/**
 * @license
 * Copyright 2020 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

import {ServerInfo} from '../types/common';
import {RestApiService} from '../services/gr-rest-api/gr-rest-api';

const PROBE_PATH = '/Documentation/index.html';
const DOCS_BASE_PATH = '/Documentation';

export function getBaseUrl(): string {
  // window is not defined in service worker, therefore no CANONICAL_PATH
  if (typeof window === 'undefined') return '';
  return self.CANONICAL_PATH || '';
}

export function prependOrigin(path: string): string {
  if (path.startsWith('http')) return path;
  if (path.startsWith('/')) return window.location.origin + path;
  throw new Error(`Cannot prepend origin to relative path '${path}'.`);
}

let getDocsBaseUrlCachedPromise: Promise<string | null> | undefined;

/**
 * Get the docs base URL from either the server config or by probing.
 *
 * @return A promise that resolves with the docs base URL.
 */
export function getDocsBaseUrl(
  config: ServerInfo | undefined,
  restApi: RestApiService
): Promise<string | null> {
  if (!getDocsBaseUrlCachedPromise) {
    getDocsBaseUrlCachedPromise = new Promise(resolve => {
      if (config?.gerrit?.doc_url) {
        resolve(config.gerrit.doc_url);
      } else {
        restApi.probePath(getBaseUrl() + PROBE_PATH).then(ok => {
          resolve(ok ? getBaseUrl() + DOCS_BASE_PATH : null);
        });
      }
    });
  }
  return getDocsBaseUrlCachedPromise;
}

export function _testOnly_clearDocsBaseUrlCache() {
  getDocsBaseUrlCachedPromise = undefined;
}

/**
 * Pretty-encodes a URL. Double-encodes the string, and then replaces
 *   benevolent characters for legibility.
 */
export function encodeURL(url: string, replaceSlashes?: boolean): string {
  // @see Issue 4255 regarding double-encoding.
  let output = encodeURIComponent(encodeURIComponent(url));
  // @see Issue 4577 regarding more readable URLs.
  output = output.replace(/%253A/g, ':');
  output = output.replace(/%2520/g, '+');
  if (replaceSlashes) {
    output = output.replace(/%252F/g, '/');
  }
  return output;
}

/**
 * Single decode for URL components. Will decode plus signs ('+') to spaces.
 * Note: because this function decodes once, it is not the inverse of
 * encodeURL.
 */
export function singleDecodeURL(url: string): string {
  const withoutPlus = url.replace(/\+/g, '%20');
  return decodeURIComponent(withoutPlus);
}

/**
 * @param path URL path including search params, but without host
 */
export function toPathname(path: string) {
  const i = path.indexOf('?');
  const hasQuery = i > -1;
  const pathname = hasQuery ? path.slice(0, i) : path;
  return pathname;
}

/**
 * @param path URL path including search params, but without host
 */
export function toSearchParams(path: string) {
  const i = path.indexOf('?');
  const hasQuery = i > -1;
  const querystring = hasQuery ? path.slice(i + 1) : '';
  return new URLSearchParams(querystring);
}

/**
 * @param pathname URL path without search params
 * @param params
 */
export function toPath(pathname: string, searchParams: URLSearchParams) {
  const paramString = searchParams.toString();
  const middle = paramString ? '?' : '';
  return pathname + middle + paramString;
}

/**
 * Primary use case is to copy the absolute comments url to clipboard.
 */
export function generateAbsoluteUrl(url: string) {
  return new URL(url, window.location.href).toString();
}