// Copyright (c) Microsoft Corporation.
// Licensed under the MIT license.

import * as frames from './frames';
import { assert, helper } from './helper';
import Injected from './injected/injected';
import * as input from './input';
import * as js from './javascript';
import * as types from './types';
import * as injectedSource from './generated/injectedSource';
import * as cssSelectorEngineSource from './generated/cssSelectorEngineSource';
import * as xpathSelectorEngineSource from './generated/xpathSelectorEngineSource';

type SelectorRoot = Element | ShadowRoot | Document;

export interface DOMWorldDelegate {
  keyboard: input.Keyboard;
  mouse: input.Mouse;
  frame: frames.Frame;
  isJavascriptEnabled(): boolean;
  contentFrame(handle: ElementHandle): Promise<frames.Frame | null>;
  boundingBox(handle: ElementHandle): Promise<types.Rect | null>;
  screenshot(handle: ElementHandle, options?: any): Promise<string | Buffer>;
  ensurePointerActionPoint(handle: ElementHandle, relativePoint?: types.Point): Promise<types.Point>;
  setInputFiles(handle: ElementHandle, files: input.FilePayload[]): Promise<void>;
  adoptElementHandle(handle: ElementHandle, to: DOMWorld): Promise<ElementHandle>;
}

export class DOMWorld {
  readonly context: js.ExecutionContext;
  readonly delegate: DOMWorldDelegate;

  private _injectedPromise?: Promise<js.JSHandle>;
  private _documentPromise?: Promise<ElementHandle>;

  constructor(context: js.ExecutionContext, delegate: DOMWorldDelegate) {
    this.context = context;
    this.delegate = delegate;
  }

  injected(): Promise<js.JSHandle> {
    if (!this._injectedPromise) {
      const engineSources = [cssSelectorEngineSource.source, xpathSelectorEngineSource.source];
      const source = `
        new (${injectedSource.source})([
          ${engineSources.join(',\n')}
        ])
      `;
      this._injectedPromise = this.context.evaluateHandle(source);
    }
    return this._injectedPromise;
  }

  _document(): Promise<ElementHandle> {
    if (!this._documentPromise)
      this._documentPromise = this.context.evaluateHandle('document').then(handle => handle.asElement()!);
    return this._documentPromise;
  }

  async adoptElementHandle(handle: ElementHandle, dispose: boolean): Promise<ElementHandle> {
    if (handle.executionContext() === this.context)
      return handle;
    const adopted = this.delegate.adoptElementHandle(handle, this);
    if (dispose)
      await handle.dispose();
    return adopted;
  }
}

export class ElementHandle extends js.JSHandle {
  private readonly _world: DOMWorld;

  constructor(context: js.ExecutionContext) {
    super(context);
    assert(context._domWorld, 'Element handle should have a dom world');
    this._world = context._domWorld;
  }

  asElement(): ElementHandle | null {
    return this;
  }

  async contentFrame(): Promise<frames.Frame | null> {
    return this._world.delegate.contentFrame(this);
  }

  async _scrollIntoViewIfNeeded() {
    const error = await this.evaluate(async (element, pageJavascriptEnabled) => {
      if (!element.isConnected)
        return 'Node is detached from document';
      if (element.nodeType !== Node.ELEMENT_NODE)
        return 'Node is not of type HTMLElement';
      // force-scroll if page's javascript is disabled.
      if (!pageJavascriptEnabled) {
        element.scrollIntoView({block: 'center', inline: 'center', behavior: 'instant'});
        return false;
      }
      const visibleRatio = await new Promise(resolve => {
        const observer = new IntersectionObserver(entries => {
          resolve(entries[0].intersectionRatio);
          observer.disconnect();
        });
        observer.observe(element);
        // Firefox doesn't call IntersectionObserver callback unless
        // there are rafs.
        requestAnimationFrame(() => {});
      });
      if (visibleRatio !== 1.0)
        element.scrollIntoView({block: 'center', inline: 'center', behavior: 'instant'});
      return false;
    }, this._world.delegate.isJavascriptEnabled());
    if (error)
      throw new Error(error);
  }

  async _performPointerAction(action: (point: types.Point) => Promise<void>, options?: input.PointerActionOptions): Promise<void> {
    const point = await this._world.delegate.ensurePointerActionPoint(this, options ? options.relativePoint : undefined);
    let restoreModifiers: input.Modifier[] | undefined;
    if (options && options.modifiers)
      restoreModifiers = await this._world.delegate.keyboard._ensureModifiers(options.modifiers);
    await action(point);
    if (restoreModifiers)
      await this._world.delegate.keyboard._ensureModifiers(restoreModifiers);
  }

  hover(options?: input.PointerActionOptions): Promise<void> {
    return this._performPointerAction(point => this._world.delegate.mouse.move(point.x, point.y), options);
  }

  click(options?: input.ClickOptions): Promise<void> {
    return this._performPointerAction(point => this._world.delegate.mouse.click(point.x, point.y, options), options);
  }

  dblclick(options?: input.MultiClickOptions): Promise<void> {
    return this._performPointerAction(point => this._world.delegate.mouse.dblclick(point.x, point.y, options), options);
  }

  tripleclick(options?: input.MultiClickOptions): Promise<void> {
    return this._performPointerAction(point => this._world.delegate.mouse.tripleclick(point.x, point.y, options), options);
  }

  async select(...values: (string | ElementHandle | input.SelectOption)[]): Promise<string[]> {
    const options = values.map(value => typeof value === 'object' ? value : { value });
    for (const option of options) {
      if (option instanceof ElementHandle)
        continue;
      if (option.value !== undefined)
        assert(helper.isString(option.value), 'Values must be strings. Found value "' + option.value + '" of type "' + (typeof option.value) + '"');
      if (option.label !== undefined)
        assert(helper.isString(option.label), 'Labels must be strings. Found label "' + option.label + '" of type "' + (typeof option.label) + '"');
      if (option.index !== undefined)
        assert(helper.isNumber(option.index), 'Indices must be numbers. Found index "' + option.index + '" of type "' + (typeof option.index) + '"');
    }
    return this.evaluate(input.selectFunction, ...options);
  }

  async fill(value: string): Promise<void> {
    assert(helper.isString(value), 'Value must be string. Found value "' + value + '" of type "' + (typeof value) + '"');
    const error = await this.evaluate(input.fillFunction);
    if (error)
      throw new Error(error);
    await this.focus();
    await this._world.delegate.keyboard.sendCharacters(value);
  }

  async setInputFiles(...files: (string|input.FilePayload)[]) {
    const multiple = await this.evaluate((element: HTMLInputElement) => !!element.multiple);
    assert(multiple || files.length <= 1, 'Non-multiple file input can only accept single file!');
    await this._world.delegate.setInputFiles(this, await input.loadFiles(files));
  }

  async focus() {
    await this.evaluate(element => element.focus());
  }

  async type(text: string, options: { delay: (number | undefined); } | undefined) {
    await this.focus();
    await this._world.delegate.keyboard.type(text, options);
  }

  async press(key: string, options: { delay?: number; text?: string; } | undefined) {
    await this.focus();
    await this._world.delegate.keyboard.press(key, options);
  }

  async boundingBox(): Promise<types.Rect | null> {
    return this._world.delegate.boundingBox(this);
  }

  async screenshot(options: any = {}): Promise<string | Buffer> {
    return this._world.delegate.screenshot(this, options);
  }

  async $(selector: string): Promise<ElementHandle | null> {
    const handle = await this.evaluateHandle(
        (root: SelectorRoot, selector: string, injected: Injected) => injected.querySelector('css=' + selector, root),
        selector, await this._world.injected()
    );
    const element = handle.asElement();
    if (element)
      return element;
    await handle.dispose();
    return null;
  }

  async $$(selector: string): Promise<ElementHandle[]> {
    const arrayHandle = await this.evaluateHandle(
        (root: SelectorRoot, selector: string, injected: Injected) => injected.querySelectorAll('css=' + selector, root),
        selector, await this._world.injected()
    );
    const properties = await arrayHandle.getProperties();
    await arrayHandle.dispose();
    const result = [];
    for (const property of properties.values()) {
      const elementHandle = property.asElement();
      if (elementHandle)
        result.push(elementHandle);
    }
    return result;
  }

  $eval: types.$Eval = async (selector, pageFunction, ...args) => {
    const elementHandle = await this.$(selector);
    if (!elementHandle)
      throw new Error(`Error: failed to find element matching selector "${selector}"`);
    const result = await elementHandle.evaluate(pageFunction, ...args as any);
    await elementHandle.dispose();
    return result;
  }

  $$eval: types.$$Eval = async (selector, pageFunction, ...args) => {
    const arrayHandle = await this.evaluateHandle(
        (root: SelectorRoot, selector: string, injected: Injected) => injected.querySelectorAll('css=' + selector, root),
        selector, await this._world.injected()
    );

    const result = await arrayHandle.evaluate(pageFunction, ...args as any);
    await arrayHandle.dispose();
    return result;
  }

  async $x(expression: string): Promise<ElementHandle[]> {
    const arrayHandle = await this.evaluateHandle(
        (root: SelectorRoot, expression: string, injected: Injected) => injected.querySelectorAll('xpath=' + expression, root),
        expression, await this._world.injected()
    );
    const properties = await arrayHandle.getProperties();
    await arrayHandle.dispose();
    const result = [];
    for (const property of properties.values()) {
      const elementHandle = property.asElement();
      if (elementHandle)
        result.push(elementHandle);
    }
    return result;
  }

  isIntersectingViewport(): Promise<boolean> {
    return this.evaluate(async element => {
      const visibleRatio = await new Promise(resolve => {
        const observer = new IntersectionObserver(entries => {
          resolve(entries[0].intersectionRatio);
          observer.disconnect();
        });
        observer.observe(element);
        // Firefox doesn't call IntersectionObserver callback unless
        // there are rafs.
        requestAnimationFrame(() => {});
      });
      return visibleRatio > 0;
    });
  }
}