/*
 This file is part of GNU Taler
 (C) 2024 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/>
 */

import { ObservabilityEvent } from "./index.js";
import { HttpRequestLibrary, HttpRequestOptions, HttpResponse } from "./http-common.js";
import { ObservabilityEventType } from "./notifications.js"
import { getErrorDetailFromException } from "./errors.js";

/**
 * Observability sink can be passed into various operations (HTTP requests, DB access)
 * to do structured logging within a particular context (task, request, ...).
 */
export interface ObservabilityContext {
  observe(evt: ObservabilityEvent): void;
}

export class ObservableHttpClientLibrary implements HttpRequestLibrary {
  constructor(
    private impl: HttpRequestLibrary,
    private oc: ObservabilityContext,
  ) { }
  async fetch(
    url: string,
    opt?: HttpRequestOptions | undefined,
  ): Promise<HttpResponse> {
    this.oc.observe({
      type: ObservabilityEventType.HttpFetchStart,
      url: url,
    });
    try {
      const res = await this.impl.fetch(url, opt);
      this.oc.observe({
        type: ObservabilityEventType.HttpFetchFinishSuccess,
        url,
        status: res.status,
      });
      return res;
    } catch (e) {
      this.oc.observe({
        type: ObservabilityEventType.HttpFetchFinishError,
        url,
        error: getErrorDetailFromException(e),
      });
      throw e;
    }
  }
}