ChannelMetadataModel.java

package com.buddycloud.model;

import java.util.Iterator;

import org.apache.http.entity.StringEntity;
import org.json.JSONObject;

import android.content.Context;

import com.buddycloud.http.BuddycloudHTTPHelper;
import com.buddycloud.model.dao.ChannelMetadataDAO;
import com.buddycloud.preferences.Preferences;

public class ChannelMetadataModel extends AbstractModel<JSONObject, JSONObject, String> {

	private static final String ENDPOINT = "/metadata/posts"; 
	private static ChannelMetadataModel instance;
	
	private ChannelMetadataModel() {}
	
	public static ChannelMetadataModel getInstance() {
		if (instance == null) {
			instance = new ChannelMetadataModel();
		}
		return instance;
	}
	
	@SuppressWarnings("unchecked")
	private void updateMetadata(ChannelMetadataDAO dao, String channel, JSONObject oldMetadata, 
			JSONObject newMetadata, ModelCallback<Void> callback) {

		// Verify if any of the data has changed
		boolean update = false;
		Iterator<String> keys = oldMetadata.keys();
		while (keys.hasNext()) {
			String key = keys.next();
			
			if (!oldMetadata.optString(key).equals(newMetadata.optString(key))) {
				update = true;
				break;
			}
		}
		
		// Update, if necessary
		if (update) {
			dao.update(channel, newMetadata);
			
			if (callback != null) {
				callback.success(null);
			}
		}
	}
	
	private void insertMetadata(ChannelMetadataDAO dao, String channel, JSONObject newMetadata, 
			ModelCallback<Void> callback) {
		dao.insert(channel, newMetadata);
		if (callback != null) {
			callback.success(null);
		}
	}
	
	@Override
	public JSONObject getFromCache(Context context, String... p) {
		if (p == null || p.length != 1) {
			return null;
		}
		String channel = p[0];
		return ChannelMetadataDAO.getInstance(context).get(channel);
	}

	private void fetchFromServer(Context context,
			final ModelCallback<Void> callback, final String channel) {
		fetchFromServer(context, callback, channel, false);
	}
	
	private void fetchFromServer(Context context,
			final ModelCallback<Void> callback, final String channel, 
			final boolean loPriority) {
		final ChannelMetadataDAO dao = ChannelMetadataDAO.getInstance(context);
		ModelCallback<JSONObject> httpCallback = new ModelCallback<JSONObject>() {
			@Override
			public void success(final JSONObject metadata) {
				JSONObject oldMetadata = dao.get(channel);
				if (oldMetadata != null) {
					updateMetadata(dao, channel, oldMetadata, metadata, callback);
				} else {
					insertMetadata(dao, channel, metadata, callback);
				}
				notifyChanged();
			}
			
			@Override
			public void error(Throwable throwable) {
				if (callback != null) {
					callback.error(throwable);
				}
			}
		};
		
		if (loPriority) {
			BuddycloudHTTPHelper.getObjectInLoPriority(url(context, channel), context, httpCallback);
		} else {
			BuddycloudHTTPHelper.getObject(url(context, channel), context, httpCallback);
		}
	}
	
	private static String url(Context context, String channel) {
		String apiAddress = Preferences.getPreference(context, Preferences.API_ADDRESS);
		return apiAddress + "/" + channel + ENDPOINT;
	}

	@Override
	public void save(final Context context, JSONObject object,
			final ModelCallback<JSONObject> callback, String... p) {
		try {
			StringEntity requestEntity = new StringEntity(object.toString(), "UTF-8");
			requestEntity.setContentType("application/json");
			final String channelJid = p[0];
			BuddycloudHTTPHelper.post(url(context, channelJid), requestEntity, context, new ModelCallback<JSONObject>() {
				@Override
				public void success(final JSONObject metadataUpdated) {
					fetchFromServer(context, new ModelCallback<Void>() {
						@Override
						public void success(Void response) {
							callback.success(metadataUpdated);
						}

						@Override
						public void error(Throwable throwable) {
							callback.error(throwable);
						}
					}, channelJid);
				}
				
				@Override
				public void error(Throwable throwable) {
					callback.error(throwable);
				}
			});
		} catch (Exception e) {
			callback.error(e);
		}
	}

	@Override
	public void getFromServer(Context context, ModelCallback<JSONObject> callback,
			String... p) {
	}

	@Override
	public void fill(Context context, ModelCallback<Void> callback, String... p) {
		fetchFromServer(context, callback, p[0]);
	}

	public void fillInLoPriority(Context context, ModelCallback<Void> callback, String... p) {
		fetchFromServer(context, callback, p[0], true);
	}
	
	@Override
	public void delete(Context context, ModelCallback<Void> callback, String... p) {
		// TODO Auto-generated method stub
		
	}

}