import fs from 'fs';
import path from 'path';
import matter from 'gray-matter';
import { mapSlugToFileSlug } from './slugs';
import { config } from '@/lib/config';

export function extractExcerpt(content: string): string {
  if (!content) return '';
  // Remove frontmatter if present (though matter() usually strips it out)
  let text = content.replace(/^---[\s\S]*?---/, '');
  // Remove MDX component imports and usages
  text = text.replace(/<[^>]+>/g, '');
  text = text.replace(/^[ \t]*import\s+.*$/gm, '');
  text = text.replace(/^[ \t]*export\s+.*$/gm, '');
  // Remove markdown headings
  text = text.replace(/^#+.*$/gm, '');
  // Extract first paragraph or combined lines
  const paragraphs = text
    .split(/\n\s*\n/)
    .filter((p) => p.trim() && !p.trim().startsWith('---') && !p.trim().startsWith('#'));
  if (paragraphs.length === 0) return '';

  const excerpt = paragraphs[0]
    .replace(/[*_`]/g, '') // remove markdown bold/italic/code
    .replace(/\[(.*?)\]\(.*?\)/g, '$1') // replace links with their text
    .replace(/\s+/g, ' ')
    .trim();

  return excerpt.length > 200 ? excerpt.slice(0, 197) + '...' : excerpt;
}

export interface PostFrontmatter {
  title: string;
  date: string;
  excerpt?: string;
  featuredImage?: string | null;
  category?: string;
  locale: string;
  public?: boolean;
}

export interface PostMdx {
  slug: string;
  frontmatter: PostFrontmatter;
  content: string;
}

export function isPostVisible(post: { frontmatter: { date: string; public?: boolean } }) {
  // If explicitly marked as not public, hide in production
  if (post.frontmatter.public === false && config.isProduction) {
    return false;
  }

  const postDate = new Date(post.frontmatter.date);
  const now = new Date();
  return !(postDate > now && config.isProduction);
}

export async function getPostBySlug(slug: string, locale: string): Promise<PostMdx | null> {
  // Map translated slug to file slug
  const fileSlug = await mapSlugToFileSlug(slug, locale);
  const postsDir = path.join(process.cwd(), 'data', 'blog', locale);
  const filePath = path.join(postsDir, `${fileSlug}.mdx`);

  if (!fs.existsSync(filePath)) {
    return null;
  }

  const fileContent = fs.readFileSync(filePath, 'utf8');
  const { data, content } = matter(fileContent);

  const postInfo = {
    slug: fileSlug,
    frontmatter: {
      ...data,
      excerpt: data.excerpt || extractExcerpt(content),
    } as PostFrontmatter,
    content,
  };

  if (!isPostVisible(postInfo)) {
    return null;
  }

  return postInfo;
}

export async function getAllPosts(locale: string): Promise<PostMdx[]> {
  const postsDir = path.join(process.cwd(), 'data', 'blog', locale);
  if (!fs.existsSync(postsDir)) return [];

  const files = fs.readdirSync(postsDir);
  const posts = files
    .filter((file) => file.endsWith('.mdx'))
    .map((file) => {
      const filePath = path.join(postsDir, file);
      const fileContent = fs.readFileSync(filePath, 'utf8');
      const { data, content } = matter(fileContent);
      return {
        slug: file.replace(/\.mdx$/, ''),
        frontmatter: {
          ...data,
          excerpt: data.excerpt || extractExcerpt(content),
        } as PostFrontmatter,
        content,
      };
    })
    .filter(isPostVisible)
    .sort(
      (a, b) => new Date(b.frontmatter.date).getTime() - new Date(a.frontmatter.date).getTime(),
    );

  return posts;
}

export async function getAllPostsMetadata(locale: string): Promise<Partial<PostMdx>[]> {
  const postsDir = path.join(process.cwd(), 'data', 'blog', locale);
  if (!fs.existsSync(postsDir)) return [];

  const files = fs.readdirSync(postsDir);
  return files
    .filter((file) => file.endsWith('.mdx'))
    .map((file) => {
      const filePath = path.join(postsDir, file);
      const fileContent = fs.readFileSync(filePath, 'utf8');
      const { data } = matter(fileContent);
      return {
        slug: file.replace(/\.mdx$/, ''),
        frontmatter: {
          ...data,
          excerpt: data.excerpt || extractExcerpt(fileContent.replace(/^---[\s\S]*?---/, '')),
        } as PostFrontmatter,
      };
    })
    .filter(isPostVisible)
    .sort(
      (a, b) =>
        new Date(b.frontmatter.date as string).getTime() -
        new Date(a.frontmatter.date as string).getTime(),
    );
}

export async function getAdjacentPosts(
  slug: string,
  locale: string,
): Promise<{
  prev: PostMdx | null;
  next: PostMdx | null;
  isPrevRandom?: boolean;
  isNextRandom?: boolean;
}> {
  const posts = await getAllPosts(locale);
  const currentIndex = posts.findIndex((post) => post.slug === slug);

  if (currentIndex === -1) {
    return { prev: null, next: null };
  }

  // Posts are sorted by date descending (newest first)
  // So "next" post (newer) is at index - 1
  // And "previous" post (older) is at index + 1
  let next = currentIndex > 0 ? posts[currentIndex - 1] : null;
  let prev = currentIndex < posts.length - 1 ? posts[currentIndex + 1] : null;

  let isNextRandom = false;
  let isPrevRandom = false;

  const getRandomPost = (excludeSlugs: string[]) => {
    const available = posts.filter((p) => !excludeSlugs.includes(p.slug));
    if (available.length === 0) return null;
    return available[Math.floor(Math.random() * available.length)];
  };

  // If there's no next post (we are at the newest post), show a random post instead
  if (!next && posts.length > 2) {
    next = getRandomPost([slug, prev?.slug].filter(Boolean) as string[]);
    isNextRandom = true;
  }

  // If there's no previous post (we are at the oldest post), show a random post instead
  if (!prev && posts.length > 2) {
    prev = getRandomPost([slug, next?.slug].filter(Boolean) as string[]);
    isPrevRandom = true;
  }

  return { prev, next, isPrevRandom, isNextRandom };
}

export function getReadingTime(content: string): number {
  const wordsPerMinute = 200;
  const noOfWords = content.split(/\s/g).length;
  const minutes = noOfWords / wordsPerMinute;
  return Math.ceil(minutes);
}

export function generateHeadingId(text: string): string {
  let id = text.toLowerCase();
  id = id.replace(/ä/g, 'ae');
  id = id.replace(/ö/g, 'oe');
  id = id.replace(/ü/g, 'ue');
  id = id.replace(/ß/g, 'ss');

  id = id.replace(/[*_`]/g, '');
  id = id.replace(/[^\w\s-]/g, '');
  id = id
    .replace(/\s+/g, '-')
    .replace(/-+/g, '-')
    .replace(/^-+|-+$/g, '');

  return id || 'heading';
}

export function getTextContent(node: any): string {
  if (typeof node === 'string') return node;
  if (typeof node === 'number') return node.toString();
  if (Array.isArray(node)) return node.map(getTextContent).join('');
  if (node && typeof node === 'object' && node.props && node.props.children) {
    return getTextContent(node.props.children);
  }
  return '';
}

export function getHeadings(content: string): { id: string; text: string; level: number }[] {
  const headingLines = content.split('\n').filter((line) => line.match(/^#{1,3}\s/));

  return headingLines.map((line) => {
    const level = (line.match(/^#+/)?.[0].length || 0) + 1; // Shift H1->H2, H2->H3, H3->H4
    const rawText = line.replace(/^#+\s/, '').trim();
    const cleanText = rawText.replace(/[*_`]/g, '');
    const id = generateHeadingId(cleanText);

    return { id, text: cleanText, level };
  });
}