/*
 This file is part of GNU Taler
 (C) 2020 Taler Systems S.A.

 GNU Taler is free software; you can redistribute it and/or modify it under the
 terms of the GNU General Public License as published by the Free Software
 Foundation; either version 3, or (at your option) any later version.

 GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

 You should have received a copy of the GNU General Public License along with
 GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 */

/**
 * Imports.
 */
import { Logger, TalerErrorCode } from "@gnu-taler/taler-util";
import {
  Headers, HttpRequestLibrary,
  HttpRequestOptions,
  HttpResponse,
  OperationFailedError
} from "@gnu-taler/taler-wallet-core";

const logger = new Logger("browserHttpLib");

/**
 * An implementation of the [[HttpRequestLibrary]] using the
 * browser's XMLHttpRequest.
 */
export class ServiceWorkerHttpLib implements HttpRequestLibrary {
  async fetch(requestUrl: string, options?: HttpRequestOptions): Promise<HttpResponse> {
    const requestMethod = options?.method ?? "GET";
    const requestBody = options?.body;
    const requestHeader = options?.headers;

    const response = await fetch(requestUrl, {
      headers: requestHeader,
      body: requestBody,
      method: requestMethod,
      // timeout: options?.timeout
    })

    const headerMap = new Headers();
    response.headers.forEach(addLineToMap(headerMap));

    return {
      headers: headerMap,
      status: response.status,
      requestMethod,
      requestUrl,
      json: makeJsonHandler(response, requestUrl),
      text: makeTextHandler(response, requestUrl),
      bytes: async () => (await response.blob()).arrayBuffer(),
    }

  }


  get(url: string, opt?: HttpRequestOptions): Promise<HttpResponse> {
    return this.fetch(url, {
      method: "GET",
      ...opt,
    });
  }

  postJson(
    url: string,
    body: any,
    opt?: HttpRequestOptions,
  ): Promise<HttpResponse> {
    return this.fetch(url, {
      method: "POST",
      body: JSON.stringify(body),
      ...opt,
    });
  }

  stop(): void {
    // Nothing to do
  }
}

function makeTextHandler(response: Response, requestUrl: string) {
  return async function getJsonFromResponse(): Promise<any> {
    let respText;
    try {
      respText = await response.text()
    } catch (e) {
      throw OperationFailedError.fromCode(
        TalerErrorCode.WALLET_RECEIVED_MALFORMED_RESPONSE,
        "Invalid JSON from HTTP response",
        {
          requestUrl,
          httpStatusCode: response.status,
        },
      );
    }
    return respText
  }
}

function makeJsonHandler(response: Response, requestUrl: string) {
  return async function getJsonFromResponse(): Promise<any> {
    let responseJson;
    try {
      responseJson = await response.json()
    } catch (e) {
      throw OperationFailedError.fromCode(
        TalerErrorCode.WALLET_RECEIVED_MALFORMED_RESPONSE,
        "Invalid JSON from HTTP response",
        {
          requestUrl,
          httpStatusCode: response.status,
        },
      );
    }
    if (responseJson === null || typeof responseJson !== "object") {
      throw OperationFailedError.fromCode(
        TalerErrorCode.WALLET_RECEIVED_MALFORMED_RESPONSE,
        "Invalid JSON from HTTP response",
        {
          requestUrl,
          httpStatusCode: response.status,
        },
      );
    }
    return responseJson
  }
}

function addLineToMap(map: { set(k: string, v: string): void }) {
  return (line: string) => {
    const parts = line.split(": ");
    const headerName = parts.shift();
    if (!headerName) {
      logger.warn("skipping invalid header");
      return;
    }
    const value = parts.join(": ");
    map.set(headerName, value);
  }
}