com.datasnap.android.cache.SettingsCache.java Source code

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Here is the source code for com.datasnap.android.cache.SettingsCache.java

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/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2014 Segment.io, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.datasnap.android.cache;

import android.content.Context;
import com.datasnap.android.Logger;
import com.datasnap.android.cache.ISettingsLayer.SettingsCallback;
import com.datasnap.android.models.EasyJSONObject;
import java.util.Calendar;
import org.json.JSONException;
import org.json.JSONObject;

public class SettingsCache extends SimpleStringCache {

    private static final String CACHE_KEY = "settings";
    private static final String SETTINGS_KEY = "settings";
    private static final String LAST_UPDATED_KEY = "lastUpdated";

    private int reloads;
    private ISettingsLayer layer;
    private int cacheForMs;

    public SettingsCache(Context context, ISettingsLayer layer, int cachedMs) {
        super(context, CACHE_KEY);
        this.layer = layer;
        this.cacheForMs = cachedMs;
    }

    @Override
    public String load() {
        return load(null);
    }

    /**
     * Load the settings asynchronously.
     *
     * @return settings
     */
    public String load(final SettingsCallback callback) {
        Logger.d("Requesting Segment.io settings ..");
        layer.fetch(new SettingsCallback() {
            @Override
            public void onSettingsLoaded(boolean success, EasyJSONObject settings) {
                if (settings == null) {
                    Logger.w("Failed to fetch new Segment.io settings.");
                } else {
                    // wrap the settings in a container object containing when
                    // it was last updated
                    EasyJSONObject container = new EasyJSONObject();

                    Calendar rightNow = Calendar.getInstance();
                    container.put(LAST_UPDATED_KEY, rightNow);
                    container.put(SETTINGS_KEY, settings);

                    reloads += 1;

                    Logger.d("Successfully fetched new Segment.io settings.");

                    set(container.toString());
                }

                if (callback != null)
                    callback.onSettingsLoaded(success, settings);
            }
        });

        return null;
    }

    private EasyJSONObject parseContainer(String json) {
        if (json != null) {
            try {
                return new EasyJSONObject(new JSONObject(json));
            } catch (JSONException e) {
                Logger.w(e, "Failed to parse json object representing cached settings.");
            }
        }

        return null;
    }

    /**
     * Returns the cached value, or calls load to get the value.
     * Will automatically refresh every cacheForMs, and will save the new value in the cache
     * afterwards.
     */
    @Override
    public String get() {
        String json = super.get();
        EasyJSONObject container = parseContainer(json);
        if (container != null) {
            // if we have it cached, let's check its time
            // to make sure its recent
            Calendar rightNow = Calendar.getInstance();
            Calendar lastUpdated = container.getCalendar(LAST_UPDATED_KEY);
            if (lastUpdated != null) {
                long timeCached = rightNow.getTimeInMillis() - lastUpdated.getTimeInMillis();
                if (timeCached > cacheForMs) {
                    Logger.d("Segment.io settings cache expired, loading new settings ...");
                    // it's been cached too long, we need to refresh
                    load();
                }

                return container.toString();
            } else {
                Logger.w("Container exists, but without last updated key. JSON: %s", container);
            }
        }

        return null;
    }

    /**
     * Returns the settings object
     */
    public EasyJSONObject getSettings() {
        String json = this.get();
        EasyJSONObject container = parseContainer(json);
        if (container != null) {
            JSONObject settings = container.getObject(SETTINGS_KEY);
            if (settings != null)
                return new EasyJSONObject(settings);
        }

        return null;
    }

    public int getReloads() {
        return reloads;
    }
}