/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.settings.password;

import static android.app.admin.DevicePolicyManager.PASSWORD_COMPLEXITY_NONE;
import static android.app.admin.DevicePolicyManager.PASSWORD_QUALITY_ALPHABETIC;
import static android.app.admin.DevicePolicyManager.PASSWORD_QUALITY_ALPHANUMERIC;
import static android.app.admin.DevicePolicyManager.PASSWORD_QUALITY_COMPLEX;
import static android.app.admin.DevicePolicyManager.PASSWORD_QUALITY_NUMERIC;
import static android.app.admin.DevicePolicyManager.PASSWORD_QUALITY_NUMERIC_COMPLEX;

import static com.android.settings.password.ChooseLockSettingsHelper.EXTRA_KEY_REQUESTED_MIN_COMPLEXITY;

import android.app.Activity;
import android.app.admin.DevicePolicyManager;
import android.app.admin.DevicePolicyManager.PasswordComplexity;
import android.app.admin.PasswordMetrics;
import android.app.settings.SettingsEnums;
import android.content.Context;
import android.content.Intent;
import android.content.res.Resources.Theme;
import android.graphics.Insets;
import android.graphics.Typeface;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.text.Editable;
import android.text.InputType;
import android.text.Selection;
import android.text.Spannable;
import android.text.TextUtils;
import android.text.TextWatcher;
import android.util.Log;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.inputmethod.EditorInfo;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.TextView.OnEditorActionListener;

import androidx.annotation.StringRes;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.widget.LockPatternUtils;
import com.android.internal.widget.LockPatternUtils.RequestThrottledException;
import com.android.internal.widget.TextViewInputDisabler;
import com.android.settings.EncryptionInterstitial;
import com.android.settings.R;
import com.android.settings.SettingsActivity;
import com.android.settings.SetupWizardUtils;
import com.android.settings.Utils;
import com.android.settings.core.InstrumentedFragment;
import com.android.settings.notification.RedactionInterstitial;
import com.android.settings.widget.ImeAwareEditText;

import com.google.android.setupcompat.template.FooterBarMixin;
import com.google.android.setupcompat.template.FooterButton;
import com.google.android.setupdesign.GlifLayout;

import java.util.ArrayList;
import java.util.List;

public class ChooseLockPassword extends SettingsActivity {
    private static final String TAG = "ChooseLockPassword";

    @Override
    public Intent getIntent() {
        Intent modIntent = new Intent(super.getIntent());
        modIntent.putExtra(EXTRA_SHOW_FRAGMENT, getFragmentClass().getName());
        return modIntent;
    }

    @Override
    protected void onApplyThemeResource(Theme theme, int resid, boolean first) {
        resid = SetupWizardUtils.getTheme(getIntent());
        super.onApplyThemeResource(theme, resid, first);
    }

    public static class IntentBuilder {

        private final Intent mIntent;

        public IntentBuilder(Context context) {
            mIntent = new Intent(context, ChooseLockPassword.class);
            mIntent.putExtra(ChooseLockGeneric.CONFIRM_CREDENTIALS, false);
            mIntent.putExtra(EncryptionInterstitial.EXTRA_REQUIRE_PASSWORD, false);
            mIntent.putExtra(ChooseLockSettingsHelper.EXTRA_KEY_HAS_CHALLENGE, false);
        }

        public IntentBuilder setPasswordQuality(int quality) {
            mIntent.putExtra(LockPatternUtils.PASSWORD_TYPE_KEY, quality);
            return this;
        }

        public IntentBuilder setUserId(int userId) {
            mIntent.putExtra(Intent.EXTRA_USER_ID, userId);
            return this;
        }

        public IntentBuilder setChallenge(long challenge) {
            mIntent.putExtra(ChooseLockSettingsHelper.EXTRA_KEY_HAS_CHALLENGE, true);
            mIntent.putExtra(ChooseLockSettingsHelper.EXTRA_KEY_CHALLENGE, challenge);
            return this;
        }

        public IntentBuilder setPassword(String password) {
            mIntent.putExtra(ChooseLockSettingsHelper.EXTRA_KEY_PASSWORD, password);
            return this;
        }

        public IntentBuilder setForFingerprint(boolean forFingerprint) {
            mIntent.putExtra(ChooseLockSettingsHelper.EXTRA_KEY_FOR_FINGERPRINT, forFingerprint);
            return this;
        }

        public IntentBuilder setForFace(boolean forFace) {
            mIntent.putExtra(ChooseLockSettingsHelper.EXTRA_KEY_FOR_FACE, forFace);
            return this;
        }

        public IntentBuilder setRequestedMinComplexity(@PasswordComplexity int level) {
            mIntent.putExtra(EXTRA_KEY_REQUESTED_MIN_COMPLEXITY, level);
            return this;
        }

        public Intent build() {
            return mIntent;
        }
    }

    @Override
    protected boolean isValidFragment(String fragmentName) {
        if (ChooseLockPasswordFragment.class.getName().equals(fragmentName)) return true;
        return false;
    }

    /* package */ Class<? extends Fragment> getFragmentClass() {
        return ChooseLockPasswordFragment.class;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        final boolean forFingerprint = getIntent()
                .getBooleanExtra(ChooseLockSettingsHelper.EXTRA_KEY_FOR_FINGERPRINT, false);
        final boolean forFace = getIntent()
                .getBooleanExtra(ChooseLockSettingsHelper.EXTRA_KEY_FOR_FACE, false);

        CharSequence msg = getText(R.string.lockpassword_choose_your_screen_lock_header);
        if (forFingerprint) {
            msg = getText(R.string.lockpassword_choose_your_password_header_for_fingerprint);
        } else if (forFace) {
            msg = getText(R.string.lockpassword_choose_your_password_header_for_face);
        }

        setTitle(msg);
        LinearLayout layout = (LinearLayout) findViewById(R.id.content_parent);
        layout.setFitsSystemWindows(false);
    }

    public static class ChooseLockPasswordFragment extends InstrumentedFragment
            implements OnEditorActionListener, TextWatcher, SaveAndFinishWorker.Listener {
        private static final String KEY_FIRST_PIN = "first_pin";
        private static final String KEY_UI_STAGE = "ui_stage";
        private static final String KEY_CURRENT_PASSWORD = "current_password";
        private static final String FRAGMENT_TAG_SAVE_AND_FINISH = "save_and_finish_worker";

        private String mCurrentPassword;
        private String mChosenPassword;
        private boolean mHasChallenge;
        private long mChallenge;
        private ImeAwareEditText mPasswordEntry;
        private TextViewInputDisabler mPasswordEntryInputDisabler;
        private int mPasswordMinLength = LockPatternUtils.MIN_LOCK_PASSWORD_SIZE;
        private int mPasswordMaxLength = 16;
        private int mPasswordMinLetters = 0;
        private int mPasswordMinUpperCase = 0;
        private int mPasswordMinLowerCase = 0;
        private int mPasswordMinSymbols = 0;
        private int mPasswordMinNumeric = 0;
        private int mPasswordMinNonLetter = 0;
        private int mPasswordMinLengthToFulfillAllPolicies = 0;
        private boolean mPasswordNumSequenceAllowed = true;
        @PasswordComplexity private int mRequestedMinComplexity = PASSWORD_COMPLEXITY_NONE;
        protected int mUserId;
        private byte[] mPasswordHistoryHashFactor;

        private LockPatternUtils mLockPatternUtils;
        private SaveAndFinishWorker mSaveAndFinishWorker;
        private int mRequestedQuality = DevicePolicyManager.PASSWORD_QUALITY_NUMERIC;
        private ChooseLockSettingsHelper mChooseLockSettingsHelper;
        protected Stage mUiStage = Stage.Introduction;
        private PasswordRequirementAdapter mPasswordRequirementAdapter;
        private GlifLayout mLayout;
        protected boolean mForFingerprint;
        protected boolean mForFace;

        private String mFirstPin;
        private RecyclerView mPasswordRestrictionView;
        protected boolean mIsAlphaMode;
        protected FooterButton mSkipOrClearButton;
        private FooterButton mNextButton;
        private TextView mMessage;

        private TextChangedHandler mTextChangedHandler;

        private static final int CONFIRM_EXISTING_REQUEST = 58;
        static final int RESULT_FINISHED = RESULT_FIRST_USER;

        private static final int MIN_LETTER_IN_PASSWORD = 0;
        private static final int MIN_UPPER_LETTERS_IN_PASSWORD = 1;
        private static final int MIN_LOWER_LETTERS_IN_PASSWORD = 2;
        private static final int MIN_SYMBOLS_IN_PASSWORD = 3;
        private static final int MIN_NUMBER_IN_PASSWORD = 4;
        private static final int MIN_NON_LETTER_IN_PASSWORD = 5;

        // Error code returned from {@link #validatePassword(String)}.
        static final int NO_ERROR = 0;
        static final int CONTAIN_INVALID_CHARACTERS = 1 << 0;
        static final int TOO_SHORT = 1 << 1;
        static final int TOO_LONG = 1 << 2;
        static final int CONTAIN_NON_DIGITS = 1 << 3;
        static final int CONTAIN_SEQUENTIAL_DIGITS = 1 << 4;
        static final int RECENTLY_USED = 1 << 5;
        static final int NOT_ENOUGH_LETTER = 1 << 6;
        static final int NOT_ENOUGH_UPPER_CASE = 1 << 7;
        static final int NOT_ENOUGH_LOWER_CASE = 1 << 8;
        static final int NOT_ENOUGH_DIGITS = 1 << 9;
        static final int NOT_ENOUGH_SYMBOLS = 1 << 10;
        static final int NOT_ENOUGH_NON_LETTER = 1 << 11;

        /**
         * Keep track internally of where the user is in choosing a pattern.
         */
        protected enum Stage {

            Introduction(
                    R.string.lockpassword_choose_your_screen_lock_header, // password
                    R.string.lockpassword_choose_your_password_header_for_fingerprint,
                    R.string.lockpassword_choose_your_password_header_for_face,
                    R.string.lockpassword_choose_your_screen_lock_header, // pin
                    R.string.lockpassword_choose_your_pin_header_for_fingerprint,
                    R.string.lockpassword_choose_your_pin_header_for_face,
                    R.string.lockpassword_choose_your_password_message, // added security message
                    R.string.lock_settings_picker_biometrics_added_security_message,
                    R.string.lockpassword_choose_your_pin_message,
                    R.string.lock_settings_picker_biometrics_added_security_message,
                    R.string.next_label),

            NeedToConfirm(
                    R.string.lockpassword_confirm_your_password_header,
                    R.string.lockpassword_confirm_your_password_header,
                    R.string.lockpassword_confirm_your_password_header,
                    R.string.lockpassword_confirm_your_pin_header,
                    R.string.lockpassword_confirm_your_pin_header,
                    R.string.lockpassword_confirm_your_pin_header,
                    0,
                    0,
                    0,
                    0,
                    R.string.lockpassword_confirm_label),

            ConfirmWrong(
                    R.string.lockpassword_confirm_passwords_dont_match,
                    R.string.lockpassword_confirm_passwords_dont_match,
                    R.string.lockpassword_confirm_passwords_dont_match,
                    R.string.lockpassword_confirm_pins_dont_match,
                    R.string.lockpassword_confirm_pins_dont_match,
                    R.string.lockpassword_confirm_pins_dont_match,
                    0,
                    0,
                    0,
                    0,
                    R.string.lockpassword_confirm_label);

            Stage(int hintInAlpha, int hintInAlphaForFingerprint, int hintInAlphaForFace,
                    int hintInNumeric, int hintInNumericForFingerprint, int hintInNumericForFace,
                    int messageInAlpha, int messageInAlphaForBiometrics,
                    int messageInNumeric, int messageInNumericForBiometrics,
                    int nextButtonText) {
                this.alphaHint = hintInAlpha;
                this.alphaHintForFingerprint = hintInAlphaForFingerprint;
                this.alphaHintForFace = hintInAlphaForFace;

                this.numericHint = hintInNumeric;
                this.numericHintForFingerprint = hintInNumericForFingerprint;
                this.numericHintForFace = hintInNumericForFace;

                this.alphaMessage = messageInAlpha;
                this.alphaMessageForBiometrics = messageInAlphaForBiometrics;
                this.numericMessage = messageInNumeric;
                this.numericMessageForBiometrics = messageInNumericForBiometrics;
                this.buttonText = nextButtonText;
            }

            public static final int TYPE_NONE = 0;
            public static final int TYPE_FINGERPRINT = 1;
            public static final int TYPE_FACE = 2;

            // Password
            public final int alphaHint;
            public final int alphaHintForFingerprint;
            public final int alphaHintForFace;

            // PIN
            public final int numericHint;
            public final int numericHintForFingerprint;
            public final int numericHintForFace;

            public final int alphaMessage;
            public final int alphaMessageForBiometrics;
            public final int numericMessage;
            public final int numericMessageForBiometrics;
            public final int buttonText;

            public @StringRes int getHint(boolean isAlpha, int type) {
                if (isAlpha) {
                    if (type == TYPE_FINGERPRINT) {
                        return alphaHintForFingerprint;
                    } else if (type == TYPE_FACE) {
                        return alphaHintForFace;
                    } else {
                        return alphaHint;
                    }
                } else {
                    if (type == TYPE_FINGERPRINT) {
                        return numericHintForFingerprint;
                    } else if (type == TYPE_FACE) {
                        return numericHintForFace;
                    } else {
                        return numericHint;
                    }
                }
            }

            public @StringRes int getMessage(boolean isAlpha, int type) {
                if (isAlpha) {
                    return type != TYPE_NONE ? alphaMessageForBiometrics : alphaMessage;
                } else {
                    return type != TYPE_NONE ? numericMessageForBiometrics : numericMessage;
                }
            }
        }

        // required constructor for fragments
        public ChooseLockPasswordFragment() {

        }

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            mLockPatternUtils = new LockPatternUtils(getActivity());
            Intent intent = getActivity().getIntent();
            if (!(getActivity() instanceof ChooseLockPassword)) {
                throw new SecurityException("Fragment contained in wrong activity");
            }
            // Only take this argument into account if it belongs to the current profile.
            mUserId = Utils.getUserIdFromBundle(getActivity(), intent.getExtras());
            mForFingerprint = intent.getBooleanExtra(
                    ChooseLockSettingsHelper.EXTRA_KEY_FOR_FINGERPRINT, false);
            mForFace = intent.getBooleanExtra(ChooseLockSettingsHelper.EXTRA_KEY_FOR_FACE, false);
            mRequestedMinComplexity = intent.getIntExtra(
                    EXTRA_KEY_REQUESTED_MIN_COMPLEXITY, PASSWORD_COMPLEXITY_NONE);
            mRequestedQuality = Math.max(
                    intent.getIntExtra(LockPatternUtils.PASSWORD_TYPE_KEY, mRequestedQuality),
                    mLockPatternUtils.getRequestedPasswordQuality(mUserId));

            loadDpmPasswordRequirements();
            mChooseLockSettingsHelper = new ChooseLockSettingsHelper(getActivity());

            if (intent.getBooleanExtra(
                    ChooseLockSettingsHelper.EXTRA_KEY_FOR_CHANGE_CRED_REQUIRED_FOR_BOOT, false)) {
                SaveAndFinishWorker w = new SaveAndFinishWorker();
                final boolean required = getActivity().getIntent().getBooleanExtra(
                        EncryptionInterstitial.EXTRA_REQUIRE_PASSWORD, true);
                String current = intent.getStringExtra(
                        ChooseLockSettingsHelper.EXTRA_KEY_PASSWORD);
                w.setBlocking(true);
                w.setListener(this);
                w.start(mChooseLockSettingsHelper.utils(), required,
                        false, 0, current, current, mRequestedQuality, mUserId);
            }
            mTextChangedHandler = new TextChangedHandler();
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            return inflater.inflate(R.layout.choose_lock_password, container, false);
        }

        @Override
        public void onViewCreated(View view, Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);

            mLayout = (GlifLayout) view;

            // Make the password container consume the optical insets so the edit text is aligned
            // with the sides of the parent visually.
            ViewGroup container = view.findViewById(R.id.password_container);
            container.setOpticalInsets(Insets.NONE);

            final FooterBarMixin mixin = mLayout.getMixin(FooterBarMixin.class);
            mixin.setSecondaryButton(
                    new FooterButton.Builder(getActivity())
                            .setText(R.string.lockpassword_clear_label)
                            .setListener(this::onSkipOrClearButtonClick)
                            .setButtonType(FooterButton.ButtonType.SKIP)
                            .setTheme(R.style.SudGlifButton_Secondary)
                            .build()
            );
            mixin.setPrimaryButton(
                    new FooterButton.Builder(getActivity())
                            .setText(R.string.next_label)
                            .setListener(this::onNextButtonClick)
                            .setButtonType(FooterButton.ButtonType.NEXT)
                            .setTheme(R.style.SudGlifButton_Primary)
                            .build()
            );
            mSkipOrClearButton = mixin.getSecondaryButton();
            mNextButton = mixin.getPrimaryButton();

            mMessage = view.findViewById(R.id.message);
            if (mForFingerprint) {
                mLayout.setIcon(getActivity().getDrawable(R.drawable.ic_fingerprint_header));
            } else if (mForFace) {
                mLayout.setIcon(getActivity().getDrawable(R.drawable.ic_face_header));
            }

            mIsAlphaMode = DevicePolicyManager.PASSWORD_QUALITY_ALPHABETIC == mRequestedQuality
                    || DevicePolicyManager.PASSWORD_QUALITY_ALPHANUMERIC == mRequestedQuality
                    || DevicePolicyManager.PASSWORD_QUALITY_COMPLEX == mRequestedQuality;

            setupPasswordRequirementsView(view);

            mPasswordRestrictionView.setLayoutManager(new LinearLayoutManager(getActivity()));
            mPasswordEntry = view.findViewById(R.id.password_entry);
            mPasswordEntry.setOnEditorActionListener(this);
            mPasswordEntry.addTextChangedListener(this);
            mPasswordEntry.requestFocus();
            mPasswordEntryInputDisabler = new TextViewInputDisabler(mPasswordEntry);

            final Activity activity = getActivity();

            int currentType = mPasswordEntry.getInputType();
            mPasswordEntry.setInputType(mIsAlphaMode ? currentType
                    : (InputType.TYPE_CLASS_NUMBER | InputType.TYPE_NUMBER_VARIATION_PASSWORD));
            // Can't set via XML since setInputType resets the fontFamily to null
            mPasswordEntry.setTypeface(Typeface.create(
                    getContext().getString(com.android.internal.R.string.config_headlineFontFamily),
                    Typeface.NORMAL));

            Intent intent = getActivity().getIntent();
            final boolean confirmCredentials = intent.getBooleanExtra(
                    ChooseLockGeneric.CONFIRM_CREDENTIALS, true);
            mCurrentPassword = intent.getStringExtra(ChooseLockSettingsHelper.EXTRA_KEY_PASSWORD);
            mHasChallenge = intent.getBooleanExtra(
                    ChooseLockSettingsHelper.EXTRA_KEY_HAS_CHALLENGE, false);
            mChallenge = intent.getLongExtra(ChooseLockSettingsHelper.EXTRA_KEY_CHALLENGE, 0);
            if (savedInstanceState == null) {
                updateStage(Stage.Introduction);
                if (confirmCredentials) {
                    mChooseLockSettingsHelper.launchConfirmationActivity(CONFIRM_EXISTING_REQUEST,
                            getString(R.string.unlock_set_unlock_launch_picker_title), true,
                            mUserId);
                }
            } else {
                // restore from previous state
                mFirstPin = savedInstanceState.getString(KEY_FIRST_PIN);
                final String state = savedInstanceState.getString(KEY_UI_STAGE);
                if (state != null) {
                    mUiStage = Stage.valueOf(state);
                    updateStage(mUiStage);
                }

                if (mCurrentPassword == null) {
                    mCurrentPassword = savedInstanceState.getString(KEY_CURRENT_PASSWORD);
                }

                // Re-attach to the exiting worker if there is one.
                mSaveAndFinishWorker = (SaveAndFinishWorker) getFragmentManager().findFragmentByTag(
                        FRAGMENT_TAG_SAVE_AND_FINISH);
            }

            if (activity instanceof SettingsActivity) {
                final SettingsActivity sa = (SettingsActivity) activity;
                int title = Stage.Introduction.getHint(mIsAlphaMode, getStageType());
                sa.setTitle(title);
                mLayout.setHeaderText(title);
            }
        }

        private int getStageType() {
            return mForFingerprint ? Stage.TYPE_FINGERPRINT :
                    mForFace ? Stage.TYPE_FACE :
                            Stage.TYPE_NONE;
        }

        private void setupPasswordRequirementsView(View view) {
            mPasswordRestrictionView = view.findViewById(R.id.password_requirements_view);
            mPasswordRestrictionView.setLayoutManager(new LinearLayoutManager(getActivity()));
            mPasswordRequirementAdapter = new PasswordRequirementAdapter();
            mPasswordRestrictionView.setAdapter(mPasswordRequirementAdapter);
        }

        @Override
        public int getMetricsCategory() {
            return SettingsEnums.CHOOSE_LOCK_PASSWORD;
        }

        @Override
        public void onResume() {
            super.onResume();
            updateStage(mUiStage);
            if (mSaveAndFinishWorker != null) {
                mSaveAndFinishWorker.setListener(this);
            } else {
                mPasswordEntry.requestFocus();
                mPasswordEntry.scheduleShowSoftInput();
            }
        }

        @Override
        public void onPause() {
            if (mSaveAndFinishWorker != null) {
                mSaveAndFinishWorker.setListener(null);
            }
            super.onPause();
        }

        @Override
        public void onSaveInstanceState(Bundle outState) {
            super.onSaveInstanceState(outState);
            outState.putString(KEY_UI_STAGE, mUiStage.name());
            outState.putString(KEY_FIRST_PIN, mFirstPin);
            outState.putString(KEY_CURRENT_PASSWORD, mCurrentPassword);
        }

        @Override
        public void onActivityResult(int requestCode, int resultCode,
                Intent data) {
            super.onActivityResult(requestCode, resultCode, data);
            switch (requestCode) {
                case CONFIRM_EXISTING_REQUEST:
                    if (resultCode != Activity.RESULT_OK) {
                        getActivity().setResult(RESULT_FINISHED);
                        getActivity().finish();
                    } else {
                        mCurrentPassword = data.getStringExtra(
                                ChooseLockSettingsHelper.EXTRA_KEY_PASSWORD);
                    }
                    break;
            }
        }

        protected Intent getRedactionInterstitialIntent(Context context) {
            return RedactionInterstitial.createStartIntent(context, mUserId);
        }

        protected void updateStage(Stage stage) {
            final Stage previousStage = mUiStage;
            mUiStage = stage;
            updateUi();

            // If the stage changed, announce the header for accessibility. This
            // is a no-op when accessibility is disabled.
            if (previousStage != stage) {
                mLayout.announceForAccessibility(mLayout.getHeaderText());
            }
        }

        /**
         * Read the requirements from {@link DevicePolicyManager} and intent and aggregate them.
         */
        private void loadDpmPasswordRequirements() {
            final int dpmPasswordQuality = mLockPatternUtils.getRequestedPasswordQuality(mUserId);
            if (dpmPasswordQuality == PASSWORD_QUALITY_NUMERIC_COMPLEX) {
                mPasswordNumSequenceAllowed = false;
            }
            mPasswordMinLength = Math.max(LockPatternUtils.MIN_LOCK_PASSWORD_SIZE,
                    mLockPatternUtils.getRequestedMinimumPasswordLength(mUserId));
            mPasswordMaxLength = mLockPatternUtils.getMaximumPasswordLength(mRequestedQuality);
            mPasswordMinLetters = mLockPatternUtils.getRequestedPasswordMinimumLetters(mUserId);
            mPasswordMinUpperCase = mLockPatternUtils.getRequestedPasswordMinimumUpperCase(mUserId);
            mPasswordMinLowerCase = mLockPatternUtils.getRequestedPasswordMinimumLowerCase(mUserId);
            mPasswordMinNumeric = mLockPatternUtils.getRequestedPasswordMinimumNumeric(mUserId);
            mPasswordMinSymbols = mLockPatternUtils.getRequestedPasswordMinimumSymbols(mUserId);
            mPasswordMinNonLetter = mLockPatternUtils.getRequestedPasswordMinimumNonLetter(mUserId);

            // Modify the value based on dpm policy
            switch (dpmPasswordQuality) {
                case PASSWORD_QUALITY_ALPHABETIC:
                    if (mPasswordMinLetters == 0) {
                        mPasswordMinLetters = 1;
                    }
                    break;
                case PASSWORD_QUALITY_ALPHANUMERIC:
                    if (mPasswordMinLetters == 0) {
                        mPasswordMinLetters = 1;
                    }
                    if (mPasswordMinNumeric == 0) {
                        mPasswordMinNumeric = 1;
                    }
                    break;
                case PASSWORD_QUALITY_COMPLEX:
                    // Reserve all the requirements.
                    break;
                default:
                    mPasswordMinNumeric = 0;
                    mPasswordMinLetters = 0;
                    mPasswordMinUpperCase = 0;
                    mPasswordMinLowerCase = 0;
                    mPasswordMinSymbols = 0;
                    mPasswordMinNonLetter = 0;
            }

            mPasswordMinLengthToFulfillAllPolicies = getMinLengthToFulfillAllPolicies();
        }

        /**
         * Merges the dpm requirements and the min complexity requirements.
         *
         * <p>Since there are more than one set of metrics to meet the min complexity requirement,
         * and we are not hard-coding any one of them to be the requirements the user must fulfil,
         * we are taking what the user has already entered into account when compiling the list of
         * requirements from min complexity. Then we merge this list with the DPM requirements, and
         * present the merged set as validation results to the user on the UI.
         *
         * <p>For example, suppose min complexity requires either ALPHABETIC(8+), or
         * ALPHANUMERIC(6+). If the user has entered "a", the length requirement displayed on the UI
         * would be 8. Then the user appends "1" to make it "a1". We now know the user is entering
         * an alphanumeric password so we would update the min complexity required min length to 6.
         * This might result in a little confusion for the user but the UI does not support showing
         * multiple sets of requirements / validation results as options to users, this is the best
         * we can do now.
         */
        private void mergeMinComplexityAndDpmRequirements(int userEnteredPasswordQuality) {
            if (mRequestedMinComplexity == PASSWORD_COMPLEXITY_NONE) {
                // dpm requirements are dominant if min complexity is none
                return;
            }

            // reset dpm requirements
            loadDpmPasswordRequirements();

            PasswordMetrics minMetrics = PasswordMetrics.getMinimumMetrics(
                    mRequestedMinComplexity, userEnteredPasswordQuality, mRequestedQuality,
                    requiresNumeric(), requiresLettersOrSymbols());
            mPasswordNumSequenceAllowed = mPasswordNumSequenceAllowed
                    && minMetrics.quality != PASSWORD_QUALITY_NUMERIC_COMPLEX;
            mPasswordMinLength = Math.max(mPasswordMinLength, minMetrics.length);
            mPasswordMinLetters = Math.max(mPasswordMinLetters, minMetrics.letters);
            mPasswordMinUpperCase = Math.max(mPasswordMinUpperCase, minMetrics.upperCase);
            mPasswordMinLowerCase = Math.max(mPasswordMinLowerCase, minMetrics.lowerCase);
            mPasswordMinNumeric = Math.max(mPasswordMinNumeric, minMetrics.numeric);
            mPasswordMinSymbols = Math.max(mPasswordMinSymbols, minMetrics.symbols);
            mPasswordMinNonLetter = Math.max(mPasswordMinNonLetter, minMetrics.nonLetter);

            if (minMetrics.quality == PASSWORD_QUALITY_ALPHABETIC) {
                if (!requiresLettersOrSymbols()) {
                    mPasswordMinLetters = 1;
                }
            }
            if (minMetrics.quality == PASSWORD_QUALITY_ALPHANUMERIC) {
                if (!requiresLettersOrSymbols()) {
                    mPasswordMinLetters = 1;
                }
                if (!requiresNumeric()) {
                    mPasswordMinNumeric = 1;
                }
            }

            mPasswordMinLengthToFulfillAllPolicies = getMinLengthToFulfillAllPolicies();
        }

        private boolean requiresLettersOrSymbols() {
            // This is the condition for the password to be considered ALPHABETIC according to
            // PasswordMetrics.computeForPassword()
            return mPasswordMinLetters + mPasswordMinUpperCase
                    + mPasswordMinLowerCase + mPasswordMinSymbols + mPasswordMinNonLetter > 0;
        }

        private boolean requiresNumeric() {
            return mPasswordMinNumeric > 0;
        }

        /**
         * Validates PIN/Password and returns the validation result.
         *
         * @param password the raw password the user typed in
         * @return the validation result.
         */
        @VisibleForTesting
        int validatePassword(String password) {
            int errorCode = NO_ERROR;
            final PasswordMetrics metrics = PasswordMetrics.computeForPassword(password);
            mergeMinComplexityAndDpmRequirements(metrics.quality);

            if (password.length() < mPasswordMinLength) {
                if (mPasswordMinLength > mPasswordMinLengthToFulfillAllPolicies) {
                    errorCode |= TOO_SHORT;
                }
            } else if (password.length() > mPasswordMaxLength) {
                errorCode |= TOO_LONG;
            } else {
                // The length requirements are fulfilled.
                if (!mPasswordNumSequenceAllowed
                        && !requiresLettersOrSymbols()
                        && metrics.numeric == password.length()) {
                    // Check for repeated characters or sequences (e.g. '1234', '0000', '2468')
                    // if DevicePolicyManager or min password complexity requires a complex numeric
                    // password. There can be two cases in the UI: 1. User chooses to enroll a
                    // PIN, 2. User chooses to enroll a password but enters a numeric-only pin. We
                    // should carry out the sequence check in both cases.
                    //
                    // Conditions for the !requiresLettersOrSymbols() to be necessary:
                    // - DPM requires NUMERIC_COMPLEX
                    // - min complexity not NONE, user picks PASSWORD type so ALPHABETIC or
                    // ALPHANUMERIC is required
                    // Imagine user has entered "12345678", if we don't skip the sequence check, the
                    // validation result would show both "requires a letter" and "sequence not
                    // allowed", while the only requirement the user needs to know is "requires a
                    // letter" because once the user has fulfilled the alphabetic requirement, the
                    // password would not be containing only digits so this check would not be
                    // performed anyway.
                    final int sequence = PasswordMetrics.maxLengthSequence(password);
                    if (sequence > PasswordMetrics.MAX_ALLOWED_SEQUENCE) {
                        errorCode |= CONTAIN_SEQUENTIAL_DIGITS;
                    }
                }
                // Is the password recently used?
                if (mLockPatternUtils.checkPasswordHistory(password, getPasswordHistoryHashFactor(),
                        mUserId)) {
                    errorCode |= RECENTLY_USED;
                }
            }

            // Allow non-control Latin-1 characters only.
            for (int i = 0; i < password.length(); i++) {
                char c = password.charAt(i);
                if (c < 32 || c > 127) {
                    errorCode |= CONTAIN_INVALID_CHARACTERS;
                    break;
                }
            }

            // Ensure no non-digits if we are requesting numbers. This shouldn't be possible unless
            // user finds some way to bring up soft keyboard.
            if (mRequestedQuality == PASSWORD_QUALITY_NUMERIC
                    || mRequestedQuality == PASSWORD_QUALITY_NUMERIC_COMPLEX) {
                if (metrics.letters > 0 || metrics.symbols > 0) {
                    errorCode |= CONTAIN_NON_DIGITS;
                }
            }

            if (metrics.letters < mPasswordMinLetters) {
                errorCode |= NOT_ENOUGH_LETTER;
            }
            if (metrics.upperCase < mPasswordMinUpperCase) {
                errorCode |= NOT_ENOUGH_UPPER_CASE;
            }
            if (metrics.lowerCase < mPasswordMinLowerCase) {
                errorCode |= NOT_ENOUGH_LOWER_CASE;
            }
            if (metrics.symbols < mPasswordMinSymbols) {
                errorCode |= NOT_ENOUGH_SYMBOLS;
            }
            if (metrics.numeric < mPasswordMinNumeric) {
                errorCode |= NOT_ENOUGH_DIGITS;
            }
            if (metrics.nonLetter < mPasswordMinNonLetter) {
                errorCode |= NOT_ENOUGH_NON_LETTER;
            }
            return errorCode;
        }

        /**
         * Lazily compute and return the history hash factor of the current user (mUserId), used for
         * password history check.
         */
        private byte[] getPasswordHistoryHashFactor() {
            if (mPasswordHistoryHashFactor == null) {
                mPasswordHistoryHashFactor = mLockPatternUtils.getPasswordHistoryHashFactor(
                        mCurrentPassword, mUserId);
            }
            return mPasswordHistoryHashFactor;
        }

        public void handleNext() {
            if (mSaveAndFinishWorker != null) return;
            mChosenPassword = mPasswordEntry.getText().toString();
            if (TextUtils.isEmpty(mChosenPassword)) {
                return;
            }
            if (mUiStage == Stage.Introduction) {
                if (validatePassword(mChosenPassword) == NO_ERROR) {
                    mFirstPin = mChosenPassword;
                    mPasswordEntry.setText("");
                    updateStage(Stage.NeedToConfirm);
                }
            } else if (mUiStage == Stage.NeedToConfirm) {
                if (mFirstPin.equals(mChosenPassword)) {
                    startSaveAndFinish();
                } else {
                    CharSequence tmp = mPasswordEntry.getText();
                    if (tmp != null) {
                        Selection.setSelection((Spannable) tmp, 0, tmp.length());
                    }
                    updateStage(Stage.ConfirmWrong);
                }
            }
        }

        protected void setNextEnabled(boolean enabled) {
            mNextButton.setEnabled(enabled);
        }

        protected void setNextText(int text) {
            mNextButton.setText(getActivity(), text);
        }

        protected void onSkipOrClearButtonClick(View view) {
            mPasswordEntry.setText("");
        }

        protected void onNextButtonClick(View view) {
            handleNext();
        }

        public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
            // Check if this was the result of hitting the enter or "done" key
            if (actionId == EditorInfo.IME_NULL
                    || actionId == EditorInfo.IME_ACTION_DONE
                    || actionId == EditorInfo.IME_ACTION_NEXT) {
                handleNext();
                return true;
            }
            return false;
        }

        /**
         * @param errorCode error code returned from {@link #validatePassword(String)}.
         * @return an array of messages describing the error, important messages come first.
         */
        String[] convertErrorCodeToMessages(int errorCode) {
            List<String> messages = new ArrayList<>();
            if ((errorCode & CONTAIN_INVALID_CHARACTERS) > 0) {
                messages.add(getString(R.string.lockpassword_illegal_character));
            }
            if ((errorCode & CONTAIN_NON_DIGITS) > 0) {
                messages.add(getString(R.string.lockpassword_pin_contains_non_digits));
            }
            if ((errorCode & NOT_ENOUGH_UPPER_CASE) > 0) {
                messages.add(getResources().getQuantityString(
                        R.plurals.lockpassword_password_requires_uppercase, mPasswordMinUpperCase,
                        mPasswordMinUpperCase));
            }
            if ((errorCode & NOT_ENOUGH_LOWER_CASE) > 0) {
                messages.add(getResources().getQuantityString(
                        R.plurals.lockpassword_password_requires_lowercase, mPasswordMinLowerCase,
                        mPasswordMinLowerCase));
            }
            if ((errorCode & NOT_ENOUGH_LETTER) > 0) {
                messages.add(getResources().getQuantityString(
                        R.plurals.lockpassword_password_requires_letters, mPasswordMinLetters,
                        mPasswordMinLetters));
            }
            if ((errorCode & NOT_ENOUGH_DIGITS) > 0) {
                messages.add(getResources().getQuantityString(
                        R.plurals.lockpassword_password_requires_numeric, mPasswordMinNumeric,
                        mPasswordMinNumeric));
            }
            if ((errorCode & NOT_ENOUGH_SYMBOLS) > 0) {
                messages.add(getResources().getQuantityString(
                        R.plurals.lockpassword_password_requires_symbols, mPasswordMinSymbols,
                        mPasswordMinSymbols));
            }
            if ((errorCode & NOT_ENOUGH_NON_LETTER) > 0) {
                messages.add(getResources().getQuantityString(
                        R.plurals.lockpassword_password_requires_nonletter, mPasswordMinNonLetter,
                        mPasswordMinNonLetter));
            }
            if ((errorCode & TOO_SHORT) > 0) {
                messages.add(getResources().getQuantityString(
                        mIsAlphaMode
                                ? R.plurals.lockpassword_password_too_short
                                : R.plurals.lockpassword_pin_too_short,
                        mPasswordMinLength,
                        mPasswordMinLength));
            }
            if ((errorCode & TOO_LONG) > 0) {
                messages.add(getResources().getQuantityString(
                        mIsAlphaMode
                                ? R.plurals.lockpassword_password_too_long
                                : R.plurals.lockpassword_pin_too_long,
                        mPasswordMaxLength + 1,
                        mPasswordMaxLength + 1));
            }
            if ((errorCode & CONTAIN_SEQUENTIAL_DIGITS) > 0) {
                messages.add(getString(R.string.lockpassword_pin_no_sequential_digits));
            }
            if ((errorCode & RECENTLY_USED) > 0) {
                messages.add(getString((mIsAlphaMode) ? R.string.lockpassword_password_recently_used
                        : R.string.lockpassword_pin_recently_used));
            }
            return messages.toArray(new String[0]);
        }

        private int getMinLengthToFulfillAllPolicies() {
            final int minLengthForLetters = Math.max(mPasswordMinLetters,
                    mPasswordMinUpperCase + mPasswordMinLowerCase);
            final int minLengthForNonLetters = Math.max(mPasswordMinNonLetter,
                    mPasswordMinSymbols + mPasswordMinNumeric);
            return minLengthForLetters + minLengthForNonLetters;
        }

        /**
         * Update the hint based on current Stage and length of password entry
         */
        protected void updateUi() {
            final boolean canInput = mSaveAndFinishWorker == null;
            String password = mPasswordEntry.getText().toString();
            final int length = password.length();
            if (mUiStage == Stage.Introduction) {
                mPasswordRestrictionView.setVisibility(View.VISIBLE);
                final int errorCode = validatePassword(password);
                String[] messages = convertErrorCodeToMessages(errorCode);
                // Update the fulfillment of requirements.
                mPasswordRequirementAdapter.setRequirements(messages);
                // Enable/Disable the next button accordingly.
                setNextEnabled(errorCode == NO_ERROR);
            } else {
                // Hide password requirement view when we are just asking user to confirm the pw.
                mPasswordRestrictionView.setVisibility(View.GONE);
                setHeaderText(getString(mUiStage.getHint(mIsAlphaMode, getStageType())));
                setNextEnabled(canInput && length >= mPasswordMinLength);
                mSkipOrClearButton.setVisibility(toVisibility(canInput && length > 0));
            }
            int message = mUiStage.getMessage(mIsAlphaMode, getStageType());
            if (message != 0) {
                mMessage.setVisibility(View.VISIBLE);
                mMessage.setText(message);
            } else {
                mMessage.setVisibility(View.INVISIBLE);
            }

            setNextText(mUiStage.buttonText);
            mPasswordEntryInputDisabler.setInputEnabled(canInput);
        }

        protected int toVisibility(boolean visibleOrGone) {
            return visibleOrGone ? View.VISIBLE : View.GONE;
        }

        private void setHeaderText(String text) {
            // Only set the text if it is different than the existing one to avoid announcing again.
            if (!TextUtils.isEmpty(mLayout.getHeaderText())
                    && mLayout.getHeaderText().toString().equals(text)) {
                return;
            }
            mLayout.setHeaderText(text);
        }

        public void afterTextChanged(Editable s) {
            // Changing the text while error displayed resets to NeedToConfirm state
            if (mUiStage == Stage.ConfirmWrong) {
                mUiStage = Stage.NeedToConfirm;
            }
            // Schedule the UI update.
            mTextChangedHandler.notifyAfterTextChanged();
        }

        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        public void onTextChanged(CharSequence s, int start, int before, int count) {

        }

        private void startSaveAndFinish() {
            if (mSaveAndFinishWorker != null) {
                Log.w(TAG, "startSaveAndFinish with an existing SaveAndFinishWorker.");
                return;
            }

            mPasswordEntryInputDisabler.setInputEnabled(false);
            setNextEnabled(false);

            mSaveAndFinishWorker = new SaveAndFinishWorker();
            mSaveAndFinishWorker.setListener(this);

            getFragmentManager().beginTransaction().add(mSaveAndFinishWorker,
                    FRAGMENT_TAG_SAVE_AND_FINISH).commit();
            getFragmentManager().executePendingTransactions();

            final boolean required = getActivity().getIntent().getBooleanExtra(
                    EncryptionInterstitial.EXTRA_REQUIRE_PASSWORD, true);
            mSaveAndFinishWorker.start(mLockPatternUtils, required, mHasChallenge, mChallenge,
                    mChosenPassword, mCurrentPassword, mRequestedQuality, mUserId);
        }

        @Override
        public void onChosenLockSaveFinished(boolean wasSecureBefore, Intent resultData) {
            getActivity().setResult(RESULT_FINISHED, resultData);

            if (!wasSecureBefore) {
                Intent intent = getRedactionInterstitialIntent(getActivity());
                if (intent != null) {
                    startActivity(intent);
                }
            }
            getActivity().finish();
        }

        class TextChangedHandler extends Handler {
            private static final int ON_TEXT_CHANGED = 1;
            private static final int DELAY_IN_MILLISECOND = 100;

            /**
             * With the introduction of delay, we batch processing the text changed event to reduce
             * unnecessary UI updates.
             */
            private void notifyAfterTextChanged() {
                removeMessages(ON_TEXT_CHANGED);
                sendEmptyMessageDelayed(ON_TEXT_CHANGED, DELAY_IN_MILLISECOND);
            }

            @Override
            public void handleMessage(Message msg) {
                if (getActivity() == null) {
                    return;
                }
                if (msg.what == ON_TEXT_CHANGED) {
                    updateUi();
                }
            }
        }
    }

    public static class SaveAndFinishWorker extends SaveChosenLockWorkerBase {

        private String mChosenPassword;
        private String mCurrentPassword;
        private int mRequestedQuality;

        public void start(LockPatternUtils utils, boolean required,
                boolean hasChallenge, long challenge,
                String chosenPassword, String currentPassword, int requestedQuality, int userId) {
            prepare(utils, required, hasChallenge, challenge, userId);

            mChosenPassword = chosenPassword;
            mCurrentPassword = currentPassword;
            mRequestedQuality = requestedQuality;
            mUserId = userId;

            start();
        }

        @Override
        protected Intent saveAndVerifyInBackground() {
            Intent result = null;
            mUtils.saveLockPassword(mChosenPassword, mCurrentPassword, mRequestedQuality,
                    mUserId);

            if (mHasChallenge) {
                byte[] token;
                try {
                    token = mUtils.verifyPassword(mChosenPassword, mChallenge, mUserId);
                } catch (RequestThrottledException e) {
                    token = null;
                }

                if (token == null) {
                    Log.e(TAG, "critical: no token returned for known good password.");
                }

                result = new Intent();
                result.putExtra(ChooseLockSettingsHelper.EXTRA_KEY_CHALLENGE_TOKEN, token);
            }

            return result;
        }
    }
}