GoodsContentProvider

public class GoodsContentProvider extends ContentProvider {

    private DbHelper dbHelper;
    private static final int GOODS = 1;
    private static final int GOODS_GOOD = 2;
    //--
    private static final int CATEGORIES = 7;
    private static final int CATEGORIES_CATEGORY = 8;
    //-

    private static final UriMatcher URI_MATCHER = new UriMatcher(UriMatcher.NO_MATCH);

    static {
        URI_MATCHER.addURI(GoodsEntity.AUTHORITY, GoodsEntity.TABLE_NAME, GOODS);
        URI_MATCHER.addURI(GoodsEntity.AUTHORITY, GoodsEntity.TABLE_NAME + "/#", GOODS_GOOD);
        URI_MATCHER.addURI(GoodsEntity.AUTHORITY, CategoryEntity.TABLE_NAME, CATEGORIES);
        URI_MATCHER.addURI(GoodsEntity.AUTHORITY, CategoryEntity.TABLE_NAME + "/#", CATEGORIES_CATEGORY);
    }

    @Override
    public boolean onCreate() {
        dbHelper = new DbHelper(getContext());
        return true;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
        String selectionToAppend = "";
        String tableName;
        String query = "";
        switch (URI_MATCHER.match(uri)) {
            case GOODS:
                tableName = GoodsEntity.TABLE_NAME;
                break;
            case GOODS_GOOD:
                tableName = GoodsEntity.TABLE_NAME;
                selectionToAppend = GoodsEntity._ID + " = " + uri.getLastPathSegment();
                break;
            default:
                throw new IllegalArgumentException("Wrong uri");
        }
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        Cursor c= db.query(tableName, projection, appendSelections(selection, selectionToAppend), selectionArgs, null, null, sortOrder);
        c.setNotificationUri(getContext().getContentResolver(), uri);
        return c;
    }


    @Override
    public String getType(Uri uri) {
        String result;
        switch (URI_MATCHER.match(uri)) {
            case GOODS:
                result = "vnd.android.cursor.dir/com.krepchenko.yourshoppinglist.provider." + GoodsEntity.TABLE_NAME;
                break;
            case GOODS_GOOD:
                result = "vnd.android.cursor.item/com.krepchenko.yourshoppinglist.provider." + GoodsEntity.TABLE_NAME;
                break;
            case CATEGORIES:
                result = "vnd.android.cursor.dir/com.krepchenko.yourshoppinglist.provider." + CategoryEntity.TABLE_NAME;
                break;
            case CATEGORIES_CATEGORY:
                result = "vnd.android.cursor.item/com.krepchenko.yourshoppinglist.provider." + CategoryEntity.TABLE_NAME;
                break;
            default:
                throw new IllegalArgumentException();
        }
        return result;
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        long result;
        String tableName;
        switch (URI_MATCHER.match(uri)) {
            case GOODS:
                tableName = GoodsEntity.TABLE_NAME;
                break;
            case CATEGORIES:
                tableName = CategoryEntity.TABLE_NAME;
                break;
            default:
                throw new IllegalArgumentException();
        }
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        result = db.insert(tableName, null, values);
        getContext().getContentResolver().notifyChange(uri, null);
        return Uri.withAppendedPath(uri, String.valueOf(result));
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        String tableName;
        String selectionToAppend = "";
        switch (URI_MATCHER.match(uri)) {
            case GOODS:
                tableName = GoodsEntity.TABLE_NAME;
                break;
            case GOODS_GOOD:
                tableName = GoodsEntity.TABLE_NAME;
                selectionToAppend = GoodsEntity._ID + " = " + uri.getLastPathSegment();
                break;
            case CATEGORIES:
                tableName = CategoryEntity.TABLE_NAME;
                break;
            case CATEGORIES_CATEGORY:
                tableName = CategoryEntity.TABLE_NAME;
                selectionToAppend = CategoryEntity._ID + " = " + uri.getLastPathSegment();
                break;
            default:
                throw new IllegalArgumentException();
        }
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        int affected = db.delete(tableName, appendSelections(selection, selectionToAppend), selectionArgs);
        if (affected > 0) {
            getContext().getContentResolver().notifyChange(uri, null);
        }
        return affected;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        String tableName;
        String selectionToAppend = "";
        switch (URI_MATCHER.match(uri)) {
            case GOODS:
                tableName = GoodsEntity.TABLE_NAME;
                break;
            case GOODS_GOOD:
                tableName = GoodsEntity.TABLE_NAME;
                selectionToAppend = GoodsEntity._ID + " = " + uri.getLastPathSegment();
                break;
            case CATEGORIES:
                tableName = CategoryEntity.TABLE_NAME;
                break;
            case CATEGORIES_CATEGORY:
                tableName = CategoryEntity.TABLE_NAME;
                selectionToAppend = CategoryEntity._ID + " = " + uri.getLastPathSegment();
                break;
            default:
                throw new IllegalArgumentException();
        }
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        int affected = db.update(tableName, values, appendSelections(selection, selectionToAppend), selectionArgs);
        if (affected > 0) {
            getContext().getContentResolver().notifyChange(uri, null);
        }
        return affected;
    }

    private static String appendSelections(String baseSelection, String selectionToAppend) {
        if (!TextUtils.isEmpty(selectionToAppend)) {
            if (!TextUtils.isEmpty(baseSelection)) {
                baseSelection = " ( " + baseSelection + " ) AND " + selectionToAppend;
            } else {
                baseSelection = selectionToAppend;
            }
        }
        return baseSelection;
    }

}