import type { Metadata } from 'next';

export interface SeoConfig {
  brandNameFa: string;
  brandNameEn: string;
  titleSeparator: string;
  titlePosition: 'suffix' | 'prefix' | 'none';
  defaultMetaTitle: string;
  defaultMetaDescription: string;
  keywords: string[];
  canonicalBaseUrl: string;
  ogImageUrl: string;
  googleSiteVerification?: string;
  googleAnalyticsId?: string;
  googleTagManagerId?: string;
  enableGoogleAnalytics?: boolean;
  enableGoogleTagManager?: boolean;
  clarityProjectId?: string;
  texts: Record<string, string>;
}

const DEFAULT_SEO_CONFIG: SeoConfig = {
  brandNameFa: 'کنینا ایران',
  brandNameEn: 'Canina Iran',
  titleSeparator: '|',
  titlePosition: 'suffix',
  defaultMetaTitle: 'کنینا ایران | نماینده رسمی مکمل‌های دارویی Canina آلمان',
  defaultMetaDescription: 'فروشگاه تخصصی و نماینده انحصاری مکمل‌های درمانی و تقویتی سگ و گربه کنینا آلمان با فرمولاسیون دارویی و تاییدیه بالینی.',
  keywords: ['کنینا', 'مکمل حیوانات خانگی', 'مکمل سگ', 'مکمل گربه', 'داروی حیوانات', 'Canina Iran'],
  canonicalBaseUrl: 'https://canina.ir',
  ogImageUrl: '/assets/images/regenerated_image_1779109861747.png',
  googleSiteVerification: '',
  googleAnalyticsId: '',
  googleTagManagerId: '',
  enableGoogleAnalytics: true,
  enableGoogleTagManager: true,
  clarityProjectId: '',
  texts: {},
};

/**
 * Fetch dynamic SEO settings and UI texts on server with 60-second revalidation
 */
export async function getSeoConfig(): Promise<SeoConfig> {
  const apiBase =
    process.env.INTERNAL_API_URL ||
    process.env.NEXT_PUBLIC_API_URL ||
    'http://localhost:4001/api';

  try {
    const res = await fetch(`${apiBase}/settings/ui-texts`, {
      next: { revalidate: 60, tags: ['ui-texts', 'settings'] },
    });

    if (res.ok) {
      const data = await res.json();
      const texts: Record<string, string> = {};

      if (Array.isArray(data)) {
        data.forEach((item: { key: string; value: string }) => {
          if (item?.key) texts[item.key] = item.value;
        });
      } else if (typeof data === 'object' && data !== null) {
        Object.entries(data).forEach(([k, v]) => {
          texts[k] = String(v);
        });
      }

      const brandNameFa =
        texts['brand_name_fa'] ||
        texts['BRAND_LOGO_TEXT_FA'] ||
        texts['site_logo_text_fa'] ||
        DEFAULT_SEO_CONFIG.brandNameFa;

      const brandNameEn =
        texts['brand_name_en'] ||
        texts['BRAND_LOGO_TEXT_EN'] ||
        DEFAULT_SEO_CONFIG.brandNameEn;

      const titleSeparator =
        texts['title_separator'] || DEFAULT_SEO_CONFIG.titleSeparator;

      const titlePositionRaw = texts['title_position']?.toLowerCase();
      const titlePosition: 'suffix' | 'prefix' | 'none' =
        titlePositionRaw === 'prefix' || titlePositionRaw === 'none'
          ? titlePositionRaw
          : 'suffix';

      const defaultMetaTitle =
        texts['defaultMetaTitle'] ||
        texts['home_meta_title'] ||
        DEFAULT_SEO_CONFIG.defaultMetaTitle;

      const defaultMetaDescription =
        texts['defaultMetaDescription'] ||
        texts['home_meta_desc'] ||
        DEFAULT_SEO_CONFIG.defaultMetaDescription;

      const rawKeywords = texts['keywords'] || texts['home_keywords'];
      const keywords = rawKeywords
        ? rawKeywords.split(',').map((k) => k.trim()).filter(Boolean)
        : DEFAULT_SEO_CONFIG.keywords;

      const canonicalBaseUrl =
        texts['canonicalBaseUrl'] ||
        process.env.NEXT_PUBLIC_SITE_URL ||
        DEFAULT_SEO_CONFIG.canonicalBaseUrl;

      const ogImageUrl =
        texts['ogImageUrl'] || DEFAULT_SEO_CONFIG.ogImageUrl;

      const googleSiteVerification =
        texts['googleSiteVerification'] ||
        texts['google_site_verification'] ||
        process.env.NEXT_PUBLIC_GOOGLE_SITE_VERIFICATION ||
        '';

      const googleAnalyticsId =
        texts['googleAnalyticsId'] ||
        texts['ga_measurement_id'] ||
        process.env.NEXT_PUBLIC_GA_MEASUREMENT_ID ||
        '';

      const googleTagManagerId =
        texts['googleTagManagerId'] ||
        texts['gtm_id'] ||
        process.env.NEXT_PUBLIC_GTM_ID ||
        '';

      const enableGoogleAnalytics =
        texts['enableGoogleAnalytics'] !== undefined
          ? texts['enableGoogleAnalytics'] === 'true'
          : true;

      const enableGoogleTagManager =
        texts['enableGoogleTagManager'] !== undefined
          ? texts['enableGoogleTagManager'] === 'true'
          : true;

      const clarityProjectId =
        texts['clarityProjectId'] ||
        texts['clarity_project_id'] ||
        process.env.NEXT_PUBLIC_CLARITY_PROJECT_ID ||
        '';

      return {
        brandNameFa,
        brandNameEn,
        titleSeparator,
        titlePosition,
        defaultMetaTitle,
        defaultMetaDescription,
        keywords,
        canonicalBaseUrl,
        ogImageUrl,
        googleSiteVerification,
        googleAnalyticsId,
        googleTagManagerId,
        enableGoogleAnalytics,
        enableGoogleTagManager,
        clarityProjectId,
        texts,
      };
    }
  } catch (error) {
    console.warn('[SEO] Unable to fetch dynamic settings from backend, using fallback:', error);
  }

  return DEFAULT_SEO_CONFIG;
}

/**
 * Uniform Page Title Formatter according to Store Brand Configuration
 */
export function formatPageTitle(
  rawTitle: string,
  brandName = 'کنینا ایران',
  separator = '|',
  position: 'suffix' | 'prefix' | 'none' = 'suffix',
  isHomePage = false
): string {
  if (!rawTitle || !rawTitle.trim()) {
    return brandName;
  }

  const clean = rawTitle.trim();

  // If this is the home page and has a custom full title configured, return it directly
  if (isHomePage) {
    return clean;
  }

  // Check if the title already explicitly contains the brand name
  const escapedBrand = brandName.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
  const brandRegex = new RegExp(`(\\s*[-|•]\\s*${escapedBrand}|${escapedBrand}\\s*[-|•]\\s*)`, 'gi');

  // Strip existing repeated brand affix if present so we can format cleanly
  const baseTitle = clean.replace(brandRegex, '').trim();

  if (position === 'none') {
    return baseTitle || clean;
  }

  if (position === 'prefix') {
    return `${brandName} ${separator} ${baseTitle || clean}`;
  }

  // Default: 'suffix' -> "{PageTitle} {separator} {BrandName}"
  return `${baseTitle || clean} ${separator} ${brandName}`;
}

export interface PageMetadataOptions {
  fallbackTitle?: string;
  fallbackDesc?: string;
  fallbackKeywords?: string[];
  canonicalPath?: string;
  ogImage?: string;
  isDynamicEntity?: boolean; // For PDP / Blog / Wiki detail
  noIndex?: boolean;
}

/**
 * Generate standard Next.js Metadata object dynamically from server settings
 */
export async function getPageMetadata(
  pageKey: string,
  options: PageMetadataOptions = {}
): Promise<Metadata> {
  const config = await getSeoConfig();
  const { texts, brandNameFa, titleSeparator, titlePosition, canonicalBaseUrl, ogImageUrl } = config;

  const isHome = pageKey === 'home';
  const rawTitle =
    texts[`${pageKey}_meta_title`] ||
    options.fallbackTitle ||
    config.defaultMetaTitle;

  const title = options.isDynamicEntity
    ? formatPageTitle(rawTitle, brandNameFa, titleSeparator, titlePosition, false)
    : formatPageTitle(rawTitle, brandNameFa, titleSeparator, titlePosition, isHome);

  const description =
    texts[`${pageKey}_meta_desc`] ||
    options.fallbackDesc ||
    config.defaultMetaDescription;

  const rawKeywords = texts[`${pageKey}_keywords`];
  const keywords = rawKeywords
    ? rawKeywords.split(',').map((k) => k.trim()).filter(Boolean)
    : options.fallbackKeywords || config.keywords;

  const explicitCanonical = texts[`${pageKey}_canonical`];
  const relativePath = options.canonicalPath ?? (isHome ? '/' : `/${pageKey.replace(/_/g, '-')}`);
  const canonicalUrl = explicitCanonical || `${canonicalBaseUrl.replace(/\/$/, '')}${relativePath}`;

  const image = options.ogImage || ogImageUrl;

  const isStaging =
    options.noIndex ||
    process.env.NEXT_PUBLIC_APP_ENV === 'staging' ||
    process.env.NODE_ENV !== 'production' ||
    (typeof process.env.NEXT_PUBLIC_SITE_URL === 'string' &&
      (process.env.NEXT_PUBLIC_SITE_URL.includes('stage') ||
        process.env.NEXT_PUBLIC_SITE_URL.includes('test') ||
        process.env.NEXT_PUBLIC_SITE_URL.includes('dev')));

  return {
    title,
    description,
    keywords,
    alternates: {
      canonical: canonicalUrl,
    },
    openGraph: {
      title,
      description,
      url: canonicalUrl,
      siteName: brandNameFa,
      locale: 'fa_IR',
      type: 'website',
      images: [
        {
          url: image,
          width: 1200,
          height: 630,
          alt: title,
        },
      ],
    },
    twitter: {
      card: 'summary_large_image',
      title,
      description,
      images: [image],
    },
    robots: isStaging
      ? {
          index: false,
          follow: false,
          nocache: true,
          googleBot: {
            index: false,
            follow: false,
            noimageindex: true,
          },
        }
      : {
          index: true,
          follow: true,
          googleBot: {
            index: true,
            follow: true,
            'max-video-preview': -1,
            'max-image-preview': 'large',
            'max-snippet': -1,
          },
        },
  };
}