import {
  fetchLinesIterator,
  maybeWithAuth,
  topicShortUrl,
  topicUrl,
  topicUrlAuth,
  topicUrlJsonPoll,
  topicUrlJsonPollWithSince,
  topicUrlWebPushSubscribe,
  topicUrlWebPushUnsubscribe,
  webPushConfigUrl,
} from "./utils";
import userManager from "./UserManager";
import { fetchOrThrow } from "./errors";

class Api {
  async poll(baseUrl, topic, since) {
    const user = await userManager.get(baseUrl);
    const shortUrl = topicShortUrl(baseUrl, topic);
    const url = since ? topicUrlJsonPollWithSince(baseUrl, topic, since) : topicUrlJsonPoll(baseUrl, topic);
    const messages = [];
    const headers = maybeWithAuth({}, user);
    console.log(`[Api] Polling ${url}`);
    for await (const line of fetchLinesIterator(url, headers)) {
      const message = JSON.parse(line);
      if (message.id) {
        console.log(`[Api, ${shortUrl}] Received message ${line}`);
        messages.push(message);
      }
    }
    return messages;
  }

  async publish(baseUrl, topic, message, options) {
    const user = await userManager.get(baseUrl);
    console.log(`[Api] Publishing message to ${topicUrl(baseUrl, topic)}`);
    const headers = {};
    const body = {
      topic,
      message,
      ...options,
    };
    await fetchOrThrow(baseUrl, {
      method: "PUT",
      body: JSON.stringify(body),
      headers: maybeWithAuth(headers, user),
    });
  }

  /**
   * Publishes to a topic using XMLHttpRequest (XHR), and returns a Promise with the active request.
   * Unfortunately, fetch() does not support a progress hook, which is why XHR has to be used.
   *
   * Firefox XHR bug:
   *    Firefox has a bug(?), which returns 0 and "" for all fields of the XHR response in the case of an error,
   *    so we cannot determine the exact error. It also sometimes complains about CORS violations, even when the
   *    correct headers are clearly set. It's quite the odd behavior.
   *
   *  There is an example, and the bug report here:
   *  - https://bugzilla.mozilla.org/show_bug.cgi?id=1733755
   *  - https://gist.github.com/binwiederhier/627f146d1959799be207ad8c17a8f345
   */
  publishXHR(url, body, headers, onProgress) {
    console.log(`[Api] Publishing message to ${url}`);
    const xhr = new XMLHttpRequest();
    const send = new Promise((resolve, reject) => {
      xhr.open("PUT", url);
      if (body.type) {
        xhr.overrideMimeType(body.type);
      }
      for (const [key, value] of Object.entries(headers)) {
        xhr.setRequestHeader(key, value);
      }
      xhr.upload.addEventListener("progress", onProgress);
      xhr.addEventListener("readystatechange", () => {
        if (xhr.readyState === 4 && xhr.status >= 200 && xhr.status <= 299) {
          console.log(`[Api] Publish successful (HTTP ${xhr.status})`, xhr.response);
          resolve(xhr.response);
        } else if (xhr.readyState === 4) {
          // Firefox bug; see description above!
          console.log(`[Api] Publish failed (HTTP ${xhr.status})`, xhr.responseText);
          let errorText;
          try {
            const error = JSON.parse(xhr.responseText);
            if (error.code && error.error) {
              errorText = `Error ${error.code}: ${error.error}`;
            }
          } catch (e) {
            // Nothing
          }
          xhr.abort();
          reject(errorText ?? "An error occurred");
        }
      });
      xhr.send(body);
    });
    send.abort = () => {
      console.log(`[Api] Publish aborted by user`);
      xhr.abort();
    };
    return send;
  }

  async topicAuth(baseUrl, topic, user) {
    const url = topicUrlAuth(baseUrl, topic);
    console.log(`[Api] Checking auth for ${url}`);
    const response = await fetch(url, {
      headers: maybeWithAuth({}, user),
    });
    if (response.status >= 200 && response.status <= 299) {
      return true;
    }
    if (response.status === 401 || response.status === 403) {
      // See server/server.go
      return false;
    }
    throw new Error(`Unexpected server response ${response.status}`);
  }

  /**
   * @returns {Promise<{ public_key: string } | undefined>}
   */
  async getWebPushConfig(baseUrl) {
    const response = await fetch(webPushConfigUrl(baseUrl));

    if (response.ok) {
      return response.json();
    }

    if (response.status === 404) {
      // web push is not enabled
      return undefined;
    }

    throw new Error(`Unexpected server response ${response.status}`);
  }

  async subscribeWebPush(baseUrl, topic, browserSubscription) {
    const user = await userManager.get(baseUrl);

    const url = topicUrlWebPushSubscribe(baseUrl, topic);
    console.log(`[Api] Sending Web Push Subscription ${url}`);

    const response = await fetch(url, {
      method: "POST",
      headers: maybeWithAuth({}, user),
      body: JSON.stringify({ browser_subscription: browserSubscription }),
    });

    if (response.ok) {
      return true;
    }

    throw new Error(`Unexpected server response ${response.status}`);
  }

  async unsubscribeWebPush(subscription) {
    const user = await userManager.get(subscription.baseUrl);

    const url = topicUrlWebPushUnsubscribe(subscription.baseUrl, subscription.topic);
    console.log(`[Api] Unsubscribing Web Push Subscription ${url}`);

    const response = await fetch(url, {
      method: "POST",
      headers: maybeWithAuth({}, user),
      body: JSON.stringify({ endpoint: subscription.webPushEndpoint }),
    });

    if (response.ok) {
      return true;
    }

    throw new Error(`Unexpected server response ${response.status}`);
  }
}

const api = new Api();
export default api;