import { Injectable } from '@angular/core';

export interface SitemapUrl {
  loc: string;
  lastmod?: string;
  changefreq?: 'always' | 'hourly' | 'daily' | 'weekly' | 'monthly' | 'yearly' | 'never';
  priority?: number;
}

@Injectable({
  providedIn: 'root'
})
export class SitemapService {
  private readonly baseUrl = 'https://biz-match.com';

  /**
   * Generate XML sitemap content
   */
  generateSitemap(urls: SitemapUrl[]): string {
    const urlElements = urls.map(url => this.generateUrlElement(url)).join('\n  ');

    return `<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  ${urlElements}
</urlset>`;
  }

  /**
   * Generate a single URL element for the sitemap
   */
  private generateUrlElement(url: SitemapUrl): string {
    let element = `<url>\n    <loc>${url.loc}</loc>`;

    if (url.lastmod) {
      element += `\n    <lastmod>${url.lastmod}</lastmod>`;
    }

    if (url.changefreq) {
      element += `\n    <changefreq>${url.changefreq}</changefreq>`;
    }

    if (url.priority !== undefined) {
      element += `\n    <priority>${url.priority.toFixed(1)}</priority>`;
    }

    element += '\n  </url>';
    return element;
  }

  /**
   * Generate sitemap URLs for static pages
   */
  getStaticPageUrls(): SitemapUrl[] {
    return [
      {
        loc: `${this.baseUrl}/`,
        changefreq: 'daily',
        priority: 1.0
      },
      {
        loc: `${this.baseUrl}/home`,
        changefreq: 'daily',
        priority: 1.0
      },
      {
        loc: `${this.baseUrl}/listings`,
        changefreq: 'daily',
        priority: 0.9
      },
      {
        loc: `${this.baseUrl}/listings-2`,
        changefreq: 'daily',
        priority: 0.8
      },
      {
        loc: `${this.baseUrl}/listings-3`,
        changefreq: 'daily',
        priority: 0.8
      },
      {
        loc: `${this.baseUrl}/listings-4`,
        changefreq: 'daily',
        priority: 0.8
      }
    ];
  }

  /**
   * Generate sitemap URLs for business listings
   */
  generateBusinessListingUrls(listings: any[]): SitemapUrl[] {
    return listings.map(listing => ({
      loc: `${this.baseUrl}/details-business-listing/${listing.id}`,
      lastmod: this.formatDate(listing.updated || listing.created),
      changefreq: 'weekly' as const,
      priority: 0.8
    }));
  }

  /**
   * Generate sitemap URLs for commercial property listings
   */
  generateCommercialPropertyUrls(properties: any[]): SitemapUrl[] {
    return properties.map(property => ({
      loc: `${this.baseUrl}/details-commercial-property/${property.id}`,
      lastmod: this.formatDate(property.updated || property.created),
      changefreq: 'weekly' as const,
      priority: 0.8
    }));
  }

  /**
   * Format date to ISO 8601 format (YYYY-MM-DD)
   */
  private formatDate(date: Date | string): string {
    const d = typeof date === 'string' ? new Date(date) : date;
    return d.toISOString().split('T')[0];
  }

  /**
   * Generate complete sitemap with all URLs
   */
  async generateCompleteSitemap(
    businessListings: any[],
    commercialProperties: any[]
  ): Promise<string> {
    const allUrls = [
      ...this.getStaticPageUrls(),
      ...this.generateBusinessListingUrls(businessListings),
      ...this.generateCommercialPropertyUrls(commercialProperties)
    ];

    return this.generateSitemap(allUrls);
  }
}