/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {NgModule, InjectionToken, Optional, Inject, isDevMode, Version} from '@angular/core';
import {HammerLoader, HAMMER_LOADER} from '@angular/platform-browser';
import {BidiModule} from '@angular/cdk/bidi';
import {VERSION as CDK_VERSION} from '@angular/cdk';

// Private version constant to circumvent test/build issues,
// i.e. avoid core to depend on the @angular/material primary entry-point
// Can be removed once the Material primary entry-point no longer
// re-exports all secondary entry-points
const VERSION = new Version('0.0.0-PLACEHOLDER');

/** @docs-private */
export function MATERIAL_SANITY_CHECKS_FACTORY(): boolean {
  return true;
}

/** Injection token that configures whether the Material sanity checks are enabled. */
export const MATERIAL_SANITY_CHECKS = new InjectionToken<boolean>('mat-sanity-checks', {
  providedIn: 'root',
  factory: MATERIAL_SANITY_CHECKS_FACTORY,
});

/**
 * Module that captures anything that should be loaded and/or run for *all* Angular Material
 * components. This includes Bidi, etc.
 *
 * This module should be imported to each top-level component module (e.g., MatTabsModule).
 */
@NgModule({
  imports: [BidiModule],
  exports: [BidiModule],
})
export class MatCommonModule {
  /** Whether we've done the global sanity checks (e.g. a theme is loaded, there is a doctype). */
  private _hasDoneGlobalChecks = false;

  /** Whether we've already checked for HammerJs availability. */
  private _hasCheckedHammer = false;

  /** Reference to the global `document` object. */
  private _document = typeof document === 'object' && document ? document : null;

  /** Reference to the global 'window' object. */
  private _window = typeof window === 'object' && window ? window : null;

  constructor(
    @Optional() @Inject(MATERIAL_SANITY_CHECKS) private _sanityChecksEnabled: boolean,
    @Optional() @Inject(HAMMER_LOADER) private _hammerLoader?: HammerLoader) {

    if (this._areChecksEnabled() && !this._hasDoneGlobalChecks) {
      this._checkDoctypeIsDefined();
      this._checkThemeIsPresent();
      this._checkCdkVersionMatch();
      this._hasDoneGlobalChecks = true;
    }
  }

  /** Whether any sanity checks are enabled */
  private _areChecksEnabled(): boolean {
    return this._sanityChecksEnabled && isDevMode() && !this._isTestEnv();
  }

  /** Whether the code is running in tests. */
  private _isTestEnv() {
    const window = this._window as any;
    return window && (window.__karma__ || window.jasmine);
  }

  private _checkDoctypeIsDefined(): void {
    if (this._document && !this._document.doctype) {
      console.warn(
        'Current document does not have a doctype. This may cause ' +
        'some Angular Material components not to behave as expected.'
      );
    }
  }

  private _checkThemeIsPresent(): void {
    // We need to assert that the `body` is defined, because these checks run very early
    // and the `body` won't be defined if the consumer put their scripts in the `head`.
    if (!this._document || !this._document.body || typeof getComputedStyle !== 'function') {
      return;
    }

    const testElement = this._document.createElement('div');

    testElement.classList.add('mat-theme-loaded-marker');
    this._document.body.appendChild(testElement);

    const computedStyle = getComputedStyle(testElement);

    // In some situations the computed style of the test element can be null. For example in
    // Firefox, the computed style is null if an application is running inside of a hidden iframe.
    // See: https://bugzilla.mozilla.org/show_bug.cgi?id=548397
    if (computedStyle && computedStyle.display !== 'none') {
      console.warn(
        'Could not find Angular Material core theme. Most Material ' +
        'components may not work as expected. For more info refer ' +
        'to the theming guide: https://material.angular.io/guide/theming'
      );
    }

    this._document.body.removeChild(testElement);
  }

  /** Checks whether the material version matches the cdk version */
  private _checkCdkVersionMatch(): void {
    if (VERSION.full !== CDK_VERSION.full) {
      console.warn(
          'The Angular Material version (' + VERSION.full + ') does not match ' +
          'the Angular CDK version (' + CDK_VERSION.full + ').\n' +
          'Please ensure the versions of these two packages exactly match.'
      );
    }
  }

  /** Checks whether HammerJS is available. */
  _checkHammerIsAvailable(): void {
    if (this._hasCheckedHammer || !this._window) {
      return;
    }

    if (this._areChecksEnabled() && !(this._window as any)['Hammer'] && !this._hammerLoader) {
      console.warn(
        'Could not find HammerJS. Certain Angular Material components may not work correctly.');
    }
    this._hasCheckedHammer = true;
  }
}