// 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.baku.toolkit;

import android.app.Activity;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;

import io.v.android.v23.V;
import io.v.baku.toolkit.blessings.AccountManagerBlessingsFragment;
import io.v.baku.toolkit.blessings.BlessingsProvider;
import io.v.baku.toolkit.blessings.BlessingsUtils;
import io.v.baku.toolkit.debug.DebugFragment;
import io.v.baku.toolkit.debug.DebugUtils;
import io.v.v23.Options;
import io.v.v23.context.VContext;
import io.v.v23.security.Blessings;
import io.v.v23.verror.VException;
import lombok.Getter;
import lombok.experimental.Accessors;
import lombok.extern.slf4j.Slf4j;

/**
 * Android context mix-in incorporating common Vanadium utilities:
 * <ul>
 * <li>Vanadium initialization during {@code onCreate}; context available via
 * {@code getVContext}</li>
 * <li>Blessings management, available via {@code getBlessingsProvider().getRxBlessings}.
 * Upon {@code subscribe}, blessings are refreshed from the {@code BlessingsManager} or sought from
 * the {@code BlessingsProvider} (by default, the Account Manager).</li>
 * </ul>
 * <p>
 * Default activity extensions incorporating this mix-in are available:
 * <ul>
 * <li>{@link VActivity} (extends {@link Activity})</li>
 * <li>{@link VAppCompatActivity} (extends {@link android.support.v7.app.AppCompatActivity})</li>
 * </ul>
 * Since Java doesn't actually support multiple inheritance, clients requiring custom inheritance
 * hierarchies will need to wire in manually, like any of the examples above.
 */
@Accessors(prefix = "m")
@Slf4j
public class VAndroidContextMixin<T extends Context> implements VAndroidContextTrait<T> {
    public static SharedPreferences getVanadiumPreferences(final Context androidContext) {
        return androidContext.getSharedPreferences(VANADIUM_OPTIONS_SHARED_PREFS,
                Context.MODE_PRIVATE);
    }

    @Getter
    private final T mAndroidContext;
    @Getter
    private final BlessingsProvider mBlessingsProvider;
    @Getter
    private final ErrorReporter mErrorReporter;
    @Getter
    private final SharedPreferences mVanadiumPreferences;
    @Getter
    private final VContext mVContext;

    public Options getSavedOptions() {
        return VOptionPreferenceUtils.getOptionsFromPreferences(mVanadiumPreferences);
    }

    private VContext vinit() {
        try {
            return V.init(mAndroidContext, getSavedOptions());
        } catch (final RuntimeException e) {
            try {
                /* V.shutdown so we might try V.init again if warranted. If we don't V.shutdown
                first, the process can abruptly die. It seems that if this happens, Android might
                just restart the app immediately, i.e. before we've been able to display an
                intelligible error message. */
                V.shutdown();
            } catch (final RuntimeException e2) {
                log.error("Unable to clean up failed Vanadium initialization", e2);
                e.addSuppressed(e2);
            }

            if (mVanadiumPreferences.getAll().isEmpty()) {
                throw e;
            } else {
                mErrorReporter.onError(R.string.err_vinit_options, e);
                // Don't actually clear/fix options here; leave that to the user
                return V.init(mAndroidContext);
            }
        }
    }

    public VAndroidContextMixin(final T androidContext, final BlessingsProvider blessingsProvider,
                                final ErrorReporter errorReporter) {
        mAndroidContext = androidContext;
        mBlessingsProvider = blessingsProvider;
        mErrorReporter = errorReporter;

        mVanadiumPreferences = getVanadiumPreferences(mAndroidContext);
        mVContext = vinit();

        //Any time our blessings change, we need to attach them to our principal.
        mBlessingsProvider.getPassiveRxBlessings().subscribe(this::processBlessings,
                t -> errorReporter.onError(R.string.err_blessings_misc, t));
    }

    protected void processBlessings(final Blessings blessings) {
        try {
            BlessingsUtils.assumeBlessings(mVContext, blessings);
        } catch (final VException e) {
            mErrorReporter.onError(R.string.err_blessings_assume, e);
        }
    }

    public static <T extends Activity> VAndroidContextMixin<T> withDefaults(
            final T activity, final Bundle savedInstanceState) {
        final FragmentManager mgr = activity.getFragmentManager();
        final AccountManagerBlessingsFragment blessingsProvider;
        final ErrorReporterFragment errorReporter;

        if (savedInstanceState == null) {
            blessingsProvider = new AccountManagerBlessingsFragment();
            errorReporter = new ErrorReporterFragment();

            final FragmentTransaction t = mgr.beginTransaction()
                    .add(blessingsProvider, AccountManagerBlessingsFragment.TAG)
                    .add(errorReporter, ErrorReporterFragment.TAG);

            if (DebugUtils.isApkDebug(activity)) {
                log.info("Debug menu enabled");
                t.add(new DebugFragment(), null);
            }
            t.commit();
        } else {
            blessingsProvider = AccountManagerBlessingsFragment.find(mgr);
            errorReporter = ErrorReporterFragment.find(mgr);
        }
        return new VAndroidContextMixin<>(activity, blessingsProvider, errorReporter);
    }
}