/**

* Created by chaoningx on 2017/2/27.

*/

const config = require('../../config');

const utils = require('../common/utils');

class DB {

constructor(collectionName) {

this.collection = config.mongodb.dbInstance.collection(collectionName);

this.doc = {};

}

assgin(info) {

return utils.merge(Object.assign({}, this.doc), info);

}

pagination(query, page, pageSize, callback, sortFields, fieldsNeed) {

let collection = this.collection;

collection.count(query, function(err, count) {

if(err) {

callback && callback(err);

return false;

}

let cursor = collection.find(query, fieldsNeed || {});

page = page * 1 || 1;

pageSize = pageSize * 1 || 10;

cursor.sort(sortFields);

cursor.skip(page ? ((page - 1) * pageSize) : (0 * pageSize));

cursor = cursor.limit(pageSize * 1);

cursor.toArray(function(err, items) {

if(err) {

callback && callback(err);

return false;

}

let pageCount = ((count / pageSize) | 0) + (count % pageSize ? 1 : 0);

page = page > pageCount ? pageCount : page;

let rs = { docs: items, page: page, pages: pageCount, limit: pageSize, total: count };

callback && callback(null, rs);

});

});

}

}

module.exports = DB;