import {Rivendell} from './Rivendell';

export type Method = 'POST' | 'PUT' | 'PATCH' | 'GET' | 'DELETE';

/**
 * Low level http handler for interacting with the Moria api.
 */
export namespace MoriaApi {

  interface ApiResponse<T = any> {
    response: Response;
    body: T;
  }

  export class ApiError extends Error {
    constructor(message: string, public responseText: string, public response?: Response) {
      super(message);
    }
  }

  export async function get<T>(shard: Rivendell.Shard, uri: string): Promise<ApiResponse<T>> {
    return request(shard, 'GET', uri);
  }

  export async function post<T>(shard: Rivendell.Shard, uri: string, body: any): Promise<ApiResponse<T>> {
    return request(shard, 'POST', uri, body);
  }

  export async function put<T>(shard: Rivendell.Shard, uri: string, body: any): Promise<ApiResponse<T>> {
    return request(shard, 'PUT', uri, body);
  }

  export async function request<T>(
    shard: Rivendell.Shard,
    method: Method,
    uri: string,
    body?: any
  ): Promise<ApiResponse<T>> {
    const url = `${shard.url}/${uri}`;
    const requestPayload: RequestInit = { method };

    requestPayload.headers = {
      'Authorization': `Bearer ${await Rivendell.jwt(shard.id)}`
    };
    if (body && method !== 'GET') {
      // @ts-ignore
      requestPayload.headers['content-type'] = 'application/json';
      requestPayload.body = JSON.stringify(body);
    }

    const response = await fetch(url, requestPayload);
    const responseText = await response.text();

    if (response.status < 200 || response.status >= 300) {
      const errorMsg = `Received a ${response.status} from OCP: ${getErrorMessage(response.status)}`;
      throw new ApiError(errorMsg, responseText, response);
    }

    return {
      response,
      body: responseText ? JSON.parse(responseText) : ''
    };
  }

  function getErrorMessage(code: number): string {
    switch (code) {
      case 400:
        return 'Bad request.';
      case 403:
        return 'Access denied.';
      case 404:
        return 'Not found.';
      case 500:
        return 'Internal service error.';
      case 502:
        return 'Bad gateway';
      case 503:
        return 'Service unavailable. Please try again.';
      case 504:
        return 'Request timed out. Please try again.';
      default:
        return 'Unhandled error.';
    }
  }
}