/*******************************************************************************
 * Copyright (c) 2004, 2010 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
 *******************************************************************************/
package org.eclipse.wst.css.ui.internal.autoedit;

import org.eclipse.core.runtime.Preferences;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DocumentCommand;
import org.eclipse.jface.text.IAutoEditStrategy;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.TextUtilities;
import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.texteditor.ITextEditor;
import org.eclipse.ui.texteditor.ITextEditorExtension3;
import org.eclipse.wst.css.core.internal.CSSCorePlugin;
import org.eclipse.wst.css.core.internal.parserz.CSSRegionContexts;
import org.eclipse.wst.css.core.internal.preferences.CSSCorePreferenceNames;
import org.eclipse.wst.css.core.internal.util.RegionIterator;
import org.eclipse.wst.css.ui.internal.Logger;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocument;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocumentRegion;
import org.eclipse.wst.sse.core.internal.provisional.text.ITextRegion;

public class StructuredAutoEditStrategyCSS implements IAutoEditStrategy {
	protected IStructuredDocument structuredDocument = null;

	class CompoundRegion {

		/* textRegion can be null if the offset is at the end of the document */
		CompoundRegion(IStructuredDocumentRegion documentRegion, ITextRegion textRegion) {
			super();
			this.documentRegion = documentRegion;
			this.textRegion = textRegion;
		}

		IStructuredDocumentRegion getDocumentRegion() {
			return documentRegion;
		}

		ITextRegion getTextRegion() {
			return textRegion;
		}

		int getStart() {
			return (textRegion != null) ? textRegion.getStart() : documentRegion.getStart();
		}

		int getEnd() {
			return (textRegion != null) ? textRegion.getEnd() : documentRegion.getEnd();
		}

		String getType() {
			return (textRegion != null) ? textRegion.getType() : CSSRegionContexts.CSS_UNKNOWN;
		}

		String getText() {
			return (textRegion != null) ? documentRegion.getText(textRegion) : ""; //$NON-NLS-1$
		}

		int getStartOffset() {
			return (textRegion != null) ? documentRegion.getStartOffset(textRegion) : documentRegion.getStartOffset();
		}

		int getEndOffset() {
			return (textRegion != null) ? documentRegion.getEndOffset(textRegion) : documentRegion.getEndOffset();
		}

		private IStructuredDocumentRegion documentRegion;
		private ITextRegion textRegion;

	}

	/**
	 */
	protected void autoIndentAfterClose(DocumentCommand command, String regionType) {
		if (!setRangeForClose(command))
			return;

		int position = command.offset + command.length;

		if (position == -1 || structuredDocument.getLength() == 0) {
			return;
		}

		// get open brace region
		CompoundRegion region = prevCorrespondence(position, regionType);

		// get indentation
		String str = getIndentFor(region, false);

		// append to input
		if (str != null)
			command.text = str + command.text;
	}

	/**
	 * Copies the indentation of the previous line.
	 */
	protected void autoIndentAfterNewLine(DocumentCommand command) {
		// select nearest white spaces to replace with new-line
		setRangeForNewLine(command);

		// get position
		int position = command.offset;

		if (position == -1 || structuredDocument.getLength() == 0) {
			return;
		}

		IStructuredDocumentRegion prev = getPreviousRegion(position);
		if (prev == null || !CSSRegionContexts.CSS_LBRACE.equals(prev.getType()))
			return;

		IStructuredDocumentRegion next = prev.getNext();

		// create text to replace
		StringBuffer buf = new StringBuffer(command.text);
		try {
			IRegion line = structuredDocument.getLineInformationOfOffset(position);
			int contentStart = findEndOfWhiteSpace(structuredDocument, position, line.getOffset() + line.getLength());
			command.length =  Math.max(contentStart - position, 0);
			buf.append(getIndentString());
			if (next != null && CSSRegionContexts.CSS_RBRACE.equals(next.getType()) && !isOneLine(prev)) {
				command.shiftsCaret = false;
				command.caretOffset = contentStart + buf.length();
				buf.append(TextUtilities.getDefaultLineDelimiter(structuredDocument));
			}
			command.text = buf.toString();
		}
		catch (BadLocationException e) {
		}

	}

	private boolean isOneLine(IStructuredDocumentRegion prev) {
		return endsWith(structuredDocument.getLegalLineDelimiters(), prev.getFullText()) != -1;
	}

	private IStructuredDocumentRegion getPreviousRegion(int offset) {
		IStructuredDocumentRegion prev = null;
		if (offset > 0)
			prev = structuredDocument.getRegionAtCharacterOffset(offset - 1);
		return prev;
	}

	/**
	 */
	public void customizeDocumentCommand(IDocument document, DocumentCommand command) {
		Object textEditor = getActiveTextEditor();
		if (!(textEditor instanceof ITextEditorExtension3 && ((ITextEditorExtension3) textEditor).getInsertMode() == ITextEditorExtension3.SMART_INSERT))
			return;

		// return;
		// /*
		structuredDocument = (IStructuredDocument) document;

		if (command.length == 0 && command.text != null) {
			if (endsWith(document.getLegalLineDelimiters(), command.text) != -1) {
				autoIndentAfterNewLine(command);
			} else if (command.text.equals("}")) {//$NON-NLS-1$
				autoIndentAfterClose(command, CSSRegionContexts.CSS_RBRACE);
			} else if (command.text.equals("]")) {//$NON-NLS-1$
				autoIndentAfterClose(command, CSSRegionContexts.CSS_SELECTOR_ATTRIBUTE_END);
			} else if (command.text.equals(")")) {//$NON-NLS-1$
				autoIndentAfterClose(command, CSSRegionContexts.CSS_DECLARATION_VALUE_PARENTHESIS_CLOSE);
			}
		}
		// */
		
		// spaces for tab character
		if (command.text != null && command.text.length() > 0 && command.text.charAt(0) == '\t')
			smartInsertForTab(command, document);
	}

	/**
	 */
	protected String getIndentFor(CompoundRegion region, boolean indentForNextRegion) {
		if (region == null)
			return null;
		IStructuredDocumentRegion flatNode = region.getDocumentRegion();
		if (flatNode == null)
			return null;

		try {
			if (region.getType() == CSSRegionContexts.CSS_LBRACE || region.getType() == CSSRegionContexts.CSS_DELIMITER || region.getType() == CSSRegionContexts.CSS_DECLARATION_DELIMITER) {
				// get meanful flat node
				RegionIterator it = new RegionIterator(flatNode, region.getTextRegion());
				it.prev();
				while (it.hasPrev()) {
					ITextRegion r = it.prev();
					region = new CompoundRegion(it.getStructuredDocumentRegion(), r);
					if (region.getType() != CSSRegionContexts.CSS_S)
						break;
				}
				flatNode = region.getDocumentRegion();
				// get indent string
				int position = flatNode.getStart();
				int line = structuredDocument.getLineOfOffset(position);
				int start = structuredDocument.getLineOffset(line);
				int end = findEndOfWhiteSpace(structuredDocument, start, position);
				return structuredDocument.get(start, end - start);
			} else if (region.getType() == CSSRegionContexts.CSS_SELECTOR_ATTRIBUTE_START ||
			// region.getType() == CSSRegionContexts.CSS_PARENTHESIS_OPEN ||
						region.getType() == CSSRegionContexts.CSS_DECLARATION_VALUE_FUNCTION || region.getType() == CSSRegionContexts.CSS_DECLARATION_SEPARATOR) {
				int position = flatNode.getStart() + region.getStart();
				int line = structuredDocument.getLineOfOffset(position);
				int start = structuredDocument.getLineOffset(line);
				int end = findEndOfWhiteSpace(structuredDocument, start, position);
				StringBuffer buf = new StringBuffer(structuredDocument.get(start, end - start));
				position += region.getText().length();
				if (indentForNextRegion) {
					int tokenStart = findEndOfWhiteSpace(structuredDocument, position, structuredDocument.getLineOffset(line) + structuredDocument.getLineLength(line) - 1);
					if (tokenStart < structuredDocument.getLineOffset(line) + structuredDocument.getLineLength(line) - 1) {
						position = tokenStart;
					}
				}
				while (position - end > 0) {
					buf.append(" ");//$NON-NLS-1$
					end++;
				}
				return buf.toString();
			} else
				return "";//$NON-NLS-1$
		} catch (BadLocationException excp) {
			Logger.logException(excp);
		}
		return null;
	}

	/**
	 */
	protected CompoundRegion getPrevKeyRegion(int position, CompoundRegion currentRegion) {
		if (currentRegion == null) {
			if (structuredDocument.getLastStructuredDocumentRegion() == null)
				return null;
		}

		if (currentRegion != null && (currentRegion.getType() == CSSRegionContexts.CSS_RBRACE || currentRegion.getType() == CSSRegionContexts.CSS_SELECTOR_ATTRIBUTE_END || currentRegion.getType() == CSSRegionContexts.CSS_DECLARATION_VALUE_PARENTHESIS_CLOSE)) {
			return prevCorrespondence(currentRegion);
		}

		RegionIterator it = new RegionIterator(structuredDocument, position - 1);
		while (it.hasPrev()) {
			ITextRegion r = it.prev();
			CompoundRegion region = new CompoundRegion(it.getStructuredDocumentRegion(), r);
			if (region.getType() == CSSRegionContexts.CSS_LBRACE ||
			// region.getType() == CSSRegionContexts.CSS_RBRACE ||
						region.getType() == CSSRegionContexts.CSS_SELECTOR_ATTRIBUTE_START ||
						// region.getType() ==
						// CSSRegionContexts.CSS_BRACKET_CLOSE ||
						// // region.getType() ==
						// CSSRegionContexts.CSS_PARENTHESIS_OPEN ||
						// region.getType() ==
						// CSSRegionContexts.CSS_PARENTHESIS_CLOSE ||
						region.getType() == CSSRegionContexts.CSS_DELIMITER || region.getType() == CSSRegionContexts.CSS_DECLARATION_DELIMITER ||
						// region.getType() == CSSRegionContexts.CSS_COLON ||
						// region.getType() == CSSRegionContexts.CSS_COMMENT
						// ||
						region.getType() == CSSRegionContexts.CSS_DECLARATION_VALUE_FUNCTION) {
				return region;
			} else if (region.getType() == CSSRegionContexts.CSS_RBRACE || region.getType() == CSSRegionContexts.CSS_SELECTOR_ATTRIBUTE_END || region.getType() == CSSRegionContexts.CSS_DECLARATION_VALUE_PARENTHESIS_CLOSE) {
				// skip to LBRACE
				CompoundRegion pc = prevCorrespondence(region);
				// guard for NPE
				//https://bugs.eclipse.org/bugs/show_bug.cgi?id=111318
				if (pc == null) break;
				it.reset(pc.getDocumentRegion(), pc.getTextRegion());
				it.prev();
			} else if (region.getType() == CSSRegionContexts.CSS_STRING) {
				RegionIterator itTmp = new RegionIterator(structuredDocument, position);
				if (region == itTmp.prev())
					return region; // position is inside of string
			} else if (region.getType() == CSSRegionContexts.CSS_COMMENT) {
				RegionIterator itTmp = new RegionIterator(structuredDocument, position);
				if (region == itTmp.prev())
					return region; // position is inside of comment
			} else if (region.getType() == CSSRegionContexts.CSS_UNKNOWN) {
				String str = region.getText();
				if (str.charAt(str.length() - 1) == '\\')
					return region;
			} else if (region.getType() == CSSRegionContexts.CSS_DECLARATION_SEPARATOR) {
				RegionIterator itPrev = new RegionIterator(region.getDocumentRegion(), region.getTextRegion());
				while (itPrev.hasPrev()) {
					ITextRegion regionPrev = itPrev.prev();
					if (regionPrev.getType() == CSSRegionContexts.CSS_RBRACE) {
						break;
					} else if (regionPrev.getType() == CSSRegionContexts.CSS_DELIMITER || regionPrev.getType() == CSSRegionContexts.CSS_DECLARATION_DELIMITER) {
						return region;
					} else if (regionPrev.getType() == CSSRegionContexts.CSS_LBRACE) {
						while (itPrev.hasPrev()) {
							regionPrev = itPrev.prev();
							if (regionPrev.getType() == CSSRegionContexts.CSS_MEDIA)
								break;
							if (regionPrev.getType() == CSSRegionContexts.CSS_LBRACE || regionPrev.getType() == CSSRegionContexts.CSS_RBRACE || regionPrev.getType() == CSSRegionContexts.CSS_DELIMITER || regionPrev.getType() == CSSRegionContexts.CSS_DECLARATION_DELIMITER)
								return region;
						}
						if (regionPrev.getType() == CSSRegionContexts.CSS_MEDIA)
							break;
						else
							return region;
					}
				}
			}
		}
		return null;
	}

	/**
	 */
	protected CompoundRegion getRegion(int position) {
		IStructuredDocumentRegion flatNode = structuredDocument.getRegionAtCharacterOffset(position);
		if (flatNode != null)
			return new CompoundRegion(flatNode, flatNode.getRegionAtCharacterOffset(position));
		return null;
	}

	/**
	 */
	protected int needShift(CompoundRegion region, int position) {
		int shift = 0;
		if (region == null || region.getType() == CSSRegionContexts.CSS_DELIMITER || region.getType() == CSSRegionContexts.CSS_DECLARATION_DELIMITER || region.getType() == CSSRegionContexts.CSS_LBRACE) {
			// get non space region
			CompoundRegion cr = getRegion(position - 1);
			RegionIterator it = new RegionIterator(cr.getDocumentRegion(), cr.getTextRegion());
			ITextRegion nearestRegion = null;
			while (it.hasPrev()) {
				nearestRegion = it.prev();
				if (nearestRegion.getType() != CSSRegionContexts.CSS_S && nearestRegion.getType() != CSSRegionContexts.CSS_COMMENT)
					break;
			}
			if (nearestRegion != null && (nearestRegion.getType() == CSSRegionContexts.CSS_LBRACE || nearestRegion.getType() == CSSRegionContexts.CSS_RBRACE || nearestRegion.getType() == CSSRegionContexts.CSS_DELIMITER || nearestRegion.getType() == CSSRegionContexts.CSS_DECLARATION_DELIMITER))
				shift--;
			else if (region == null)
				shift--;
			shift++;
		}
		if (region != null && region.getType() == CSSRegionContexts.CSS_LBRACE) {
			RegionIterator it = new RegionIterator(structuredDocument, position);
			if (!it.hasPrev() || it.prev().getType() != CSSRegionContexts.CSS_RBRACE)
				shift++;
			else
				shift = 0;
		}
		return shift;
	}

	/**
	 */
	protected CompoundRegion prevCorrespondence(int position, String regionType) {
		RegionIterator it = new RegionIterator(structuredDocument, position - 1);
		ITextRegion region = null;
		int nest = 1;
		if (regionType == CSSRegionContexts.CSS_RBRACE) {
			// skip to LBRACE
			while (it.hasPrev()) {
				region = it.prev();
				if (region.getType() == CSSRegionContexts.CSS_LBRACE)
					nest--;
				else if (region.getType() == CSSRegionContexts.CSS_RBRACE)
					nest++;
				if (nest <= 0)
					break;
			}
			if (nest == 0)
				return new CompoundRegion(it.getStructuredDocumentRegion(), region);
		}
		if (regionType == CSSRegionContexts.CSS_SELECTOR_ATTRIBUTE_END) {
			// skip to BRACKET_OPEN
			while (it.hasPrev()) {
				region = it.prev();
				if (region.getType() == CSSRegionContexts.CSS_SELECTOR_ATTRIBUTE_START)
					nest--;
				else if (region.getType() == CSSRegionContexts.CSS_SELECTOR_ATTRIBUTE_END)
					nest++;
				if (nest <= 0)
					break;
			}
			if (nest == 0)
				return new CompoundRegion(it.getStructuredDocumentRegion(), region);
		}
		if (regionType == CSSRegionContexts.CSS_DECLARATION_VALUE_PARENTHESIS_CLOSE) {
			// skip to PARENTHESIS_OPEN
			while (it.hasPrev()) {
				region = it.prev();
				if (// region.getType() ==
				// CSSRegionContexts.CSS_PARENTHESIS_OPEN ||
				region.getType() == CSSRegionContexts.CSS_DECLARATION_VALUE_FUNCTION)
					nest--;
				else if (region.getType() == CSSRegionContexts.CSS_DECLARATION_VALUE_PARENTHESIS_CLOSE)
					nest++;
				if (nest <= 0)
					break;
			}
			if (nest == 0)
				return new CompoundRegion(it.getStructuredDocumentRegion(), region);
		}
		return null;
	}

	/**
	 */
	protected CompoundRegion prevCorrespondence(CompoundRegion region) {
		if (region == null)
			return null;

		IStructuredDocumentRegion flatNode = region.getDocumentRegion();
		int position = flatNode.getStart() + region.getStart();
		return prevCorrespondence(position, region.getType());
	}

	/**
	 * Insert the method's description here.
	 * 
	 * @return boolean
	 * @param command
	 *            org.eclipse.jface.text.DocumentCommand
	 */
	protected boolean setRangeForClose(DocumentCommand command) {
		int position = command.offset;

		if (position == -1 || structuredDocument.getLength() == 0) {
			return false;
		}

		try {
			// find start of line
			int p = (position == structuredDocument.getLength() ? position - 1 : position);

			int line = structuredDocument.getLineOfOffset(p);
			int start = structuredDocument.getLineOffset(line);
			RegionIterator it = new RegionIterator(structuredDocument, start);
			boolean allWhiteSpace = false;
			// check whether the text from lStart to position is white space
			// or not
			while (it.hasNext()) {
				ITextRegion region = it.next();
				if (region.getType() != CSSRegionContexts.CSS_S)
					break;
				if (it.getStructuredDocumentRegion().getEndOffset(region) > p) {
					allWhiteSpace = true;
					break;
				}
			}
			if (allWhiteSpace) {
				command.length = command.length - (start - command.offset);
				command.offset = start;
				return true;
			}
		} catch (BadLocationException excp) {
			Logger.logException(excp);
		}
		return false;
	}

	/**
	 */
	protected void setRangeForNewLine(DocumentCommand command) {
		int position = command.offset;

		if (position == -1 || structuredDocument.getLength() == 0) {
			return;
		}

		try {
			// add pre-nearest white spaces to replace target
			if (position > 0) {
				IStructuredDocumentRegion flatNode = structuredDocument.getRegionAtCharacterOffset(position - 1);
				if (flatNode != null) {
					ITextRegion region = flatNode.getRegionAtCharacterOffset(position - 1);
					if (region.getType() == CSSRegionContexts.CSS_S) {
						int end = command.offset + command.length;
						int nLine = structuredDocument.getLineOfOffset(position);
						int nStartPos = structuredDocument.getLineOffset(nLine);
						if (nStartPos < flatNode.getStartOffset(region))
							nStartPos = flatNode.getStartOffset(region);
						command.offset = nStartPos;
						command.length = end - command.offset;
					}
				}
			}

			// add post-nearest white spaces to replace target
			if (position < structuredDocument.getLength()) {
				IStructuredDocumentRegion flatNode = structuredDocument.getRegionAtCharacterOffset(position);
				if (flatNode != null) {
					ITextRegion region = flatNode.getRegionAtCharacterOffset(position);
					if (region.getType() == CSSRegionContexts.CSS_S) {
						int nLine = structuredDocument.getLineOfOffset(position);
						String currentLineDelim = structuredDocument.getLineDelimiter(nLine);
						int nEndPos = structuredDocument.getLineOffset(nLine) + structuredDocument.getLineLength(nLine) - ((currentLineDelim != null) ? currentLineDelim.length() : 0);
						if (nEndPos > flatNode.getEndOffset(region))
							nEndPos = flatNode.getEndOffset(region);
						command.length = nEndPos - command.offset;
					}
				}
			}
		} catch (BadLocationException e) {
			// do not customize command
		}

	}

	private static int endsWith(String[] searchStrings, String text) {
		for (int i = 0; i < searchStrings.length; i++) {
			if (text.endsWith(searchStrings[i]))
				return i;
		}
		return -1;
	}

	private static int findEndOfWhiteSpace(IDocument document, int offset, int end) throws BadLocationException {
		while (offset < end) {
			char c = document.getChar(offset);
			if (c != ' ' && c != '\t') {
				return offset;
			}
			offset++;
		}
		return end;
	}


	private String getIndentString() {
		StringBuffer indent = new StringBuffer();

		Preferences preferences = CSSCorePlugin.getDefault().getPluginPreferences();
		if (preferences != null) {
			char indentChar = ' ';
			String indentCharPref = preferences.getString(CSSCorePreferenceNames.INDENTATION_CHAR);
			if (CSSCorePreferenceNames.TAB.equals(indentCharPref)) {
				indentChar = '\t';
			}
			int indentationWidth = preferences.getInt(CSSCorePreferenceNames.INDENTATION_SIZE);

			for (int i = 0; i < indentationWidth; i++) {
				indent.append(indentChar);
			}
		}
		return indent.toString();
	}
	
	/**
	 * Return the active text editor if possible, otherwise the active editor
	 * part.
	 * 
	 * @return
	 */
	private Object getActiveTextEditor() {
		IWorkbenchWindow window = PlatformUI.getWorkbench().getActiveWorkbenchWindow();
		if (window != null) {
			IWorkbenchPage page = window.getActivePage();
			if (page != null) {
				IEditorPart editor = page.getActiveEditor();
				if (editor != null) {
					if (editor instanceof ITextEditor)
						return editor;
					ITextEditor textEditor = (ITextEditor) editor.getAdapter(ITextEditor.class);
					if (textEditor != null)
						return textEditor;
					return editor;
				}
			}
		}
		return null;
	}
	
	/**
	 * Insert spaces for tabs
	 * 
	 * @param command
	 */
	private void smartInsertForTab(DocumentCommand command, IDocument document) {
		// tab key was pressed. now check preferences to see if need to insert
		// spaces instead of tab
		Preferences preferences = CSSCorePlugin.getDefault().getPluginPreferences();
		if (CSSCorePreferenceNames.SPACE.equals(preferences.getString(CSSCorePreferenceNames.INDENTATION_CHAR))) {
			int indentationWidth = preferences.getInt(CSSCorePreferenceNames.INDENTATION_SIZE);

			StringBuffer indent = new StringBuffer();
			if (indentationWidth != 0) {
				int indentSize = indentationWidth;
				try {
					IRegion firstLine = document.getLineInformationOfOffset(command.offset);
					int offsetInLine = command.offset - firstLine.getOffset();
					int remainder = offsetInLine % indentationWidth;

					indentSize = indentationWidth - remainder;
				} catch (BadLocationException e) {
					Logger.log(Logger.WARNING_DEBUG, e.getMessage(), e);
				}

				for (int i = 0; i < indentSize; i++)
					indent.append(' ');
			}

			// replace \t characters with spaces
			command.text = indent.toString();
		}
	}
}