(function() {
var tagStore = 'tags';
define(
['db', 'reference'], function(db, reference) {
    return {
        Capable: function() {
            return db.Capable();
        },
        // UpdateTags updates a given references tags asynchronously.
        // ref should be a Reference object.
        // tags should be a list of strings representing the tags for this
        // reference.
        // callbacks.success is expected to be a function that takes
        // an IDBRequest as an argument.
        // callbacks.error is expected to be a function that takes
        // an IDBRequest as an argument.
        UpdateTags: function(ref, tags, callbacks) {
            db.Capable() && db.Transaction(
                [tagStore], function(trans) {
                    db.Update(
                        'tags', ref.toString(),
                        {tagList: tags, Ref: ref.toDict()},
                        callbacks, trans);
                }, 'readwrite');
        },
        // GetTags retrieves a given references tags asynchronously.
        // ref should be a Reference object.
        // callbacks.success is expected to be a function that takes
        // the list of tags as an argument.
        // callbacks.error is expected to be a function that takes
        // an IDBRequest as an argument.
        GetTags: function(ref, callbacks) {
            db.Capable() && db.Get(tagStore, ref.toString(),
                   {success: function(req) {
                        var data = req.target.result;
                        // TODO suppport book and chapter indexes for
                        // range lookups.
                        callbacks.success(data);
                    }});
        },
        GetVersesForTag: function() {
            console.log('TODO(jwall): Implement GetVersesForTag');
        },
        // Sync retrieves a given references tags asynchronously.
        // url should be a valid http URL to the service to sync the tags
        // to.
        // callbacks
        Sync: function(url, callbacks) {
            console.log('TODO(jwall): Implement Sync');
        }
    };
});
})();