/**
 * Copyright 2019 Google Inc. All rights reserved.
 * Modifications 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 * as dom from './dom';
import { helper } from './helper';
import { Page } from './page';
import * as types from './types';
import { Progress } from './progress';
import { assert } from '../utils/utils';

export class Screenshotter {
  private _queue = new TaskQueue();
  private _page: Page;

  constructor(page: Page) {
    this._page = page;
    this._queue = new TaskQueue();
  }

  private async _originalViewportSize(progress: Progress): Promise<{ viewportSize: types.Size, originalViewportSize: types.Size | null }> {
    const originalViewportSize = this._page.viewportSize();
    let viewportSize = originalViewportSize;
    if (!viewportSize)
      viewportSize = await this._page.mainFrame().waitForFunctionValueInUtility(progress, () => ({ width: window.innerWidth, height: window.innerHeight }));
    return { viewportSize, originalViewportSize };
  }

  private async _fullPageSize(progress: Progress): Promise<types.Size> {
    const fullPageSize = await this._page.mainFrame().waitForFunctionValueInUtility(progress, () => {
      if (!document.body || !document.documentElement)
        return null;
      return {
        width: Math.max(
            document.body.scrollWidth, document.documentElement.scrollWidth,
            document.body.offsetWidth, document.documentElement.offsetWidth,
            document.body.clientWidth, document.documentElement.clientWidth
        ),
        height: Math.max(
            document.body.scrollHeight, document.documentElement.scrollHeight,
            document.body.offsetHeight, document.documentElement.offsetHeight,
            document.body.clientHeight, document.documentElement.clientHeight
        ),
      };
    });
    return fullPageSize!;
  }

  async screenshotPage(progress: Progress, options: types.ScreenshotOptions): Promise<Buffer> {
    const format = validateScreenshotOptions(options);
    return this._queue.postTask(async () => {
      const { viewportSize } = await this._originalViewportSize(progress);

      if (options.fullPage) {
        const fullPageSize = await this._fullPageSize(progress);
        let documentRect = { x: 0, y: 0, width: fullPageSize.width, height: fullPageSize.height };
        const fitsViewport = fullPageSize.width <= viewportSize.width && fullPageSize.height <= viewportSize.height;
        if (options.clip)
          documentRect = trimClipToSize(options.clip, documentRect);
        const buffer = await this._screenshot(progress, format, documentRect, undefined, fitsViewport, options);
        progress.throwIfAborted(); // Avoid restoring after failure - should be done by cleanup.
        return buffer;
      }

      const viewportRect = options.clip ? trimClipToSize(options.clip, viewportSize) : { x: 0, y: 0, ...viewportSize };
      return await this._screenshot(progress, format, undefined, viewportRect, true, options);
    });
  }

  async screenshotElement(progress: Progress, handle: dom.ElementHandle, options: types.ElementScreenshotOptions = {}): Promise<Buffer> {
    const format = validateScreenshotOptions(options);
    return this._queue.postTask(async () => {
      const { viewportSize } = await this._originalViewportSize(progress);

      await handle._waitAndScrollIntoViewIfNeeded(progress);

      progress.throwIfAborted(); // Do not do extra work.
      const boundingBox = await handle.boundingBox();
      assert(boundingBox, 'Node is either not visible or not an HTMLElement');
      assert(boundingBox.width !== 0, 'Node has 0 width.');
      assert(boundingBox.height !== 0, 'Node has 0 height.');

      const fitsViewport = boundingBox.width <= viewportSize.width && boundingBox.height <= viewportSize.height;
      progress.throwIfAborted(); // Avoid extra work.
      const scrollOffset = await this._page.mainFrame().waitForFunctionValueInUtility(progress, () => ({ x: window.scrollX, y: window.scrollY }));
      const documentRect = { ...boundingBox };
      documentRect.x += scrollOffset.x;
      documentRect.y += scrollOffset.y;
      const buffer = await this._screenshot(progress, format, helper.enclosingIntRect(documentRect), undefined, fitsViewport, options);
      progress.throwIfAborted(); // Avoid restoring after failure - should be done by cleanup.
      return buffer;
    });
  }

  private async _screenshot(progress: Progress, format: 'png' | 'jpeg', documentRect: types.Rect | undefined, viewportRect: types.Rect | undefined, fitsViewport: boolean | undefined, options: types.ElementScreenshotOptions): Promise<Buffer> {
    if ((options as any).__testHookBeforeScreenshot)
      await (options as any).__testHookBeforeScreenshot();
    progress.throwIfAborted(); // Screenshotting is expensive - avoid extra work.
    const shouldSetDefaultBackground = options.omitBackground && format === 'png';
    if (shouldSetDefaultBackground) {
      await this._page._delegate.setBackgroundColor({ r: 0, g: 0, b: 0, a: 0 });
      progress.cleanupWhenAborted(() => this._page._delegate.setBackgroundColor());
    }
    progress.throwIfAborted(); // Avoid extra work.
    const buffer = await this._page._delegate.takeScreenshot(progress, format, documentRect, viewportRect, options.quality, fitsViewport);
    progress.throwIfAborted(); // Avoid restoring after failure - should be done by cleanup.
    if (shouldSetDefaultBackground)
      await this._page._delegate.setBackgroundColor();
    progress.throwIfAborted(); // Avoid side effects.
    if ((options as any).__testHookAfterScreenshot)
      await (options as any).__testHookAfterScreenshot();
    return buffer;
  }
}

class TaskQueue {
  private _chain: Promise<any>;

  constructor() {
    this._chain = Promise.resolve();
  }

  postTask(task: () => any): Promise<any> {
    const result = this._chain.then(task);
    this._chain = result.catch(() => {});
    return result;
  }
}

function trimClipToSize(clip: types.Rect, size: types.Size): types.Rect {
  const p1 = {
    x: Math.max(0, Math.min(clip.x, size.width)),
    y: Math.max(0, Math.min(clip.y, size.height))
  };
  const p2 = {
    x: Math.max(0, Math.min(clip.x + clip.width, size.width)),
    y: Math.max(0, Math.min(clip.y + clip.height, size.height))
  };
  const result = { x: p1.x, y: p1.y, width: p2.x - p1.x, height: p2.y - p1.y };
  assert(result.width && result.height, 'Clipped area is either empty or outside the resulting image');
  return result;
}

function validateScreenshotOptions(options: types.ScreenshotOptions): 'png' | 'jpeg' {
  let format: 'png' | 'jpeg' | null = null;
  // options.type takes precedence over inferring the type from options.path
  // because it may be a 0-length file with no extension created beforehand (i.e. as a temp file).
  if (options.type) {
    assert(options.type === 'png' || options.type === 'jpeg', 'Unknown options.type value: ' + options.type);
    format = options.type;
  }

  if (!format)
    format = 'png';

  if (options.quality !== undefined) {
    assert(format === 'jpeg', 'options.quality is unsupported for the ' + format + ' screenshots');
    assert(typeof options.quality === 'number', 'Expected options.quality to be a number but found ' + (typeof options.quality));
    assert(Number.isInteger(options.quality), 'Expected options.quality to be an integer');
    assert(options.quality >= 0 && options.quality <= 100, 'Expected options.quality to be between 0 and 100 (inclusive), got ' + options.quality);
  }
  if (options.clip) {
    assert(typeof options.clip.x === 'number', 'Expected options.clip.x to be a number but found ' + (typeof options.clip.x));
    assert(typeof options.clip.y === 'number', 'Expected options.clip.y to be a number but found ' + (typeof options.clip.y));
    assert(typeof options.clip.width === 'number', 'Expected options.clip.width to be a number but found ' + (typeof options.clip.width));
    assert(typeof options.clip.height === 'number', 'Expected options.clip.height to be a number but found ' + (typeof options.clip.height));
    assert(options.clip.width !== 0, 'Expected options.clip.width not to be 0.');
    assert(options.clip.height !== 0, 'Expected options.clip.height not to be 0.');
  }
  return format;
}