BEGIN LICENSE BLOCK *****
Version: EPL 2.0/GPL 2.0/LGPL 2.1
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
IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
implied. See the License for the specific language governing
rights and limitations under the License.
Copyright (C) 2006 Ola Bini 
Alternatively, the contents of this file may be used under the terms of
either of the GNU General Public License Version 2 or later (the "GPL"),
or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
in which case the provisions of the GPL or the LGPL are applicable instead
of those above. If you wish to allow use of your version of this file only
under the terms of either the GPL or the LGPL, and not to allow others to
use your version of this file under the terms of the EPL, indicate your
decision by deleting the provisions above and replace them with the notice
and other provisions required by the GPL or the LGPL. If you do not delete
the provisions above, a recipient may use your version of this file under
the terms of any one of the EPL, the GPL or the LGPL.
END LICENSE BLOCK /***** BEGIN LICENSE BLOCK *****
 * Version: EPL 2.0/GPL 2.0/LGPL 2.1
 *
 * 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
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2006 Ola Bini <Ola.Bini@ki.se>
 * 
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the EPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the EPL, the GPL or the LGPL.
 ***** END LICENSE BLOCK *****/

package org.jruby.util;

import java.io.InputStream;
import java.io.IOException;
import org.jcodings.Encoding;

import org.jruby.Ruby;
import org.jruby.RubyFixnum;
import org.jruby.RubyIO;
import org.jruby.RubyString;
import org.jruby.runtime.CallSite;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.runtime.MethodIndex;

This class wraps a IRubyObject in an InputStream. Depending on which messages
the IRubyObject answers to, it will have different functionality.
The point is that the IRubyObject could exhibit duck typing, in the style of IO versus StringIO, for example.
At the moment, the only functionality supported is reading, and the only requirement on the io-object is
that it responds to read() like IO.
/**
 * This class wraps a IRubyObject in an InputStream. Depending on which messages
 * the IRubyObject answers to, it will have different functionality.
 * 
 * The point is that the IRubyObject could exhibit duck typing, in the style of IO versus StringIO, for example.
 *
 * At the moment, the only functionality supported is reading, and the only requirement on the io-object is
 * that it responds to read() like IO.
 */
public class IOInputStream extends InputStream {
    private final IRubyObject io;
    private final InputStream in;
    private final IRubyObject numOne;
    private final CallSite readAdapter = MethodIndex.getFunctionalCallSite("read");
    private final CallSite closeAdapter = MethodIndex.getFunctionalCallSite("close");

    
Creates a new InputStream with the object provided.
Params:
io – the ruby object/**
     * Creates a new InputStream with the object provided.
     *
     * @param io the ruby object
     */
    public IOInputStream(IRubyObject io) {
        this(io, true);
    }

    public IOInputStream(final IRubyObject io, boolean verifyCanRead) {
        this.io = io;
        this.in = ( io instanceof RubyIO && !((RubyIO) io).isClosed() &&
                ((RubyIO) io).isBuiltin("read") ) ?
                    ((RubyIO) io).getInStream() : null;
        if (this.in == null) {
            if (verifyCanRead && !io.respondsTo("read")) {
                throw new IllegalArgumentException("Object: " + io + " is not a legal argument to this wrapper, " +
                        "cause it doesn't respond to \"read\".");
            }
        }
        this.numOne = RubyFixnum.one(io.getRuntime());
    }

    @Override
    public void close() throws IOException {
        if (in != null) {
            in.close();
        } else if (io.respondsTo("close")) {
            closeAdapter.call(io.getRuntime().getCurrentContext(), io, io);
        }
    }

    // Note: this method produces meaningful results
    // only for RubyIO objects. For everything else returns 0.
    @Override
    public int available() throws IOException {
        if (in != null) {
            return in.available();
        } else {
            return 0;
        }
    }
    
    public int read() throws IOException {
        if (in != null) {
            return in.read();
        }
        final Ruby runtime = io.getRuntime();
        IRubyObject readValue = readAdapter.call(runtime.getCurrentContext(), io, io, numOne);
        if (readValue.isNil()) return -1;
        return readValue.convertToString().getByteList().get(0) & 0xff;
    }

    @Override
    public int read(byte[] b) throws IOException {
        return read(b, 0, b.length);
    }

    @Override
    public int read(byte[] b, int off, int len) throws IOException {
        if (in != null) {
            return in.read(b, off, len);
        }
        final Ruby runtime = io.getRuntime();
        IRubyObject readValue = readAdapter.call(runtime.getCurrentContext(), io, io, runtime.newFixnum(len));
        if (readValue.isNil()) return -1;
        ByteList str = readValue.convertToString().getByteList();
        System.arraycopy(str.getUnsafeBytes(), str.getBegin(), b, off, str.getRealSize());
        return str.getRealSize();
     }
}