/*
  Copyright 2018 Google LLC

  Use of this source code is governed by an MIT-style
  license that can be found in the LICENSE file or at
  https://opensource.org/licenses/MIT.
*/

import type { MapLikeObject } from "../../types.js";
import { assert } from "../../utils/assert.js";

type SerializableProperties = "method" | "referrer" | "referrerPolicy" | "mode" | "credentials" | "cache" | "redirect" | "integrity" | "keepalive";

const serializableProperties: SerializableProperties[] = [
  "method",
  "referrer",
  "referrerPolicy",
  "mode",
  "credentials",
  "cache",
  "redirect",
  "integrity",
  "keepalive",
];

export interface RequestData extends MapLikeObject {
  url: string;
  headers: MapLikeObject;
  body?: ArrayBuffer;
}

/**
 * A class to make it easier to serialize and de-serialize requests so they
 * can be stored in IndexedDB.
 *
 * Most developers will not need to access this class directly;
 * it is exposed for advanced use cases.
 */
export class StorableRequest {
  private readonly _requestData: RequestData;

  /**
   * Converts a Request object to a plain object that can be structured
   * cloned or stringified to JSON.
   *
   * @param request
   * @returns
   */
  static async fromRequest(request: Request): Promise<StorableRequest> {
    const requestData: RequestData = {
      url: request.url,
      headers: {},
    };

    // Set the body if present.
    if (request.method !== "GET") {
      // Use ArrayBuffer to support non-text request bodies.
      // NOTE: we can't use Blobs becuse Safari doesn't support storing
      // Blobs in IndexedDB in some cases:
      // https://github.com/dfahlander/Dexie.js/issues/618#issuecomment-398348457
      requestData.body = await request.clone().arrayBuffer();
    }

    request.headers.forEach((value, key) => {
      requestData.headers[key] = value;
    });

    // Add all other serializable request properties
    for (const prop of serializableProperties) {
      if (request[prop] !== undefined) {
        requestData[prop] = request[prop];
      }
    }

    return new StorableRequest(requestData);
  }

  /**
   * Accepts an object of request data that can be used to construct a
   * `Request` object but can also be stored in IndexedDB.
   *
   * @param requestData An object of request data that includes the `url` plus any relevant property of
   * [`requestInit`](https://fetch.spec.whatwg.org/#requestinit).
   */
  constructor(requestData: RequestData) {
    if (process.env.NODE_ENV !== "production") {
      assert!.isType(requestData, "object", {
        moduleName: "serwist",
        className: "StorableRequest",
        funcName: "constructor",
        paramName: "requestData",
      });
      assert!.isType(requestData.url, "string", {
        moduleName: "serwist",
        className: "StorableRequest",
        funcName: "constructor",
        paramName: "requestData.url",
      });
    }

    // If the request's mode is `navigate`, convert it to `same-origin` since
    // navigation requests can't be constructed via script.
    if (requestData.mode === "navigate") {
      requestData.mode = "same-origin";
    }

    this._requestData = requestData;
  }

  /**
   * Returns a deep clone of the instance's `requestData` object.
   *
   * @returns
   */
  toObject(): RequestData {
    const requestData = Object.assign({}, this._requestData);
    requestData.headers = Object.assign({}, this._requestData.headers);
    if (requestData.body) {
      requestData.body = requestData.body.slice(0);
    }

    return requestData;
  }

  /**
   * Converts this instance to a Request.
   *
   * @returns
   */
  toRequest(): Request {
    return new Request(this._requestData.url, this._requestData);
  }

  /**
   * Creates and returns a deep clone of the instance.
   *
   * @returns
   */
  clone(): StorableRequest {
    return new StorableRequest(this.toObject());
  }
}