/*
 * Copyright Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags and
 * the COPYRIGHT.txt file distributed with this work.
 *
 * Licensed 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.teiid.common.buffer;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
import java.lang.ref.PhantomReference;
import java.nio.charset.Charset;

import org.teiid.common.buffer.FileStore.FileStoreOutputStream;
import org.teiid.core.types.DataTypeManager;
import org.teiid.core.types.InputStreamFactory;

public final class FileStoreInputStreamFactory extends InputStreamFactory {
	private final FileStore lobBuffer;
	private FileStoreOutputStream fsos;
	private String encoding;
	private PhantomReference<Object> cleanup;
	private Writer writer;

	public FileStoreInputStreamFactory(FileStore lobBuffer, String encoding) {
		this.encoding = encoding;
		this.lobBuffer = lobBuffer;
		cleanup = AutoCleanupUtil.setCleanupReference(this, lobBuffer);
	}

	@Override
	public InputStream getInputStream() {
		return getInputStream(0, -1);
	}
	
	public InputStream getInputStream(long start, long len) {
		if (fsos != null && !fsos.bytesWritten()) {
			if (start > Integer.MAX_VALUE) {
				throw new AssertionError("Invalid start " + start); //$NON-NLS-1$
			}
			int s = (int)start;
			int intLen = fsos.getCount() - s;
			if (len >= 0) {
				intLen = (int)Math.min(len, len);
			}
			return new ByteArrayInputStream(fsos.getBuffer(), s, intLen);
		}
		return lobBuffer.createInputStream(start, len);
	}
	
	public byte[] getMemoryBytes() {
		if (fsos != null && !fsos.bytesWritten() && fsos.getBuffer().length == fsos.getCount()) {
			return fsos.getBuffer();
		}
		throw new IllegalStateException("In persistent mode or not closed for writing"); //$NON-NLS-1$
	}
	
	@Override
	public Reader getCharacterStream() throws IOException {
		return new InputStreamReader(getInputStream(), Charset.forName(encoding).newDecoder());
	}

	@Override
	public long getLength() {
		if (fsos != null && !fsos.bytesWritten()) {
			return fsos.getCount();
		}
		return lobBuffer.getLength();
	}

	/**
	 * Returns a new writer instance that is backed by the shared output stream.
	 * Closing a writer will prevent further writes.
	 * @return
	 */
	public Writer getWriter() {
		if (writer == null) {
			writer = new OutputStreamWriter(getOuputStream(), Charset.forName(encoding));
		}
		return writer;
	}
	
	/**
	 * The returned output stream is shared among all uses.
	 * Once closed no further writing can occur
	 * @return
	 */
	public FileStoreOutputStream getOuputStream() {
		return getOuputStream(DataTypeManager.MAX_LOB_MEMORY_BYTES);
	}
	
	/**
	 * The returned output stream is shared among all uses.
	 * Once closed no further writing can occur
	 * @return
	 */
	public FileStoreOutputStream getOuputStream(int maxMemorySize) {
		if (fsos == null) {
			fsos = lobBuffer.createOutputStream(maxMemorySize);
		}
		return fsos;
	}

	@Override
	public void free() {
		fsos = null;
		lobBuffer.remove();
		AutoCleanupUtil.removeCleanupReference(cleanup);
		cleanup = null;
	}
	
	@Override
	public StorageMode getStorageMode() {
		if (fsos == null || fsos.bytesWritten()) {
			return StorageMode.PERSISTENT;
		}
		return StorageMode.MEMORY;
	}
}