import {v4 as createUuid} from 'uuid'
import { Book } from './book'

interface ClientOptions {
  clientId: string
  clientSecret: string
  redirectUrl: string
}

interface GetTokenResponse {
  access_token: string
}
export class Client {
  clientId: string
  clientSecret: string
  redirectUrl: string
  accessToken: string
  private state: string

  endpoint = 'https://reflect.app'
  authPath = '/oauth'
  tokenPath = '/api/oauth/token'
  booksPath = '/api/books'
  syncBooksPath = '/api/books/sync'
  notesPath = '/api/notes'
  backlinksPath = '/api/backlinks'

  constructor ({clientId, clientSecret, redirectUrl}: ClientOptions) {
    this.clientId = clientId
    this.clientSecret = clientSecret
    this.redirectUrl = redirectUrl
  }

  private generateState () {
    return this.state = createUuid()
  }

  generateAuthUrl () {
    const url = new URL(this.endpoint + this.authPath)
    url.searchParams.append('client_id', this.clientId)
    url.searchParams.append('state', this.generateState())
    url.searchParams.append('redirect_uri', this.redirectUrl)
    return url.href
  }

  setToken (value: string) {
    this.accessToken = value
  }

  async getToken (code: string):Promise<string> {
    const {access_token} = await this.jsonPost(this.endpoint + this.tokenPath, {
      client_id: this.clientId,
      client_secret: this.clientSecret,
      code,
    })

    this.accessToken = access_token

    return access_token
  }

  createBook (attrs) {
    return this.jsonPost(
      this.endpoint + this.booksPath,
      attrs
    )
  }

  syncBooks (books: Book[]) {
    return this.jsonPost(
      this.endpoint + this.syncBooksPath,
      {books: books}
    )
  }

  createNote (attrs) {
    return this.jsonPost(
      this.endpoint + this.notesPath,
      attrs
    )
  }

  getNotes () {
    return this.jsonGet(
      this.endpoint + this.notesPath
    )
  }

  getBacklinks () {
    return this.jsonGet(
      this.endpoint + this.backlinksPath
    )
  }

  private async jsonGet (url: string) {
    const result = await this.fetchWithAuth(url, {
      method: 'GET',
    })

    return result.json()
  }

  private async jsonPost (url: string, params = {}) {
    const headers = {
      'Content-Type': 'application/json; charset=utf-8',
    }

    const result = await this.fetchWithAuth(url, {
      method: 'POST',
      headers,
      body: JSON.stringify(params)
    })

    return result.json()
  }

  private fetchWithAuth (url: string, init?: RequestInit) {
    const headers = init?.headers || {}

    if (this.accessToken) {
      Object.assign(headers, {
        'Authorization': `Bearer ${this.accessToken}`
      })
    }

    return fetch(url, {
      ...(init || {}),
      headers
    })
  }
}