/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache 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.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.catalina.connector;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;

import org.apache.catalina.security.SecurityUtil;
import org.apache.tomcat.util.res.StringManager;

/**
 * This class handles reading bytes.
 *
 * @author Remy Maucherat
 */
public class CoyoteInputStream extends ServletInputStream {

    protected static final StringManager sm = StringManager.getManager(CoyoteInputStream.class);


    protected InputBuffer ib;


    protected CoyoteInputStream(InputBuffer ib) {
        this.ib = ib;
    }


    /**
     * Clear facade.
     */
    void clear() {
        ib = null;
    }


    /**
     * Prevent cloning the facade.
     */
    @Override
    protected Object clone() throws CloneNotSupportedException {
        throw new CloneNotSupportedException();
    }


    @Override
    public int read() throws IOException {
        checkNonBlockingRead();

        if (SecurityUtil.isPackageProtectionEnabled()) {

            try {
                Integer result = AccessController.doPrivileged(new PrivilegedRead(ib));
                return result.intValue();
            } catch (PrivilegedActionException pae) {
                Exception e = pae.getException();
                if (e instanceof IOException) {
                    throw (IOException) e;
                } else {
                    throw new RuntimeException(e.getMessage(), e);
                }
            }
        } else {
            return ib.readByte();
        }
    }

    @Override
    public int available() throws IOException {

        if (SecurityUtil.isPackageProtectionEnabled()) {
            try {
                Integer result = AccessController.doPrivileged(new PrivilegedAvailable(ib));
                return result.intValue();
            } catch (PrivilegedActionException pae) {
                Exception e = pae.getException();
                if (e instanceof IOException) {
                    throw (IOException) e;
                } else {
                    throw new RuntimeException(e.getMessage(), e);
                }
            }
        } else {
            return ib.available();
        }
    }

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


    @Override
    public int read(final byte[] b, final int off, final int len) throws IOException {
        checkNonBlockingRead();

        if (SecurityUtil.isPackageProtectionEnabled()) {
            try {
                Integer result = AccessController.doPrivileged(
                        new PrivilegedReadArray(ib, b, off, len));
                return result.intValue();
            } catch (PrivilegedActionException pae) {
                Exception e = pae.getException();
                if (e instanceof IOException) {
                    throw (IOException) e;
                } else {
                    throw new RuntimeException(e.getMessage(), e);
                }
            }
        } else {
            return ib.read(b, off, len);
        }
    }


    /**
     * Transfers bytes from the buffer to the specified ByteBuffer. After the
     * operation the position of the ByteBuffer will be returned to the one
     * before the operation, the limit will be the position incremented by
     * the number of the transferred bytes.
     *
     * @param b the ByteBuffer into which bytes are to be written.
     * @return an integer specifying the actual number of bytes read, or -1 if
     *         the end of the stream is reached
     * @throws IOException if an input or output exception has occurred
     */
    public int read(final ByteBuffer b) throws IOException {
        checkNonBlockingRead();

        if (SecurityUtil.isPackageProtectionEnabled()) {
            try {
                Integer result = AccessController.doPrivileged(new PrivilegedReadBuffer(ib, b));
                return result.intValue();
            } catch (PrivilegedActionException pae) {
                Exception e = pae.getException();
                if (e instanceof IOException) {
                    throw (IOException) e;
                } else {
                    throw new RuntimeException(e.getMessage(), e);
                }
            }
        } else {
            return ib.read(b);
        }
    }


    /**
     * Close the stream
     * Since we re-cycle, we can't allow the call to super.close()
     * which would permanently disable us.
     */
    @Override
    public void close() throws IOException {

        if (SecurityUtil.isPackageProtectionEnabled()) {
            try {
                AccessController.doPrivileged(new PrivilegedClose(ib));
            } catch (PrivilegedActionException pae) {
                Exception e = pae.getException();
                if (e instanceof IOException) {
                    throw (IOException) e;
                } else {
                    throw new RuntimeException(e.getMessage(), e);
                }
            }
        } else {
            ib.close();
        }
    }

    @Override
    public boolean isFinished() {
        return ib.isFinished();
    }


    @Override
    public boolean isReady() {
        if (ib == null) {
            throw new IllegalStateException(sm.getString("coyoteInputStream.null"));
        }
        return ib.isReady();
    }


    @Override
    public void setReadListener(ReadListener listener) {
        ib.setReadListener(listener);
    }


    private void checkNonBlockingRead() {
        if (!ib.isBlocking() && !ib.isReady()) {
            throw new IllegalStateException(sm.getString("coyoteInputStream.nbNotready"));
        }
    }


    private static class PrivilegedAvailable implements PrivilegedExceptionAction<Integer> {

        private final InputBuffer inputBuffer;

        public PrivilegedAvailable(InputBuffer inputBuffer) {
            this.inputBuffer = inputBuffer;
        }

        @Override
        public Integer run() throws IOException {
            return Integer.valueOf(inputBuffer.available());
        }
    }


    private static class PrivilegedClose implements PrivilegedExceptionAction<Void> {

        private final InputBuffer inputBuffer;

        public PrivilegedClose(InputBuffer inputBuffer) {
            this.inputBuffer = inputBuffer;
        }

        @Override
        public Void run() throws IOException {
            inputBuffer.close();
            return null;
        }
    }


    private static class PrivilegedRead implements PrivilegedExceptionAction<Integer> {

        private final InputBuffer inputBuffer;

        public PrivilegedRead(InputBuffer inputBuffer) {
            this.inputBuffer = inputBuffer;
        }

        @Override
        public Integer run() throws IOException {
            Integer integer = Integer.valueOf(inputBuffer.readByte());
            return integer;
        }
    }


    private static class PrivilegedReadArray implements PrivilegedExceptionAction<Integer> {

        private final InputBuffer inputBuffer;
        private final byte[] buf;
        private final int off;
        private final int len;

        public PrivilegedReadArray(InputBuffer inputBuffer, byte[] buf, int off, int len) {
            this.inputBuffer = inputBuffer;
            this.buf = buf;
            this.off = off;
            this.len = len;
        }

        @Override
        public Integer run() throws IOException {
            Integer integer = Integer.valueOf(inputBuffer.read(buf, off, len));
            return integer;
        }
    }


    private static class PrivilegedReadBuffer implements PrivilegedExceptionAction<Integer> {

        private final InputBuffer inputBuffer;
        private final ByteBuffer bb;

        public PrivilegedReadBuffer(InputBuffer inputBuffer, ByteBuffer bb) {
            this.inputBuffer = inputBuffer;
            this.bb = bb;
        }

        @Override
        public Integer run() throws IOException {
            Integer integer = Integer.valueOf(inputBuffer.read(bb));
            return integer;
        }
    }
}
