/*******************************************************************************
 * Copyright (c) 2000, 2017 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
 *
 *******************************************************************************/
package org.eclipse.dltk.internal.ui.text.hover;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.StringTokenizer;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtensionRegistry;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Status;
import org.eclipse.dltk.internal.ui.editor.EditorUtility;
import org.eclipse.dltk.ui.DLTKUIPlugin;
import org.eclipse.dltk.ui.PreferenceConstants;
import org.eclipse.dltk.ui.text.hover.IScriptEditorTextHover;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.swt.SWT;
import org.osgi.framework.Bundle;

/**
 * Describes a editor text hover.
 */
public class EditorTextHoverDescriptor {
	private static final String EDITOR_TEXT_HOVER_EXTENSION_POINT = "org.eclipse.dltk.ui.editorTextHovers"; //$NON-NLS-1$
	private static final String HOVER_TAG = "hover"; //$NON-NLS-1$
	private static final String ID_ATTRIBUTE = "id"; //$NON-NLS-1$
	private static final String CLASS_ATTRIBUTE = "class"; //$NON-NLS-1$
	private static final String LABEL_ATTRIBUTE = "label"; //$NON-NLS-1$
	private static final String ACTIVATE_PLUG_IN_ATTRIBUTE = "activate"; //$NON-NLS-1$
	private static final String DESCRIPTION_ATTRIBUTE = "description"; //$NON-NLS-1$
	private static final String NATURE_ATTRIBUTE = "nature"; //$NON-NLS-1$
	public static final String NO_MODIFIER = "0"; //$NON-NLS-1$
	public static final String DISABLED_TAG = "!"; //$NON-NLS-1$
	public static final String VALUE_SEPARATOR = ";"; //$NON-NLS-1$
	private int fStateMask;
	private String fModifierString;
	private boolean fIsEnabled;
	private IConfigurationElement fElement;

	/**
	 * Returns all editor text hovers contributed to the workbench.
	 *
	 * @deprecated
	 */
	@Deprecated
	public static EditorTextHoverDescriptor[] getContributedHovers(
			IPreferenceStore store) {
		return getContributedHovers(null, store);
	}

	/**
	 * Returns all editor text hovers contributed to the workbench for the
	 * specified nature.
	 */
	public static EditorTextHoverDescriptor[] getContributedHovers(
			String natureId, IPreferenceStore store) {
		IExtensionRegistry registry = Platform.getExtensionRegistry();
		IConfigurationElement[] elements = registry
				.getConfigurationElementsFor(EDITOR_TEXT_HOVER_EXTENSION_POINT);
		EditorTextHoverDescriptor[] hoverDescs = createDescriptors(elements,
				natureId);
		initializeFromPreferences(hoverDescs, store);
		return hoverDescs;
	}

	/**
	 * Computes the state mask for the given modifier string.
	 *
	 * @param modifiers
	 *            the string with the modifiers, separated by '+', '-', ';', ','
	 *            or '.'
	 * @return the state mask or -1 if the input is invalid
	 */
	public static int computeStateMask(String modifiers) {
		if (modifiers == null)
			return -1;
		if (modifiers.length() == 0)
			return SWT.NONE;
		int stateMask = 0;
		StringTokenizer modifierTokenizer = new StringTokenizer(modifiers,
				",;.:+-* "); //$NON-NLS-1$
		while (modifierTokenizer.hasMoreTokens()) {
			int modifier = EditorUtility
					.findLocalizedModifier(modifierTokenizer.nextToken());
			if (modifier == 0 || (stateMask & modifier) == modifier)
				return -1;
			stateMask = stateMask | modifier;
		}
		return stateMask;
	}

	/**
	 * Creates a new Script Editor text hover descriptor from the given
	 * configuration element.
	 */
	private EditorTextHoverDescriptor(IConfigurationElement element) {
		fElement = element;
	}

	/**
	 * Creates the editor text hover.
	 */
	public IScriptEditorTextHover createTextHover() {
		String pluginId = fElement.getContributor().getName();
		boolean isHoversPlugInActivated = Platform.getBundle(pluginId)
				.getState() == Bundle.ACTIVE;
		if (isHoversPlugInActivated || canActivatePlugIn()) {
			try {
				return (IScriptEditorTextHover) fElement
						.createExecutableExtension(CLASS_ATTRIBUTE);
			} catch (CoreException x) {
				DLTKUIPlugin.log(new Status(IStatus.ERROR,
						DLTKUIPlugin.getPluginId(), 0,
						"DLTKHoverMessages.JavaTextHover_createTextHover", //$NON-NLS-1$
						null));
			}
		}
		return null;
	}

	// ---- XML Attribute accessors
	// ---------------------------------------------
	/**
	 * Returns the hover's id.
	 */
	public String getId() {
		return fElement.getAttribute(ID_ATTRIBUTE);
	}

	/**
	 * Returns the hover's class name.
	 */
	public String getHoverClassName() {
		return fElement.getAttribute(CLASS_ATTRIBUTE);
	}

	/**
	 * Returns the hover's label.
	 */
	public String getLabel() {
		String label = fElement.getAttribute(LABEL_ATTRIBUTE);
		if (label != null)
			return label;
		// Return simple class name
		label = getHoverClassName();
		int lastDot = label.lastIndexOf('.');
		if (lastDot >= 0 && lastDot < label.length() - 1)
			return label.substring(lastDot + 1);
		else
			return label;
	}

	/**
	 * Returns the hover's description.
	 *
	 * @return the hover's description or <code>null</code> if not provided
	 */
	public String getDescription() {
		return fElement.getAttribute(DESCRIPTION_ATTRIBUTE);
	}

	public String getNature() {
		return fElement.getAttribute(NATURE_ATTRIBUTE);
	}

	public boolean canActivatePlugIn() {
		return Boolean
				.valueOf(fElement.getAttribute(ACTIVATE_PLUG_IN_ATTRIBUTE))
				.booleanValue();
	}

	@Override
	public boolean equals(Object obj) {
		if (obj == null || !obj.getClass().equals(this.getClass())
				|| getId() == null)
			return false;
		return getId().equals(((EditorTextHoverDescriptor) obj).getId());
	}

	@Override
	public int hashCode() {
		return getId().hashCode();
	}

	private static EditorTextHoverDescriptor[] createDescriptors(
			IConfigurationElement[] elements, String natureId) {
		List<EditorTextHoverDescriptor> result = new ArrayList<>(
				elements.length);
		for (int i = 0; i < elements.length; i++) {
			IConfigurationElement element = elements[i];
			if (HOVER_TAG.equals(element.getName())) {
				final String elementNature = element
						.getAttribute(NATURE_ATTRIBUTE);
				if (elementNature == null || elementNature.equals(natureId)) {
					EditorTextHoverDescriptor desc = new EditorTextHoverDescriptor(
							element);
					result.add(desc);
				}
			}
		}
		return result.toArray(new EditorTextHoverDescriptor[result.size()]);
	}

	private static void initializeFromPreferences(
			EditorTextHoverDescriptor[] hovers, IPreferenceStore store) {
		String compiledTextHoverModifiers = store
				.getString(PreferenceConstants.EDITOR_TEXT_HOVER_MODIFIERS);
		StringTokenizer tokenizer = new StringTokenizer(
				compiledTextHoverModifiers, VALUE_SEPARATOR);
		HashMap<String, String> idToModifier = new HashMap<>(
				tokenizer.countTokens() / 2);
		while (tokenizer.hasMoreTokens()) {
			String id = tokenizer.nextToken();
			if (tokenizer.hasMoreTokens())
				idToModifier.put(id, tokenizer.nextToken());
		}
		String compiledTextHoverModifierMasks = store.getString(
				PreferenceConstants.EDITOR_TEXT_HOVER_MODIFIER_MASKS);
		tokenizer = new StringTokenizer(compiledTextHoverModifierMasks,
				VALUE_SEPARATOR);
		HashMap<String, String> idToModifierMask = new HashMap<>(
				tokenizer.countTokens() / 2);
		while (tokenizer.hasMoreTokens()) {
			String id = tokenizer.nextToken();
			if (tokenizer.hasMoreTokens())
				idToModifierMask.put(id, tokenizer.nextToken());
		}
		for (int i = 0; i < hovers.length; i++) {
			String modifierString = idToModifier.get(hovers[i].getId());
			boolean enabled = true;
			if (modifierString == null)
				modifierString = DISABLED_TAG;
			if (modifierString.startsWith(DISABLED_TAG)) {
				enabled = false;
				modifierString = modifierString.substring(1);
			}
			if (modifierString.equals(NO_MODIFIER))
				modifierString = ""; //$NON-NLS-1$
			hovers[i].fModifierString = modifierString;
			hovers[i].fIsEnabled = enabled;
			hovers[i].fStateMask = computeStateMask(modifierString);
			if (hovers[i].fStateMask == -1) {
				// Fallback: use stored modifier masks
				try {
					hovers[i].fStateMask = Integer
							.parseInt(idToModifierMask.get(hovers[i].getId()));
				} catch (NumberFormatException ex) {
					hovers[i].fStateMask = -1;
				}
				// Fix modifier string
				int stateMask = hovers[i].fStateMask;
				if (stateMask == -1)
					hovers[i].fModifierString = ""; //$NON-NLS-1$
				else
					hovers[i].fModifierString = EditorUtility
							.getModifierString(stateMask);
			}
		}
	}

	/**
	 * Returns the configured modifier getStateMask for this hover.
	 *
	 * @return the hover modifier stateMask or -1 if no hover is configured
	 */
	public int getStateMask() {
		return fStateMask;
	}

	/**
	 * Returns the modifier String as set in the preference store.
	 *
	 * @return the modifier string
	 */
	public String getModifierString() {
		return fModifierString;
	}

	/**
	 * Returns whether this hover is enabled or not.
	 *
	 * @return <code>true</code> if enabled
	 */
	public boolean isEnabled() {
		return fIsEnabled;
	}

	/**
	 * Returns this hover descriptors configuration element.
	 *
	 * @return the configuration element
	 *
	 */
	public IConfigurationElement getConfigurationElement() {
		return fElement;
	}
}