/**
 * Copyright 2018 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

export default class Critters {
  /**
   * Create an instance of Critters with custom options.
   * The `.process()` method can be called repeatedly to re-use this instance and its cache.
   */
  constructor(options: Options);
  /**
   * Process an HTML document to inline critical CSS from its stylesheets.
   * @param {string} html String containing a full HTML document to be parsed.
   * @returns {string} A modified copy of the provided HTML with critical CSS inlined.
   */
  process(html: string): Promise<string>;
  /**
   * Read the contents of a file from the specified filesystem or disk.
   * Override this method to customize how stylesheets are loaded.
   */
  readFile(filename: string): Promise<string> | string;
  /**
   * Given a stylesheet URL, returns the corresponding CSS asset.
   * Overriding this method requires doing your own URL normalization, so it's generally better to override `readFile()`.
   */
  getCssAsset(href: string): Promise<string | undefined> | string | undefined;
}

export interface Options {
  path?: string;
  publicPath?: string;
  external?: boolean;
  inlineThreshold?: number;
  minimumExternalSize?: number;
  pruneSource?: boolean;
  mergeStylesheets?: boolean;
  additionalStylesheets?: string[];
  preload?: 'body' | 'media' | 'swap' | 'js' | 'js-lazy';
  noscriptFallback?: boolean;
  inlineFonts?: boolean;
  preloadFonts?: boolean;
  fonts?: boolean;
  keyframes?: string;
  compress?: boolean;
  logLevel?: 'info' | 'warn' | 'error' | 'trace' | 'debug' | 'silent';
  reduceInlineStyles?: boolean;
  logger?: Logger;
}

export interface Logger {
  trace?: (message: string) => void;
  debug?: (message: string) => void;
  info?: (message: string) => void;
  warn?: (message: string) => void;
  error?: (message: string) => void;
}