import React from "react";
import { notFound } from 'next/navigation';
import type { Metadata } from 'next';
import BlogPostClient from "../../../components/BlogPostClient";
import { getSeoConfig, formatPageTitle } from "../../../lib/seo";
import { safeJsonLd } from "../../../lib/schema";

function safeIso(val: any, fallback?: string): string | undefined {
  if (!val) return fallback;
  try {
    const d = new Date(val);
    return isNaN(d.getTime()) ? fallback : d.toISOString();
  } catch {
    return fallback;
  }
}

function safeLocalDate(val: any): string {
  if (!val) return '';
  try {
    const d = new Date(val);
    return isNaN(d.getTime()) ? '' : d.toLocaleDateString('fa-IR');
  } catch {
    return '';
  }
}

async function getBlog(rawSlug: string) {
  if (!rawSlug) return null;
  try {
    const slug = decodeURIComponent(rawSlug);
    const apiUrl = process.env.INTERNAL_API_URL || process.env.NEXT_PUBLIC_API_URL || 'http://localhost:4001/api';
    const apiBase = apiUrl.endsWith('/api') ? apiUrl : `${apiUrl.replace(/\/$/, '')}/api`;
    const res = await fetch(`${apiBase}/blogs/${encodeURIComponent(slug)}`, {
      next: {
        tags: ['blogs', `blog-${slug}`],
        revalidate: 3600,
      },
    });
    if (!res.ok) {
      console.warn(`[Blog] Failed to fetch blog ${slug}: ${res.status}`);
      return null;
    }
    const b = await res.json();
    return b;
  } catch (error) {
    console.error('[Blog] Error fetching blog detail:', error);
    return null;
  }
}

export const revalidate = 3600;

export async function generateMetadata({ params }: { params: Promise<{ slug: string }> }): Promise<Metadata> {
  const { slug } = await params;
  const blog = await getBlog(slug);
  const config = await getSeoConfig();

  if (!blog) {
    return {
      title: formatPageTitle('مقاله یافت نشد', config.brandNameFa, config.titleSeparator, config.titlePosition),
    };
  }

  const rawSiteUrl = process.env.NEXT_PUBLIC_SITE_URL || config.canonicalBaseUrl || 'https://canina.ir';
  const siteUrl = rawSiteUrl.replace(/\/+$/, '');

  const metaTitle = blog.metaTitle || blog.title || 'مقاله آموزشی و تخصصی کنینا';
  const title = formatPageTitle(metaTitle, config.brandNameFa, config.titleSeparator, config.titlePosition, false);
  const description =
    blog.metaDescription ||
    blog.excerpt ||
    (typeof blog.content === 'string' ? blog.content.substring(0, 155).replace(/<[^>]+>/g, '') : '') ||
    config.defaultMetaDescription;
  const canonicalUrl = blog.canonicalUrl ? blog.canonicalUrl.replace(/\/+$/, '') : `${siteUrl}/blog/${slug}`;
  const ogImageUrl = blog.ogImage || blog.imageUrl || config.ogImageUrl;
  const ogTitle = blog.ogTitle || title;
  const ogDesc = blog.ogDescription || description;

  const authorName = blog.author
    ? `${blog.author.firstName || ''} ${blog.author.lastName || ''}`.trim() || 'نویسنده کنینا'
    : 'نویسنده و پژوهشگر کنینا';

  const publishedTime = safeIso(blog.publishedAt) || safeIso(blog.createdAt);
  const modifiedTime = safeIso(blog.updatedAt) || publishedTime;

  const keywordsList = blog.focusKeywords
    ? blog.focusKeywords.split(',').map((k: string) => k.trim())
    : blog.keywords
    ? blog.keywords.split(',').map((k: string) => k.trim())
    : undefined;

  return {
    title,
    description,
    keywords: keywordsList,
    alternates: {
      canonical: canonicalUrl,
    },
    robots: {
      index: !blog.noIndex,
      follow: !blog.noFollow,
      googleBot: {
        index: !blog.noIndex,
        follow: !blog.noFollow,
        'max-image-preview': 'large',
        'max-snippet': -1,
        'max-video-preview': -1,
      },
    },
    openGraph: {
      title: ogTitle,
      description: ogDesc,
      images: [
        {
          url: ogImageUrl,
          width: 1200,
          height: 630,
          alt: blog.imageAlt || blog.title || title,
        },
      ],
      url: canonicalUrl,
      siteName: config.brandNameFa,
      type: "article",
      publishedTime,
      modifiedTime,
      authors: [authorName],
      tags: blog.tags?.map((t: any) => typeof t === 'string' ? t : t?.name).filter(Boolean) || [],
    },
    twitter: {
      card: "summary_large_image",
      title: ogTitle,
      description: ogDesc,
      images: [ogImageUrl],
    },
  };
}

export default async function BlogPostPage({ params }: { params: Promise<{ slug: string }> }) {
  const { slug } = await params;
  const blog = await getBlog(slug);
  const config = await getSeoConfig();

  if (!blog) {
    notFound();
  }

  const rawSiteUrl = process.env.NEXT_PUBLIC_SITE_URL || config.canonicalBaseUrl || 'https://canina.ir';
  const siteUrl = rawSiteUrl.replace(/\/+$/, '');

  const authorName = blog.author
    ? `${blog.author.firstName || ''} ${blog.author.lastName || ''}`.trim() || 'نویسنده کنینا'
    : 'نویسنده و پژوهشگر کنینا';
  const publishedDate = safeLocalDate(blog.publishedAt) || safeLocalDate(blog.createdAt);

  const canonicalUrl = blog.canonicalUrl
    ? blog.canonicalUrl.replace(/\/+$/, '')
    : `${siteUrl}/blog/${slug}`;

  const publishedIso = safeIso(blog.publishedAt) || safeIso(blog.createdAt) || new Date().toISOString();
  const modifiedIso = safeIso(blog.updatedAt) || publishedIso;

  const schemaType = blog.schemaType || 'BlogPosting';

  const authorSchema = blog.author && (blog.author.firstName || blog.author.lastName)
    ? {
        '@type': 'Person',
        name: authorName,
        url: `${siteUrl}/about`,
      }
    : {
        '@type': 'Organization',
        name: config.brandNameFa || 'کنینا ایران',
        url: siteUrl,
      };

  const articleJsonLd = {
    '@context': 'https://schema.org',
    '@type': schemaType,
    mainEntityOfPage: {
      '@type': 'WebPage',
      '@id': canonicalUrl,
    },
    headline: blog.title,
    description: blog.excerpt || blog.metaDescription || blog.title,
    image: blog.imageUrl
      ? [blog.imageUrl.startsWith('http') ? blog.imageUrl : `${siteUrl}${blog.imageUrl.startsWith('/') ? '' : '/'}${blog.imageUrl}`]
      : [config.ogImageUrl.startsWith('http') ? config.ogImageUrl : `${siteUrl}${config.ogImageUrl.startsWith('/') ? '' : '/'}${config.ogImageUrl}`],
    datePublished: publishedIso,
    dateModified: modifiedIso,
    author: authorSchema,
    publisher: {
      '@type': 'Organization',
      name: config.brandNameFa || 'کنینا ایران',
      logo: {
        '@type': 'ImageObject',
        url: `${siteUrl}/assets/logo.png`,
      },
    },
    articleSection: blog.category?.name || 'دانشنامه سلامت حیوانات',
    keywords: blog.focusKeywords || (Array.isArray(blog.tags) ? blog.tags.map((t: any) => typeof t === 'string' ? t : t?.name).filter(Boolean).join(', ') : undefined),
  };

  const breadcrumbJsonLd = {
    '@context': 'https://schema.org',
    '@type': 'BreadcrumbList',
    itemListElement: [
      {
        '@type': 'ListItem',
        position: 1,
        name: 'خانه',
        item: siteUrl,
      },
      {
        '@type': 'ListItem',
        position: 2,
        name: 'مجله سلامت',
        item: `${siteUrl}/blog`,
      },
      ...(blog.category
        ? [
            {
              '@type': 'ListItem',
              position: 3,
              name: blog.category.name,
              item: `${siteUrl}/blog?categoryId=${blog.category.id}`,
            },
            {
              '@type': 'ListItem',
              position: 4,
              name: blog.title,
              item: canonicalUrl,
            },
          ]
        : [
            {
              '@type': 'ListItem',
              position: 3,
              name: blog.title,
              item: canonicalUrl,
            },
          ]),
    ],
  };

  return (
    <>
      <script
        type="application/ld+json"
        dangerouslySetInnerHTML={{ __html: safeJsonLd(articleJsonLd) }}
      />
      <script
        type="application/ld+json"
        dangerouslySetInnerHTML={{ __html: safeJsonLd(breadcrumbJsonLd) }}
      />
      <BlogPostClient
        blog={blog}
        publishedDate={publishedDate}
        authorName={authorName}
      />
    </>
  );
}