/*
 * Copyright (C) 2012-2014 Dominik Schürmann <dominik@dominikschuermann.de>
 *
 * 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.dialog;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.Messenger;
import android.os.RemoteException;
import android.support.v4.app.DialogFragment;
import android.support.v4.app.FragmentActivity;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.inputmethod.EditorInfo;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.TextView.OnEditorActionListener;
import android.widget.Toast;

import org.sufficientlysecure.keychain.Constants;
import org.sufficientlysecure.keychain.R;
import org.sufficientlysecure.keychain.compatibility.DialogFragmentWorkaround;
import org.sufficientlysecure.keychain.pgp.CanonicalizedSecretKey;
import org.sufficientlysecure.keychain.pgp.CanonicalizedSecretKeyRing;
import org.sufficientlysecure.keychain.pgp.exception.PgpGeneralException;
import org.sufficientlysecure.keychain.provider.CachedPublicKeyRing;
import org.sufficientlysecure.keychain.provider.KeychainContract.KeyRings;
import org.sufficientlysecure.keychain.provider.ProviderHelper;
import org.sufficientlysecure.keychain.service.PassphraseCacheService;
import org.sufficientlysecure.keychain.util.Log;

public class PassphraseDialogFragment extends DialogFragment implements OnEditorActionListener {
    private static final String ARG_MESSENGER = "messenger";
    private static final String ARG_SECRET_KEY_ID = "secret_key_id";

    public static final int MESSAGE_OKAY = 1;
    public static final int MESSAGE_CANCEL = 2;

    public static final String MESSAGE_DATA_PASSPHRASE = "passphrase";

    private Messenger mMessenger;
    private EditText mPassphraseEditText;
    private View mInput, mProgress;

    /**
     * Shows passphrase dialog to cache a new passphrase the user enters for using it later for
     * encryption. Based on mSecretKeyId it asks for a passphrase to open a private key or it asks
     * for a symmetric passphrase
     */
    public static void show(final FragmentActivity context, final long keyId, final Handler returnHandler) {
        // Create a new Messenger for the communication back
        final Messenger messenger = new Messenger(returnHandler);

        DialogFragmentWorkaround.INTERFACE.runnableRunDelayed(new Runnable() {
            public void run() {
                try {
                    PassphraseDialogFragment passphraseDialog =
                            PassphraseDialogFragment.newInstance(messenger, keyId);

                    passphraseDialog.show(context.getSupportFragmentManager(), "passphraseDialog");
                } catch (PgpGeneralException e) {
                    Log.d(Constants.TAG, "No passphrase for this secret key!");
                    // send message to handler to start encryption directly
                    returnHandler.sendEmptyMessage(PassphraseDialogFragment.MESSAGE_OKAY);
                }
            }
        });
    }

    /**
     * Creates new instance of this dialog fragment
     *
     * @param secretKeyId secret key id you want to use
     * @param messenger   to communicate back after caching the passphrase
     * @return
     * @throws PgpGeneralException
     */
    public static PassphraseDialogFragment newInstance(Messenger messenger, long secretKeyId)
            throws PgpGeneralException {
        // do NOT check if the key even needs a passphrase. that's not our job here.
        PassphraseDialogFragment frag = new PassphraseDialogFragment();
        Bundle args = new Bundle();
        args.putLong(ARG_SECRET_KEY_ID, secretKeyId);
        args.putParcelable(ARG_MESSENGER, messenger);

        frag.setArguments(args);

        return frag;
    }

    CanonicalizedSecretKeyRing mSecretRing = null;
    boolean mIsCancelled = false;
    long mSubKeyId;

    /**
     * Creates dialog
     */
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        final Activity activity = getActivity();
        mSubKeyId = getArguments().getLong(ARG_SECRET_KEY_ID);
        mMessenger = getArguments().getParcelable(ARG_MESSENGER);

        CustomAlertDialogBuilder alert = new CustomAlertDialogBuilder(activity);

        alert.setTitle(R.string.title_authentication);

        String userId;

        if (mSubKeyId == Constants.key.symmetric || mSubKeyId == Constants.key.none) {
            alert.setMessage(R.string.passphrase_for_symmetric_encryption);
        } else {
            String message;
            try {
                ProviderHelper helper = new ProviderHelper(activity);
                mSecretRing = helper.getCanonicalizedSecretKeyRing(
                        KeyRings.buildUnifiedKeyRingsFindBySubkeyUri(mSubKeyId));
                // yes the inner try/catch block is necessary, otherwise the final variable
                // above can't be statically verified to have been set in all cases because
                // the catch clause doesn't return.
                try {
                    userId = mSecretRing.getPrimaryUserIdWithFallback();
                } catch (ProviderHelper.NotFoundException e) {
                    userId = null;
                }

                /* Get key type for message */
                // find a master key id for our key
                long masterKeyId = new ProviderHelper(getActivity()).getMasterKeyId(mSubKeyId);
                CachedPublicKeyRing keyRing = new ProviderHelper(getActivity()).getCachedPublicKeyRing(masterKeyId);
                // get the type of key (from the database)
                CanonicalizedSecretKey.SecretKeyType keyType = keyRing.getSecretKeyType(mSubKeyId);
                switch (keyType) {
                    case PASSPHRASE:
                        message = getString(R.string.passphrase_for, userId);
                        break;
                    case DIVERT_TO_CARD:
                        message = getString(R.string.yubikey_pin, userId);
                        break;
                    default:
                        message = "This should not happen!";
                        break;
                }

            } catch (ProviderHelper.NotFoundException e) {
                alert.setTitle(R.string.title_key_not_found);
                alert.setMessage(getString(R.string.key_not_found, mSubKeyId));
                alert.setPositiveButton(android.R.string.ok, new OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        dismiss();
                    }
                });
                alert.setCancelable(false);
                return alert.create();
            }

            alert.setMessage(message);
        }

        LayoutInflater inflater = activity.getLayoutInflater();
        View view = inflater.inflate(R.layout.passphrase_dialog, null);
        alert.setView(view);

        mPassphraseEditText = (EditText) view.findViewById(R.id.passphrase_passphrase);
        mInput = view.findViewById(R.id.input);
        mProgress = view.findViewById(R.id.progress);

        alert.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int id) {
                dialog.cancel();
            }
        });

        // Hack to open keyboard.
        // This is the only method that I found to work across all Android versions
        // http://turbomanage.wordpress.com/2012/05/02/show-soft-keyboard-automatically-when-edittext-receives-focus/
        // Notes: * onCreateView can't be used because we want to add buttons to the dialog
        //        * opening in onActivityCreated does not work on Android 4.4
        mPassphraseEditText.setOnFocusChangeListener(new View.OnFocusChangeListener() {
            @Override
            public void onFocusChange(View v, boolean hasFocus) {
                mPassphraseEditText.post(new Runnable() {
                    @Override
                    public void run() {
                        // The activity might already be gone! Nvm in that case.
                        if (getActivity() == null) {
                            return;
                        }
                        InputMethodManager imm = (InputMethodManager) getActivity()
                                .getSystemService(Context.INPUT_METHOD_SERVICE);
                        imm.showSoftInput(mPassphraseEditText, InputMethodManager.SHOW_IMPLICIT);
                    }
                });
            }
        });
        mPassphraseEditText.requestFocus();

        mPassphraseEditText.setImeActionLabel(getString(android.R.string.ok), EditorInfo.IME_ACTION_DONE);
        mPassphraseEditText.setOnEditorActionListener(this);

        AlertDialog dialog = alert.create();
        dialog.setButton(DialogInterface.BUTTON_POSITIVE,
                activity.getString(android.R.string.ok), (DialogInterface.OnClickListener) null);

        return dialog;
    }

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

        // Override the default behavior so the dialog is NOT dismissed on click
        final Button positive = ((AlertDialog) getDialog()).getButton(DialogInterface.BUTTON_POSITIVE);
        positive.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                final String passphrase = mPassphraseEditText.getText().toString();

                // Early breakout if we are dealing with a symmetric key
                if (mSecretRing == null) {
                    PassphraseCacheService.addCachedPassphrase(getActivity(), Constants.key.symmetric,
                            Constants.key.symmetric, passphrase, getString(R.string.passp_cache_notif_pwd));
                    // also return passphrase back to activity
                    Bundle data = new Bundle();
                    data.putString(MESSAGE_DATA_PASSPHRASE, passphrase);
                    sendMessageToHandler(MESSAGE_OKAY, data);
                    dismiss();
                    return;
                }

                mInput.setVisibility(View.GONE);
                mProgress.setVisibility(View.VISIBLE);
                positive.setEnabled(false);

                new AsyncTask<Void,Void,Boolean>() {
                    @Override
                    protected Boolean doInBackground(Void... params) {
                        try {
                            // wait some 100ms here, give the user time to appreciate the progress bar
                            try {
                                Thread.sleep(100);
                            } catch (InterruptedException e) {
                                // never mind
                            }
                            // make sure this unlocks
                            return mSecretRing.getSecretKey(mSubKeyId).unlock(passphrase);
                        } catch (PgpGeneralException e) {
                            Toast.makeText(getActivity(), R.string.error_could_not_extract_private_key,
                                    Toast.LENGTH_SHORT).show();

                            sendMessageToHandler(MESSAGE_CANCEL);
                            dismiss();
                            return false;
                        }
                    }

                    /** Handle a good or bad passphrase. This happens in the UI thread!  */
                    @Override
                    protected void onPostExecute(Boolean result) {
                        super.onPostExecute(result);

                        // if we were cancelled in the meantime, the result isn't relevant anymore
                        if (mIsCancelled) {
                            return;
                        }

                        // if the passphrase was wrong, reset and re-enable the dialogue
                        if (!result) {
                            mPassphraseEditText.setText("");
                            mPassphraseEditText.setError(getString(R.string.wrong_passphrase));
                            mInput.setVisibility(View.VISIBLE);
                            mProgress.setVisibility(View.GONE);
                            positive.setEnabled(true);
                            return;
                        }

                        // cache the new passphrase
                        Log.d(Constants.TAG, "Everything okay! Caching entered passphrase");

                        try {
                            PassphraseCacheService.addCachedPassphrase(getActivity(),
                                    mSecretRing.getMasterKeyId(), mSubKeyId, passphrase,
                                    mSecretRing.getPrimaryUserIdWithFallback());
                        } catch (ProviderHelper.NotFoundException e) {
                            Log.e(Constants.TAG, "adding of a passphrase failed", e);
                        }

                        // also return passphrase back to activity
                        Bundle data = new Bundle();
                        data.putString(MESSAGE_DATA_PASSPHRASE, passphrase);
                        sendMessageToHandler(MESSAGE_OKAY, data);
                        dismiss();
                    }
                }.execute();
            }
        });

    }

    @Override
    public void onCancel(DialogInterface dialog) {
        super.onCancel(dialog);

        // note we need no synchronization here, this variable is only accessed in the ui thread
        mIsCancelled = true;

        // dismiss the dialogue
        dismiss();
        sendMessageToHandler(MESSAGE_CANCEL);
    }

    @Override
    public void onDismiss(DialogInterface dialog) {
        super.onDismiss(dialog);
        Log.d(Constants.TAG, "onDismiss");

        // hide keyboard on dismiss
        hideKeyboard();
    }

    private void hideKeyboard() {
        // The activity which called the dialog might no longer exist. Nvm in that case...
        if (getActivity() == null) {
            return;
        }
        InputMethodManager inputManager = (InputMethodManager) getActivity()
                .getSystemService(Context.INPUT_METHOD_SERVICE);

        //check if no view has focus:
        View v = getActivity().getCurrentFocus();
        if (v == null) {
            return;
        }

        inputManager.hideSoftInputFromWindow(v.getWindowToken(), 0);
    }

    /**
     * Associate the "done" button on the soft keyboard with the okay button in the view
     */
    @Override
    public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
        if (EditorInfo.IME_ACTION_DONE == actionId) {
            AlertDialog dialog = ((AlertDialog) getDialog());
            Button bt = dialog.getButton(AlertDialog.BUTTON_POSITIVE);

            bt.performClick();
            return true;
        }
        return false;
    }

    /**
     * Send message back to handler which is initialized in a activity
     *
     * @param what Message integer you want to send
     */
    private void sendMessageToHandler(Integer what) {
        Message msg = Message.obtain();
        msg.what = what;

        try {
            mMessenger.send(msg);
        } catch (RemoteException e) {
            Log.w(Constants.TAG, "Exception sending message, Is handler present?", e);
        } catch (NullPointerException e) {
            Log.w(Constants.TAG, "Messenger is null!", e);
        }
    }

    /**
     * Send message back to handler which is initialized in a activity
     *
     * @param what Message integer you want to send
     */
    private void sendMessageToHandler(Integer what, Bundle data) {
        Message msg = Message.obtain();
        msg.what = what;
        if (data != null) {
            msg.setData(data);
        }

        try {
            mMessenger.send(msg);
        } catch (RemoteException e) {
            Log.w(Constants.TAG, "Exception sending message, Is handler present?", e);
        } catch (NullPointerException e) {
            Log.w(Constants.TAG, "Messenger is null!", e);
        }
    }

}