/*******************************************************************************
 * Copyright (c) 2008, 2016 xored software, Inc.
 *
 * 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:
 *     xored software, Inc. - initial API and Implementation (Alex Panchenko)
 *******************************************************************************/
package org.eclipse.dltk.ruby.internal.ui.text;

import java.util.HashSet;
import java.util.Set;
import java.util.Stack;

import org.eclipse.dltk.ast.ASTNode;
import org.eclipse.dltk.ast.ASTVisitor;
import org.eclipse.dltk.ast.declarations.Declaration;
import org.eclipse.dltk.ast.declarations.ModuleDeclaration;
import org.eclipse.dltk.ast.expressions.BigNumericLiteral;
import org.eclipse.dltk.ast.expressions.CallExpression;
import org.eclipse.dltk.ast.expressions.FloatNumericLiteral;
import org.eclipse.dltk.ast.expressions.NumericLiteral;
import org.eclipse.dltk.ast.expressions.StringLiteral;
import org.eclipse.dltk.ast.parser.IModuleDeclaration;
import org.eclipse.dltk.ast.references.SimpleReference;
import org.eclipse.dltk.ast.references.VariableReference;
import org.eclipse.dltk.compiler.env.IModuleSource;
import org.eclipse.dltk.core.ISourceModule;
import org.eclipse.dltk.core.ModelException;
import org.eclipse.dltk.core.SourceParserUtil;
import org.eclipse.dltk.ruby.ast.RubyConstantDeclaration;
import org.eclipse.dltk.ruby.ast.RubyDAssgnExpression;
import org.eclipse.dltk.ruby.ast.RubyDRegexpExpression;
import org.eclipse.dltk.ruby.ast.RubyDVarExpression;
import org.eclipse.dltk.ruby.ast.RubyDynamicStringExpression;
import org.eclipse.dltk.ruby.ast.RubyEvaluatableStringExpression;
import org.eclipse.dltk.ruby.ast.RubyRegexpExpression;
import org.eclipse.dltk.ruby.ast.RubySymbolReference;
import org.eclipse.dltk.ruby.core.RubyNature;
import org.eclipse.dltk.ruby.core.utils.RubySyntaxUtils;
import org.eclipse.dltk.ruby.internal.ui.RubyPreferenceConstants;
import org.eclipse.dltk.ruby.ui.preferences.RubyPreferencesMessages;
import org.eclipse.dltk.ui.editor.highlighting.AbortSemanticHighlightingException;
import org.eclipse.dltk.ui.editor.highlighting.ISemanticHighlighter;
import org.eclipse.dltk.ui.editor.highlighting.ISemanticHighlighterExtension;
import org.eclipse.dltk.ui.editor.highlighting.ISemanticHighlightingRequestor;
import org.eclipse.dltk.ui.editor.highlighting.SemanticHighlighting;
import org.eclipse.dltk.ui.preferences.PreferencesMessages;

public class RubySemanticUpdateWorker extends ASTVisitor implements
		ISemanticHighlighter, ISemanticHighlighterExtension {

	@Override
	public SemanticHighlighting[] getSemanticHighlightings() {
		return new SemanticHighlighting[] {
				new RubySemanticHighlighting(
						RubyPreferenceConstants.EDITOR_REGEXP_COLOR,
						PreferencesMessages.DLTKEditorPreferencePage_regexps),
				new RubySemanticHighlighting(
						RubyPreferenceConstants.EDITOR_STRING_COLOR, null),
				new RubySemanticHighlighting(
						RubyPreferenceConstants.EDITOR_SYMBOLS_COLOR, null),
				new RubySemanticHighlighting(
						RubyPreferenceConstants.EDITOR_VARIABLE_COLOR,
						RubyPreferencesMessages.RubyLocalVariable),
				new RubySemanticHighlighting(
						RubyPreferenceConstants.EDITOR_INSTANCE_VARIABLE_COLOR,
						null),
				new RubySemanticHighlighting(
						RubyPreferenceConstants.EDITOR_CLASS_VARIABLE_COLOR,
						null),
				new RubySemanticHighlighting(
						RubyPreferenceConstants.EDITOR_GLOBAL_VARIABLE_COLOR,
						null),
				new RubySemanticHighlighting(
						RubyPreferenceConstants.EDITOR_CONST_COLOR,
						RubyPreferencesMessages.RubyConstants),
				new RubySemanticHighlighting(
						RubyPreferenceConstants.EDITOR_NUMBER_COLOR, null),
				new RubySemanticHighlighting(
						RubyPreferenceConstants.EDITOR_EVAL_EXPR_COLOR,
						PreferencesMessages.DLTKEditorPreferencePage_evaluated_expressions),
				new RubySemanticHighlighting(IRubyColorConstants.RUBY_DEFAULT,
						null) };
	}

	private static final String HL_REGEXP = RubyPreferenceConstants.EDITOR_REGEXP_COLOR;
	private static final String HL_STRING = RubyPreferenceConstants.EDITOR_STRING_COLOR;
	private static final String HL_SYMBOL = RubyPreferenceConstants.EDITOR_SYMBOLS_COLOR;
	private static final String HL_LOCAL_VARIABLE = RubyPreferenceConstants.EDITOR_VARIABLE_COLOR;
	private static final String HL_INSTANCE_VARIABLE = RubyPreferenceConstants.EDITOR_INSTANCE_VARIABLE_COLOR;
	private static final String HL_CLASS_VARIABLE = RubyPreferenceConstants.EDITOR_CLASS_VARIABLE_COLOR;
	private static final String HL_GLOBAL_VARIABLE = RubyPreferenceConstants.EDITOR_GLOBAL_VARIABLE_COLOR;
	private static final String HL_CONST = RubyPreferenceConstants.EDITOR_CONST_COLOR;
	private static final String HL_NUMBER = RubyPreferenceConstants.EDITOR_NUMBER_COLOR;
	private static final String HL_EVAL_EXPR = RubyPreferenceConstants.EDITOR_EVAL_EXPR_COLOR;
	private static final String HL_DEFAULT = IRubyColorConstants.RUBY_DEFAULT;

	private ISemanticHighlightingRequestor requestor;
	private char[] content;

	private static final boolean ACTIVE = true;

	@Override
	public boolean visitGeneral(ASTNode node) throws Exception {
		if (!ACTIVE) {
			return true;
		}
		if (node instanceof RubyRegexpExpression
				|| node instanceof RubyDRegexpExpression) {
			handleRegexp(node);
		} else if (node instanceof RubySymbolReference) {
			requestor.addPosition(node.sourceStart(), node.sourceEnd(),
					HL_SYMBOL);
		} else if (node instanceof VariableReference) {
			handleVariableReference((VariableReference) node);
		} else if (node instanceof RubyDVarExpression) {
			requestor.addPosition(node.sourceStart(), node.sourceEnd(),
					HL_LOCAL_VARIABLE);
		} else if (node instanceof RubyDAssgnExpression) {
			ASTNode var = ((RubyDAssgnExpression) node).getLeft();
			requestor.addPosition(var.sourceStart(), var.sourceEnd(),
					HL_LOCAL_VARIABLE);
		} else if (node instanceof StringLiteral) {
			if (isStringLiteralNeeded(node)) {
				requestor.addPosition(node.sourceStart(), node.sourceEnd(),
						HL_STRING);
			}
		} else if (node instanceof NumericLiteral
				|| node instanceof FloatNumericLiteral
				|| node instanceof BigNumericLiteral) {
			requestor.addPosition(node.sourceStart(), node.sourceEnd(),
					HL_NUMBER);
		} else if (node instanceof RubyEvaluatableStringExpression) {
			handleEvaluatableExpression(node);
		} else if (node instanceof CallExpression) {
			final CallExpression call = (CallExpression) node;
			if (!(RubySyntaxUtils.isRubyOperator(call.getName()) || call
					.getReceiver() == null
					&& RubyCodeScanner.isPseudoKeyword(call.getName()))) {
				final SimpleReference callName = call.getCallName();
				if (callName.sourceStart() >= 0
						&& callName.sourceEnd() > callName.sourceStart()) {
					requestor.addPosition(callName.sourceStart(),
							callName.sourceEnd(), HL_DEFAULT);
				}
			}
		} else if (node instanceof Declaration) {
			final Declaration declaration = (Declaration) node;
			requestor.addPosition(declaration.getNameStart(),
					declaration.getNameEnd(), HL_DEFAULT);
		} else if (node instanceof RubyConstantDeclaration) {
			final RubyConstantDeclaration declaration = (RubyConstantDeclaration) node;
			final SimpleReference name = declaration.getName();
			requestor.addPosition(name.sourceStart(), name.sourceEnd(),
					HL_CONST);
		}
		stack.push(node);
		return true;
	}

	private boolean isStringLiteralNeeded(ASTNode node) {
		if (stack.empty()) {
			return true;
		}
		final ASTNode top = stack.peek();
		if (top instanceof RubyDRegexpExpression) {
			return false;
		}
		if (top instanceof RubyDynamicStringExpression) {
			return node.sourceStart() >= top.sourceStart()
					&& node.sourceEnd() <= top.sourceEnd();
		}
		return true;
	}

	@Override
	public void endvisitGeneral(ASTNode node) throws Exception {
		stack.pop();
	}

	private final Stack<ASTNode> stack = new Stack<ASTNode>();

	private void handleVariableReference(VariableReference ref) {
		final String varName = ref.getName();
		if (varName.length() != 0) {
			if (varName.charAt(0) == '$') {
				requestor.addPosition(ref.sourceStart(), ref.sourceEnd(),
						HL_GLOBAL_VARIABLE);
			} else if (varName.charAt(0) == '@') {
				if (varName.length() > 2 && varName.charAt(1) == '@') {
					requestor.addPosition(ref.sourceStart(), ref.sourceEnd(),
							HL_CLASS_VARIABLE);
				} else {
					requestor.addPosition(ref.sourceStart(), ref.sourceEnd(),
							HL_INSTANCE_VARIABLE);
				}
			} else {
				requestor.addPosition(ref.sourceStart(), ref.sourceEnd(),
						HL_LOCAL_VARIABLE);
			}
		}
	}

	private void handleEvaluatableExpression(ASTNode node) {
		int start = node.sourceStart();
		int end = node.sourceEnd();
		if (content[start] == '#' && content[start + 1] == '{') {
			if (content[end - 1] == '\r') {
				// FIXME JRuby bug
				--end;
			}
			if (content[end - 1] == '}') {
				requestor.addPosition(start, start + 2, HL_EVAL_EXPR);
				requestor.addPosition(end - 1, end - 0, HL_EVAL_EXPR);
			}
		}
	}

	private void handleRegexp(ASTNode node) {
		int start = node.sourceStart();
		int end = node.sourceEnd();
		if (start >= 1 && content[start - 1] == '/') {
			--start;
			if (end < content.length && content[end] == '/') {
				++end;
			}
			while (end < content.length
					&& RubySyntaxUtils.isValidRegexpModifier(content[end])) {
				++end;
			}
		} else if (start >= 3 && content[start - 3] == '%'
				&& content[start - 2] == 'r') {
			char terminator = RubySyntaxUtils
					.getPercentStringTerminator(content[start - 1]);
			if (terminator != 0 && end < content.length
					&& content[end] == terminator) {
				start -= 3;
				++end;
				while (end < content.length
						&& RubySyntaxUtils.isValidRegexpModifier(content[end])) {
					++end;
				}
			}
		}
		requestor.addPosition(start, end, HL_REGEXP);
	}

	@Override
	public String[] getHighlightingKeys() {
		final Set<String> result = new HashSet<String>();
		for (SemanticHighlighting highlighting : getSemanticHighlightings()) {
			result.add(highlighting.getPreferenceKey());
		}
		return result.toArray(new String[result.size()]);
	}

	@Override
	public void process(IModuleSource code,
			ISemanticHighlightingRequestor requestor) {
		this.requestor = requestor;
		this.content = code.getContentsAsCharArray();
		try {
			((ModuleDeclaration) parseCode(code)).traverse(this);
		} catch (ModelException e) {
			throw new AbortSemanticHighlightingException();
		} catch (Exception e) {
			throw new AbortSemanticHighlightingException();
		}
	}

	/**
	 * @param code
	 * @return
	 * @throws ModelException
	 */
	protected IModuleDeclaration parseCode(IModuleSource code)
			throws ModelException {
		if (code instanceof ISourceModule) {
			return parseSourceModule((ISourceModule) code);
		} else {
			return parseSourceCode(code);
		}
	}

	private IModuleDeclaration parseSourceCode(IModuleSource code) {
		return SourceParserUtil.parse(code, RubyNature.NATURE_ID, null);
	}

	private IModuleDeclaration parseSourceModule(
			final ISourceModule sourceModule) {
		return SourceParserUtil.parse(sourceModule, null);
	}

}