malinink / easy-tests

import java.io.BufferedReader;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStreamReader;

import javax.servlet.ReadListener;

import javax.servlet.ServletInputStream;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletRequestWrapper;

/**

 * @author atlassian

 * A {@link javax.servlet.http.HttpServletRequestWrapper} those {@link ServletInputStream} is

 * cached and can be reset and read again as often as necessary.

 */

public class ResettableRequestServletWrapper extends HttpServletRequestWrapper {

    private ServletInputStream servletInputStream;

    private BufferedReader reader;

    ResettableRequestServletWrapper(final HttpServletRequest request) {

        super(request);

    }

    /**

     * Will rewind the {@link ServletInputStream} to its beginning so it can be

     * read again.

     * <p>

     * Additionally the {@link #getReader()} will be removed if it was used. It will be

     * created again on its next usage.

     * <p>

     * Before resetting the stream the first time it has to be read entirely. The

     * reset will only provide a view from position 0 to the already read bytes from

     * that stream.

     * If the stream wasn't read at all the content will be empty.

     */

    public void resetInputStream() throws IOException {

        if (servletInputStream == null) {

            this.servletInputStream = new CachedServletInputStream(new byte[0]);

        } else if (servletInputStream instanceof WrappedOriginalServletInputStream) {

            final byte[] bytes = ((WrappedOriginalServletInputStream) servletInputStream)

                    .byteArrayOutputStream.toByteArray();

            this.servletInputStream = new CachedServletInputStream(bytes);

        } else if (servletInputStream instanceof CachedServletInputStream) {

            // just reset the already cached stream

            this.servletInputStream.reset();

        }

        this.reader = null;

    }

    @Override

    public ServletInputStream getInputStream() throws IOException {

        if (servletInputStream == null) {

            this.servletInputStream = new WrappedOriginalServletInputStream(

                    super.getInputStream(),

                    super.getContentLength()

            );

        }

        return this.servletInputStream;

    }

    @Override

    public BufferedReader getReader() throws IOException {

        if (this.reader == null) {

            final String encoding = super.getCharacterEncoding();

            final InputStreamReader streamReader = encoding == null

                    ? new InputStreamReader(this.getInputStream())

                    : new InputStreamReader(this.getInputStream(), encoding);

            this.reader = new BufferedReader(streamReader);

        }

        return this.reader;

    }

    /**

     * A {@link ServletInputStream} wrapping the original request and saving all read bytes.

     */

    private static final class WrappedOriginalServletInputStream extends ServletInputStream {

        private final ServletInputStream originalServletInputStream;

        private final ByteArrayOutputStream byteArrayOutputStream;

        @Override

        public boolean isFinished() {

            return originalServletInputStream.isFinished();

        }

        @Override

        public boolean isReady() {

            return originalServletInputStream.isReady();

        }

        @Override

        public void setReadListener(final ReadListener readListener) {

            originalServletInputStream.setReadListener(readListener);

        }

        @Override

        public int read() throws IOException {

            final int value = originalServletInputStream.read();

            if (value != -1) {

                byteArrayOutputStream.write(value);

            }

            return value;

        }

        @Override

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

            final int result = originalServletInputStream.read(b, off, len);

            if (result > 0) {

                byteArrayOutputStream.write(b, off, result);

            }

            return result;

        }

    }

    /**

     * A {@link ServletInputStream} backed by a non-blocking {@link java.io.InputStream}

     * which can be reset freely.

     */

    private static final class CachedServletInputStream extends ServletInputStream {

        private final ByteArrayInputStream inputStream;

        private CachedServletInputStream(final byte[] bytes) {

            this.inputStream = new ByteArrayInputStream(bytes);

        }

        @Override

        public int read() throws IOException {

            return inputStream.read();

        }

        @Override

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

            return inputStream.read(b, off, len);

        }

        @Override

        public boolean isFinished() {

            return inputStream.available() == 0;

        }

        @Override

        public boolean isReady() {

            return true;

        }

        @Override

        public void setReadListener(final ReadListener readListener) {

            throw new IllegalStateException("Can't set ReadListener on CachedServletInputStream.");

        }

        @Override

        public void reset() {

            inputStream.reset();

        }

    }

}