/*******************************************************************************
 * Copyright (c) 2000, 2009 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Tom Eicher (Avaloq Evolution AG) - block selection mode
 *******************************************************************************/
package ts.eclipse.ide.jsdt.internal.ui.actions;

import java.util.ResourceBundle;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.IRewriteTarget;
import org.eclipse.jface.text.ITextSelection;
import org.eclipse.jface.text.ITypedRegion;
import org.eclipse.jface.text.Position;
import org.eclipse.jface.text.TextSelection;
import org.eclipse.jface.text.TextUtilities;
import org.eclipse.jface.text.source.ISourceViewer;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.ISelectionProvider;
import org.eclipse.swt.custom.BusyIndicator;
import org.eclipse.swt.widgets.Display;
import org.eclipse.ui.IEditorInput;
import org.eclipse.ui.texteditor.IDocumentProvider;
import org.eclipse.ui.texteditor.ITextEditor;
import org.eclipse.ui.texteditor.ITextEditorExtension3;
import org.eclipse.ui.texteditor.TextEditorAction;
import org.eclipse.wst.jsdt.internal.ui.text.JavaHeuristicScanner;
import org.eclipse.wst.jsdt.ui.text.IJavaScriptPartitions;

import ts.eclipse.ide.core.resources.IIDETypeScriptProject;
import ts.eclipse.ide.core.utils.TypeScriptResourceUtil;
import ts.eclipse.ide.jsdt.internal.ui.editor.TypeScriptEditor;
import ts.eclipse.ide.jsdt.internal.ui.editor.TypeScriptIndenter;
import ts.eclipse.ide.ui.TypeScriptUIPlugin;
import ts.eclipse.ide.ui.utils.EditorUtils;
import ts.resources.ITypeScriptFile;

/**
 * Indents a line or range of lines in a Java document to its correct position.
 * No complete AST must be present, the indentation is computed using
 * heuristics. The algorithm used is fast for single lines, but does not store
 * any information and therefore not so efficient for large line ranges.
 * 
 * @see org.eclipse.wst.jsdt.internal.ui.text.JavaHeuristicScanner
 * @see org.eclipse.wst.jsdt.internal.ui.text.TypeScriptIndenter
 * 
 */
public class IndentAction extends TextEditorAction {

	/** The caret offset after an indent operation. */
	private int fCaretOffset;

	/**
	 * Whether this is the action invoked by TAB. When <code>true</code>,
	 * indentation behaves differently to accommodate normal TAB operation.
	 */
	private final boolean fIsTabAction;

	/**
	 * Creates a new instance.
	 * 
	 * @param bundle
	 *            the resource bundle
	 * @param prefix
	 *            the prefix to use for keys in <code>bundle</code>
	 * @param editor
	 *            the text editor
	 * @param isTabAction
	 *            whether the action should insert tabs if over the indentation
	 */
	public IndentAction(ResourceBundle bundle, String prefix, ITextEditor editor, boolean isTabAction) {
		super(bundle, prefix, editor);
		fIsTabAction = isTabAction;
	}

	/*
	 * @see org.eclipse.jface.action.Action#run()
	 */
	public void run() {
		// update has been called by the framework
		if (!isEnabled() || !validateEditorInputState())
			return;

		ITextSelection selection = getSelection();
		final IDocument document = getDocument();

		if (document != null) {

			final int offset = selection.getOffset();
			final int length = selection.getLength();
			final Position end = new Position(offset + length);
			final int firstLine, nLines;
			fCaretOffset = -1;

			try {
				document.addPosition(end);
				firstLine = selection.getStartLine();
				nLines = selection.getEndLine() - firstLine + 1;
			} catch (BadLocationException e) {
				// will only happen on concurrent modification
				TypeScriptUIPlugin.log(new Status(IStatus.ERROR, TypeScriptUIPlugin.PLUGIN_ID, IStatus.OK, "", e)); //$NON-NLS-1$
				return;
			}

			Runnable runnable = new Runnable() {
				public void run() {
					IRewriteTarget target = (IRewriteTarget) getTextEditor().getAdapter(IRewriteTarget.class);
					if (target != null)
						target.beginCompoundChange();

					try {
						JavaHeuristicScanner scanner = new JavaHeuristicScanner(document);
						TypeScriptIndenter indenter = new TypeScriptIndenter(document, scanner, getJavaProject());
						final boolean multiLine = nLines > 1;
						boolean hasChanged = false;
						for (int i = 0; i < nLines; i++) {
							hasChanged |= indentLine(document, firstLine + i, offset, indenter, scanner, multiLine);
						}

						// update caret position: move to new position when
						// indenting just one line
						// keep selection when indenting multiple
						int newOffset, newLength;
						if (!fIsTabAction && multiLine) {
							newOffset = offset;
							newLength = end.getOffset() - offset;
						} else {
							newOffset = fCaretOffset;
							newLength = 0;
						}

						// always reset the selection if anything was replaced
						// but not when we had a single line non-tab invocation
						if (newOffset != -1 && (hasChanged || newOffset != offset || newLength != length))
							selectAndReveal(newOffset, newLength);

						document.removePosition(end);
					} catch (BadLocationException e) {
						// will only happen on concurrent modification
						TypeScriptUIPlugin.log(new Status(IStatus.ERROR, TypeScriptUIPlugin.PLUGIN_ID, IStatus.OK,
								"ConcurrentModification in IndentAction", e)); //$NON-NLS-1$

					} finally {
						if (target != null)
							target.endCompoundChange();
					}
				}
			};

			if (nLines > 50) {
				Display display = getTextEditor().getEditorSite().getWorkbenchWindow().getShell().getDisplay();
				BusyIndicator.showWhile(display, runnable);
			} else
				runnable.run();

		}
	}

	/**
	 * Selects the given range on the editor.
	 * 
	 * @param newOffset
	 *            the selection offset
	 * @param newLength
	 *            the selection range
	 */
	private void selectAndReveal(int newOffset, int newLength) {
		Assert.isTrue(newOffset >= 0);
		Assert.isTrue(newLength >= 0);
		ITextEditor editor = getTextEditor();
		if (editor instanceof TypeScriptEditor) {
			ISourceViewer viewer = ((TypeScriptEditor) editor).getViewer();
			if (viewer != null)
				viewer.setSelectedRange(newOffset, newLength);
		} else
			// this is too intrusive, but will never get called anyway
			getTextEditor().selectAndReveal(newOffset, newLength);

	}

	/**
	 * Indents a single line using the java heuristic scanner. Javadoc and
	 * multiline comments are indented as specified by the
	 * <code>JavaDocAutoIndentStrategy</code>.
	 * 
	 * @param document
	 *            the document
	 * @param line
	 *            the line to be indented
	 * @param caret
	 *            the caret position
	 * @param indenter
	 *            the java indenter
	 * @param scanner
	 *            the heuristic scanner
	 * @param multiLine
	 *            <code>true</code> if more than one line is being indented
	 * @return <code>true</code> if <code>document</code> was modified,
	 *         <code>false</code> otherwise
	 * @throws BadLocationException
	 *             if the document got changed concurrently
	 */
	private boolean indentLine(IDocument document, int line, int caret, TypeScriptIndenter indenter,
			JavaHeuristicScanner scanner, boolean multiLine) throws BadLocationException {
		IRegion currentLine = document.getLineInformation(line);
		int offset = currentLine.getOffset();
		int wsStart = offset; // where we start searching for non-WS; after the
								// "//" in single line comments

		String indent = null;
		if (offset < document.getLength()) {
			ITypedRegion partition = TextUtilities.getPartition(document, IJavaScriptPartitions.JAVA_PARTITIONING,
					offset, true);
			ITypedRegion startingPartition = TextUtilities.getPartition(document,
					IJavaScriptPartitions.JAVA_PARTITIONING, offset, false);
			String type = partition.getType();
			if (type.equals(IJavaScriptPartitions.JAVA_DOC)
					|| type.equals(IJavaScriptPartitions.JAVA_MULTI_LINE_COMMENT)) {
				indent = computeJavadocIndent(document, line, scanner, startingPartition);
			} else if (!fIsTabAction && startingPartition.getOffset() == offset
					&& startingPartition.getType().equals(IJavaScriptPartitions.JAVA_SINGLE_LINE_COMMENT)) {

				// line comment starting at position 0 -> indent inside
				int max = document.getLength() - offset;
				int slashes = 2;
				while (slashes < max - 1 && document.get(offset + slashes, 2).equals("//")) //$NON-NLS-1$
					slashes += 2;

				wsStart = offset + slashes;

				StringBuffer computed = indenter.computeIndentation(offset);
				if (computed == null)
					computed = new StringBuffer(0);
				int tabSize = getTabSize();
				while (slashes > 0 && computed.length() > 0) {
					char c = computed.charAt(0);
					if (c == '\t')
						if (slashes > tabSize)
							slashes -= tabSize;
						else
							break;
					else if (c == ' ')
						slashes--;
					else
						break;

					computed.deleteCharAt(0);
				}

				indent = document.get(offset, wsStart - offset) + computed;

			}
		}

		// standard java indentation
		if (indent == null) {
			StringBuffer computed = indenter.computeIndentation(offset);
			if (computed != null)
				indent = computed.toString();
			else
				indent = ""; //$NON-NLS-1$
		}

		// change document:
		// get current white space
		int lineLength = currentLine.getLength();
		int end = scanner.findNonWhitespaceForwardInAnyPartition(wsStart, offset + lineLength);
		if (end == JavaHeuristicScanner.NOT_FOUND) {
			// an empty line
			end = offset + lineLength;
			if (multiLine && !indentEmptyLines())
				indent = ""; //$NON-NLS-1$
		}
		int length = end - offset;
		String currentIndent = document.get(offset, length);

		// if we are right before the text start / line end, and already after
		// the insertion point
		// then just insert a tab.
		if (fIsTabAction && caret == end && whiteSpaceLength(currentIndent) >= whiteSpaceLength(indent)) {
			String tab = getTabEquivalent();
			document.replace(caret, 0, tab);
			fCaretOffset = caret + tab.length();
			return true;
		}

		// set the caret offset so it can be used when setting the selection
		if (caret >= offset && caret <= end)
			fCaretOffset = offset + indent.length();
		else
			fCaretOffset = -1;

		// only change the document if it is a real change
		if (!indent.equals(currentIndent)) {
			document.replace(offset, length, indent);
			return true;
		} else
			return false;
	}

	/**
	 * Computes and returns the indentation for a javadoc line. The line must be
	 * inside a javadoc comment.
	 * 
	 * @param document
	 *            the document
	 * @param line
	 *            the line in document
	 * @param scanner
	 *            the scanner
	 * @param partition
	 *            the javadoc partition
	 * @return the indent, or <code>null</code> if not computable
	 * @throws BadLocationException
	 * 
	 */
	private String computeJavadocIndent(IDocument document, int line, JavaHeuristicScanner scanner,
			ITypedRegion partition) throws BadLocationException {
		if (line == 0) // impossible - the first line is never inside a javadoc
						// comment
			return null;

		// don't make any assumptions if the line does not start with \s*\* - it
		// might be
		// commented out code, for which we don't want to change the indent
		final IRegion lineInfo = document.getLineInformation(line);
		final int lineStart = lineInfo.getOffset();
		final int lineLength = lineInfo.getLength();
		final int lineEnd = lineStart + lineLength;
		int nonWS = scanner.findNonWhitespaceForwardInAnyPartition(lineStart, lineEnd);
		if (nonWS == JavaHeuristicScanner.NOT_FOUND || document.getChar(nonWS) != '*') {
			if (nonWS == JavaHeuristicScanner.NOT_FOUND)
				return document.get(lineStart, lineLength);
			return document.get(lineStart, nonWS - lineStart);
		}

		// take the indent from the previous line and reuse
		IRegion previousLine = document.getLineInformation(line - 1);
		int previousLineStart = previousLine.getOffset();
		int previousLineLength = previousLine.getLength();
		int previousLineEnd = previousLineStart + previousLineLength;

		StringBuffer buf = new StringBuffer();
		int previousLineNonWS = scanner.findNonWhitespaceForwardInAnyPartition(previousLineStart, previousLineEnd);
		if (previousLineNonWS == JavaHeuristicScanner.NOT_FOUND || document.getChar(previousLineNonWS) != '*') {
			// align with the comment start if the previous line is not an
			// asterisked line
			previousLine = document.getLineInformationOfOffset(partition.getOffset());
			previousLineStart = previousLine.getOffset();
			previousLineLength = previousLine.getLength();
			previousLineEnd = previousLineStart + previousLineLength;
			previousLineNonWS = scanner.findNonWhitespaceForwardInAnyPartition(previousLineStart, previousLineEnd);
			if (previousLineNonWS == JavaHeuristicScanner.NOT_FOUND)
				previousLineNonWS = previousLineEnd;

			// add the initial space
			// TODO this may be controlled by a formatter preference in the
			// future
			buf.append(' ');
		}

		String indentation = document.get(previousLineStart, previousLineNonWS - previousLineStart);
		buf.insert(0, indentation);
		return buf.toString();
	}

	/**
	 * Returns the size in characters of a string. All characters count one,
	 * tabs count the editor's preference for the tab display
	 * 
	 * @param indent
	 *            the string to be measured.
	 * @return the size in characters of a string
	 */
	private int whiteSpaceLength(String indent) {
		if (indent == null)
			return 0;
		else {
			int size = 0;
			int l = indent.length();
			int tabSize = getTabSize();

			for (int i = 0; i < l; i++)
				size += indent.charAt(i) == '\t' ? tabSize : 1;
			return size;
		}
	}

	/**
	 * Returns a tab equivalent, either as a tab character or as spaces,
	 * depending on the editor and formatter preferences.
	 * 
	 * @return a string representing one tab in the editor, never
	 *         <code>null</code>
	 */
	private String getTabEquivalent() {
		String tab;
		if (getJavaProject().getFormatOptions().getConvertTabsToSpaces()) {
			// if
			// (JavaScriptCore.SPACE.equals(getCoreFormatterOption(DefaultCodeFormatterConstants.FORMATTER_TAB_CHAR)))
			// {
			int size = getTabSize();
			StringBuffer buf = new StringBuffer();
			for (int i = 0; i < size; i++)
				buf.append(' ');
			tab = buf.toString();
		} else
			tab = "\t"; //$NON-NLS-1$

		return tab;
	}

	/**
	 * Returns the tab size used by the java editor, which is deduced from the
	 * formatter preferences.
	 * 
	 * @return the tab size as defined in the current formatter preferences
	 */
	private int getTabSize() {
		return getJavaProject().getFormatOptions().getTabSize();// getCoreFormatterOption(DefaultCodeFormatterConstants.FORMATTER_TAB_SIZE,
																// 4);
	}

	/**
	 * Returns <code>true</code> if empty lines should be indented, false
	 * otherwise.
	 * 
	 * @return <code>true</code> if empty lines should be indented, false
	 *         otherwise
	 * 
	 */
	private boolean indentEmptyLines() {
		return true; // DefaultCodeFormatterConstants.TRUE.equals(getCoreFormatterOption(DefaultCodeFormatterConstants.FORMATTER_INDENT_EMPTY_LINES));
	}

	/**
	 * Returns the <code>IJavaScriptProject</code> of the current editor input,
	 * or <code>null</code> if it cannot be found.
	 * 
	 * @return the <code>IJavaScriptProject</code> of the current editor input,
	 *         or <code>null</code> if it cannot be found
	 * 
	 */
	private ITypeScriptFile getJavaProject() {
		ITextEditor editor = getTextEditor();
		if (editor == null)
			return null;

		IFile file = EditorUtils.getFile(editor);
		if (file == null || !TypeScriptResourceUtil.canConsumeTsserver(file)) {
			return null;
		}
		IDocument document = EditorUtils.getDocument(editor);
		if (document == null) {
			return null;
		}
		try {
			IProject project = file.getProject();
			IIDETypeScriptProject tsProject = TypeScriptResourceUtil.getTypeScriptProject(project);
			if (tsProject != null) {
				return tsProject.openFile(file, document);
			}
		} catch (Exception e) {
			return null;
		}
		return null;
	}

	/**
	 * Returns the editor's selection provider.
	 * 
	 * @return the editor's selection provider or <code>null</code>
	 */
	private ISelectionProvider getSelectionProvider() {
		ITextEditor editor = getTextEditor();
		if (editor != null) {
			return editor.getSelectionProvider();
		}
		return null;
	}

	/*
	 * @see org.eclipse.ui.texteditor.IUpdate#update()
	 */
	public void update() {
		super.update();

		if (isEnabled())
			if (fIsTabAction)
				setEnabled(canModifyEditor() && isSmartMode() && isValidSelection());
			else
				setEnabled(canModifyEditor() && !getSelection().isEmpty());
	}

	/**
	 * Returns if the current selection is valid, i.e. whether it is empty and
	 * the caret in the whitespace at the start of a line, or covers multiple
	 * lines.
	 * 
	 * @return <code>true</code> if the selection is valid for an indent
	 *         operation
	 */
	private boolean isValidSelection() {
		ITextSelection selection = getSelection();
		if (selection.isEmpty())
			return false;

		int offset = selection.getOffset();
		int length = selection.getLength();

		IDocument document = getDocument();
		if (document == null)
			return false;

		try {
			IRegion firstLine = document.getLineInformationOfOffset(offset);
			int lineOffset = firstLine.getOffset();

			// either the selection has to be empty and the caret in the WS at
			// the line start
			// or the selection has to extend over multiple lines
			if (length == 0)
				return document.get(lineOffset, offset - lineOffset).trim().length() == 0;
			else
				// return lineOffset + firstLine.getLength() < offset + length;
				return false; // only enable for empty selections for now

		} catch (BadLocationException e) {
		}

		return false;
	}

	/**
	 * Returns the smart preference state.
	 * 
	 * @return <code>true</code> if smart mode is on, <code>false</code>
	 *         otherwise
	 */
	private boolean isSmartMode() {
		ITextEditor editor = getTextEditor();

		if (editor instanceof ITextEditorExtension3)
			return ((ITextEditorExtension3) editor).getInsertMode() == ITextEditorExtension3.SMART_INSERT;

		return false;
	}

	/**
	 * Returns the document currently displayed in the editor, or
	 * <code>null</code> if none can be obtained.
	 * 
	 * @return the current document or <code>null</code>
	 */
	private IDocument getDocument() {

		ITextEditor editor = getTextEditor();
		if (editor != null) {

			IDocumentProvider provider = editor.getDocumentProvider();
			IEditorInput input = editor.getEditorInput();
			if (provider != null && input != null)
				return provider.getDocument(input);

		}
		return null;
	}

	/**
	 * Returns the selection on the editor or an invalid selection if none can
	 * be obtained. Returns never <code>null</code>.
	 * 
	 * @return the current selection, never <code>null</code>
	 */
	private ITextSelection getSelection() {
		ISelectionProvider provider = getSelectionProvider();
		if (provider != null) {

			ISelection selection = provider.getSelection();
			if (selection instanceof ITextSelection)
				return (ITextSelection) selection;
		}

		// null object
		return TextSelection.emptySelection();
	}

}