/*
 * Copyright (C) 2013 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 android.support.v4.text;

import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.view.ViewCompat;

import java.util.Locale;

public class TextUtilsCompat {

    /**
     * Html-encode the string.
     * @param s the string to be encoded
     * @return the encoded string
     */
    @NonNull
    public static String htmlEncode(@NonNull String s) {
        StringBuilder sb = new StringBuilder();
        char c;
        for (int i = 0; i < s.length(); i++) {
            c = s.charAt(i);
            switch (c) {
                case '<':
                    sb.append("<"); //$NON-NLS-1$
                    break;
                case '>':
                    sb.append(">"); //$NON-NLS-1$
                    break;
                case '&':
                    sb.append("&"); //$NON-NLS-1$
                    break;
                case '\'':
                    //http://www.w3.org/TR/xhtml1
                    // The named character reference ' (the apostrophe, U+0027) was introduced in
                    // XML 1.0 but does not appear in HTML. Authors should therefore use ' instead
                    // of ' to work as expected in HTML 4 user agents.
                    sb.append("'"); //$NON-NLS-1$
                    break;
                case '"':
                    sb.append("""); //$NON-NLS-1$
                    break;
                default:
                    sb.append(c);
            }
        }
        return sb.toString();
    }

    /**
     * Return the layout direction for a given Locale
     *
     * @param locale the Locale for which we want the layout direction. Can be null.
     * @return the layout direction. This may be one of:
     * {@link ViewCompat#LAYOUT_DIRECTION_LTR} or
     * {@link ViewCompat#LAYOUT_DIRECTION_RTL}.
     *
     * Be careful: this code will need to be updated when vertical scripts will be supported
     */
    public static int getLayoutDirectionFromLocale(@Nullable Locale locale) {
        if (locale != null && !locale.equals(ROOT)) {
            final String scriptSubtag = ICUCompat.getScript(
                    ICUCompat.addLikelySubtags(locale.toString()));
            if (scriptSubtag == null) return getLayoutDirectionFromFirstChar(locale);

            if (scriptSubtag.equalsIgnoreCase(ARAB_SCRIPT_SUBTAG) ||
                    scriptSubtag.equalsIgnoreCase(HEBR_SCRIPT_SUBTAG)) {
                return ViewCompat.LAYOUT_DIRECTION_RTL;
            }
        }

        return ViewCompat.LAYOUT_DIRECTION_LTR;
    }

    /**
     * Fallback algorithm to detect the locale direction. Rely on the fist char of the
     * localized locale name. This will not work if the localized locale name is in English
     * (this is the case for ICU 4.4 and "Urdu" script)
     *
     * @param locale
     * @return the layout direction. This may be one of:
     * {@link ViewCompat#LAYOUT_DIRECTION_LTR} or
     * {@link ViewCompat#LAYOUT_DIRECTION_RTL}.
     *
     * Be careful: this code will need to be updated when vertical scripts will be supported
     */
    private static int getLayoutDirectionFromFirstChar(Locale locale) {
        switch(Character.getDirectionality(locale.getDisplayName(locale).charAt(0))) {
            case Character.DIRECTIONALITY_RIGHT_TO_LEFT:
            case Character.DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC:
                return ViewCompat.LAYOUT_DIRECTION_RTL;

            case Character.DIRECTIONALITY_LEFT_TO_RIGHT:
            default:
                return ViewCompat.LAYOUT_DIRECTION_LTR;
        }
    }

    public static final Locale ROOT = new Locale("", "");

    private static String ARAB_SCRIPT_SUBTAG = "Arab";
    private static String HEBR_SCRIPT_SUBTAG = "Hebr";
}