/*
 * Copyright (C) 2016 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.inputmethod;

import android.annotation.NonNull;
import android.annotation.Nullable;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.database.ContentObserver;
import android.hardware.input.InputDeviceIdentifier;
import android.hardware.input.InputManager;
import android.hardware.input.KeyboardLayout;
import android.os.Bundle;
import android.os.Handler;
import android.os.UserHandle;
import android.provider.SearchIndexableResource;
import android.provider.Settings.Secure;
import android.support.v14.preference.SwitchPreference;
import android.support.v7.preference.Preference;
import android.support.v7.preference.Preference.OnPreferenceChangeListener;
import android.support.v7.preference.PreferenceCategory;
import android.support.v7.preference.PreferenceScreen;
import android.text.TextUtils;
import android.view.InputDevice;

import com.android.internal.inputmethod.InputMethodUtils;
import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
import com.android.internal.util.Preconditions;
import com.android.settings.R;
import com.android.settings.Settings;
import com.android.settings.SettingsPreferenceFragment;
import com.android.settings.search.BaseSearchIndexProvider;
import com.android.settings.search.Indexable;
import com.android.settingslib.utils.ThreadUtils;

import java.text.Collator;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Objects;

public final class PhysicalKeyboardFragment extends SettingsPreferenceFragment
        implements InputManager.InputDeviceListener,
        KeyboardLayoutDialogFragment.OnSetupKeyboardLayoutsListener, Indexable {

    private static final String KEYBOARD_ASSISTANCE_CATEGORY = "keyboard_assistance_category";
    private static final String SHOW_VIRTUAL_KEYBOARD_SWITCH = "show_virtual_keyboard_switch";
    private static final String KEYBOARD_SHORTCUTS_HELPER = "keyboard_shortcuts_helper";

    @NonNull
    private final ArrayList<HardKeyboardDeviceInfo> mLastHardKeyboards = new ArrayList<>();

    private InputManager mIm;
    @NonNull
    private PreferenceCategory mKeyboardAssistanceCategory;
    @NonNull
    private SwitchPreference mShowVirtualKeyboardSwitch;
    @NonNull
    private InputMethodUtils.InputMethodSettings mSettings;

    private Intent mIntentWaitingForResult;

    @Override
    public void onCreatePreferences(Bundle bundle, String s) {
        Activity activity = Preconditions.checkNotNull(getActivity());
        addPreferencesFromResource(R.xml.physical_keyboard_settings);
        mIm = Preconditions.checkNotNull(activity.getSystemService(InputManager.class));
        mSettings = new InputMethodUtils.InputMethodSettings(
                activity.getResources(),
                getContentResolver(),
                new HashMap<>(),
                new ArrayList<>(),
                UserHandle.myUserId(),
                false /* copyOnWrite */);
        mKeyboardAssistanceCategory = Preconditions.checkNotNull(
                (PreferenceCategory) findPreference(KEYBOARD_ASSISTANCE_CATEGORY));
        mShowVirtualKeyboardSwitch = Preconditions.checkNotNull(
                (SwitchPreference) mKeyboardAssistanceCategory.findPreference(
                        SHOW_VIRTUAL_KEYBOARD_SWITCH));
        findPreference(KEYBOARD_SHORTCUTS_HELPER).setOnPreferenceClickListener(
                new Preference.OnPreferenceClickListener() {
                    @Override
                    public boolean onPreferenceClick(Preference preference) {
                        toggleKeyboardShortcutsMenu();
                        return true;
                    }
                });
    }

    @Override
    public void onResume() {
        super.onResume();
        mLastHardKeyboards.clear();
        scheduleUpdateHardKeyboards();
        mIm.registerInputDeviceListener(this, null);
        mShowVirtualKeyboardSwitch.setOnPreferenceChangeListener(
                mShowVirtualKeyboardSwitchPreferenceChangeListener);
        registerShowVirtualKeyboardSettingsObserver();
    }

    @Override
    public void onPause() {
        super.onPause();
        mLastHardKeyboards.clear();
        mIm.unregisterInputDeviceListener(this);
        mShowVirtualKeyboardSwitch.setOnPreferenceChangeListener(null);
        unregisterShowVirtualKeyboardSettingsObserver();
    }

    @Override
    public void onInputDeviceAdded(int deviceId) {
        scheduleUpdateHardKeyboards();
    }

    @Override
    public void onInputDeviceRemoved(int deviceId) {
        scheduleUpdateHardKeyboards();
    }

    @Override
    public void onInputDeviceChanged(int deviceId) {
        scheduleUpdateHardKeyboards();
    }

    @Override
    public int getMetricsCategory() {
        return MetricsEvent.PHYSICAL_KEYBOARDS;
    }

    private void scheduleUpdateHardKeyboards() {
        final Context context = getContext();
        ThreadUtils.postOnBackgroundThread(() -> {
            final List<HardKeyboardDeviceInfo> newHardKeyboards = getHardKeyboards(context);
            ThreadUtils.postOnMainThread(() -> updateHardKeyboards(newHardKeyboards));
        });
    }

    private void updateHardKeyboards(@NonNull List<HardKeyboardDeviceInfo> newHardKeyboards) {
        if (Objects.equals(mLastHardKeyboards, newHardKeyboards)) {
            // Nothing has changed.  Ignore.
            return;
        }

        // TODO(yukawa): Maybe we should follow the style used in ConnectedDeviceDashboardFragment.

        mLastHardKeyboards.clear();
        mLastHardKeyboards.addAll(newHardKeyboards);

        final PreferenceScreen preferenceScreen = getPreferenceScreen();
        preferenceScreen.removeAll();
        final PreferenceCategory category = new PreferenceCategory(getPrefContext());
        category.setTitle(R.string.builtin_keyboard_settings_title);
        category.setOrder(0);
        preferenceScreen.addPreference(category);

        for (HardKeyboardDeviceInfo hardKeyboardDeviceInfo : newHardKeyboards) {
            // TODO(yukawa): Consider using com.android.settings.widget.GearPreference
            final Preference pref = new Preference(getPrefContext());
            pref.setTitle(hardKeyboardDeviceInfo.mDeviceName);
            pref.setSummary(hardKeyboardDeviceInfo.mLayoutLabel);
            pref.setOnPreferenceClickListener(preference -> {
                showKeyboardLayoutDialog(hardKeyboardDeviceInfo.mDeviceIdentifier);
                return true;
            });
            category.addPreference(pref);
        }

        mKeyboardAssistanceCategory.setOrder(1);
        preferenceScreen.addPreference(mKeyboardAssistanceCategory);
        updateShowVirtualKeyboardSwitch();
    }

    private void showKeyboardLayoutDialog(InputDeviceIdentifier inputDeviceIdentifier) {
        KeyboardLayoutDialogFragment fragment = new KeyboardLayoutDialogFragment(
                inputDeviceIdentifier);
        fragment.setTargetFragment(this, 0);
        fragment.show(getActivity().getFragmentManager(), "keyboardLayout");
    }

    private void registerShowVirtualKeyboardSettingsObserver() {
        unregisterShowVirtualKeyboardSettingsObserver();
        getActivity().getContentResolver().registerContentObserver(
                Secure.getUriFor(Secure.SHOW_IME_WITH_HARD_KEYBOARD),
                false,
                mContentObserver,
                UserHandle.myUserId());
        updateShowVirtualKeyboardSwitch();
    }

    private void unregisterShowVirtualKeyboardSettingsObserver() {
        getActivity().getContentResolver().unregisterContentObserver(mContentObserver);
    }

    private void updateShowVirtualKeyboardSwitch() {
        mShowVirtualKeyboardSwitch.setChecked(mSettings.isShowImeWithHardKeyboardEnabled());
    }

    private void toggleKeyboardShortcutsMenu() {
        getActivity().requestShowKeyboardShortcuts();
    }

    private final OnPreferenceChangeListener mShowVirtualKeyboardSwitchPreferenceChangeListener =
            new OnPreferenceChangeListener() {
                @Override
                public boolean onPreferenceChange(Preference preference, Object newValue) {
                    mSettings.setShowImeWithHardKeyboard((Boolean) newValue);
                    return true;
                }
            };

    private final ContentObserver mContentObserver = new ContentObserver(new Handler(true)) {
        @Override
        public void onChange(boolean selfChange) {
            updateShowVirtualKeyboardSwitch();
        }
    };

    @Override
    public void onSetupKeyboardLayouts(InputDeviceIdentifier inputDeviceIdentifier) {
        final Intent intent = new Intent(Intent.ACTION_MAIN);
        intent.setClass(getActivity(), Settings.KeyboardLayoutPickerActivity.class);
        intent.putExtra(KeyboardLayoutPickerFragment.EXTRA_INPUT_DEVICE_IDENTIFIER,
                inputDeviceIdentifier);
        mIntentWaitingForResult = intent;
        startActivityForResult(intent, 0);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (mIntentWaitingForResult != null) {
            InputDeviceIdentifier inputDeviceIdentifier = mIntentWaitingForResult
                    .getParcelableExtra(KeyboardLayoutPickerFragment.EXTRA_INPUT_DEVICE_IDENTIFIER);
            mIntentWaitingForResult = null;
            showKeyboardLayoutDialog(inputDeviceIdentifier);
        }
    }

    private static String getLayoutLabel(@NonNull InputDevice device,
            @NonNull Context context, @NonNull InputManager im) {
        final String currentLayoutDesc =
                im.getCurrentKeyboardLayoutForInputDevice(device.getIdentifier());
        if (currentLayoutDesc == null) {
            return context.getString(R.string.keyboard_layout_default_label);
        }
        final KeyboardLayout currentLayout = im.getKeyboardLayout(currentLayoutDesc);
        if (currentLayout == null) {
            return context.getString(R.string.keyboard_layout_default_label);
        }
        // If current layout is specified but the layout is null, just return an empty string
        // instead of falling back to R.string.keyboard_layout_default_label.
        return TextUtils.emptyIfNull(currentLayout.getLabel());
    }

    @NonNull
    static List<HardKeyboardDeviceInfo> getHardKeyboards(@NonNull Context context) {
        final List<HardKeyboardDeviceInfo> keyboards = new ArrayList<>();
        final InputManager im = context.getSystemService(InputManager.class);
        if (im == null) {
            return new ArrayList<>();
        }
        for (int deviceId : InputDevice.getDeviceIds()) {
            final InputDevice device = InputDevice.getDevice(deviceId);
            if (device == null || device.isVirtual() || !device.isFullKeyboard()) {
                continue;
            }
            keyboards.add(new HardKeyboardDeviceInfo(
                    device.getName(), device.getIdentifier(), getLayoutLabel(device, context, im)));
        }

        // We intentionally don't reuse Comparator because Collator may not be thread-safe.
        final Collator collator = Collator.getInstance();
        keyboards.sort((a, b) -> {
            int result = collator.compare(a.mDeviceName, b.mDeviceName);
            if (result != 0) {
                return result;
            }
            result = a.mDeviceIdentifier.getDescriptor().compareTo(
                    b.mDeviceIdentifier.getDescriptor());
            if (result != 0) {
                return result;
            }
            return collator.compare(a.mLayoutLabel, b.mLayoutLabel);
        });
        return keyboards;
    }

    public static final class HardKeyboardDeviceInfo {
        @NonNull
        public final String mDeviceName;
        @NonNull
        public final InputDeviceIdentifier mDeviceIdentifier;
        @NonNull
        public final String mLayoutLabel;

        public HardKeyboardDeviceInfo(
                @Nullable String deviceName,
                @NonNull InputDeviceIdentifier deviceIdentifier,
                @NonNull String layoutLabel) {
            mDeviceName = TextUtils.emptyIfNull(deviceName);
            mDeviceIdentifier = deviceIdentifier;
            mLayoutLabel = layoutLabel;
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) return true;
            if (o == null) return false;

            if (!(o instanceof HardKeyboardDeviceInfo)) return false;

            final HardKeyboardDeviceInfo that = (HardKeyboardDeviceInfo) o;
            if (!TextUtils.equals(mDeviceName, that.mDeviceName)) {
                return false;
            }
            if (!Objects.equals(mDeviceIdentifier, that.mDeviceIdentifier)) {
                return false;
            }
            if (!TextUtils.equals(mLayoutLabel, that.mLayoutLabel)) {
                return false;
            }

            return true;
        }
    }

    public static final Indexable.SearchIndexProvider SEARCH_INDEX_DATA_PROVIDER =
            new BaseSearchIndexProvider() {
                @Override
                public List<SearchIndexableResource> getXmlResourcesToIndex(
                        Context context, boolean enabled) {
                    final SearchIndexableResource sir = new SearchIndexableResource(context);
                    sir.xmlResId = R.xml.physical_keyboard_settings;
                    return Arrays.asList(sir);
                }
            };
}