android-calculatorpp/src/main/java/org/solovyev/android/ResourceCache.java

/*
 * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
 * For more information, please, contact se.solovyev@gmail.com
 * or visit http://se.solovyev.org
 */

package org.solovyev.android;

import android.app.Activity;
import android.content.Context;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.solovyev.android.view.widgets.DragButton;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.*;

/**
 * User: serso
 * Date: 11/25/11
 * Time: 1:52 PM
 */
public enum ResourceCache {

	instance;

	@NotNull
	private static final Locale DEFAULT_LOCALE = Locale.ENGLISH;

	// ids of drag buttons in R.class
	private List<Integer> dragButtonIds = null;

	// ids of buttons in R.class
	private List<Integer> buttonIds = null;

	// first map: key: language id, value: map of captions and translations
	// second mal: key: caption id, value: translation
	private final Map<String, Map<String, String>> captions = new HashMap<String, Map<String, String>>();

	private Class<?> resourceClass;

	private Context context;

	@NotNull
	private final NameToIdCache nameToIdCache = new NameToIdCache();

	public List<Integer> getDragButtonIds() {
		return dragButtonIds;
	}

	public List<Integer> getButtonIds() {
		return buttonIds;
	}

	/**
	 * Method load captions for default locale using android R class
	 *
	 * @param context	   STATIC CONTEXT
	 * @param resourceClass class of captions in android (SUBCLASS of R class)
	 */
	public void initCaptions(@NotNull Context context, @NotNull Class<?> resourceClass) {
		initCaptions(context, resourceClass, Locale.getDefault());
	}

	/**
	 * Method load captions for specified locale using android R class
	 *
	 * @param context	   STATIC CONTEXT
	 * @param resourceClass class of captions in android (SUBCLASS of R class)
	 * @param locale		language to be used for translation
	 */
	public void initCaptions(@NotNull Context context, @NotNull Class<?> resourceClass, @NotNull Locale locale) {
		assert this.resourceClass == null || this.resourceClass.equals(resourceClass);

		this.context = context;
		this.resourceClass = resourceClass;

		if (!initialized(locale)) {
			final Map<String, String> captionsByLanguage = new HashMap<String, String>();

			final Locale defaultLocale = Locale.getDefault();

			try {
				if (!defaultLocale.getLanguage().equals(locale.getLanguage())) {
					updateConfiguration(context, locale);
				}

				for (Field field : resourceClass.getDeclaredFields()) {
					int modifiers = field.getModifiers();
					if (Modifier.isFinal(modifiers) && Modifier.isStatic(modifiers)) {
						try {
							int captionId = field.getInt(resourceClass);
							captionsByLanguage.put(field.getName(), context.getString(captionId));
						} catch (IllegalAccessException e) {
							Log.e(ResourceCache.class.getName(), e.getMessage());
						} catch (Resources.NotFoundException e) {
							Log.e(ResourceCache.class.getName(), "Caption with name " + field.getName() + " was not found for " + locale.getLanguage() + " language: " + e.getMessage());
						}
					}
				}
			} finally {
				if (!defaultLocale.getLanguage().equals(locale.getLanguage())) {
					updateConfiguration(context, defaultLocale);
				}
			}

			captions.put(locale.getLanguage(), captionsByLanguage);
		}
	}

	private static void updateConfiguration(@NotNull Context context, @NotNull Locale locale) {
		Locale.setDefault(locale);
		final Configuration config = new Configuration();
		config.locale = locale;
		context.getResources().updateConfiguration(config, context.getResources().getDisplayMetrics());
	}

	private boolean initialized(@NotNull Locale locale) {
		return captions.containsKey(locale.getLanguage());
	}

	/**
	 * @param captionId id of caption to be translated
	 * @return translation by caption id in default language, null if no translation in default language present
	 */
	@Nullable
	public String getCaption(@NotNull String captionId) {
		return getCaption(captionId, Locale.getDefault());
	}


	/**
	 * @param captionId id of caption to be translated
	 * @param locale	language to be used for translation
	 * @return translation by caption id in specified language, null if no translation in specified language present
	 */
	@Nullable
	public String getCaption(@NotNull String captionId, @NotNull final Locale locale) {
		Map<String, String> captionsByLanguage = captions.get(locale.getLanguage());
		if (captionsByLanguage != null) {
			return getCaption(captionsByLanguage, captionId, locale);
		} else {
			assert resourceClass != null && context != null;

			initCaptions(context, resourceClass, locale);

			captionsByLanguage = captions.get(locale.getLanguage());
			if (captionsByLanguage != null) {
				return getCaption(captionsByLanguage, captionId, locale);
			}
		}

		return null;
	}

	@Nullable
	private String getCaption(@NotNull Map<String, String> captionsByLanguage, @NotNull String captionId, @NotNull Locale locale) {
		String result = captionsByLanguage.get(captionId);
		if (result == null && !locale.getLanguage().equals(DEFAULT_LOCALE.getLanguage())) {
			result = getCaption(captionId, DEFAULT_LOCALE);
		}
		return result;
	}

	public void init(@NotNull Class<?> resourceClass, @NotNull Activity activity) {
		dragButtonIds = new ArrayList<Integer>();
		buttonIds = new ArrayList<Integer>();

		for (Field field : resourceClass.getDeclaredFields()) {
			int modifiers = field.getModifiers();
			if (Modifier.isFinal(modifiers) && Modifier.isStatic(modifiers)) {
				try {
					int viewId = field.getInt(resourceClass);
					final View view = activity.findViewById(viewId);
					if (view instanceof DragButton) {
						dragButtonIds.add(viewId);
					}
					if (view instanceof Button) {
						buttonIds.add(viewId);
					}
				} catch (IllegalAccessException e) {
					Log.e(ResourceCache.class.getName(), e.getMessage());
				}
			}
		}
	}

	@NotNull
	public Map<String, Integer> getNameToIdCache(@NotNull Class<?> clazz) {
		return this.nameToIdCache.getCache(clazz);
	}

	private static class NameToIdCache {

		@NotNull
		private final Map<Class<?>, Map<String, Integer>> caches = new HashMap<Class<?>, Map<String, Integer>>(3);

		// not intended for instantiation
		private NameToIdCache() {
		}

		@NotNull
		public Map<String, Integer> getCache(@NotNull Class<?> clazz) {
			Map<String, Integer> result = caches.get(clazz);

			if (result == null) {
				result = new HashMap<String, Integer>();

				for (Field field : clazz.getDeclaredFields()) {
					int modifiers = field.getModifiers();
					if (Modifier.isFinal(modifiers) && Modifier.isStatic(modifiers)) {
						try {
							result.put(field.getName(), field.getInt(clazz));
						} catch (IllegalAccessException e) {
							Log.e(ResourceCache.class.getName(), e.getMessage());
						}
					}
				}

				caches.put(clazz, result);
			}

			return result;
		}
	}

}