Copyright (c) 2007, 2014 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
    James Blackburn  - [implementation] FileStoreTextFileBuffer eats IOException on external file save - https://bugs.eclipse.org/333660
/*******************************************************************************
 * Copyright (c) 2007, 2014 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     James Blackburn <jamesblackburn+eclipse@gmail.com> - [implementation] FileStoreTextFileBuffer eats IOException on external file save - https://bugs.eclipse.org/333660
 *******************************************************************************/
package org.eclipse.core.internal.filebuffers;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.Reader;
import java.io.SequenceInputStream;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CodingErrorAction;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.StandardCharsets;
import java.nio.charset.UnmappableCharacterException;
import java.nio.charset.UnsupportedCharsetException;

import org.eclipse.core.filesystem.EFS;
import org.eclipse.core.filesystem.IFileInfo;
import org.eclipse.core.filesystem.IFileStore;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Path;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.QualifiedName;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.content.IContentDescription;
import org.eclipse.core.runtime.content.IContentType;

import org.eclipse.core.resources.IResourceStatus;

import org.eclipse.core.filebuffers.IFileBufferStatusCodes;
import org.eclipse.core.filebuffers.IPersistableAnnotationModel;
import org.eclipse.core.filebuffers.ITextFileBuffer;
import org.eclipse.core.filebuffers.LocationKind;

import org.eclipse.jface.text.DocumentEvent;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IDocumentListener;
import org.eclipse.jface.text.source.IAnnotationModel;

Since:
3.3 (previously available as JavaTextFileBuffer since 3.3)/**
 * @since 3.3 (previously available as JavaTextFileBuffer since 3.3)
 */
public class FileStoreTextFileBuffer extends FileStoreFileBuffer implements ITextFileBuffer {


	private class DocumentListener implements IDocumentListener {

		@Override
		public void documentAboutToBeChanged(DocumentEvent event) {
			// do nothing
		}

		@Override
		public void documentChanged(DocumentEvent event) {
			fCanBeSaved= true;
			removeFileBufferContentListeners();
			fManager.fireDirtyStateChanged(FileStoreTextFileBuffer.this, fCanBeSaved);
		}
	}

	
Reader chunk size.
/**
	 * Reader chunk size.
	 */
	private static final int READER_CHUNK_SIZE= 2048;
	
Buffer size.
/**
	 * Buffer size.
	 */
	private static final int BUFFER_SIZE= 8 * READER_CHUNK_SIZE;
	
Constant for representing the error status. This is considered a value object.
/**
	 * Constant for representing the error status. This is considered a value object.
	 */
	private static final IStatus STATUS_ERROR= new Status(IStatus.ERROR, FileBuffersPlugin.PLUGIN_ID, IStatus.OK, FileBuffersMessages.FileBuffer_status_error, null);

	
Constant denoting an empty set of properties
Since:
3.1/**
	 * Constant denoting an empty set of properties
	 * @since 3.1
	 */
	private static final QualifiedName[] NO_PROPERTIES= new QualifiedName[0];


	
The element's document /** The element's document */
	protected IDocument fDocument;
	
The encoding used to create the document from the storage or null for workbench encoding. /** The encoding used to create the document from the storage or <code>null</code> for workbench encoding. */
	protected String fEncoding;
	
Internal document listener /** Internal document listener */
	protected IDocumentListener fDocumentListener= new DocumentListener();
	
The encoding which has explicitly been set on the file. /** The encoding which has explicitly been set on the file. */
	private String fExplicitEncoding;
	
Tells whether the file on disk has a BOM. /** Tells whether the file on disk has a BOM. */
	private boolean fHasBOM;
	
The annotation model of this file buffer /** The annotation model of this file buffer */
	private IAnnotationModel fAnnotationModel;
	
Lock for lazy creation of annotation model.
Since:
3.2/**
	 * Lock for lazy creation of annotation model.
	 * @since 3.2
	 */
	private final Object fAnnotationModelCreationLock= new Object();
	
Tells whether the cache is up to date.
Since:
3.2/**
	 * Tells whether the cache is up to date.
	 * @since 3.2
	 */
	private boolean fIsCacheUpdated= false;


	public FileStoreTextFileBuffer(TextFileBufferManager manager) {
		super(manager);
	}

	@Override
	public IDocument getDocument() {
		return fDocument;
	}

	@Override
	public IAnnotationModel getAnnotationModel() {
		synchronized (fAnnotationModelCreationLock) {
			if (fAnnotationModel == null && !isDisconnected()) {
				fAnnotationModel= fManager.createAnnotationModel(getLocationOrName(), LocationKind.LOCATION);
				if (fAnnotationModel != null)
					fAnnotationModel.connect(fDocument);
			}
		}
		return fAnnotationModel;
	}

	@Override
	public String getEncoding() {
		if (!fIsCacheUpdated)
			cacheEncodingState();
		return fEncoding;
	}

	@Override
	public void setEncoding(String encoding) {
		fExplicitEncoding= encoding;
		if (encoding == null || encoding.equals(fEncoding))
			fIsCacheUpdated= false;
		else {
			fEncoding= encoding;
			fHasBOM= false;
		}
	}

	@Override
	public IStatus getStatus() {
		if (!isDisconnected()) {
			if (fStatus != null)
				return fStatus;
			return (fDocument == null ? STATUS_ERROR : Status.OK_STATUS);
		}
		return STATUS_ERROR;
	}

	private InputStream getFileContents(IFileStore fileStore) throws CoreException {
		if (!fFileStore.fetchInfo().exists())
			return null;

		return fileStore.openInputStream(EFS.NONE, null);
	}

	private void setFileContents(InputStream stream, IProgressMonitor monitor) throws CoreException {
		try(OutputStream out= fFileStore.openOutputStream(EFS.NONE, null)) {
			byte[] buffer= new byte[8192];
			while (true) {
				int bytesRead= -1;
				bytesRead= stream.read(buffer);
				if (bytesRead == -1) {
					out.close();
					break;
				}
				out.write(buffer, 0, bytesRead);
				if (monitor != null)
					monitor.worked(1);
			}
		} catch (IOException ex) {
			String message= (ex.getMessage() != null ? ex.getMessage() : ""); //$NON-NLS-1$
			IStatus s= new Status(IStatus.ERROR, FileBuffersPlugin.PLUGIN_ID, IStatus.OK, message, ex);
			throw new CoreException(s);
		} finally {
			try {
				stream.close();
			} catch (IOException e) {
				// ignore
			}
		}
	}

	@Override
	public void revert(IProgressMonitor monitor) throws CoreException {
		if (isDisconnected())
			return;

		IDocument original= null;
		fStatus= null;

		try {
			original= fManager.createEmptyDocument(getLocationOrName(), LocationKind.LOCATION);
			cacheEncodingState();
			setDocumentContent(original, fFileStore, fEncoding, fHasBOM, monitor);
		} catch (CoreException x) {
			fStatus= x.getStatus();
		}

		if (original == null)
			return;

		String originalContents= original.get();
		boolean replaceContents= !originalContents.equals(fDocument.get());

		if (!replaceContents && !fCanBeSaved)
			return;

		fManager.fireStateChanging(this);
		try {

			if (replaceContents)  {
				fManager.fireBufferContentAboutToBeReplaced(this);
				fDocument.set(original.get());
			}

			boolean fireDirtyStateChanged= fCanBeSaved;
			if (fCanBeSaved) {
				fCanBeSaved= false;
				addFileBufferContentListeners();
			}

			if (replaceContents)
				fManager.fireBufferContentReplaced(this);

			IFileInfo info= fFileStore.fetchInfo();
			if (info.exists())
				fSynchronizationStamp= fFileStore.fetchInfo().getLastModified();

			if (fAnnotationModel instanceof IPersistableAnnotationModel) {
				IPersistableAnnotationModel persistableModel= (IPersistableAnnotationModel) fAnnotationModel;
				try {
					persistableModel.revert(fDocument);
				} catch (CoreException x) {
					fStatus= x.getStatus();
				}
			}

			if (fireDirtyStateChanged)
				fManager.fireDirtyStateChanged(this, fCanBeSaved);

		} catch (RuntimeException x) {
			fManager.fireStateChangeFailed(this);
			throw x;
		}
	}

	/*
	 * @see org.eclipse.core.filebuffers.IFileBuffer#getContentType()
	 * @since 3.1
	 */
	@Override
	public IContentType getContentType () throws CoreException {
		try {
			if (isDirty()) {
				try(Reader reader= new DocumentReader(getDocument())) {
					IContentDescription desc= Platform.getContentTypeManager().getDescriptionFor(reader, fFileStore.getName(), NO_PROPERTIES);
					if (desc != null && desc.getContentType() != null)
						return desc.getContentType();
				}
			}

			try(InputStream stream= fFileStore.openInputStream(EFS.NONE, null)) {
				IContentDescription desc= Platform.getContentTypeManager().getDescriptionFor(stream, fFileStore.getName(), NO_PROPERTIES);
				if (desc != null && desc.getContentType() != null)
					return desc.getContentType();
				return null;
			}
		} catch (IOException x) {
			throw new CoreException(new Status(IStatus.ERROR, FileBuffersPlugin.PLUGIN_ID, IStatus.OK, NLSUtility.format(FileBuffersMessages.FileBuffer_error_queryContentDescription, fFileStore.toString()), x));
		}
	}

	@Override
	protected void addFileBufferContentListeners() {
		if (fDocument != null)
			fDocument.addDocumentListener(fDocumentListener);
	}

	@Override
	protected void removeFileBufferContentListeners() {
		if (fDocument != null)
			fDocument.removeDocumentListener(fDocumentListener);
	}

	@Override
	protected void initializeFileBufferContent(IProgressMonitor monitor) throws CoreException {
		try {
			fDocument= fManager.createEmptyDocument(getLocationOrName(), LocationKind.LOCATION);
			cacheEncodingState();
			setDocumentContent(fDocument, fFileStore, fEncoding, fHasBOM, monitor);
		} catch (CoreException x) {
			fDocument= fManager.createEmptyDocument(getLocationOrName(), LocationKind.LOCATION);
			fStatus= x.getStatus();
		}
	}

	@Override
	protected void connected() {
		super.connected();
		if (fAnnotationModel != null)
			fAnnotationModel.connect(fDocument);
	}

	@Override
	protected void disconnected() {
		if (fAnnotationModel != null)
			fAnnotationModel.disconnect(fDocument);
		super.disconnected();
	}

	protected void cacheEncodingState() {
		fEncoding= fExplicitEncoding;
		fHasBOM= false;
		fIsCacheUpdated= true;

		try(InputStream stream= getFileContents(fFileStore)) {
			if (stream == null)
				return;

			QualifiedName[] options= new QualifiedName[] { IContentDescription.CHARSET, IContentDescription.BYTE_ORDER_MARK };
			IContentDescription description= Platform.getContentTypeManager().getDescriptionFor(stream, fFileStore.getName(), options);
			if (description != null) {
				fHasBOM= description.getProperty(IContentDescription.BYTE_ORDER_MARK) != null;
				if (fEncoding == null)
					fEncoding= description.getCharset();
			}
		} catch (CoreException | IOException e) {
			// do nothing
		}

		// Use global default
		if (fEncoding == null)
			fEncoding= fManager.getDefaultEncoding();

	}

	@Override
	protected void commitFileBufferContent(IProgressMonitor monitor, boolean overwrite) throws CoreException {
		if (!isSynchronized() && !overwrite) {
			String message= NLSUtility.format(FileBuffersMessages.FileBuffer_error_outOfSync, getFileStore().toURI());
			throw new CoreException(new Status(IStatus.WARNING, FileBuffersPlugin.PLUGIN_ID, IResourceStatus.OUT_OF_SYNC_LOCAL, message, null));
		}

		String encoding= computeEncoding();

		Charset charset;
		try {
			charset= Charset.forName(encoding);
		} catch (UnsupportedCharsetException ex) {
			String message= NLSUtility.format(FileBuffersMessages.ResourceTextFileBuffer_error_unsupported_encoding_message_arg, encoding);
			IStatus s= new Status(IStatus.ERROR, FileBuffersPlugin.PLUGIN_ID, IStatus.OK, message, ex);
			throw new CoreException(s);
		} catch (IllegalCharsetNameException ex) {
			String message= NLSUtility.format(FileBuffersMessages.ResourceTextFileBuffer_error_illegal_encoding_message_arg, encoding);
			IStatus s= new Status(IStatus.ERROR, FileBuffersPlugin.PLUGIN_ID, IStatus.OK, message, ex);
			throw new CoreException(s);
		}

		CharsetEncoder encoder= charset.newEncoder();
		encoder.onMalformedInput(CodingErrorAction.REPLACE);
		encoder.onUnmappableCharacter(CodingErrorAction.REPORT);

		byte[] bytes;
		int bytesLength;

		try {
			ByteBuffer byteBuffer= encoder.encode(CharBuffer.wrap(fDocument.get()));
			bytesLength= byteBuffer.limit();
			if (byteBuffer.hasArray())
				bytes= byteBuffer.array();
			else {
				bytes= new byte[bytesLength];
				byteBuffer.get(bytes);
			}
		} catch (CharacterCodingException ex) {
			Assert.isTrue(ex instanceof UnmappableCharacterException);
			String message= NLSUtility.format(FileBuffersMessages.ResourceTextFileBuffer_error_charset_mapping_failed_message_arg, encoding);
			IStatus s= new Status(IStatus.ERROR, FileBuffersPlugin.PLUGIN_ID, IFileBufferStatusCodes.CHARSET_MAPPING_FAILED, message, null);
			throw new CoreException(s);
		}

		IFileInfo fileInfo= fFileStore.fetchInfo();
		if (fileInfo != null && fileInfo.exists()) {

			if (!overwrite)
				checkSynchronizationState();

			InputStream stream= new ByteArrayInputStream(bytes, 0, bytesLength);

			/*
			 * XXX:
			 * This is a workaround for a corresponding bug in Java readers and writer,
			 * see http://developer.java.sun.com/developer/bugParade/bugs/4508058.html
			 */
			if (fHasBOM && StandardCharsets.UTF_8.name().equals(encoding))
				stream= new SequenceInputStream(new ByteArrayInputStream(IContentDescription.BOM_UTF_8), stream);


			// here the file synchronizer should actually be removed and afterwards added again. However,
			// we are already inside an operation, so the delta is sent AFTER we have added the listener
			setFileContents(stream, monitor);
			// set synchronization stamp to know whether the file synchronizer must become active
			fSynchronizationStamp= fFileStore.fetchInfo().getLastModified();

			if (fAnnotationModel instanceof IPersistableAnnotationModel) {
				IPersistableAnnotationModel persistableModel= (IPersistableAnnotationModel) fAnnotationModel;
				persistableModel.commit(fDocument);
			}

		} else {
			fFileStore.getParent().mkdir(EFS.NONE, null);

			try(OutputStream out= fFileStore.openOutputStream(EFS.NONE, null)) {
				/*
				 * XXX:
				 * This is a workaround for a corresponding bug in Java readers and writer,
				 * see http://developer.java.sun.com/developer/bugParade/bugs/4508058.html
				 */
				if (fHasBOM && StandardCharsets.UTF_8.name().equals(encoding))
					out.write(IContentDescription.BOM_UTF_8);

				out.write(bytes, 0, bytesLength);
				out.flush();
				out.close();
			} catch (IOException x) {
				IStatus s= new Status(IStatus.ERROR, FileBuffersPlugin.PLUGIN_ID, IStatus.OK, x.getLocalizedMessage(), x);
				throw new CoreException(s);
			}

			// set synchronization stamp to know whether the file synchronizer must become active
			fSynchronizationStamp= fFileStore.fetchInfo().getLastModified();

		}
	}

	private String computeEncoding() {
		// Make sure cache is up to date
		if (!fIsCacheUpdated)
			cacheEncodingState();

		// User-defined encoding has first priority
		if (fExplicitEncoding != null)
			return fExplicitEncoding;

		// Probe content
		try(Reader reader= new DocumentReader(fDocument)) {
			QualifiedName[] options= new QualifiedName[] { IContentDescription.CHARSET, IContentDescription.BYTE_ORDER_MARK };
			IContentDescription description= Platform.getContentTypeManager().getDescriptionFor(reader, fFileStore.getName(), options);
			if (description != null) {
				String encoding= description.getCharset();
				if (encoding != null)
					return encoding;
			}
		} catch (IOException ex) {
			// Try next strategy
		}

		// Use file's encoding if the file has a BOM
		if (fHasBOM)
			return fEncoding;

		// Use global default
		return fManager.getDefaultEncoding();
	}

	
Initializes the given document with the given file's content using the given encoding.
Params:
document – the document to be initialized
file – the file which delivers the document content
encoding – the character encoding for reading the given stream
hasBOM – tell whether the given file has a BOM
monitor – the progress monitor
Throws:
CoreException – if the given stream can not be read/**
	 * Initializes the given document with the given file's content using the given encoding.
	 *
	 * @param document the document to be initialized
	 * @param file the file which delivers the document content
	 * @param encoding the character encoding for reading the given stream
	 * @param hasBOM tell whether the given file has a BOM
	 * @param monitor the progress monitor
	 * @exception CoreException if the given stream can not be read
	 */
	private void setDocumentContent(IDocument document, IFileStore file, String encoding, boolean hasBOM, IProgressMonitor monitor) throws CoreException {
		InputStream contentStream= getFileContents(file);
		if (contentStream == null)
			return;

		Reader in= null;
		try {

			if (encoding == null)
				encoding= fManager.getDefaultEncoding();

			/*
			 * XXX:
			 * This is a workaround for a corresponding bug in Java readers and writer,
			 * see http://developer.java.sun.com/developer/bugParade/bugs/4508058.html
			 */
			if (hasBOM && StandardCharsets.UTF_8.name().equals(encoding)) {
				int n= 0;
				do {
					int bytes= contentStream.read(new byte[IContentDescription.BOM_UTF_8.length]);
					if (bytes == -1)
						throw new IOException();
					n += bytes;
				} while (n < IContentDescription.BOM_UTF_8.length);
			}

			in= new BufferedReader(new InputStreamReader(contentStream, encoding), BUFFER_SIZE);
			StringBuilder buffer= new StringBuilder(BUFFER_SIZE);
			char[] readBuffer= new char[READER_CHUNK_SIZE];
			int n= in.read(readBuffer);
			while (n > 0) {
				buffer.append(readBuffer, 0, n);
				n= in.read(readBuffer);
			}

			document.set(buffer.toString());

		} catch (IOException x) {
			String msg= x.getMessage() == null ? "" : x.getMessage(); //$NON-NLS-1$
			IStatus s= new Status(IStatus.ERROR, FileBuffersPlugin.PLUGIN_ID, IStatus.OK, msg, x);
			throw new CoreException(s);
		} finally {
			try {
				if (in != null)
					in.close();
				else
					contentStream.close();
			} catch (IOException x) {
			}
		}
	}

	
Checks whether the given file is synchronized with the local file system.
If the file has been changed, a CoreException is thrown.
Throws:
CoreException – if file has been changed on the file system/**
	 * Checks whether the given file is synchronized with the local file system.
	 * If the file has been changed, a <code>CoreException</code> is thrown.
	 *
	 * @exception CoreException if file has been changed on the file system
	 */
	private void checkSynchronizationState() throws CoreException {
		if (!isSynchronized()) {
			String message= NLSUtility.format(FileBuffersMessages.FileBuffer_error_outOfSync, getFileStore().toURI());
			Status status= new Status(IStatus.ERROR, FileBuffersPlugin.PLUGIN_ID, 274 /* IResourceStatus.OUT_OF_SYNC_LOCAL */, message, null);
			throw new CoreException(status);
		}
	}

	
Returns the location if it is null or
the name as IPath otherwise.
Returns:
a non-null IPath
Since:
3.3.1/**
	 * Returns the location if it is <code>null</code> or
	 * the name as <code>IPath</code> otherwise.
	 *
	 * @return a non-null <code>IPath</code>
	 * @since 3.3.1
	 */
	private IPath getLocationOrName() {
		IPath path= getLocation();
		if (path == null)
			path= new Path(fFileStore.getName());
		return path;
	}
}