// CRUD create read update delete
// const mongodb = require("mongodb");
// const mongoClient = mongodb.MongoClient;
// const objectId = mongodb.ObjectId;
// 把上面destructure
const { MongoClient, ObjectID } = require("mongodb");
const id = new ObjectID();
console.log(id.id);
console.log(id.id.length);
console.log(id.toHexString().length);
console.log(id.getTimestamp());
const connectionURL = "mongodb://127.0.0.1:27017";
const databaseName = "task-manager";
let Tasks = class {
  constructor(taskName, description, ifcomplete) {
    this.taskName = taskName;
    this.description = description;
    this.completed = ifcomplete;
  }
};
function convertToJSON(task) {
  const taskString = JSON.stringify(task);
  return JSON.parse(taskString);
}
MongoClient.connect(
  connectionURL,
  { useNewUrlParser: true },
  (error, client) => {
    if (error) {
      return console.log("unable to connect to database");
    }
    console.log("connected successfully");
    const db = client.db(databaseName);
    // find
    db.collection("tasks").findOne(
      { _id: new ObjectID("5c8cb2820b211d6508f36cab") },
      (error, task) => {
        if (error) {
          return console.log("Unable to fetch");
        }
        console.log(task);
      }
    );
    db.collection("tasks")
      .find({ completed: "false" })
      .toArray((error, uncompletedTasks) => {
        console.log(uncompletedTasks);
      });
  }
  // update
   db.collection("tasks")
      .updateMany(
        {
          completed: "true"
        },
        {
          $set: {
            completed: true
          }
        }
      )
      .then(result => {
        console.log(result.modifiedCount);
      })
      .catch(error => {
        console.log(error);
      });
  // delete
  db.collection("user")
      .deleteMany({
        age: 24
      })
      .then(result => {
        console.log(result);
      })
      .catch(error => {
        console.log(error);
      });
    db.collection("user")
      .deleteOne({
        name: "Kevin"
      })
      .then(result => {
        console.log(result);
      })
      .catch(error => {
        console.log(error);
      });


);