module.exports = function(Self) {
    Self.installCrudModel = function(methodName) {
        let Model = this;
        Model.remoteMethod(methodName, {
            description: 'create, update or delete model',
            accessType: 'WRITE',
            accepts: [
                {
                    arg: 'crudStruct',
                    type: 'Object',
                    require: true,
                    description: 'object with instances of model to create, update or delete, Example: {create: [], update: [], delete: []}',
                    http: {source: 'body'}
                }
            ],
            http: {
                path: `/${methodName}`,
                verb: 'post'
            }
        });
        Model[methodName] = async crudStruct => {
            let promises = [];
            let tx = await Model.beginTransaction({});
            let options = {transaction: tx};

            try {
                if (crudStruct.delete && crudStruct.delete.length) {
                    promises.push(Model.destroyAll({id: {inq: crudStruct.delete}}, options));
                }
                if (crudStruct.create.length) {
                    promises.push(Model.create(crudStruct.create, options));
                }
                if (crudStruct.update.length) {
                    crudStruct.update.forEach(toUpdate => {
                        promises.push(Model.upsert(toUpdate, options));
                    });
                }
                await Promise.all(promises);
                await tx.commit();
            } catch (e) {
                await tx.rollback();
                throw Array.isArray(e) ? e[0] : e;
            }
        };
    };
};