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

import * as strings from 'CustomBrandingApplicationCustomizerStrings';

const LOG_SOURCE: string = 'CustomBrandingApplicationCustomizer';

/**
 * CSS-Datei Definition
 */
export interface ICssFile {
  path: string;
}

/**
 * Definition eines HTML-Elements
 */
export interface IBrandingElement {
  type: 'div' | 'span' | 'p' | 'a' | 'button' | 'img' | 'h1' | 'h2' | 'h3' | 'strong' | 'em';
  content?: string;
  attributes?: { [key: string]: string };
  styles?: { [key: string]: string };
  children?: IBrandingElement[];
}

export interface IPlaceholderConfig {
  elements?: IBrandingElement[];
}

/**
 * Hauptkonfiguration für das Branding
 */
export interface IBrandingConfig {
  cssfiles?: ICssFile[];
  placeholdertop?: IBrandingElement[];
  placeholderbottom?: IBrandingElement[];
}

/**
 * Properties für den CustomBranding Application Customizer
 */
export interface ICustomBrandingApplicationCustomizerProperties {
  /**
   * Array von CSS-Dateien die geladen werden sollen
   */
  cssfiles?: ICssFile[];

  /**
   * Array von HTML-Elementen für den Placeholder Top
   */
  placeholdertop?: IPlaceholderConfig;

  /**
   * Array von HTML-Elementen für den Placeholder Bottom
   */
  placeholderbottom?: IPlaceholderConfig;
}

/**
 * CustomBranding Application Customizer
 * Kompiliert JSON-Konfiguration zu HTML und fügt es in den Top Placeholder ein
 * Lädt optional CSS-Dateien
 */
export default class CustomBrandingApplicationCustomizer
  extends BaseApplicationCustomizer<ICustomBrandingApplicationCustomizerProperties> {

  private _topPlaceholder: PlaceholderContent | undefined;
  private _bottomPlaceholder: PlaceholderContent | undefined;
  private _loadedCssFiles: string[] = [];

  @override
  public onInit(): Promise<void> {
    Log.info(LOG_SOURCE, 'Initialized CustomBrandingApplicationCustomizer');

    // CSS-Dateien laden
    this._loadCssFiles();

    // Auf Placeholder-Änderungen reagieren
    this.context.placeholderProvider.changedEvent.add(this, this._renderPlaceHolders);

    // Initial rendern
    this._renderPlaceHolders();

    return Promise.resolve();
  }

  /**
   * Lädt CSS-Dateien aus der Konfiguration
   */
  private _loadCssFiles(): void {
    if (this.properties && this.properties.cssfiles && Array.isArray(this.properties.cssfiles)) {
      console.log('CustomBranding: Loading CSS files...');

      for (let i = 0; i < this.properties.cssfiles.length; i++) {
        const cssFile = this.properties.cssfiles[i];

        if (cssFile && cssFile.path) {
          this._injectCssFile(cssFile.path);
        }
      }
    }
  }

  /**
   * Fügt eine CSS-Datei in den Head ein
   */
  private _injectCssFile(cssPath: string): void {
    // Prüfen ob die Datei bereits geladen wurde
    for (let i = 0; i < this._loadedCssFiles.length; i++) {
      if (this._loadedCssFiles[i] === cssPath) {
        console.log('CustomBranding: CSS file already loaded: ' + cssPath);
        return;
      }
    }

    try {
      // Link-Element erstellen
      const linkElement: HTMLLinkElement = document.createElement('link');
      linkElement.rel = 'stylesheet';
      linkElement.type = 'text/css';
      linkElement.href = cssPath;
      linkElement.setAttribute('data-custom-branding', 'true');

      // Event-Handler für erfolgreiches Laden
      linkElement.onload = function () {
        console.log('CustomBranding: CSS loaded successfully: ' + cssPath);
      };

      // Event-Handler für Fehler
      linkElement.onerror = function () {
        console.error('CustomBranding: Failed to load CSS: ' + cssPath);
      };

      // In Head einfügen
      document.head.appendChild(linkElement);

      // Zur Liste hinzufügen
      this._loadedCssFiles.push(cssPath);

      console.log('CustomBranding: CSS file injected: ' + cssPath);
    } catch (error) {
      console.error('CustomBranding: Error injecting CSS file: ' + cssPath, error);
    }
  }

  private _renderPlaceHolders(): void {
    console.log('CustomBrandingApplicationCustomizer._renderPlaceHolders()');

    // Prüfen ob Top Placeholder verfügbar ist
    if (!this._topPlaceholder && !this._bottomPlaceholder) {
      this._topPlaceholder = this.context.placeholderProvider.tryCreateContent(
        PlaceholderName.Top,
        { onDispose: this._onDispose }
      );

      this._bottomPlaceholder = this.context.placeholderProvider.tryCreateContent(
        PlaceholderName.Bottom,
        { onDispose: this._onDispose }
      );

      // Falls Placeholder nicht verfügbar, abbrechen
      if (!this._topPlaceholder) {
        console.error('CustomBranding: Top placeholder not found');
        return;
      }

      // Falls Placeholder nicht verfügbar, abbrechen
      if (!this._bottomPlaceholder) {
        console.error('CustomBranding: Bottom placeholder not found');
        return;
      }

      if (this._topPlaceholder.domElement && this._bottomPlaceholder.domElement) {
        // Container erstellen mit hoher Priorität
        this.renderPlaceHolder(this._topPlaceholder.domElement, this._bottomPlaceholder.domElement);

        console.log('CustomBranding: HTML injected successfully');
      }
    }
  }

  private renderPlaceHolder(topcontainer: HTMLElement, bottomcontainer: HTMLElement) {

    if (!this.properties) {
      console.log('CustomBranding: No properties provided');
      return;
    }

    try {
      // Top-Konfiguration unverändert übernehmen
      const topConfig: IPlaceholderConfig | undefined =
        this.properties.placeholdertop;

      // Bottom-Konfiguration klonen oder initialisieren
      const bottomConfig: IPlaceholderConfig =
        this.properties.placeholderbottom
          ? { ...this.properties.placeholderbottom }
          : { elements: [] };

      // Admin-Link nur für Site Collection Admins ergänzen
      if (this._isSiteAdmin()) {
        bottomConfig.elements = bottomConfig.elements || [];
        bottomConfig.elements.push(this._getAdminFooterElement());
      }

      const config: IBrandingConfig = {
        cssfiles: this.properties.cssfiles,
        placeholdertop: topConfig.elements,
        placeholderbottom: bottomConfig.elements
      };

      console.log('CustomBranding: Compiling JSON to HTML...');
      const compiled = this._compileToHtml(config);

      topcontainer.id = 'CustomHeader';
      topcontainer.innerHTML = compiled.top;

      bottomcontainer.id = 'CustomFooter';
      bottomcontainer.innerHTML = compiled.bottom;

    } catch (error) {
      console.error('CustomBranding: Error compiling configuration', error);
    }
  }


  /**
   * Kompiliert die JSON-Konfiguration zu HTML
   */
  private _compileToHtml(config: IBrandingConfig): { top: string; bottom: string } {
    // Compile Top and Bottom separately 
    let topHtml: string = '';
    let bottomHtml: string = '';
    if (config.placeholdertop && Array.isArray(config.placeholdertop)) {
      for (let i = 0; i < config.placeholdertop.length; i++) { topHtml += this._createElement(config.placeholdertop[i]); }
    }
    if (config.placeholderbottom && Array.isArray(config.placeholderbottom)) {
      for (let i = 0; i < config.placeholderbottom.length; i++) { bottomHtml += this._createElement(config.placeholderbottom[i]); }
    }
    return { top: topHtml, bottom: bottomHtml };
  }

  /**
   * Erstellt HTML für ein einzelnes Element
   */
  private _createElement(element: IBrandingElement): string {
    const tag = element.type || 'div';
    let html = '<' + tag;

    // Attribute hinzufügen
    if (element.attributes) {
      for (const key in element.attributes) {
        if (element.attributes.hasOwnProperty(key)) {
          const value = element.attributes[key];
          html += ' ' + key + '="' + this._escapeHtml(value) + '"';
        }
      }
    }

    // Styles hinzufügen
    if (element.styles) {
      const styleArray: string[] = [];
      for (const key in element.styles) {
        if (element.styles.hasOwnProperty(key)) {
          const value = element.styles[key];
          styleArray.push(key + ':' + value);
        }
      }
      if (styleArray.length > 0) {
        const styleString = styleArray.join(';');
        html += ' style="' + styleString + '"';
      }
    }

    html += '>';

    // Content hinzufügen
    if (element.content) {
      html += this._escapeHtml(element.content);
    }

    // Kinder hinzufügen
    if (element.children && Array.isArray(element.children)) {
      for (let i = 0; i < element.children.length; i++) {
        html += this._createElement(element.children[i]);
      }
    }

    // Self-closing Tags behandeln
    const selfClosingTags = ['img', 'br', 'hr', 'input'];
    let isSelfClosing = false;
    for (let i = 0; i < selfClosingTags.length; i++) {
      if (selfClosingTags[i] === tag) {
        isSelfClosing = true;
        break;
      }
    }

    if (!isSelfClosing) {
      html += '</' + tag + '>';
    }

    return html;
  }

  private _isSiteAdmin(): boolean {
    return this.context.pageContext.legacyPageContext.isSiteAdmin === true;
  }

  private _getAdminFooterElement(): IBrandingElement {
    const siteUrl = this.context.pageContext.site.absoluteUrl;

    return {
      type: 'div',
      styles: {
        'text-align': 'right',
        'padding': '8px 16px',
        'border-top': '1px solid #e1e1e1',
        'background-color': '#f8f8f8',
        'font-size': '13px'
      },
      children: [
        {
          type: 'a',
          content: 'Einstellungen',
          attributes: {
            href: `${siteUrl}/SitePages/PortalSettings.aspx`
          },
          styles: {
            'text-decoration': 'none',
            'font-weight': '600'
          }
        }
      ]
    };
  }

  /**
   * Escaped HTML-Zeichen für Sicherheit
   */
  private _escapeHtml(text: string): string {
    const map: { [key: string]: string } = {
      '&': '&amp;',
      '<': '&lt;',
      '>': '&gt;',
      '"': '&quot;',
      "'": '&#039;'
    };

    return text.replace(/[&<>"']/g, function (m) {
      return map[m];
    });
  }

  private _onDispose(): void {
    console.log('CustomBrandingApplicationCustomizer._onDispose()');

    // CSS-Dateien beim Dispose entfernen
    const cssLinks = document.querySelectorAll('link[data-custom-branding="true"]');
    for (let i = 0; i < cssLinks.length; i++) {
      const link = cssLinks[i];
      if (link.parentNode) {
        link.parentNode.removeChild(link);
      }
    }
  }
}