MapDataProvider.java

package edu.purdue.app.map;

import edu.purdue.app.map.MapData.Building;
import android.app.SearchManager;
import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.net.Uri;
import android.util.Log;

/** Content Provider which interfaces with MapData for its data. 
 *  This only exists because Android demands a ContentProvider to provide dropdown box
 *  search suggestions. This only supports the Query method; update/delete do nothing as 
 *  we are reading data from a JSON file. Also, this provider won't work outside of Purdue App, 
 *  as it needs to access Purdue App's resources. 
 */
public class MapDataProvider extends ContentProvider {

	/** Strings for constructing URIs */
	private static final String AUTH = "content://edu.purdue.app.map.MapDataProvider";
	private static final String BUILDINGS_PATH = "buildings";
	private static final String BIKERACKS_PATH = "bikeracks";
	
	/** Publicly accessible URIs */
	public static final Uri BUILDINGS_URI = Uri.parse(AUTH + "/" + BUILDINGS_PATH);
	public static final Uri BIKERACKS_URI = Uri.parse(AUTH + "/" + BIKERACKS_PATH);
	
	/** Column names for the returned cursor */
	public static final String _ID = "_ID";
	public static final String FULL_NAME = "FULL_NAME";
	public static final String SHORT_NAME = "SHORT_NAME";
	
	/** Class members */
	MapData data;
	
	@Override
	public boolean onCreate() {
		data = null;
		return true;
	}

	@Override
	public String getType(Uri arg0) {
		return null;
	}
	
	/** Query data from the MapDataProvider.
	 *  uri : one of the URIs statically defined in this class (BUILDINGS_URI, BIKE_RACKS_URI, etc)
	 *  projection : unused
	 *  selection : unused
	 *  selection_args : unused
	 *  sortorder : unused
	 *  Wow, we really use the full power of this class, don't we?
	 *  
	 *  Returns a cursor to the data requested. Each row of the cursor is formatted as such:
	 *  	_ID (int)	SHORT_NAME (string) 	FULL_NAME (string)
	 *  With the types you'd expect for each.
	 */
	public Cursor query(Uri uri, String[] projection, String selection, String[] selection_args, String sortorder) {
		
		Log.d(MapActivity.LOG_MAP_TAG, "MapDataProvider query with uri: " + uri.toString());
		data = new MapData(getContext());
		
		// Determine which type of data the user requested.
		// For some reason I can't get the default UriMatcher class to work. Probably my fault. So this is more manual.
		String path = uri.getPathSegments().get(0);
		if (path.equals(BUILDINGS_PATH)) {
			return constructCursorBuildings();
		}
		else if (path.equals(SearchManager.SUGGEST_URI_PATH_QUERY)) {
			// This request is coming from our search box.
			String query = uri.getLastPathSegment().toLowerCase();
			return constructCursorBuildingsSearch(query);
		}
		
		return null;
	}

	/** Constructs and returns the cursor for all buildings recognized by the app */
	private MatrixCursor constructCursorBuildings() {
		MatrixCursor c = new MatrixCursor(new String[]{_ID, FULL_NAME, SHORT_NAME});
		int id = 0;
		for (Building loc : data.getBuildings()) {
			c.newRow().add(id++).add(loc.full_name).add(loc.short_name);
		}
		return c;
	}
	
	/** Constructs and returns the cursor for buildings which somehow match the query given as input */
	private Cursor constructCursorBuildingsSearch(String query) {
		MatrixCursor c = new MatrixCursor(new String[]{"_ID", SearchManager.SUGGEST_COLUMN_TEXT_1, 
				SearchManager.SUGGEST_COLUMN_TEXT_2, SearchManager.SUGGEST_COLUMN_INTENT_DATA});
		int id = 0;
		
		for (Building loc : data.getBuildings()) {
			if (loc.full_name.toLowerCase().contains(query) || loc.short_name.toLowerCase().contains(query)) {
				c.newRow().add(id).add(loc.short_name).add(loc.full_name).add(loc.full_name);
			}
		}
		
		return c;
	}
	
	/** The update operating is not currently supported for this Provider, as the data is sourced from
	 *  JSON files. As such, this method does nothing. */
	public int update(Uri arg0, ContentValues arg1, String arg2, String[] arg3) {
		return -1;
	}
	
	/** The insert operation is not currently supported for this Provider, as it is all sourced from
	 *  JSON files. As such, this method does nothing. */
	public Uri insert(Uri arg0, ContentValues arg1) {
		return null;
	}
	
	/** The delete operation is not currently supported for this Provider, as it is all sourced from
	 *  JSON files. As such, this method does nothing. */
	public int delete(Uri arg0, String arg1, String[] arg2) {
		return -1;
	}

}