/**
 * @module RESTController
 *
 * RESTController for MongoDB.
 */
import * as debugStuff from 'debug'
const debug = debugStuff.debug('dbApiRESTCtrl')
import mongoose from 'mongoose'
mongoose.Promise = Promise
import { Router } from 'express'

const MAX_RESULTS = 100

/**
 * REST controller for MongoDB backend.
 */
class RESTController {
  /**
   * Generates a controller for a model type.
   *
   * @param  {mongoose.Model} mongoose model to use
   * @param  {key} Key to use as index. Default is '_id'
   * @return {null}
   */
  constructor (model, key = '_id') {
    this.model = model
    this.modelName = model.modelName.toLowerCase()
    this.key = key
  }

  /**
   * Creates a DB item.
   *
   * @param  {object} data object
   * @return {null}
   */
  create (data) {
    return this.model
      .create(data)
      .then(instance => {
        const response = {}
        response[this.modelName] = instance
        return response
      })
  }

  read (id) {
    const filter = {}
    filter[this.key] = id
    return this.model
      .findOne(filter)
      .then(instance => {
        const response = {}
        response[this.modelName] = instance
        return response
      })
  }

  list () {
    return this.model
      .find({})
      .limit(MAX_RESULTS)
      .then(instance => {
        const response = {}
        response[this.modelName] = instance
        return response
      })
  }

  update (id, data) {
    const filter = {}
    filter[this.key] = id

    return this.model
      .findOne(filter)
      .then(instance => {
        console.log(instance)
        for (let attribute in data) {
          if (data.hasOwnProperty(attribute) && attribute !== this.key && attribute !== '_id') {
            instance[attribute] = data[attribute]
          }
        }
        return instance.save()
      })
      .then(instance => {
        const response = {}
        response[this.modelName] = instance
        return response
      })
  }

  delete (id) {
    const filter = {}
    filter[this.key] = id

    return this.model
      .remove(filter)
      .then(() => {
        return {}
      })
  }

  route () {
    const router = new Router()

    router.get('/', (req, res) => {
      this
        .list()
        .then(data => res.json(data))
        .then(null, error => res.status(404).send(error))
    })

    router.post('/', (req, res) => {
      this
        .create(req.body)
        .then(data => res.json(data))
        .then(null, error => res.status(404).send(error))
    })

    router.get('/:key', (req, res) => {
      this
        .read(req.params.key)
        .then(data => res.json(data))
        .then(null, error => res.status(404).send(error))
    })

    router.put('/:key', (req, res) => {
      this
        .update(req.params.key, req.body)
        .then(data => res.json(data))
        .then(null, error => res.status(404).send(error))
    })

    router.delete('/:key', (req, res) => {
      this
        .delete(req.params.key)
        .then(data => res.json(data))
        .then(null, error => res.status(404).send(error))
    })

    return router
  }
}

debug('Defined RESTController')
export default RESTController