UserSchema.statics.findByCredentials = function (email, password) {
  var User = this;

  return User.findOne({email}).then((user) => {
    if (!user) {
      return Promise.reject();
    }

    return new Promise((resolve, reject) => {
      // Use bcrypt.compare to compare password and user.password
      bcrypt.compare(password, user.password, (err, res) => {
        if (res) {
          resolve(user);
        } else {
          reject();
        }
      });
    });
  });
};

// POST /users/login {email, password}
app.post('/users/login', (req, res) => {
  var body = _.pick(req.body, ['email', 'password']);

  User.findByCredentials(body.email, body.password).then((user) => {
    return user.generateAuthToken().then((token) => {
      res.header('x-auth', token).send(user);
    });
  }).catch((e) => {
    res.status(400).send();
  });
});

var mongoose = require('mongoose');
var express = require('express');
var bodyParser = require('body-parser');
const {ObjectID} = require('mongodb');
var _ = require('lodash');

const validator = require('validator');


const jwt = require('jsonwebtoken');
const bcrypt = require('bcryptjs');
//app
var app = express();
const port = process.env.PORT || 3000;
//express middleware  Jonson對象與字符串轉換。
app.use(bodyParser.json());

//
mongoose.Promise = global.Promise;
//連接mogodb
mongoose.connect(process.env.MONGODB_URI || 'mongodb://localhost:27017/TodoApp');

//模版
var Todo = mongoose.model('Todo',{
    text:{
      type:String,  //類型
      required:true, //必須要有
      minlength:1, //最小長度
      trim:true   //去除空格
    },
    completed:{
      type:Boolean,
      default:false  //默認值
    },
    completedAt:{
      type:Number,
      default:null
    }
});

var UserSchema = new mongoose.Schema({
  email: {
    type: String,
    required: true,
    trim: true,
    minlength: 1,
    unique: true,
    validate: {
      validator: validator.isEmail,
      message: '{VALUE} is not a valid email'
    }
  },
  password: {
    type: String,
    require: true,
    minlength: 6
  },
  tokens: [{
    access: {
      type: String,
      required: true
    },
    token: {
      type: String,
      required: true
    }
  }]
});

UserSchema.methods.toJSON = function () {
  var user = this;
  var userObject = user.toObject();

  return _.pick(userObject, ['_id', 'email']);
};

UserSchema.methods.generateAuthToken = function () {
  var user = this;
  var access = 'auth';
  var token = jwt.sign({_id: user._id.toHexString(), access}, 'abc123').toString();

  user.tokens = user.tokens.concat([{access,token}]);

  return user.save().then(() => {
    return token;  //返回token
  });
};


UserSchema.statics.findByToken = function (token) {
  var User = this;
  var decoded;

  try {
    decoded = jwt.verify(token, 'abc123');
  } catch (e) {
    return Promise.reject();
  }

  return User.findOne({
    '_id': decoded._id,
    'tokens.token': token,
    'tokens.access': 'auth'
  });
};


UserSchema.statics.findByCredentials = function (email, password) {
  var User = this;

  return User.findOne({email}).then((user) => {
    if (!user) {
      return Promise.reject();
    }

    return new Promise((resolve, reject) => {
      // Use bcrypt.compare to compare password and user.password
      bcrypt.compare(password, user.password, (err, res) => {
        if (res) {
          resolve(user);
        } else {
          reject();
        }
      });
    });
  });
};

//在保存之前執行操作。
UserSchema.pre('save', function (next) {
  var user = this;

//保存時對于密碼的更新
  if (user.isModified('password')) {
    bcrypt.genSalt(10, (err, salt) => {
      //密碼變為了hash
      bcrypt.hash(user.password, salt, (err, hash) => {
        user.password = hash;
        next();
      });
    });
  } else {
    next();
  }
});

var User = mongoose.model('User', UserSchema);

//auth middlewire

var authenticate = (req, res, next) => {
  var token = req.header('x-auth');

  User.findByToken(token).then((user) => {
    if (!user) {
      return Promise.reject();
    }

    req.user = user;
    req.token = token;
    next();
  }).catch((e) => {
    res.status(401).send();
  });
};



app.get('/users/me', authenticate, (req, res) => {
  res.send(req.user);
});

// POST /users/login {email, password}
app.post('/users/login', (req, res) => {
  var body = _.pick(req.body, ['email', 'password']);

  User.findByCredentials(body.email, body.password).then((user) => {
    return user.generateAuthToken().then((token) => {
      res.header('x-auth', token).send(user);
    });
  }).catch((e) => {
    res.status(400).send();
  });
});

// POST /users
app.post('/users', (req, res) => {
  var body = _.pick(req.body, ['email', 'password']);
  var user = new User(body);

  user.save().then(() => {
    return user.generateAuthToken(); //調用方法，產生auth token并保存。
  }).then((token) => {
    res.header('x-auth', token).send(user); //設置了響應頭
  }).catch((e) => {
    res.status(400).send(e);
  })
});

//express route
app.post('/todos',(req,res)=>{
//  console.log(req.body);

    //建立對象document
    var todo = new Todo({
        text:req.body.text
    });
    //保存
      todo.save().then((doc)=>{
      res.send(doc);
    },(e)=>{
        res.status(400).send(e);
    });

})
//獲取所有屬性

app.get('/todos', (req, res) => {
  Todo.find().then((todos) => {
    res.send({todos});
  }, (e) => {
    res.status(400).send(e);
  })
});


//查詢id
app.get('/todos/:id', (req, res) => {
  var id = req.params.id;

  if (!ObjectID.isValid(id)) {
    return res.status(404).send();
  }

  Todo.findById(id).then((todo) => {
    if (!todo) {
      return res.status(404).send();
    }

    res.send({todo});
  }).catch((e) => {
    res.status(400).send();
  });
});


//刪除
app.delete('/todos/:id', (req, res) => {
  var id = req.params.id;

  if (!ObjectID.isValid(id)) {
    return res.status(404).send();
  }

  Todo.findByIdAndRemove(id).then((todo) => {
    if (!todo) {
      return res.status(404).send();
    }

    res.send({todo});
  }).catch((e) => {
    res.status(400).send();
  });
});

//更新
app.patch('/todos/:id', (req, res) => {
  var id = req.params.id;
  var body = _.pick(req.body, ['text', 'completed']);

  if (!ObjectID.isValid(id)) {
    return res.status(404).send();
  }

  if (_.isBoolean(body.completed) && body.completed) {
    body.completedAt = new Date().getTime();
  } else {
    body.completed = false;
    body.completedAt = null;
  }

  Todo.findByIdAndUpdate(id, {$set: body}, {new: true}).then((todo) => {
    if (!todo) {
      return res.status(404).send();
    }

    res.send({todo});
  }).catch((e) => {
    res.status(400).send();
  })
});




//監聽
app.listen(port,()=>{
    console.log(`Start on port ${port}`);
});
module.exports = {
   app,
   Todo
}

1、打開mongoDB > ./mongod -dbpath /Users/jackson/Downloads/mongodb-data
2、運行 >node postman.js
3、打開postman 選擇post 輸入 >localhost:3000/users  保存user
Body中填入：
{
	"email": "zhuimengshaonian07@gmail.com",
	"password" : "123abc!"
}
返回：
{
    "_id": "5bfe716591e78c6a4ad8c164",
    "email": "zhuimengshaonian07@gmail.com"
}

header:
x-auth →eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJfaWQiOiI1YmZlNzE2NTkxZTc4YzZhNGFkOGMxNjQiLCJhY2Nlc3MiOiJhdXRoIiwiaWF0IjoxNTQzNDAxODI5fQ.wOKNzkls_w_jA5YVkCo0r9gFZ4-KtD6GarRiCDpAPr8

4、 選擇post 輸入 >localhost:3000/login   登陸user
Body中填入：
{
	"email": "zhuimengshaonian07@gmail.com",
	"password" : "123abc!"
}
返回：
{
    "_id": "5bfe716591e78c6a4ad8c164",
    "email": "zhuimengshaonian07@gmail.com"
}

header附帶返回：
x-auth →eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJfaWQiOiI1YmZlNzE2NTkxZTc4YzZhNGFkOGMxNjQiLCJhY2Nlc3MiOiJhdXRoIiwiaWF0IjoxNTQzNDAxODI5fQ.wOKNzkls_w_jA5YVkCo0r9gFZ4-KtD6GarRiCDpAPr8