var MongoClient = require('mongodb').MongoClient;
var dburl;
let add = (set,data,url = dburl) =>{
    return new Promise((resolve, reject) => {
        MongoClient.connect(url.url, { useNewUrlParser: true }, function(err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            // var myobj = { name: "菜鸟教程", url: "www.runoob" };
            try {
                dbo.collection(set).insertOne(data, function(err, res) {
                    if (err) throw err;
                    // console.log("文档插入成功");
                    db.close();
                    resolve({code:0});
                });
            } catch (error) {
                reject({code:1,error})
            }
            
        });
    })
}
let adds = (set,data,url = dburl) =>{
    return new Promise((resolve, reject) => {
        MongoClient.connect(url.url, { useNewUrlParser: true }, function(err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            // var myobj = { name: "菜鸟教程", url: "www.runoob" };
            try {
                dbo.collection(set).insertMany(data, function(err, res) {
                    if (err) throw err;
                    // console.log("文档插入成功");
                    db.close();
                    resolve({code:0,num:res.insertedCount});
                });
            } catch (error) {
                reject({code:1,error})
            }
            
        });
    })
}
let remove = (set,where,url = dburl) =>{
    return new Promise((resolve, reject) => {
        MongoClient.connect(url.url, { useNewUrlParser: true }, function(err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            // var myobj = { name: "菜鸟教程", url: "www.runoob" };
            try {
                dbo.collection(set).deleteOne(where, function(err, obj) {
                    if (err) throw err;
                    // console.log("文档插入成功");
                    db.close();
                    resolve({code:0});
                });
            } catch (error) {
                reject({code:1,error})
            }
            
        });
    })
}
let removes = (set,where,url = dburl) =>{
    return new Promise((resolve, reject) => {
        MongoClient.connect(url.url, { useNewUrlParser: true }, function(err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            // var myobj = { name: "菜鸟教程", url: "www.runoob" };
            try {
                dbo.collection(set).deleteMany(where, function(err, obj) {
                    if (err) throw err;
                    // console.log("文档插入成功");
                    db.close();
                    resolve({code:0,num:obj.result.n});
                });
            } catch (error) {
                reject({code:1,error})
            }
            
        });
    })
}
let find = (set,where = {},page = 0,num = 0,url = dburl) =>{
    return new Promise((resolve, reject) => {
        if(num == 0){
            MongoClient.connect(url.url, { useNewUrlParser: true }, function(err, db) {
                if (err) throw err;
                var dbo = db.db(url.dbname);
                // var myobj = { name: "菜鸟教程", url: "www.runoob" };
                try {
                    dbo.collection(set). find(where).toArray(function(err, result) { // 返回集合中所有数据
                        if (err) throw err;
                        // console.log(result);
                        resolve({code:0,data:result});
                        db.close();
                    });
                } catch (error) {
                    reject({code:1,error})
                }
                
            });
        }else{
            MongoClient.connect(url.url, { useNewUrlParser: true }, function(err, db) {
                if (err) throw err;
                var dbo = db.db(url.dbname);
                // var myobj = { name: "菜鸟教程", url: "www.runoob" };
                try {
                    dbo.collection(set). find(where).skip(num * page).limit(num).toArray(function(err, result) { // 返回集合中所有数据
                        if (err) throw err;
                        // console.log(result);
                        resolve({code:0,data:result});
                        db.close();
                    });
                } catch (error) {
                    reject({code:1,error})
                }
                
            });
        }
        
    })
}
let update = (set,where = {},data,url = dburl) =>{
    return new Promise((resolve, reject) => {
        MongoClient.connect(url.url, { useNewUrlParser: true }, function(err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            // var myobj = { name: "菜鸟教程", url: "www.runoob" };
            data = {$set:data}
            try {
                dbo.collection(set).updateOne(where, data, function(err, res) {
                    if (err) throw err;
                    // console.log(result);
                    resolve({code:0});
                    db.close();
                });
            } catch (error) {
                reject({code:1,error})
            }
            
        });
    })
}
let updates = (set,where = {},data,url = dburl) =>{
    return new Promise((resolve, reject) => {
        MongoClient.connect(url.url, { useNewUrlParser: true }, function(err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            // var myobj = { name: "菜鸟教程", url: "www.runoob" };
            data = {$set:data}
            try {
                dbo.collection(set).updateMany(where, data, function(err, res) {
                    if (err) throw err;
                    // console.log("文档插入成功");
                    db.close();
                    resolve({code:0,num:res.result.nModified});
                });
            } catch (error) {
                reject({code:1,error})
            }
            
        });
    })
}

module.exports = function (url,dbname){
    dburl = {url,dbname};
    return{
        add,
        adds,
        remove,
        find,
        update,
        updates,
        removes
    }
}