/*******************************************************************************
 * Copyright (c) 2000, 2013 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
 *******************************************************************************/
package org.eclipse.ui.internal.console;

import java.lang.reflect.Field;
import java.text.MessageFormat;

import org.eclipse.core.expressions.EvaluationContext;
import org.eclipse.core.expressions.EvaluationResult;
import org.eclipse.core.expressions.Expression;
import org.eclipse.core.expressions.ExpressionConverter;
import org.eclipse.core.expressions.ExpressionTagNames;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.variables.VariablesPlugin;
import org.eclipse.ui.IPluginContribution;
import org.eclipse.ui.console.ConsolePlugin;
import org.eclipse.ui.console.IConsole;
import org.eclipse.ui.console.IPatternMatchListenerDelegate;


public class PatternMatchListenerExtension implements IPluginContribution {

	private IConfigurationElement fConfig;
	private Expression fEnablementExpression;
	private String fPattern;
	private String fQualifier;
	private int fFlags = -1;

	public PatternMatchListenerExtension(IConfigurationElement extension) {
		fConfig = extension;
	}

	/*
	 * returns the integer value of the flags defined in java.util.regex.Pattern.
	 * Both <code>Pattern.MULTILINE</code> and <code>MULTILINE</code> will return
	 * the same value.
	 */
	public int parseFlags(String flagsElement) {
		int val = 0;
		if (flagsElement == null) {
			return val;
		}

		try {
			String flags = flagsElement.replaceAll("Pattern.", ""); //$NON-NLS-1$ //$NON-NLS-2$
			String[] tokens = flags.split("\\s\\|\\s"); //$NON-NLS-1$
			Class<?> clazz = Class.forName("java.util.regex.Pattern"); //$NON-NLS-1$
			for (String token : tokens) {
				Field field = clazz.getDeclaredField(token);
				val |= field.getInt(null);
			}
		} catch (ClassNotFoundException e) {
			ConsolePlugin.log(e);
		} catch (NoSuchFieldException e) {
			ConsolePlugin.log(e);
		} catch (IllegalAccessException e) {
			ConsolePlugin.log(e);
		}
		return val;
	}

	public boolean isEnabledFor(IConsole console) throws CoreException {
		EvaluationContext context = new EvaluationContext(null, console);
		EvaluationResult evaluationResult = getEnablementExpression().evaluate(context);
		return evaluationResult == EvaluationResult.TRUE;
	}

	public IPatternMatchListenerDelegate createDelegate() throws CoreException {
		return (IPatternMatchListenerDelegate) fConfig.createExecutableExtension("class"); //$NON-NLS-1$
	}

	public Expression getEnablementExpression() throws CoreException {
		if (fEnablementExpression == null) {
			IConfigurationElement[] elements = fConfig.getChildren(ExpressionTagNames.ENABLEMENT);
			if (elements.length == 0) {
				String message = MessageFormat.format("{0} " + getLocalId() + " {1} " + getPluginId() + " {2}", new Object[] { ConsoleMessages.PatternMatchListenerExtension_3, ConsoleMessages.PatternMatchListenerExtension_4, ConsoleMessages.PatternMatchListenerExtension_5 }); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
				ConsolePlugin.log(new Status(IStatus.WARNING, ConsolePlugin.getUniqueIdentifier(), IStatus.OK, message, null));
			}
			IConfigurationElement enablement = elements.length > 0 ? elements[0] : null;

			if (enablement != null) {
				fEnablementExpression = ExpressionConverter.getDefault().perform(enablement);
			}
		}
		return fEnablementExpression;
	}

	/*
	 * returns the regular expression to be matched.
	 */
	public String getPattern() {
		if (fPattern == null) {
			fPattern = fConfig.getAttribute("regex"); //$NON-NLS-1$
			try {
				fPattern = VariablesPlugin.getDefault().getStringVariableManager().performStringSubstitution(fPattern, false);
			} catch (CoreException e) {
				ConsolePlugin.log(e);
			}
		}
		return fPattern;
	}

	/*
	 * returns the flags to be used by <code>Pattern.compile(pattern, flags)</code>
	 */
	public int getCompilerFlags() {
		if(fFlags < 0) {
			String flagsAttribute = fConfig.getAttribute("flags"); //$NON-NLS-1$
			fFlags = parseFlags(flagsAttribute);
		}
		return fFlags;
	}

	@Override
	public String getLocalId() {
		return fConfig.getAttribute("id"); //$NON-NLS-1$
	}

	@Override
	public String getPluginId() {
		return fConfig.getContributor().getName();
	}

	public String getQuickPattern() {
		if (fQualifier == null) {
			fQualifier = fConfig.getAttribute("qualifier"); //$NON-NLS-1$
			try {
				if (fQualifier != null) {
					fQualifier = VariablesPlugin.getDefault().getStringVariableManager().performStringSubstitution(fQualifier, false);
				}
			} catch (CoreException e) {
				ConsolePlugin.log(e);
			}
		}
		return fQualifier;
	}
}