/*
 * Copyright (C) 2014 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.inputmethod.latin.utils;

import android.view.inputmethod.InputMethodSubtype;

import com.android.inputmethod.latin.RichInputMethodSubtype;

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

import javax.annotation.Nonnull;

/**
 * This class determines that the language name on the spacebar should be displayed in what format.
 */
public final class LanguageOnSpacebarUtils {
    public static final int FORMAT_TYPE_NONE = 0;
    public static final int FORMAT_TYPE_LANGUAGE_ONLY = 1;
    public static final int FORMAT_TYPE_FULL_LOCALE = 2;

    private static List<InputMethodSubtype> sEnabledSubtypes = Collections.emptyList();
    private static boolean sIsSystemLanguageSameAsInputLanguage;

    private LanguageOnSpacebarUtils() {
        // This utility class is not publicly instantiable.
    }

    public static int getLanguageOnSpacebarFormatType(
            @Nonnull final RichInputMethodSubtype subtype) {
        if (subtype.isNoLanguage()) {
            return FORMAT_TYPE_FULL_LOCALE;
        }
        // Only this subtype is enabled and equals to the system locale.
        if (sEnabledSubtypes.size() < 2 && sIsSystemLanguageSameAsInputLanguage) {
            return FORMAT_TYPE_NONE;
        }
        final Locale locale = subtype.getLocale();
        if (locale == null) {
            return FORMAT_TYPE_NONE;
        }
        final String keyboardLanguage = locale.getLanguage();
        final String keyboardLayout = subtype.getKeyboardLayoutSetName();
        int sameLanguageAndLayoutCount = 0;
        for (final InputMethodSubtype ims : sEnabledSubtypes) {
            final String language = SubtypeLocaleUtils.getSubtypeLocale(ims).getLanguage();
            if (keyboardLanguage.equals(language) && keyboardLayout.equals(
                    SubtypeLocaleUtils.getKeyboardLayoutSetName(ims))) {
                sameLanguageAndLayoutCount++;
            }
        }
        // Display full locale name only when there are multiple subtypes that have the same
        // locale and keyboard layout. Otherwise displaying language name is enough.
        return sameLanguageAndLayoutCount > 1 ? FORMAT_TYPE_FULL_LOCALE
                : FORMAT_TYPE_LANGUAGE_ONLY;
    }

    public static void setEnabledSubtypes(@Nonnull final List<InputMethodSubtype> enabledSubtypes) {
        sEnabledSubtypes = enabledSubtypes;
    }

    public static void onSubtypeChanged(@Nonnull final RichInputMethodSubtype subtype,
           final boolean implicitlyEnabledSubtype, @Nonnull final Locale systemLocale) {
        final Locale newLocale = subtype.getLocale();
        if (systemLocale.equals(newLocale)) {
            sIsSystemLanguageSameAsInputLanguage = true;
            return;
        }
        if (!systemLocale.getLanguage().equals(newLocale.getLanguage())) {
            sIsSystemLanguageSameAsInputLanguage = false;
            return;
        }
        // If the subtype is enabled explicitly, the language name should be displayed even when
        // the keyboard language and the system language are equal.
        sIsSystemLanguageSameAsInputLanguage = implicitlyEnabledSubtype;
    }
}