import axios from 'axios'
import { AxiosResponse } from 'axios'
import * as urljoin from 'url-join'
import { ServerError, APIError } from '../errors/errors'
import { SignatureHandler } from '../types'

export async function getAuthHeaders(account: string, sign: SignatureHandler): Promise<{}> {
  const message = RequestHandler.BASE_MESSAGE + '@' + Date.now()
  return {
    [RequestHandler.HEADER]: [account, message, await sign(message)].join('#')
  }
}
/**
 * Handle building requests to the server, including authentication
 * in the request header.
 */
export class RequestHandler {
  static BASE_MESSAGE: string = 'HYDRO-AUTHENTICATION'
  static BASE_URL: string = 'https://api.ddex.io/v2/'
  static HEADER: string = 'Hydro-Authentication'

  baseUrl: string

  constructor(readonly sign: SignatureHandler, readonly account?: string, baseUrl?: string) {
    this.baseUrl = baseUrl || RequestHandler.BASE_URL
  }

  /**
   * Methods to perform standard get/post/delete requests to the api server.
   * Only implemented these three since they are the only ones the api
   * currently requires.
   */
  public async get(path: string, params?: {}, sign: boolean = false): Promise<any> {
    const res = await axios.get(this.getURL(path), {
      params: params,
      headers: sign ? await this.getAuthHeaders() : {}
    })
    return this.handleResponse(res)
  }

  public async post(path: string, data?: {}): Promise<any> {
    const res = await axios.post(this.getURL(path), data, { headers: await this.getAuthHeaders() })
    return this.handleResponse(res)
  }

  public async delete(path: string): Promise<any> {
    const res = await axios.delete(this.getURL(path), { headers: await this.getAuthHeaders() })
    return this.handleResponse(res)
  }

  /**
   * The baseUrl MUST have a trailing slash for this to work.
   * TODO: fix
   * @param path
   */
  private getURL(path: string): string {
    return urljoin(this.baseUrl, path)
  }

  private async getAuthHeaders(): Promise<{}> {
    const message = RequestHandler.BASE_MESSAGE + '@' + Date.now()
    return {
      [RequestHandler.HEADER]: [this.account, message, await this.sign(message)].join('#')
    }
  }

  private handleResponse(res: AxiosResponse): any {
    if (res.status !== 200) {
      throw new ServerError('Server Error ' + res.status + ': ' + res.statusText)
    }
    if (res.data.status !== 0) {
      throw new APIError('API Error: ' + res.data.desc)
    }
    return res.data.data
  }
}