }
        return dst;
    }

    @JRubyMethod(name = "getc")
    public IRubyObject getc_19() {
        try {
            int value = bufferedStream.read();
            if (value == -1) return getRuntime().getNil();

            position++;
            // TODO: must handle encoding. Move encoding handling methods to util class from RubyIO and use it.
            // TODO: StringIO needs a love, too.
            return getRuntime().newString(String.valueOf((char) (value & 0xFF)));
        } catch (IOException ioe) {
            throw getRuntime().newIOErrorFromException(ioe);
        }
    }

    private boolean isEof() throws IOException {
        if (bufferedStream.available() == 0) return true;

        // Java's GZIPInputStream behavior is such
        // that it says that more bytes available even
        // when we are right before the EOF, but not yet
        // encountered the actual EOF during the reading.
        // So, we compensate for that to provide MRI
        // compatible behavior.
        byte[] bytes = new byte[16];
        int read = bufferedStream.read(bytes, 0, bytes.length);

        // We are already at EOF.
        if (read == -1) return true;

        bufferedStream.unread(bytes, 0, read);

        return bufferedStream.available() == 0;
    }

    @Override
    @JRubyMethod(name = "close")
    public IRubyObject close() {
        if (!closed) {
            try {
                /**
                 * We call internal IO#close directly, not via
                 * IOInputStream#close. IOInputStream#close directly invoke
                 * IO.getOutputStream().close() for IO object instead of just
                 * calling IO#cloase of Ruby. It causes EBADF at
                 * OpenFile#finalize.
                 *
                 * CAUTION: bufferedStream.close() will not cause
                 * 'IO.getOutputStream().close()', becase 'false' has been given
                 * as third augument in constructing GZIPInputStream.
                 *
                 * TODO: implement this without IOInputStream? Not so hard.
                 */
                bufferedStream.close();
                if (realIo.respondsTo("close")) {
                    realIo.callMethod(realIo.getRuntime().getCurrentContext(), "close");
                }
            } catch (IOException ioe) {
                throw getRuntime().newIOErrorFromException(ioe);
            }
        }
        this.closed = true;
        return realIo;
    }

    @JRubyMethod(name = "eof")
    public IRubyObject eof() {
        try {
            return isEof() ? getRuntime().getTrue() : getRuntime().getFalse();
        } catch (IOException ioe) {
            throw getRuntime().newIOErrorFromException(ioe);
        }
    }

    @JRubyMethod(name = "eof?")
    public IRubyObject eof_p() {
        return eof();
    }

    @JRubyMethod
    public IRubyObject unused() {
        byte[] tmp = io.getAvailIn();
        
        if (tmp == null) return getRuntime().getNil();

        return RubyString.newString(getRuntime(), tmp);
    }

    @Override
    @JRubyMethod
    public IRubyObject crc() {
        long crc = 0;

        try {
            crc = io.getCRC();
        } catch (GZIPException e) {
        }

        return getRuntime().newFixnum(crc);
    }

    @Override
    @JRubyMethod
    public IRubyObject os_code() {
        int os = io.getOS();
        
        if (os == 255) os = (byte) 0x0b; // NTFS filesystem (NT), because CRuby's test_zlib expect it.
        
        return getRuntime().newFixnum(os & 0xff);
    }

    @Override
    @JRubyMethod
    public IRubyObject orig_name() {
        String name = io.getName();

        nullFreeOrigName = getRuntime().newString(name);

        return super.orig_name();
    }

    @Override
    @JRubyMethod
    public IRubyObject comment() {
        String comment = io.getComment();

        nullFreeComment = getRuntime().newString(comment);

        return super.comment();
    }

    @JRubyMethod(optional = 1)
    public IRubyObject each(ThreadContext context, IRubyObject[] args, Block block) {
        if (!block.isGiven()) return RubyEnumerator.enumeratorize(context.runtime, this, "each", args);

        ByteList sep = ((RubyString) context.runtime.getGlobalVariables().get("$/")).getByteList();

        if (args.length > 0 && !args[0].isNil()) {
            sep = args[0].convertToString().getByteList();
        }

        try {
            for (IRubyObject result = internalSepGets(sep); !result.isNil(); result = internalSepGets(sep)) {
                block.yield(context, result);
            }
        } catch (IOException ioe) {
            throw context.runtime.newIOErrorFromException(ioe);
        }

        return context.nil;
    }

    @JRubyMethod(optional = 1)
    public IRubyObject each_line(ThreadContext context, IRubyObject[] args, Block block) {
        if (!block.isGiven()) return RubyEnumerator.enumeratorize(context.runtime, this, "each_line", args);

        return each(context, args, block);
    }

    @JRubyMethod
    public IRubyObject ungetc(ThreadContext context, IRubyObject c) {
        if (c.isNil()) return c;
        if (c instanceof RubyInteger) {
            c = EncodingUtils.encUintChr(context, ((RubyInteger) c).getIntValue(), getReadEncoding());
        } else {
            c = c.convertToString();
        }

        try {
            byte[] bytes = ((RubyString) c).getBytes();
            bufferedStream.unread(bytes);
            position -= bytes.length;
        } catch (IOException ioe) {
            throw context.runtime.newIOErrorFromException(ioe);
        }

        return context.nil;
    }

    @JRubyMethod
    public IRubyObject ungetbyte(IRubyObject b) {
        if (b.isNil()) return b;

        try {
            bufferedStream.unread(b.convertToInteger().getIntValue());
            position--;
        } catch (IOException ioe) {
            throw getRuntime().newIOErrorFromException(ioe);
        }

        return getRuntime().getNil();
    }

    @JRubyMethod(optional = 1)
    public IRubyObject readlines(ThreadContext context, IRubyObject[] args) {
        List<IRubyObject> array = new ArrayList<>();

        if (args.length != 0 && args[0].isNil()) {
            array.add(read(context, IRubyObject.NULL_ARRAY));

        } else {
            ByteList sep = ((RubyString) context.runtime.getGlobalVariables().get("$/")).getByteList();

            if (args.length > 0) sep = args[0].convertToString().getByteList();

            try {
                for (IRubyObject result = internalSepGets(sep); !result.isNil(); result = internalSepGets(sep)) {
                    array.add(result);
                }
            } catch (IOException ioe) {
                throw context.runtime.newIOErrorFromException(ioe);
            }
        }

        return getRuntime().newArray(array);
    }

    @JRubyMethod
    public IRubyObject each_byte(ThreadContext context, Block block) {
        final Ruby runtime = context.runtime;
        if (!block.isGiven()) return RubyEnumerator.enumeratorize(runtime, this, "each_byte");

        try {
            int value = bufferedStream.read();

            while (value != -1) {
                position++;
                block.yield(context, runtime.newFixnum(value));
                value = bufferedStream.read();
            }
        } catch (IOException ioe) {
            throw runtime.newIOErrorFromException(ioe);
        }

        return context.nil;
    }

    private void fixBrokenTrailingCharacter(ByteList result) throws IOException {
        // fix broken trailing character
        int extraBytes = StringSupport.bytesToFixBrokenTrailingCharacter(result.getUnsafeBytes(), result.getBegin(), result.getRealSize(), getReadEncoding(), result.length());

        for (int i = 0; i < extraBytes; i++) {
            int read = bufferedStream.read();
            if (read == -1) break;
            
            result.append(read);
        }
    }

    private int line = 0;
    private long position = 0;
    private IOInputStream ioInputStream;
    private GZIPInputStream io;
    private PushbackInputStream bufferedStream;
}