/*
 * Copyright (C) 2017 Schürmann & Breitmoser GbR
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.sufficientlysecure.keychain.ui.keyview;


import java.util.Collections;
import java.util.List;

import android.arch.lifecycle.LiveData;
import android.arch.lifecycle.ViewModel;
import android.arch.lifecycle.ViewModelProviders;
import android.content.Context;
import android.content.Intent;
import android.graphics.PorterDuff;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Parcelable;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentManager.OnBackStackChangedListener;
import android.support.v4.content.ContextCompat;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextSwitcher;
import android.widget.TextView;
import android.widget.ViewAnimator;

import org.sufficientlysecure.keychain.Constants.key;
import org.sufficientlysecure.keychain.R;
import org.sufficientlysecure.keychain.linked.LinkedAttribute;
import org.sufficientlysecure.keychain.linked.LinkedResource;
import org.sufficientlysecure.keychain.linked.LinkedTokenResource;
import org.sufficientlysecure.keychain.linked.UriAttribute;
import org.sufficientlysecure.keychain.daos.CertificationDao;
import org.sufficientlysecure.keychain.livedata.GenericLiveData;
import org.sufficientlysecure.keychain.model.Certification.CertDetails;
import org.sufficientlysecure.keychain.model.SubKey.UnifiedKeyInfo;
import org.sufficientlysecure.keychain.operations.results.LinkedVerifyResult;
import org.sufficientlysecure.keychain.operations.results.OperationResult;
import org.sufficientlysecure.keychain.daos.KeyRepository;
import org.sufficientlysecure.keychain.daos.KeyRepository.NotFoundException;
import org.sufficientlysecure.keychain.service.CertifyActionsParcel;
import org.sufficientlysecure.keychain.service.CertifyActionsParcel.CertifyAction;
import org.sufficientlysecure.keychain.ui.adapter.IdentityAdapter;
import org.sufficientlysecure.keychain.ui.base.CryptoOperationFragment;
import org.sufficientlysecure.keychain.ui.keyview.LinkedIdViewFragment.ViewHolder.VerifyState;
import org.sufficientlysecure.keychain.ui.keyview.loader.IdentityDao;
import org.sufficientlysecure.keychain.ui.keyview.loader.IdentityDao.LinkedIdInfo;
import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils.State;
import org.sufficientlysecure.keychain.ui.util.Notify;
import org.sufficientlysecure.keychain.ui.util.Notify.Style;
import org.sufficientlysecure.keychain.ui.util.SubtleAttentionSeeker;
import org.sufficientlysecure.keychain.ui.widget.CertListWidget;
import org.sufficientlysecure.keychain.ui.widget.KeySpinner;
import timber.log.Timber;


public class LinkedIdViewFragment extends CryptoOperationFragment implements OnBackStackChangedListener {

    private static final String ARG_LID_RANK = "rank";
    private static final String ARG_IS_SECRET = "verified";
    private static final String ARG_MASTER_KEY_ID = "master_key_id";

    private long masterKeyId;
    private boolean isSecret;

    private UriAttribute linkedId;
    private LinkedTokenResource linkedResource;

    private AsyncTask taskInProgress;

    private ViewHolder viewHolder;
    private int lidRank;
    private long certifyKeyId;

    public static LinkedIdViewFragment newInstance(long masterKeyId, int rank, boolean isSecret) {
        LinkedIdViewFragment frag = new LinkedIdViewFragment();

        Bundle args = new Bundle();
        args.putInt(ARG_LID_RANK, rank);
        args.putBoolean(ARG_IS_SECRET, isSecret);
        args.putLong(ARG_MASTER_KEY_ID, masterKeyId);
        frag.setArguments(args);

        return frag;
    }

    public LinkedIdViewFragment() {
        // IMPORTANT: the id must be unique in the ViewKeyActivity CryptoOperationHelper id namespace!
        // no initial progress message -> we handle progress ourselves!
        super(5, null);
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Bundle args = getArguments();
        lidRank = args.getInt(ARG_LID_RANK);

        isSecret = args.getBoolean(ARG_IS_SECRET);
        masterKeyId = args.getLong(ARG_MASTER_KEY_ID);
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        LinkedIdViewModel viewModel = ViewModelProviders.of(this).get(LinkedIdViewModel.class);
        viewModel.getLinkedIdInfo(requireContext(), masterKeyId, lidRank).observe(this, this::onLinkedIdInfoLoaded);
        viewModel.getCertifyingKeys(requireContext()).observe(this, viewHolder.vKeySpinner::setData);
    }

    private void onLinkedIdInfoLoaded(LinkedIdInfo linkedIdInfo) {
        if (linkedIdInfo == null) {
            Timber.e("error loading identity");
            Notify.create(getActivity(), "Error loading linked identity!",
                    Notify.LENGTH_LONG, Style.ERROR).show();
            finishFragment();
            return;
        }

        loadIdentity(linkedIdInfo.getLinkedAttribute(), linkedIdInfo.isVerified());
    }

    public void finishFragment() {
        new Handler().post(() -> {
            FragmentManager manager = getFragmentManager();
            manager.removeOnBackStackChangedListener(LinkedIdViewFragment.this);
            manager.popBackStack("linked_id", FragmentManager.POP_BACK_STACK_INCLUSIVE);
        });
    }

    private void loadIdentity(LinkedAttribute linkedId, boolean isVerified) {
        this.linkedId = linkedId;

        LinkedResource res = ((LinkedAttribute) this.linkedId).mResource;
        linkedResource = (LinkedTokenResource) res;

        if (!isSecret) {
            if (isVerified) {
                KeyFormattingUtils.setStatusImage(getContext(), viewHolder.mLinkedIdHolder.vVerified,
                        null, State.VERIFIED, KeyFormattingUtils.DEFAULT_COLOR);
            } else {
                KeyFormattingUtils.setStatusImage(getContext(), viewHolder.mLinkedIdHolder.vVerified,
                        null, State.UNVERIFIED, KeyFormattingUtils.DEFAULT_COLOR);
            }
        } else {
            viewHolder.mLinkedIdHolder.vVerified.setImageResource(R.drawable.octo_link_24dp);
        }

        viewHolder.mLinkedIdHolder.bind(getContext(), this.linkedId);

        setShowVerifying(false);

        if (linkedResource.isViewable()) {
            viewHolder.vButtonView.setVisibility(View.VISIBLE);
            viewHolder.vButtonView.setOnClickListener(v -> {
                Intent intent = linkedResource.getViewIntent();
                if (intent == null) {
                    return;
                }
                startActivity(intent);
            });
        } else {
            viewHolder.vButtonView.setVisibility(View.GONE);
        }

    }

    static class ViewHolder {
        private final View vButtonView;
        private final ViewAnimator vVerifyingContainer;
        private final ViewAnimator vItemCertified;
        private final View vKeySpinnerContainer;
        IdentityAdapter.LinkedIdViewHolder mLinkedIdHolder;

        private ViewAnimator vButtonSwitcher;
        private CertListWidget vLinkedCerts;
        private KeySpinner vKeySpinner;
        private final View vButtonVerify;
        private final View vButtonRetry;
        private final View vButtonConfirm;

        private final ViewAnimator vProgress;
        private final TextSwitcher vText;

        ViewHolder(View root) {
            vLinkedCerts = root.findViewById(R.id.linked_id_certs);
            vKeySpinner = root.findViewById(R.id.cert_key_spinner);
            vKeySpinnerContainer = root.findViewById(R.id.cert_key_spincontainer);
            vButtonSwitcher = root.findViewById(R.id.button_animator);

            mLinkedIdHolder = new IdentityAdapter.LinkedIdViewHolder(root, null);

            vButtonVerify = root.findViewById(R.id.button_verify);
            vButtonRetry = root.findViewById(R.id.button_retry);
            vButtonConfirm = root.findViewById(R.id.button_confirm);
            vButtonView = root.findViewById(R.id.button_view);

            vVerifyingContainer = root.findViewById(R.id.linked_verify_container);
            vItemCertified = root.findViewById(R.id.linked_id_certified);

            vProgress = root.findViewById(R.id.linked_cert_progress);
            vText = root.findViewById(R.id.linked_cert_text);

            vKeySpinner.setShowNone(R.string.choice_select_cert);
        }

        enum VerifyState {
            VERIFYING, VERIFY_OK, VERIFY_ERROR, CERTIFYING
        }

        void setVerifyingState(Context context, VerifyState state, boolean isSecret) {
            switch (state) {
                case VERIFYING:
                    vProgress.setDisplayedChild(0);
                    vText.setText(context.getString(R.string.linked_text_verifying));
                    vKeySpinnerContainer.setVisibility(View.GONE);
                    break;

                case VERIFY_OK:
                    vProgress.setDisplayedChild(1);
                    if (!isSecret) {
                        showButton(2);
                        if (!vKeySpinner.isSingleEntry()) {
                            vKeySpinnerContainer.setVisibility(View.VISIBLE);
                        }
                    } else {
                        showButton(1);
                        vKeySpinnerContainer.setVisibility(View.GONE);
                    }
                    break;

                case VERIFY_ERROR:
                    showButton(1);
                    vProgress.setDisplayedChild(2);
                    vText.setText(context.getString(R.string.linked_text_error));
                    vKeySpinnerContainer.setVisibility(View.GONE);
                    break;

                case CERTIFYING:
                    vProgress.setDisplayedChild(0);
                    vText.setText(context.getString(R.string.linked_text_confirming));
                    vKeySpinnerContainer.setVisibility(View.GONE);
                    vButtonConfirm.setEnabled(false);
                    break;
            }
        }

        void showVerifyingContainer(Context context, boolean show, boolean isSecret) {
            if (vVerifyingContainer.getDisplayedChild() == (show ? 1 : 0)) {
                return;
            }

            vVerifyingContainer.setInAnimation(context, show ? R.anim.fade_in_up : R.anim.fade_in_down);
            vVerifyingContainer.setOutAnimation(context, show ? R.anim.fade_out_up : R.anim.fade_out_down);
            vVerifyingContainer.setDisplayedChild(show ? 1 : 0);

            vItemCertified.setInAnimation(context, show ? R.anim.fade_in_up : R.anim.fade_in_down);
            vItemCertified.setOutAnimation(context, show ? R.anim.fade_out_up : R.anim.fade_out_down);
            vItemCertified.setDisplayedChild(show || isSecret ? 1 : 0);
        }

        void showButton(int which) {
            if (vButtonSwitcher.getDisplayedChild() == which) {
                return;
            }
            vButtonSwitcher.setDisplayedChild(which);
        }

    }

    private boolean mVerificationState = false;
    /** Switches between the 'verifying' ui bit and certificate status. This method
     * must behave correctly in all states, showing or hiding the appropriate views
     * and cancelling pending operations where necessary.
     *
     * This method also handles back button functionality in combination with
     * onBackStateChanged.
     */
    void setShowVerifying(boolean show) {
        if (!show) {
            if (taskInProgress != null) {
                taskInProgress.cancel(false);
                taskInProgress = null;
            }
            getFragmentManager().removeOnBackStackChangedListener(this);
            new Handler().post(() -> getFragmentManager().popBackStack("verification",
                    FragmentManager.POP_BACK_STACK_INCLUSIVE));

            if (!mVerificationState) {
                return;
            }
            mVerificationState = false;

            viewHolder.showButton(0);
            viewHolder.vKeySpinnerContainer.setVisibility(View.GONE);
            viewHolder.showVerifyingContainer(getContext(), false, isSecret);
            return;
        }

        if (mVerificationState) {
            return;
        }
        mVerificationState = true;

        FragmentManager manager = getFragmentManager();
        manager.beginTransaction().addToBackStack("verification").commit();
        manager.executePendingTransactions();
        manager.addOnBackStackChangedListener(this);
        viewHolder.showVerifyingContainer(getContext(), true, isSecret);

    }

    @Override
    public void onBackStackChanged() {
        setShowVerifying(false);
    }

    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup superContainer, Bundle savedInstanceState) {
        View root = inflater.inflate(R.layout.linked_id_view_fragment, superContainer, false);
        Context context = getContext();
        if (context == null) {
            throw new NullPointerException();
        }

        viewHolder = new ViewHolder(root);
        root.setTag(viewHolder);

        ((ImageView) root.findViewById(R.id.status_icon_verified))
                .setColorFilter(ContextCompat.getColor(context, R.color.android_green_light),
                        PorterDuff.Mode.SRC_IN);
        ((ImageView) root.findViewById(R.id.status_icon_invalid))
                .setColorFilter(ContextCompat.getColor(context, R.color.android_red_light),
                        PorterDuff.Mode.SRC_IN);

        viewHolder.vButtonVerify.setOnClickListener(v -> verifyResource());
        viewHolder.vButtonRetry.setOnClickListener(v -> verifyResource());
        viewHolder.vButtonConfirm.setOnClickListener(v -> initiateCertifying());

        LinkedIdViewModel viewModel = ViewModelProviders.of(this).get(LinkedIdViewModel.class);
        viewModel.getCertDetails(context, masterKeyId, lidRank).observe(this, this::onLoadCertDetails);

        return root;
    }

    private void onLoadCertDetails(CertDetails certDetails) {
        viewHolder.vLinkedCerts.setData(certDetails, isSecret);
    }

    void verifyResource() {

        // only one at a time (no sync needed, taskInProgress is only touched in ui thread)
        if (taskInProgress != null) {
            return;
        }

        setShowVerifying(true);

        viewHolder.vKeySpinnerContainer.setVisibility(View.GONE);
        viewHolder.setVerifyingState(getContext(), VerifyState.VERIFYING, isSecret);

        taskInProgress = new AsyncTask<Void,Void,LinkedVerifyResult>() {
            @Override
            protected LinkedVerifyResult doInBackground(Void... params) {
                FragmentActivity activity = getActivity();

                byte[] fingerprint;
                try {
                    fingerprint = KeyRepository.create(activity).getFingerprintByKeyId(masterKeyId);
                } catch (NotFoundException e) {
                    throw new IllegalStateException("Key to verify linked id for must exist in db!");
                }

                long timer = System.currentTimeMillis();
                LinkedVerifyResult result = linkedResource.verify(activity, fingerprint);

                // ux flow: this operation should take at last a second
                timer = System.currentTimeMillis() -timer;
                if (timer < 1000) try {
                    Thread.sleep(1000 -timer);
                } catch (InterruptedException e) {
                    // never mind
                }

                return result;
            }

            @Override
            protected void onPostExecute(LinkedVerifyResult result) {
                if (isCancelled()) {
                    return;
                }
                if (result.success()) {
                    viewHolder.vText.setText(getString(linkedResource.getVerifiedText(isSecret)));
                    // hack to preserve bold text
                    ((TextView) viewHolder.vText.getCurrentView()).setText(
                            linkedResource.getVerifiedText(isSecret));
                    viewHolder.setVerifyingState(getContext(), VerifyState.VERIFY_OK, isSecret);
                    viewHolder.mLinkedIdHolder.seekAttention();
                } else {
                    viewHolder.setVerifyingState(getContext(), VerifyState.VERIFY_ERROR, isSecret);
                    result.createNotify(getActivity()).show();
                }
                taskInProgress = null;
            }
        }.execute();

    }

    private void initiateCertifying() {

        if (isSecret) {
            return;
        }

        // get the user's passphrase for this key (if required)
        certifyKeyId = viewHolder.vKeySpinner.getSelectedKeyId();
        if (certifyKeyId == key.none || certifyKeyId == key.symmetric) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                SubtleAttentionSeeker.tintBackground(viewHolder.vKeySpinnerContainer, 600).start();
            } else {
                Notify.create(getActivity(), R.string.select_key_to_certify, Style.ERROR).show();
            }
            return;
        }

        viewHolder.setVerifyingState(getContext(), VerifyState.CERTIFYING, false);
        cryptoOperation();

    }

    @Override
    public void onCryptoOperationCancelled() {
        super.onCryptoOperationCancelled();

        // go back to 'verified ok'
        setShowVerifying(false);

    }

    @Nullable
    @Override
    public Parcelable createOperationInput() {
        CertifyAction action = CertifyAction.createForUserAttributes(masterKeyId,
                Collections.singletonList(linkedId.toUserAttribute()));

        // fill values for this action
        CertifyActionsParcel.Builder builder = CertifyActionsParcel.builder(certifyKeyId);
        builder.addActions(Collections.singletonList(action));

        return builder.build();
    }

    @Override
    public void onCryptoOperationSuccess(OperationResult result) {
        result.createNotify(getActivity()).show();
        // no need to do anything else, we will get a loader refresh!
    }

    @Override
    public void onCryptoOperationError(OperationResult result) {
        result.createNotify(getActivity()).show();
    }

    @Override
    public boolean onCryptoSetProgress(String msg, int progress, int max) {
        return true;
    }

    public static class LinkedIdViewModel extends ViewModel {
        LiveData<List<UnifiedKeyInfo>> certifyingKeysLiveData;
        LiveData<CertDetails> certDetailsLiveData;
        LiveData<LinkedIdInfo> linkedIfInfoLiveData;

        LiveData<List<UnifiedKeyInfo>> getCertifyingKeys(Context context) {
            if (certifyingKeysLiveData == null) {
                certifyingKeysLiveData = new GenericLiveData<>(context, () -> {
                    KeyRepository keyRepository = KeyRepository.create(context);
                    return keyRepository.getAllUnifiedKeyInfoWithSecret();
                });
            }
            return certifyingKeysLiveData;
        }

        LiveData<CertDetails> getCertDetails(Context context, long masterKeyId, int lidRank) {
            if (certDetailsLiveData == null) {
                CertificationDao certificationDao = CertificationDao.getInstance(context);
                certDetailsLiveData = new GenericLiveData<>(context, masterKeyId,
                        () -> certificationDao.getVerifyingCertDetails(masterKeyId, lidRank));
            }
            return certDetailsLiveData;
        }

        public LiveData<LinkedIdInfo> getLinkedIdInfo(Context context, long masterKeyId, int lidRank) {
            if (linkedIfInfoLiveData == null) {
                IdentityDao identityDao = IdentityDao.getInstance(context);
                linkedIfInfoLiveData = new GenericLiveData<>(context, masterKeyId,
                        () -> identityDao.getLinkedIdInfo(masterKeyId, lidRank));
            }
            return linkedIfInfoLiveData;
        }
    }

}