var Kinvey = require('kinvey-node-sdk');
var CacheMiddleware = require('kinvey-node-sdk/dist/export').CacheMiddleware;
var Storage = require('kinvey-node-sdk/dist/export').Storage;
var express = require('express');
var bodyParser = require('body-parser');
var service = express();

// Create a dumb storage adapter that does not actually store any data.
class DumbStorageAdapter {
  find(collection) {
    return Promise.resolve([]);
  }

  findById(collection, id) {
    return Promise.reject(new NotFoundError(`An entity with _id = ${id} was not found in the ${collection}`
            + ` collection on the ${this.name} memory database.`));
  }

  save(collection, entities) {
    return Promise.resolve(entities);
  }

  removeById(collection, id) {
    return Promise.reject(new NotFoundError(`An entity with _id = ${id} was not found in the ${collection}`
            + ` collection on the ${this.name} memory database.`));
  }

  clear() {
    return Promise.resolve(null);
  }

  static load(name) {
    return new DumbStorageAdapter(name);
  }
}

// Create a custom storage class that uses the DumbStorageAdapter
class CustomStorage extends Storage {
  loadAdapter() {
    return Promise.resolve()
      .then(() => DumbStorageAdapter.load(this.name))
      .then((adapter) => {
        if (isDefined(adapter) === false) {
          throw new Error('Unable to load a storage adapter.');
        }

        return adapter;
      });
  }
}

// Create a custom cache middleware that uses the CustomStorage
class CustomCacheMiddleware extends CacheMiddleware {
  loadStorage(name) {
    return new CustomStorage(name);
  }
}

// Update the Kinvey CacheRack with our CustomCacheMiddleware
Kinvey.CacheRack.reset();
Kinvey.CacheRack.use(new CustomCacheMiddleware());

// Setup the service
service.use(bodyParser.json()); // for parsing application/json

// Service endpoints
service.post('/login', function (req, res) {
  Kinvey.User.loginWithMIC(req.body.redirectUri, Kinvey.AuthorizationGrant.AuthorizationCodeAPI, {
    username: req.body.username,
    password: req.body.password
  })
    .then(function(user) {
      res.send(user);
    })
    .catch(function(error) {
      res.status(error.code || 500).send({
        message: error.message,
        debug: error.debug
      });
    })
});

Kinvey.initialize({
  appKey: '<appKey>',
  appSecret: '<appSecret>'
})
  .then(function() {
    // Start the service
    service.listen(3000, function () {
      console.log('Kinvey MIC proxy service is listening on port 3000...')
    });
  })
  .catch(function(error) {
    console.log(error);
  });