/**
 * Copyright (c) Microsoft Corporation.
 *
 * 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.
 */

import path from 'path';
import fs from 'fs';
import * as util from 'util';
import { Page } from './page';
import { assert } from '../utils/utils';

type SaveCallback = (localPath: string, error?: string) => Promise<void>;

export class Download {
  private _downloadsPath: string;
  private _uuid: string;
  private _finishedCallback: () => void;
  private _finishedPromise: Promise<void>;
  private _saveCallbacks: SaveCallback[] = [];
  private _finished: boolean = false;
  private _page: Page;
  private _acceptDownloads: boolean;
  private _failure: string | null = null;
  private _deleted = false;
  private _url: string;
  private _suggestedFilename: string | undefined;

  constructor(page: Page, downloadsPath: string, uuid: string, url: string, suggestedFilename?: string) {
    this._page = page;
    this._downloadsPath = downloadsPath;
    this._uuid = uuid;
    this._url = url;
    this._suggestedFilename = suggestedFilename;
    this._finishedCallback = () => {};
    this._finishedPromise = new Promise(f => this._finishedCallback = f);
    page._browserContext._downloads.add(this);
    this._acceptDownloads = !!this._page._browserContext._options.acceptDownloads;
    if (suggestedFilename !== undefined)
      this._page.emit(Page.Events.Download, this);
  }

  _filenameSuggested(suggestedFilename: string) {
    assert(this._suggestedFilename === undefined);
    this._suggestedFilename = suggestedFilename;
    this._page.emit(Page.Events.Download, this);
  }

  url(): string {
    return this._url;
  }

  suggestedFilename(): string {
    return this._suggestedFilename!;
  }

  async localPath(): Promise<string | null> {
    if (!this._acceptDownloads)
      throw new Error('Pass { acceptDownloads: true } when you are creating your browser context.');
    const fileName = path.join(this._downloadsPath, this._uuid);
    await this._finishedPromise;
    if (this._failure)
      return null;
    return fileName;
  }

  saveAs(saveCallback: SaveCallback) {
    if (!this._acceptDownloads)
      throw new Error('Pass { acceptDownloads: true } when you are creating your browser context.');
    if (this._deleted)
      throw new Error('Download already deleted. Save before deleting.');
    if (this._failure)
      throw new Error('Download not found on disk. Check download.failure() for details.');

    if (this._finished) {
      saveCallback(path.join(this._downloadsPath, this._uuid));
      return;
    }
    this._saveCallbacks.push(saveCallback);
  }

  async failure(): Promise<string | null> {
    if (!this._acceptDownloads)
      return 'Pass { acceptDownloads: true } when you are creating your browser context.';
    await this._finishedPromise;
    return this._failure;
  }

  async delete(): Promise<void> {
    if (!this._acceptDownloads)
      return;
    const fileName = await this.localPath();
    if (this._deleted)
      return;
    this._deleted = true;
    if (fileName)
      await util.promisify(fs.unlink)(fileName).catch(e => {});
  }

  async _reportFinished(error?: string) {
    this._finished = true;
    this._failure = error || null;

    if (error) {
      for (const callback of this._saveCallbacks)
        callback('', error);
    } else {
      const fullPath = path.join(this._downloadsPath, this._uuid);
      for (const callback of this._saveCallbacks)
        await callback(fullPath);
    }
    this._saveCallbacks = [];

    this._finishedCallback();
  }
}