// tslint:disable:max-line-length
// tslint:disable:match-default-export-name
// tslint:disable:typedef
// tslint:disable:variable-name

import { override } from '@microsoft/decorators';
import {
  BaseApplicationCustomizer,
  PlaceholderContent,
  PlaceholderName
} from '@microsoft/sp-application-base';

import * as strings from 'MegaMenuApplicationCustomizerStrings';
import { TaxonomyNavigationService } from '../../services/TaxonomyNavigationService';
import { MegaMenuRenderer } from './MegaMenuRenderer';
import { IMenuItem } from '../../services/IMenuItem';
import { debugError, debugLog, debugWarn } from '../../services/MegaMenuDebug';

import './MegaMenu.module.scss';

const LOG_SOURCE: string = 'MegaMenuApplicationCustomizer';
export const UserCustomActionMegaMenuId: string = 'abc3361f-bb2d-491f-aba3-cd51c19a299b';

export interface IMegaMenuApplicationCustomizerProperties {
  termSetName?: string;
  termSetId?: string;
  cacheMinutes?: number;
  cssUrl?: string;
  debug?: boolean;
}

export default class MegaMenuApplicationCustomizer
  extends BaseApplicationCustomizer<IMegaMenuApplicationCustomizerProperties> {

  private _topPlaceholder: PlaceholderContent | undefined;
  private _menuContainer: HTMLElement | undefined;
  private _renderer: MegaMenuRenderer | undefined;

  @override
  public onInit(): Promise<void> {
    debugLog(this._isDebugEnabled(), LOG_SOURCE, 'Initialized ' + strings.Title);

    if (this.properties.cssUrl) {
      this._loadExternalCss(this.properties.cssUrl);
    }

    this.context.placeholderProvider.changedEvent.add(this, this._renderPlaceHolders);
    this._renderPlaceHolders();

    return Promise.resolve();
  }

  private _renderPlaceHolders(): void {
    const availablePlaceholders: string = this.context.placeholderProvider.placeholderNames
      .map(name => PlaceholderName[name])
      .join(', ');

    debugLog(this._isDebugEnabled(), LOG_SOURCE, 'Available placeholders:', availablePlaceholders);

    if (!this._topPlaceholder) {
      this._topPlaceholder = this.context.placeholderProvider.tryCreateContent(
        PlaceholderName.Top,
        { onDispose: this._onDispose }
      );

      if (!this._topPlaceholder) {
        debugError(this._isDebugEnabled(), LOG_SOURCE, 'The expected placeholder (Top) was not found.');
        return;
      }

      const termSetIdentifier: string = this._getTermSetIdentifier();
      if (!termSetIdentifier) {
        debugWarn(this._isDebugEnabled(), LOG_SOURCE, 'No termSetId or termSetName configured. Mega Menu rendering is skipped.');
        this._renderStatus(strings.ConfigurationMissing);
        return;
      }

      this._renderMegaMenu(termSetIdentifier);
    }
  }

  private async _renderMegaMenu(termSetIdentifier: string, debug: boolean = this._isDebugEnabled()): Promise<void> {
    if (!this._topPlaceholder) {
      return;
    }

    try {
      const taxonomyService: TaxonomyNavigationService = new TaxonomyNavigationService(
        this.context,
        termSetIdentifier,
        debug,
        this._getCacheMinutes()
      );

      const menuItems: IMenuItem[] = await taxonomyService.getMenuItems();

      if (this._renderer) {
        this._renderer.dispose();
      }

      this._renderer = new MegaMenuRenderer(
        menuItems,
        debug
      );

      this._menuContainer = this._getOrCreateContainer('CustomHeader', this._topPlaceholder);

      if (this._menuContainer) {
        this._renderer.render(this._menuContainer);
      } else {
        this._renderer.render(this._topPlaceholder.domElement);
      }

      debugLog(debug, LOG_SOURCE, 'MegaMenu rendered successfully with ' + menuItems.length + ' top-level items.');
    } catch (error) {
      debugError(debug, LOG_SOURCE, 'Error rendering MegaMenu.', error);
      this._renderStatus(strings.LoadError);
    }
  }

  private _getOrCreateContainer(id: string, placeholder: PlaceholderContent): HTMLElement {
    const container = document.getElementById(id);

    if (container) {
      let host: HTMLElement = document.getElementById('MegaMenuHost');
      if (!host) {
        host = document.createElement('div');
        host.id = 'MegaMenuHost';
        container.appendChild(host);
      }
      return host;
    }

    return placeholder.domElement;
  }

  private _loadExternalCss(cssUrl?: string, debug: boolean = this._isDebugEnabled()): void {
    const externalCssLinkId: string = 'mega-menu-additional-css-34FAB720';
    let link: HTMLLinkElement = document.getElementById(externalCssLinkId) as HTMLLinkElement;

    if (cssUrl && cssUrl.trim() !== '') {
      const validatedUrl: string | undefined = this._validateCssUrl(cssUrl);
      if (!validatedUrl) {
        debugWarn(debug, LOG_SOURCE, 'Rejected unsafe external CSS URL:', cssUrl);
        if (link) {
          link.remove();
        }
        return;
      }

      if (!link) {
        const head: HTMLHeadElement = document.getElementsByTagName('head')[0];
        link = document.createElement('link');
        link.rel = 'stylesheet';
        link.type = 'text/css';
        link.id = externalCssLinkId;
        link.onload = () => {
          debugLog(debug, LOG_SOURCE, 'External CSS loaded successfully from:', cssUrl);
        };
        link.onerror = () => {
          debugWarn(debug, LOG_SOURCE, 'Failed to load external CSS from:', cssUrl);
        };
        head.appendChild(link);
      }

      link.href = validatedUrl;
    } else if (link) {
      link.remove();
    }
  }

  private _onDispose = (): void => {
    this.context.placeholderProvider.changedEvent.remove(this, this._renderPlaceHolders);
    if (this._renderer) {
      this._renderer.dispose();
      this._renderer = undefined;
    }
    const externalCssLink: HTMLElement = document.getElementById('mega-menu-additional-css-34FAB720');
    if (externalCssLink) {
      externalCssLink.remove();
    }
    this._menuContainer = undefined;
    this._topPlaceholder = undefined;
    debugLog(this._isDebugEnabled(), LOG_SOURCE, 'Disposed custom top placeholder.');
  }

  private _getTermSetIdentifier(): string {
    const termSetId: string = this.properties && this.properties.termSetId
      ? this.properties.termSetId.trim()
      : '';
    if (termSetId && this._isGuid(termSetId)) {
      return termSetId;
    }
    return this.properties && this.properties.termSetName
      ? this.properties.termSetName.trim()
      : '';
  }

  private _getCacheMinutes(): number {
    const value: number = this.properties ? Number(this.properties.cacheMinutes) : 15;
    return isFinite(value) ? Math.min(Math.max(Math.floor(value), 1), 1440) : 15;
  }

  private _validateCssUrl(cssUrl: string): string | undefined {
    try {
      const parsed: URL = new URL(cssUrl.trim(), window.location.origin);
      const isHttp: boolean = parsed.protocol === 'http:' || parsed.protocol === 'https:';
      const isSameOrigin: boolean = parsed.origin === window.location.origin;
      if (!isHttp || (!isSameOrigin && parsed.protocol !== 'https:')) {
        return undefined;
      }
      return parsed.href;
    } catch (error) {
      return undefined;
    }
  }

  private _renderStatus(message: string): void {
    if (!this._topPlaceholder) {
      return;
    }
    this._menuContainer = this._getOrCreateContainer('CustomHeader', this._topPlaceholder);
    const container: HTMLElement = this._menuContainer || this._topPlaceholder.domElement;
    container.innerHTML = '';
    const status: HTMLElement = document.createElement('div');
    status.className = 'mega-menu-status';
    status.setAttribute('role', 'status');
    status.textContent = message;
    container.appendChild(status);
  }

  private _isGuid(value: string): boolean {
    return /^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$/.test(value);
  }

  private _isDebugEnabled(debugOverride?: boolean): boolean {
    if (typeof debugOverride === 'boolean') {
      return debugOverride;
    }

    return !!(this.properties && this.properties.debug === true);
  }
}