module.exports = function(self) {
    self.setup = function() {
        self.super_.setup.call(this);

        let disableMethods = {
            create: true,
            replaceOrCreate: true,
            patchOrCreate: true,
            upsert: true,
            updateOrCreate: true,
            exists: true,
            find: true,
            findOne: true,
            findById: true,
            deleteById: true,
            replaceById: true,
            updateAttributes: false,
            createChangeStream: true,
            updateAll: true,
            upsertWithWhere: true,
            count: true
        };
        for (let method in disableMethods) {
            //this.disableRemoteMethod(method, disableMethods[method]);
        }
    };

    self.defineScope = function(serverFilter) {
        this.remoteMethodCtx('list', {
            accepts: [
                {
                    arg: 'filter',
                    type: 'object',
                    description: 'Filter defining where'
                }
            ],
            returns: {
                type: [this.modelName],
                root: true
            },
            http: {
                verb: 'get',
                path: '/list'
            }
        });

        this.list = function(ctx, clientFilter, cb) {
            var clientFields = (clientFilter && clientFilter.fields) ? clientFilter.fields : [];
            var serverFields = (serverFilter && serverFilter.fields) ? serverFilter.fields : [];
            var fields = clientFields.filter(itemC => {
                return serverFields.some(itemS => itemS === itemC);
            });
            
            var and = [];
            (clientFilter && clientFilter.where) && and.push(clientFilter.where);
            (serverFilter && serverFilter.where) && and.push(serverFilter.where);
            
            var order;
            var limit;
            
            if (clientFilter && clientFilter.order)
                order = clientFilter.order;
            else if (serverFilter && serverFilter.order)
                order = serverFilter.order;

            if (serverFilter && serverFilter.limit)
                limit = serverFilter.limit;
            else if (clientFilter && clientFilter.limit)
                limit = clientFilter.limit;

            var filter = {order: order, limit: limit};
            filter.where = (and.length > 0) && {and: and};
            filter.fields = fields;

            this.find(filter, function(err, states) {
                (err) ? cb(err, null) : cb(null, states);
            });
        };
    };

    self.rawSql = function(query, params, cb) {
        this.dataSource.connector.execute(query, params, function(error, response) {
            cb(error, response);
        });
    };

    self.remoteMethodCtx = function(methodName, args) {
        if (args.accepts !== undefined && Array.isArray(args.accepts)) {
            var ctx = {
                arg: 'context',
                type: 'object',
                http: function(ctx) {
                    return ctx;
                }
            };
            args.accepts.unshift(ctx);
        }
        this.remoteMethod(methodName, args);
    };

    self.connectToService = function(ctx, dataSource) {
        this.app.dataSources[dataSource].connector.remotes.auth = {
            bearer: new Buffer(ctx.req.accessToken.id).toString('base64'),
            sendImmediately: true
        };
    };

    self.disconnectFromService = function(dataSource) {
        this.app.dataSources[dataSource].connector.remotes.auth = {
            bearer: new Buffer("").toString('base64'),
            sendImmediately: true
        };
    };

    self.installMethod = function(methodName, filterCb) {
        this.remoteMethod(methodName, {
            description: 'List items using a filter',
            accessType: 'READ',
            accepts: [
                {
                    arg: 'filter',
                    type: 'object',
                    required: true,
                    description: 'Filter defining where',
                    http: function(ctx) {
                        return ctx.req.query;
                    }
                }
            ],
            returns: {
                arg: 'data',
                type: [this.modelName],
                root: true
            },
            http: {
                verb: 'get',
                path: `/${methodName}`
            }
        });

        this[methodName] = (params, cb) => {
            let filter = removeEmpty(filterCb(params));
            var response = {};

            function returnValues() {
                if (response.instances !== undefined && response.count !== undefined)
                    cb(null, response);
            }

            function error() {
                cb(null, response);
            }

            this.find(filter, function(err, instances) {
                if (err) {
                    error();
                } else {
                    response.instances = instances;
                    returnValues();
                }
            });
            this.count(filter.where, function(err, totalCount){
                if (err) {
                    error();
                } else {
                    response.count = totalCount;
                    returnValues();
                }
            });
        };
    };
};
function removeEmpty(o) {
    if (Array.isArray(o)) {
        let array = [];
        for (let item of o) {
            let i = removeEmpty(item);
            if (!isEmpty(item))
                array.push(item);
        }
        if (array.length > 0)
            return array;
    } else if (typeof o === 'object') {
        let object = {};
        for (let key in o) {
            let i = removeEmpty(o[key]);
            if (!isEmpty(i))
                object[key] = i;
        }
        if (Object.keys(object).length > 0)
            return object;
    } else if (!isEmpty(o))
        return o;

    return undefined;
}

function isEmpty(value) {
    return value === undefined || value === "";
}