// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package io.v.debug;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;

import org.joda.time.Duration;

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

import io.v.android.v23.V;
import io.v.baku.toolkit.BlessingsUtils;
import io.v.impl.google.services.syncbase.SyncbaseServer;
import io.v.rx.VFn;
import io.v.v23.context.VContext;
import io.v.v23.rpc.Server;
import io.v.v23.verror.VException;
import lombok.Value;
import lombok.experimental.Accessors;
import lombok.extern.slf4j.Slf4j;
import rx.Observable;
import rx.Subscription;
import rx.schedulers.Schedulers;
import rx.util.async.Async;

/**
 * Syncbase Android service in lieu of GMS Core Syncbase. Exposes Syncbase as a simplistic bound
 * service, relying on Vanadium RPC in lieu of IPC, with open permissions, returning the local
 * Vanadium name in {@code Binder.getName}.
 */
@Slf4j
public class SyncbaseAndroidService extends Service {
    private static final Duration
            STOP_TIMEOUT = Duration.standardSeconds(5),
            KEEP_ALIVE = Duration.standardMinutes(5);

    @Accessors(prefix = "m")
    @Value
    public static class BindResult {
        Server mServer;
        String mName;
    }

    private VContext mVContext;
    private Observable<BindResult> mObservable;
    private Subscription mKill;

    public class Binder extends android.os.Binder {
        private Binder() {
        }

        public Observable<BindResult> getObservable() {
            return mObservable;
        }
    }

    @Override
    public void onCreate() {
        mVContext = V.init(this);
        // If we don't proxy, it seems we can't even mount.
        try {
            mVContext = V.withListenSpec(mVContext, V.getListenSpec(mVContext).withProxy("proxy"));
        } catch (final VException e) {
            log.warn("Unable to set up Vanadium proxy for Syncbase", e);
        }

        mObservable = Async.fromCallable(this::startServer, Schedulers.io())
                .replay(1).autoConnect(0); //cache last result; connect immediately
    }

    @Override
    public void onDestroy() {
        try {
            mObservable.doOnNext(VFn.unchecked(b -> {
                log.info("Stopping Syncbase");
                b.mServer.stop();
            }))
                    .timeout(STOP_TIMEOUT.getMillis(), TimeUnit.MILLISECONDS)
                    .toBlocking()
                    .single();
            log.info("Syncbase is over");
            System.exit(0);
        } catch (final RuntimeException e) {
            log.error("Failed to shut down Syncbase", e);
            System.exit(1);
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        return new Binder();
    }

    @Override
    public boolean onUnbind(Intent intent) {
        mKill = Observable.timer(KEEP_ALIVE.getMillis(), TimeUnit.MILLISECONDS)
                .subscribe(x -> stopSelf());
        return true;
    }

    @Override
    public void onRebind(Intent intent) {
        mKill.unsubscribe();
    }

    private BindResult startServer() throws SyncbaseServer.StartException {
        final File storageRoot = new File(getFilesDir(), "syncbase");
        storageRoot.mkdirs();

        log.info("Starting Syncbase");
        final VContext sbCtx = SyncbaseServer.withNewServer(mVContext, new SyncbaseServer.Params()
                .withPermissions(BlessingsUtils.OPEN_DATA_PERMS)
                .withStorageRootDir(storageRoot.getAbsolutePath()));
        final Server server = V.getServer(sbCtx);
        return new BindResult(server, "/" + server.getStatus().getEndpoints()[0]);
    }
}