/*******************************************************************************
 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
 * in Industry THTH ry.
 * 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:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics;

import java.io.File;
import java.util.UUID;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.core.runtime.Platform;
import org.simantics.SimanticsPlatform.OntologyRecoveryPolicy;
import org.simantics.SimanticsPlatform.RecoveryPolicy;
import org.simantics.application.arguments.IArguments;
import org.simantics.application.arguments.SimanticsArguments;
import org.simantics.db.ReadGraph;
import org.simantics.db.RequestProcessor;
import org.simantics.db.Resource;
import org.simantics.db.Session;
import org.simantics.db.WriteGraph;
import org.simantics.db.common.Indexing;
import org.simantics.db.common.procedure.adapter.ProcedureAdapter;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.exception.RuntimeDatabaseException;
import org.simantics.db.indexing.IndexUtils;
import org.simantics.db.layer0.util.SimanticsClipboard;
import org.simantics.db.layer0.util.SimanticsKeys;
import org.simantics.db.layer0.variable.Variable;
import org.simantics.db.layer0.variable.Variables;
import org.simantics.db.management.ISessionContext;
import org.simantics.db.management.ISessionContextProvider;
import org.simantics.db.management.ISessionContextProviderSource;
import org.simantics.db.management.SessionContextProvider;
import org.simantics.db.management.SingleSessionContextProviderSource;
import org.simantics.db.request.ReadInterface;
import org.simantics.db.request.WriteInterface;
import org.simantics.db.service.XSupport;
import org.simantics.internal.FileServiceImpl;
import org.simantics.layer0.Layer0;
import org.simantics.project.IProject;
import org.simantics.project.ProjectKeys;
import org.simantics.scl.compiler.top.ValueNotFound;
import org.simantics.scl.osgi.SCLOsgi;
import org.simantics.scl.runtime.SCLContext;
import org.simantics.scl.runtime.function.Function;
import org.simantics.scl.runtime.function.Function1;
import org.simantics.scl.runtime.function.Function2;
import org.simantics.utils.FileService;
import org.simantics.utils.FileUtils;
import org.simantics.utils.TempFiles;
import org.simantics.utils.threads.ThreadUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A facade for accessing basic Simantics platform services. Usable without a
 * graphical UI, i.e. in headless contexts.
 *
 * TODO: in time, move headless functionality of SimanticsUI into this class but
 * originals as delegates in SimanticsUI.
 *
 * TODO: duplicate of org.simantics.db.layer0.util.Simantics, do something about this!!
 */
public class Simantics {
    private static final Logger LOGGER = LoggerFactory.getLogger(Simantics.class);

    /**
     * Default database driver ID
     */
    private static final String DEFAULT_DATABASE_DRIVER_ID = "acorn";

    private static String defaultDatabaseDriverId = DEFAULT_DATABASE_DRIVER_ID;

    private static ISessionContextProviderSource providerSource = null;
    private static volatile FileServiceImpl fileService = null;

    /**
     * Sets the database driver to be used by the platform. To have any effect,
     * this must be set before platform startup.
     * 
     * @param id driver id
     */
    public static void setDefaultDatabaseDriver(String id) {
        defaultDatabaseDriverId = id;
    }

    /**
     * Returns currently set default database driver id.
     */
    public static String getDefaultDatabaseDriver() {
        return defaultDatabaseDriverId;
    }

    /**
     * @param args
     * @param progress
     * @return
     * @throws PlatformException
     */
    public static ISessionContext startUpHeadless(IArguments args, IProgressMonitor progress) throws PlatformException {
        if (SimanticsPlatform.INSTANCE.sessionContext != null) {
            throw new RuntimeDatabaseException("Simantics is already up and running.");
        }

        RecoveryPolicy workspacePolicy = Platform.inDevelopmentMode() ? RecoveryPolicy.FixError : RecoveryPolicy.ThrowError;
        OntologyRecoveryPolicy ontologyPolicy = Platform.inDevelopmentMode() ? OntologyRecoveryPolicy.Merge : OntologyRecoveryPolicy.ThrowError;

        if (args.contains(SimanticsArguments.RECOVERY_POLICY_FIX_ERRORS)) {
            workspacePolicy = RecoveryPolicy.FixError;
            ontologyPolicy = OntologyRecoveryPolicy.Merge;
        }

        if (args.contains(SimanticsArguments.ONTOLOGY_RECOVERY_POLICY_REINSTALL)) {
            ontologyPolicy = OntologyRecoveryPolicy.ReinstallDatabase;
        }

        if (args.contains(SimanticsArguments.ONTOLOGY_RECOVERY_POLICY_REINSTALL)) {
            ontologyPolicy = OntologyRecoveryPolicy.ReinstallDatabase;
        }

        if (args.contains(SimanticsArguments.DISABLE_INDEX)) {
            Indexing.setDefaultDependenciesIndexingEnabled(false);
        }

        String databaseDriverId = defaultDatabaseDriverId;
        if (args.contains(SimanticsArguments.DATABASE_ID)) {
            databaseDriverId = args.get(SimanticsArguments.DATABASE_ID);
            Simantics.setDefaultDatabaseDriver(databaseDriverId);
        }

        int localPort = 0;
        if (args.contains(SimanticsArguments.LOCAL_SERVER_PORT)) {
            try {
                localPort = args.get(SimanticsArguments.LOCAL_SERVER_PORT);
            } catch (IllegalArgumentException e) {
                throw new PlatformException("Failed to open database session", e);
            }
        }

//        ServerAddress remoteDatabase = null;
//        if (args.contains(SimanticsArguments.SERVER)) {
//            String serverAddress = args.get(SimanticsArguments.SERVER);
//            try {
//                remoteDatabase = new ServerAddress(serverAddress);
//            } catch (IllegalArgumentException e) {
//                throw new PlatformException("Failed to open database session", e);
//            }
//        }

        return startUpHeadless(progress, workspacePolicy, ontologyPolicy, localPort, databaseDriverId /*, remoteDatabase*/);
    }

    /**
     * @param progress
     * @param workspacePolicy
     * @param ontologyPolicy
     * @param localPort
     * @param remoteDatabase
     * @return
     * @throws PlatformException
     */
    public static ISessionContext startUpHeadless(IProgressMonitor progress, RecoveryPolicy workspacePolicy, OntologyRecoveryPolicy ontologyPolicy, int localPort, String databaseDriverId) throws PlatformException {
        if (SimanticsPlatform.INSTANCE.sessionContext != null) {
            throw new RuntimeDatabaseException("Simantics is already up and running.");
        }

        // Set session context provider.
        final ISessionContextProvider provider = new SessionContextProvider(null);
        ISessionContextProviderSource source = new SingleSessionContextProviderSource(provider);
        setSessionContextProviderSource(source);
        org.simantics.db.layer0.internal.SimanticsInternal.setSessionContextProviderSource(source);

        if (progress == null)
            progress = new NullProgressMonitor();
        return SimanticsPlatform.INSTANCE.startUp(databaseDriverId, progress, workspacePolicy, ontologyPolicy, true, new ConsoleUserAgent());
    }

    /**
     * @param progress
     * @throws PlatformException
     */
    public static void shutdown(IProgressMonitor progress) throws PlatformException {
        SimanticsPlatform.INSTANCE.shutdown(progress);
    }

    /**
     * Queue execution of a runnable.
     *
     * @param runnable
     */
    public static void async(Runnable runnable) {
        ThreadUtils.getBlockingWorkExecutor().execute(runnable);
    }

    public static void async(Runnable runnable, int delay, TimeUnit unit) {
        ThreadUtils.getTimer().schedule(runnable, delay, unit);
    }

    public static ScheduledFuture<?> scheduleAtFixedRate(Runnable runnable, int initialDelay, int period, TimeUnit unit) {
        return ThreadUtils.getTimer().scheduleAtFixedRate(runnable, initialDelay, period, unit);
    }

    /**
     * Queue execution of a non-blocking runnable. Use this method with caution.
     * A non-blocking runnable nevers locks anything, No Locks, No semaphores,
     * No Object.wait(), No synchronized() {} blocks.
     *
     * @param runnable a non-blocking runnable
     */
    public static void asyncNonblocking(Runnable runnable) {
        ThreadUtils.getNonBlockingWorkExecutor().execute(runnable);
    }

    /**
     * Schedule execution of a non-blocking runnable. Use this method with caution.
     * A non-blocking runnable never locks anything, No Locks, No semaphores,
     * No Object,wait(), No synchronized() {} blocks.
     *
     * @param runnable a non-blocking runnable
     * @param initialDelay
     * @param period
     */
    public static void asyncNonblocking(Runnable runnable, int initialDelay, int period) {
        ThreadUtils.getNonBlockingWorkExecutor().scheduleAtFixedRate(runnable, initialDelay, period, TimeUnit.MILLISECONDS);
    }

    public static synchronized ISessionContext setSessionContext(ISessionContext ctx) {
        return getSessionContextProvider().setSessionContext(ctx);
    }

    public static void setSessionContextProviderSource(ISessionContextProviderSource source) {
        if (source == null)
            throw new IllegalArgumentException("null provider source");
        providerSource = source;
    }

    public static ISessionContextProviderSource getProviderSource() {
        if (providerSource == null)
            throw new IllegalStateException(
            "providerSource must be initialized by the application before using class Simantics");
        return providerSource;
    }

    public static ISessionContextProvider getSessionContextProvider() {
        return getProviderSource().getActive();
    }

    /**
     * Returns the database session context associated with the currently active
     * context. This method should be used to retrieve session contexts only
     * when the client is sure that the correct context is active.
     *
     * @return the session context associated with the currently active context
     *         or <code>null</code> if the context has no session context
     */
    public static ISessionContext getSessionContext() {
        ISessionContextProvider provider = getSessionContextProvider();
        return provider != null ? provider.getSessionContext() : null;
    }

    /**
     * Returns the database Session bound to the currently active context.
     *
     * <p>
     * The method always returns a non-null Session or produces an
     * IllegalStateException if a Session was not attainable.
     * </p>
     *
     * @return the Session bound to the currently active workbench window
     * @throws IllegalStateException if no Session was available
     */
    public static Session getSession() {
        ISessionContext ctx = getSessionContext();
        if (ctx == null)
            throw new IllegalStateException("Session unavailable, no database session open");
        return ctx.getSession();
    }
    
    public static RequestProcessor getAvailableRequestProcessor() {
        Object graph = SCLContext.getCurrent().get("graph");
        if(graph instanceof ReadGraph)
            return (RequestProcessor)graph;
        else
            return Simantics.getSession();
    }

    /**
     * Returns the database Session bound to the currently active context.
     * Differently from {@link #getSession()}, this method returns
     * <code>null</code> if there is no current Session available.
     *
     * @see #getSession()
     * @return the Session bound to the currently active context or
     *         <code>null</code>
     */
    public static Session peekSession() {
        ISessionContext ctx = getSessionContext();
        return ctx == null ? null : ctx.peekSession();
    }

    /**
     * @return the currently open and active project as a Resource
     * @throws IllegalStateException if there is no currently active database
     *         session, which also means there is no active project at the
     *         moment
     */
    public static Resource getProjectResource() {
        ISessionContext ctx = getSessionContext();
        if (ctx == null)
            throw new IllegalStateException("No current database session");
        Resource project = ctx.getHint(SimanticsKeys.KEY_PROJECT);
        if (project == null)
            throw new IllegalStateException("No current project resource in session context " + ctx);
        return project;
    }

    /**
     * @return the currently open and active project as a {@link Resource}
     */
    public static Resource peekProjectResource() {
        ISessionContext ctx = getSessionContext();
        return ctx != null ? ctx.<Resource>getHint(SimanticsKeys.KEY_PROJECT) : null;
    }

    /**
     * @return the currently open and active project as an {@link IProject}
     * @throws IllegalStateException if there is no currently active database
     *         session, which also means there is no active project at the
     *         moment
     */
    public static IProject getProject() {
        ISessionContext ctx = getSessionContext();
        if (ctx == null)
            throw new IllegalStateException("No current database session");
        IProject project = ctx.getHint(ProjectKeys.KEY_PROJECT);
        if (project == null)
            throw new IllegalStateException("No current project in session context " + ctx);
        return project;
    }

    /**
     * @return the currently open and active project as an {@link IProject} or
     *         <code>null</code> if there is no active session or project
     */
    public static IProject peekProject() {
        ISessionContext ctx = getSessionContext();
        return ctx == null ? null : ctx.<IProject>getHint(ProjectKeys.KEY_PROJECT);
    }

    // FIXME: once org.simantics.db.layer0.util.Simantics is gone, re-enable this
//    private static SimanticsClipboard clipboard = SimanticsClipboard.EMPTY;

    /**
     * @param content
     */
    public static void setClipboard(SimanticsClipboard content) {
        // FIXME: once org.simantics.db.layer0.util.Simantics is gone, re-enable this
//        if (content == null)
//            throw new NullPointerException("null clipboard content");
//        clipboard = content;
        org.simantics.db.layer0.internal.SimanticsInternal.setClipboard(content);
    }

    public static SimanticsClipboard getClipboard() {
        // FIXME: once org.simantics.db.layer0.util.Simantics is gone, re-enable this
        //return clipboard;
        return org.simantics.db.layer0.internal.SimanticsInternal.getClipboard();
    }

    public static Layer0 getLayer0() throws DatabaseException {
        return Layer0.getInstance(getSession());
    }

    public static <T> T sync(ReadInterface<T> r) throws DatabaseException {
    	return getSession().sync(r);
    }

    public static <T> T sync(WriteInterface<T> r) throws DatabaseException {
    	return getSession().sync(r);
    }

    public static <T> void async(ReadInterface<T> r) {
    	getSession().async(r, new ProcedureAdapter<T>());
    }

    public static <T> void async(WriteInterface<T> r) {
    	getSession().async(r);
    }

    public static void clearTemporaryDirectory() {
        FileUtils.deleteDir(getTemporaryDirectory());
    }

    public static File getTempfile(String directory, String suffix) {
        File dir = getTemporaryDirectory(directory);
        return new File(dir, UUID.randomUUID().toString() + "." + suffix);
    }

    public static File getTemporaryDirectory(String directory) {
        File sub = new File(getTemporaryDirectory(), directory);
        sub.mkdirs();
        return sub;
    }

    public static File getTemporaryDirectory() {
        File workspace = Platform.getLocation().toFile();
        File temp = new File(workspace, "tempFiles");
        temp.mkdirs();
        return temp;
    }

    public static TempFiles getTempFiles() {
        return TEMP_FILES;
    }

    private static class TempFilesImpl implements TempFiles {
        private final TempFilesImpl parent;
        private final String prefix;
        private final String fullPrefix;

        private TempFilesImpl(TempFilesImpl parent, String directory) {
            this.parent = parent;
            this.prefix = directory;
            this.fullPrefix = getPrefix(new StringBuilder()).toString();
        }

        private StringBuilder getPrefix(StringBuilder sb) {
            if (parent != null)
                parent.getPrefix(sb);
            if (prefix != null && !prefix.isEmpty())
                sb.append(prefix).append(File.separatorChar);
            return sb;
        }

        @Override
        public File getRoot() {
            return Simantics.getTemporaryDirectory(fullPrefix);
        }

        @Override
        public File getTempfile(String directory, String suffix) {
            return Simantics.getTempfile(fullPrefix.isEmpty() ? directory : fullPrefix + directory, suffix);
        }

        @Override
        public TempFiles subdirectory(String directory) {
            return new TempFilesImpl(this, directory);
        }
    }

    public static TempFiles TEMP_FILES = new TempFilesImpl(null, null);

    public static void flushIndexCaches(IProgressMonitor progress, Session session) {
        try {
            IndexUtils.flushIndexCaches(progress, session);
        } catch (Exception e) {
            LOGGER.error("Flushing index caches failed.", e);
        }
    }

    public static void saveQueries(Session session) {
        try {
            XSupport xs = session.getService(XSupport.class);
            xs.saveQueries();
        } catch (Exception e) {
            LOGGER.error("Saving database queries failed.", e);
        }
    }

    @SuppressWarnings({ "unchecked", "rawtypes" })
    public static <T> T applySCL(String module, String function, Object ... args) throws DatabaseException {
        try {
            T t = (T)((Function)SCLOsgi.MODULE_REPOSITORY.getValue(module, function)).applyArray(args);
            return t;
        } catch (ValueNotFound e) {
            throw new DatabaseException("SCL Value not found: " + e.name);
        } catch (Throwable t) {
            if (t instanceof DatabaseException)
                throw (DatabaseException) t;
            throw new DatabaseException(t);
        }
    }

    public static <T> T applySCL(String module, String function, ReadGraph graph, Object ... args) throws DatabaseException {
        SCLContext sclContext = SCLContext.getCurrent();
        Object oldGraph = sclContext.put("graph", graph);
        try {
            return applySCL(module, function, args);
        } catch (DatabaseException dbe) {
            throw dbe;
        } catch (Throwable t) {
            throw new DatabaseException(t);
        } finally {
            sclContext.put("graph", oldGraph);
        }
    }

    @SuppressWarnings("unchecked")
    public static <T> T applySCLWrite(WriteGraph graph, @SuppressWarnings("rawtypes") Function f, Object ... args) throws DatabaseException {
        SCLContext sclContext = SCLContext.getCurrent();
        Object oldGraph = sclContext.put("graph", graph);
        try {
            return (T)f.applyArray(args);
        } catch (Throwable t) {
            if (t instanceof DatabaseException)
                throw (DatabaseException) t;
            throw new DatabaseException(t);
        } finally {
            sclContext.put("graph", oldGraph);
        }
    }

    @SuppressWarnings("unchecked")
    public static <T> T applySCLRead(ReadGraph graph, @SuppressWarnings("rawtypes") Function f, Object ... args) throws DatabaseException {
        SCLContext sclContext = SCLContext.getCurrent();
        Object oldGraph = sclContext.put("graph", graph);
        try {
            return (T)f.applyArray(args);
        } catch (Throwable t) {
            if (t instanceof DatabaseException)
                throw (DatabaseException) t;
            throw new DatabaseException(t);
        } finally {
            sclContext.put("graph", oldGraph);
        }
    }
    
    public static <P0,R> R applySCLWrite(WriteGraph graph, Function1<P0,R> function, P0 p0) throws DatabaseException {
        SCLContext sclContext = SCLContext.getCurrent();
        Object oldGraph = sclContext.put("graph", graph);
        try {
            return function.apply(p0);
        } catch (Throwable t) {
            if (t instanceof DatabaseException)
                throw (DatabaseException) t;
            throw new DatabaseException(t);
        } finally {
            sclContext.put("graph", oldGraph);
        }
    }

    public static <P0,R> R applySCLRead(ReadGraph graph, Function1<P0,R> function, P0 p0) throws DatabaseException {
        SCLContext sclContext = SCLContext.getCurrent();
        Object oldGraph = sclContext.put("graph", graph);
        try {
            return function.apply(p0);
        } catch (Throwable t) {
            if (t instanceof DatabaseException)
                throw (DatabaseException) t;
            throw new DatabaseException(t);
        } finally {
            sclContext.put("graph", oldGraph);
        }
    }

    public static <P0,P1,R> R applySCLRead(ReadGraph graph, Function2<P0,P1,R> function, P0 p0, P1 p1) throws DatabaseException {
        SCLContext sclContext = SCLContext.getCurrent();
        Object oldGraph = sclContext.put("graph", graph);
        try {
            return function.apply(p0, p1);
        } catch (Throwable t) {
            if (t instanceof DatabaseException)
                throw (DatabaseException) t;
            throw new DatabaseException(t);
        } finally {
            sclContext.put("graph", oldGraph);
        }
    }

    public static <P0,R> R invokeSCLWrite(WriteGraph graph, Variable property, P0 p0) throws DatabaseException {
        Function1<P0,R> fn = property.getPossibleValue(graph);
        if(fn == null) throw new DatabaseException("No function for " + property.getURI(graph));
        return Simantics.applySCLWrite(graph, fn, p0);
    }

    public static <P0,R> R invokeSCL(ReadGraph graph, Variable property, P0 p0) throws DatabaseException {
        Function1<P0,R> fn = property.getPossibleValue(graph);
        if(fn == null) throw new DatabaseException("No function for " + property.getURI(graph));
        return Simantics.applySCLRead(graph, fn, p0);
    }

    public static <P0,P1,R> R invokeSCL(ReadGraph graph, Variable property, P0 p0, P1 p1) throws DatabaseException {
        Function2<P0,P1,R> fn = property.getPossibleValue(graph);
        if(fn == null) throw new DatabaseException("No function for " + property.getURI(graph));
        return Simantics.applySCLRead(graph, fn, p0, p1);
    }

    public static <P0,R> R invokeSCLWrite(WriteGraph graph, Resource entity, Resource property, P0 p0) throws DatabaseException {
        return invokeSCLWrite(graph, getProperty(graph, entity, property), p0);
    }

    public static <P0,R> R invokeSCL(ReadGraph graph, Resource entity, Resource property, P0 p0) throws DatabaseException {
        return invokeSCL(graph, getProperty(graph, entity, property), p0);
    }

    public static <P0,P1,R> R invokeSCL(ReadGraph graph, Resource entity, Resource property, P0 p0, P1 p1) throws DatabaseException {
        return invokeSCL(graph, getProperty(graph, entity, property), p0, p1);
    }

	public static <P0,R> R tryInvokeSCL(ReadGraph graph, Resource entity, Resource property, P0 p0) throws DatabaseException {
    	Variable p = Variables.tryGetProperty(graph, entity, property);
    	if (p == null)
    		return null;
        return invokeSCL(graph, p, p0);
    }

	public static <P0,P1,R> R tryInvokeSCL(ReadGraph graph, Resource entity, Resource property, P0 p0, P1 p1) throws DatabaseException {
    	Variable p = Variables.tryGetProperty(graph, entity, property);
    	if (p == null)
    		return null;
        return invokeSCL(graph, p, p0, p1);
    }

	private static Variable getProperty(ReadGraph graph, Resource entity, Resource property) throws DatabaseException {
        return Variables.getVariable(graph, entity).getProperty(graph, property);
    }

    public static boolean ensureMemoryBytes(long bytes) {

    	Runtime runtime = Runtime.getRuntime();
    	long consumedMemory = runtime.totalMemory() - runtime.freeMemory();
    	long available = runtime.maxMemory() - consumedMemory;

    	return available > bytes;

    }

    public static long getDiskBytes() {

        File ws = new File(Platform.getInstanceLocation().getURL().getFile());
        return ws.getUsableSpace();

    }

    /**
     * @return a service for dealing with recurring file system handling cases
     */
    public static FileService getFileService() {
        FileService fs = fileService;
        if (fs == null) {
            synchronized (Simantics.class) {
                fs = fileService;
                if (fs == null)
                    fs = fileService = new FileServiceImpl();
            }
        }
        return fs;
    }

}