import { Deserializer, Serializer } from '../core/storage'

const CREATED = 201
const NO_CONTENT = 204
const NOT_FOUND = 404
const GONE = 410

export default class RemoteStorage<U, T> {
  constructor(
    private readonly baseUrl: string,
    private readonly getItemId = item => item['id'],
    private readonly serializers: Map<string, Serializer> = new Map([
      ['*/*', JSON.stringify],
      ['application/json', JSON.stringify],
      ['text/json', JSON.stringify],
    ]),
    private readonly deserializers: Map<string, Deserializer> = new Map([
      ['*/*', JSON.parse],
      ['application/json', JSON.parse],
      ['text/json', JSON.parse],
    ]),
  ) {}

  async getCollection(collectionId: string) {
    const response = await window.fetch([this.baseUrl, collectionId].join('/'))
    const contentType = response.headers.get('content-type')
    const { [contentType]: deserializer = this.deserializers.get('*/*'), } = Object.fromEntries(this.deserializers.entries())
    const payload = await response.text()
    return deserializer(payload)
  }

  async setItem(collectionId: string, item: U, contentType = 'application/json') {
    const { [contentType]: serializer = this.serializers.get('application/json'), } = Object.fromEntries(this.serializers.entries())
    const response = await window.fetch([this.baseUrl, collectionId, this.getItemId(item)].join('/'), {
      method: 'put',
      body: serializer(item),
    })
    // resource is created
    if (response.status === CREATED) {
      return
    }
    if (100 <= response.status && response.status <= 399) {
      console.warn(`Expected response is ${CREATED}, got ${response.status}.`)
      return
    }
    throw new Error(response.statusText)
  }

  async removeItem(collectionId: string, item: U) {
    const response = await window.fetch([this.baseUrl, collectionId, this.getItemId(item)].join('/'), {
      method: 'delete',
    })
    // resource is deleted
    if (response.status === NO_CONTENT) {
      return true
    }
    // resource is already deleted
    if (response.status === NOT_FOUND || response.status === GONE) {
      return false
    }
    if (100 <= response.status && response.status <= 399) {
      console.warn(`Expected response is ${NO_CONTENT}, got ${response.status}.`)
      // assume there's a change in the collection
      return true
    }
    throw new Error(response.statusText)
  }

  // TODO do removeCollection for account closing?
}