/*
 This file is part of GNU Taler
 (C) 2019 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/>

 SPDX-License-Identifier: AGPL3.0-or-later
*/

/**
 * Imports.
 */
import { Logger } from "@gnu-taler/taler-util";
import { TalerError } from "./errors.js";
import { encodeBody, getDefaultHeaders, HttpLibArgs } from "./http-common.js";
import {
  Headers,
  HttpRequestLibrary,
  HttpRequestOptions,
  HttpResponse,
} from "./http.js";
import { RequestThrottler, TalerErrorCode, URL } from "./index.js";
import { qjsOs } from "./qtart.js";

const logger = new Logger("http-impl.qtart.ts");

const textDecoder = new TextDecoder();

/**
 * Implementation of the HTTP request library interface for node.
 */
export class HttpLibImpl implements HttpRequestLibrary {
  private throttle = new RequestThrottler();
  private throttlingEnabled = true;
  private requireTls = false;

  constructor(args?: HttpLibArgs) {
    this.throttlingEnabled = args?.enableThrottling ?? true;
    this.requireTls = args?.requireTls ?? false;
  }

  /**
   * Set whether requests should be throttled.
   */
  setThrottling(enabled: boolean): void {
    this.throttlingEnabled = enabled;
  }

  async fetch(url: string, opt?: HttpRequestOptions): Promise<HttpResponse> {
    const method = (opt?.method ?? "GET").toUpperCase();

    logger.trace(`Requesting ${method} ${url}`);

    const parsedUrl = new URL(url);
    if (this.throttlingEnabled && this.throttle.applyThrottle(url)) {
      throw TalerError.fromDetail(
        TalerErrorCode.WALLET_HTTP_REQUEST_THROTTLED,
        {
          requestMethod: method,
          requestUrl: url,
          throttleStats: this.throttle.getThrottleStats(url),
        },
        `request to origin ${parsedUrl.origin} was throttled`,
      );
    }
    if (this.requireTls && parsedUrl.protocol !== "https:") {
      throw TalerError.fromDetail(
        TalerErrorCode.WALLET_NETWORK_ERROR,
        {
          requestMethod: method,
          requestUrl: url,
        },
        `request to ${parsedUrl.origin} is not possible with protocol ${parsedUrl.protocol}`,
      );
    }

    let data: ArrayBuffer | undefined = undefined;
    const requestHeadersMap = { ...getDefaultHeaders(method), ...opt?.headers };
    let headersList: string[] = [];
    for (let headerName of Object.keys(requestHeadersMap)) {
      headersList.push(`${headerName}: ${requestHeadersMap[headerName]}`);
    }
    if (method === "POST") {
      data = encodeBody(opt?.body);
    }
    const res = await qjsOs.fetchHttp(url, {
      method,
      data,
      headers: headersList,
    });

    const headers: Headers = new Headers();

    if (res.headers) {
      for (const headerStr of res.headers) {
        const splitPos = headerStr.indexOf(":");
        if (splitPos < 0) {
          continue;
        }
        const headerName = headerStr.slice(0, splitPos).trim().toLowerCase();
        const headerValue = headerStr.slice(splitPos + 1).trim();
        headers.set(headerName, headerValue);
      }
    }

    return {
      requestMethod: method,
      headers,
      async bytes() {
        return res.data;
      },
      json() {
        const text = textDecoder.decode(res.data);
        return JSON.parse(text);
      },
      async text() {
        const text = textDecoder.decode(res.data);
        return text;
      },
      requestUrl: url,
      status: res.status,
    };
  }
}