/*******************************************************************************
 * Copyright (c) 2000, 2017 IBM Corporation and others.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 * 
 * SPDX-License-Identifier: EPL-2.0
 *
 *******************************************************************************/
package org.eclipse.dltk.core.search;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.OperationCanceledException;
import org.eclipse.core.runtime.Path;
import org.eclipse.core.runtime.SubProgressMonitor;
import org.eclipse.dltk.core.DLTKLanguageManager;
import org.eclipse.dltk.core.IDLTKLanguageToolkit;
import org.eclipse.dltk.core.ISourceModule;
import org.eclipse.dltk.core.search.index.Index;
import org.eclipse.dltk.core.search.index.MixinIndex;
import org.eclipse.dltk.core.search.indexing.IndexManager;
import org.eclipse.dltk.core.search.matching.IMatchLocator;
import org.eclipse.dltk.core.search.matching.MatchLocator;
import org.eclipse.dltk.core.search.matching.ModuleFactory;
import org.eclipse.dltk.internal.core.Model;
import org.eclipse.dltk.internal.core.search.IndexSelector;
import org.eclipse.dltk.internal.core.search.LazyDLTKSearchDocument;
import org.eclipse.dltk.internal.core.util.Util;

/**
 * A search participant describes a particular extension to a generic search
 * mechanism, allowing thus to perform combined search actions which will
 * involve all required participants
 *
 * A search scope defines which participants are involved.
 *
 * A search participant is responsible for holding index files, and selecting
 * the appropriate ones to feed to index queries. It also can map a document
 * path to an actual document (note that documents could live outside the
 * workspace or no exist yet, and thus aren't just resources).
 */
public class DLTKSearchParticipant extends SearchParticipant {
	private IndexSelector indexSelector;
	private boolean bOnlyMixin = false;

	@Override
	public void beginSearching() {
		super.beginSearching();
		this.indexSelector = null;
	}

	@Override
	public void doneSearching() {
		this.indexSelector = null;
		super.doneSearching();
	}

	@Override
	public String getDescription() {
		return "DLTK"; //$NON-NLS-1$
	}

	@Override
	public SearchDocument getDocument(String documentPath, IProject project) {
		return new LazyDLTKSearchDocument(documentPath, this,
				isExternal(documentPath), project);
	}

	private boolean isExternal(String documentPath) {
		Object target = Model.getTarget(
				ResourcesPlugin.getWorkspace().getRoot(),
				new Path(documentPath), true);
		if (target instanceof IResource)
			return false;
		else
			return true;

	}

	@Override
	public void locateMatches(SearchDocument[] indexMatches,
			SearchPattern pattern, IDLTKSearchScope scope,
			SearchRequestor requestor, IProgressMonitor monitor)
			throws CoreException {
		IMatchLocator matchLocator = createMatchLocator(
				scope.getLanguageToolkit());
		matchLocator.initialize(pattern, scope);
		matchLocator.setRequestor(requestor);
		matchLocator.setProgressMonitor(
				monitor == null ? null : new SubProgressMonitor(monitor, 95));
		/* eliminating false matches and locating them */
		if (monitor != null && monitor.isCanceled())
			throw new OperationCanceledException();
		matchLocator.locateMatches(indexMatches);
		if (monitor != null && monitor.isCanceled())
			throw new OperationCanceledException();
		// matchLocator.locatePackageDeclarations(this);
	}

	@Override
	public ISourceModule[] locateModules(SearchDocument[] indexMatches,
			IDLTKSearchScope scope, IProgressMonitor monitor)
			throws CoreException {
		if (monitor != null && monitor.isCanceled())
			throw new OperationCanceledException();
		return doLocateModules(indexMatches, scope, monitor);
	}

	private ISourceModule[] doLocateModules(SearchDocument[] searchDocuments,
			IDLTKSearchScope scope, IProgressMonitor progressMonitor) {
		final List<ISourceModule> modules = new ArrayList<>(
				searchDocuments.length);
		int docsLength = searchDocuments.length;
		if (BasicSearchEngine.VERBOSE) {
			System.out.println("Locating matches in documents ["); //$NON-NLS-1$
			for (int i = 0; i < docsLength; i++)
				System.out.println("\t" + searchDocuments[i]); //$NON-NLS-1$
			System.out.println("]"); //$NON-NLS-1$
		}
		// init infos for progress increasing
		int n = docsLength < 1000
				? Math.min(Math.max(docsLength / 200 + 1, 2), 4)
				: 5 * (docsLength / 1000);
		// step should not be 0
		final int progressStep = docsLength < n ? 1 : docsLength / n;
		int progressWorked = 0;
		// initialize handle factory
		final ModuleFactory moduleFactory = new ModuleFactory(scope);
		if (progressMonitor != null) {
			progressMonitor.beginTask("", searchDocuments.length); //$NON-NLS-1$
		}
		Util.sort(searchDocuments, (a, b) -> ((SearchDocument) a).getPath()
				.compareTo(((SearchDocument) b).getPath()));
		final Set<String> previousPaths = new HashSet<>();
		for (int i = 0; i < docsLength; i++) {
			if (progressMonitor != null && progressMonitor.isCanceled()) {
				throw new OperationCanceledException();
			}
			if (progressMonitor != null) {
				progressWorked++;
				if ((progressWorked % progressStep) == 0)
					progressMonitor.worked(progressStep);
			}
			SearchDocument searchDocument = searchDocuments[i];
			searchDocuments[i] = null; // free current document
			// skip duplicate paths
			if (previousPaths.add(searchDocument.getPath())) {
				final ISourceModule openable = moduleFactory
						.create(searchDocument);
				if (openable == null) {
					continue; // match is outside buildpath
				}
				modules.add(openable);
			}
		}
		if (progressMonitor != null)
			progressMonitor.done();
		return modules.toArray(new ISourceModule[modules.size()]);
	}

	protected IMatchLocator createMatchLocator(IDLTKLanguageToolkit toolkit) {
		if (toolkit != null) {
			return DLTKLanguageManager
					.createMatchLocator(toolkit.getNatureId());
		} else {
			return new MatchLocator();
		}
	}

	@Override
	public IPath[] selectIndexes(SearchPattern pattern,
			IDLTKSearchScope scope) {
		if (this.indexSelector == null) {
			this.indexSelector = new IndexSelector(scope, pattern);
			this.indexSelector.setMixinOnly(this.bOnlyMixin);
		}
		return this.indexSelector.getIndexLocations();
	}

	@Override
	public IPath[] selectMixinIndexes(SearchPattern query,
			IDLTKSearchScope scope) {
		this.skipNotMixin();
		return selectIndexes(query, scope);
	}

	@Override
	public void skipNotMixin() {
		this.bOnlyMixin = true;
	}

	@Override
	public boolean isSkipped(Index index) {
		final boolean mixinIndex = index instanceof MixinIndex
				|| index.containerPath.startsWith(IndexManager.SPECIAL_MIXIN);
		return this.bOnlyMixin != mixinIndex;
	}
}