var MongoClient = require('mongodb').MongoClient;
var dburl;
let idadd = async (set) => {
    let id = 0
    if (set == "idadd") {
        return 0;
    } else {
        await find('idadd', { 'set': set }).then((res) => {
            if (res.data.length != 0) {
                id = res.data[0].num_key
            } else {
                id = 1
            }
        })
    }

    if (id == 1) {
        await add('idadd', { set, 'num_key': 2 })
    } else if (set != "idadd") {
        console.log(id)

        await update('idadd', { 'set': set }, { 'num_key': id + 1 })
    }
    console.log(id)
    return id

}
let add = async (set, data, url = dburl) => {
    if (set != "idadd") {
        let id = await idadd(set)
        data.num_key = id
    }

    return new Promise((resolve, reject) => {

        MongoClient.connect(url.url, { useUnifiedTopology: true, useNewUrlParser: true }, function (err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            try {
                dbo.collection(set).insertOne(data, function (err, res) {
                    if (err) throw err;
                    db.close();
                    resolve({ code: 0 ,msg:"添加成功"});
                });
            } catch (error) {
                reject({ code: 1, error })
            }

        });
    })
}
let adds = async (set, data, url = dburl) => {

    if (set != "idadd") {
        for (let i in data) {
            let id = await idadd(set)
            data[i].num_key = id
        }
    }
    return new Promise((resolve, reject) => {

        MongoClient.connect(url.url, { useUnifiedTopology: true, useNewUrlParser: true }, function (err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            try {
                dbo.collection(set).insertMany(data, function (err, res) {
                    if (err) throw err;
                    db.close();
                    resolve({ code: 0, num: res.insertedCount });
                });
            } catch (error) {
                reject({ code: 1, error })
            }

        });
    })
}
let remove = async (set, where, url = dburl) => {
    return new Promise((resolve, reject) => {
        MongoClient.connect(url.url, { useUnifiedTopology: true, useNewUrlParser: true }, function (err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            try {
                dbo.collection(set).deleteOne(where, function (err, obj) {
                    if (err) throw err;
                    db.close();
                    resolve({ code: 0 });
                });
            } catch (error) {
                reject({ code: 1, error })
            }

        });
    })
}
let removes = async (set, where, url = dburl) => {
    return new Promise((resolve, reject) => {
        if (where == "" || Object.keys(where).length == 0) {
            reject({ code: 1 })
        }
        MongoClient.connect(url.url, { useUnifiedTopology: true, useNewUrlParser: true }, function (err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            try {
                dbo.collection(set).deleteMany(where, function (err, obj) {
                    if (err) throw err;
                    db.close();
                    resolve({ code: 0, num: obj.result.n });
                });
            } catch (error) {
                reject({ code: 1, error })
            }

        });
    })
}
let find = async (set, where = {}, page = 0, num = 0, url = dburl) => {
    return new Promise((resolve, reject) => {
        if (num == 0) {
            MongoClient.connect(url.url, { useUnifiedTopology: true, useNewUrlParser: true }, function (err, db) {
                if (err) throw err;
                var dbo = db.db(url.dbname);
                try {
                    dbo.collection(set).find(where).toArray(function (err, result) {
                        if (err) throw err;
                        resolve({ code: 0, data: result });
                        db.close();
                    });
                } catch (error) {
                    reject({ code: 1, error })
                }

            });
        } else {
            MongoClient.connect(url.url, { useUnifiedTopology: true, useNewUrlParser: true }, function (err, db) {
                if (err) throw err;
                var dbo = db.db(url.dbname);
                try {
                    dbo.collection(set).find(where).skip(num * page).limit(num).toArray(function (err, result) {
                        if (err) throw err;
                        resolve({ code: 0, data: result });
                        db.close();
                    });
                } catch (error) {
                    reject({ code: 1, error })
                }

            });
        }

    })
}
let update = async (set, where = {}, data, defin = true, url = dburl) => {
    return new Promise((resolve, reject) => {
        MongoClient.connect(url.url, { useUnifiedTopology: true, useNewUrlParser: true }, function (err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            if (defin) {
                data = { $set: data }
            }
            try {
                dbo.collection(set).updateOne(where, data, function (err, res) {
                    if (err) throw err;
                    resolve({ code: 0 });
                    db.close();
                });
            } catch (error) {
                reject({ code: 1, error })
            }

        });
    })
}
let updates = async (set, where = {}, data, url = dburl) => {
    return new Promise((resolve, reject) => {
        MongoClient.connect(url.url, { useUnifiedTopology: true, useNewUrlParser: true }, function (err, db) {
            if (err) throw err;
            var dbo = db.db(url.dbname);
            data = { $set: data }
            try {
                dbo.collection(set).updateMany(where, data, function (err, res) {
                    if (err) throw err;
                    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
    }
}