import fs from 'fs/promises';
import path from 'path';
import matter from 'gray-matter';
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;
  focalX?: number;
  focalY?: number;
  category?: string;
  public?: boolean;
}

export interface PostData {
  slug: string;
  frontmatter: PostFrontmatter;
  content: any; // Mapped to Lexical SerializedEditorState
}

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);
}

import { mapSlugToFileSlug, mapFileSlugToTranslated } from './slugs';

export async function getPostBySlug(slug: string, locale: string): Promise<PostData | null> {
  try {
    const fileSlug = await mapSlugToFileSlug(slug, locale);
    const filePath = path.join(process.cwd(), 'content', 'posts', `${fileSlug}.mdx`);
    const fileContent = await fs.readFile(filePath, 'utf-8');
    const { data, content } = matter(fileContent);

    // Fix MDX data props dropped by next-mdx-remote
    // Payload serializes as data={{"items":...}} which Acorn treats as a Block statement.
    const fixedContent = content.replace(/data=\{\{([\s\S]*?)\}\}/g, (match, p1) => {
      return 'data="{' + p1.replace(/"/g, '&quot;') + '}"';
    });

    let parsedContent = fixedContent;
    try {
      if (content.trim().startsWith('{')) {
        parsedContent = JSON.parse(content);
      }
    } catch (e) {
      // Not JSON
    }

    const resolvedSlug = await mapFileSlugToTranslated(fileSlug, locale);

    return {
      slug: resolvedSlug,
      frontmatter: {
        title: data.title || '',
        date: data.date || '',
        excerpt: data.excerpt || '',
        category: data.category || '',
        featuredImage: data.featuredImage?.url || data.featuredImage || null,
        focalX: data.featuredImage?.focalX || data.focalX || 50,
        focalY: data.featuredImage?.focalY || data.focalY || 50,
        public: data.public ?? true,
      },
      content: parsedContent,
    };
  } catch (error) {
    console.error(`getPostBySlug failed for ${slug}:`, error);
    return null;
  }
}

export async function getPostSlugs(slug: string, locale: string): Promise<Record<string, string>> {
  const fileSlug = await mapSlugToFileSlug(slug, locale);
  const de = await mapFileSlugToTranslated(fileSlug, 'de');
  const en = await mapFileSlugToTranslated(fileSlug, 'en');
  return { de, en };
}

export async function getAllPosts(locale: string): Promise<PostData[]> {
  try {
    const dir = path.join(process.cwd(), 'content', 'posts');
    const files = await fs.readdir(dir);
    const slugs = files.filter((f) => f.endsWith('.mdx')).map((f) => f.replace('.mdx', ''));
    const posts = await Promise.all(slugs.map((slug) => getPostBySlug(slug, locale)));

    const validPosts = posts.filter(
      (p): p is PostData => p !== null && !!p.frontmatter.featuredImage,
    );
    return validPosts.sort(
      (a, b) => new Date(b.frontmatter.date).getTime() - new Date(a.frontmatter.date).getTime(),
    );
  } catch (error) {
    console.error(`getAllPosts failed for ${locale}:`, error);
    return [];
  }
}

export async function getAllPostsMetadata(locale: string): Promise<Partial<PostData>[]> {
  const posts = await getAllPosts(locale);
  return posts.map((p) => ({
    slug: p.slug,
    frontmatter: p.frontmatter,
  }));
}

export async function getAdjacentPosts(
  slug: string,
  locale: string,
): Promise<{
  prev: PostData | null;
  next: PostData | 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 };
  });
}

export function extractLexicalHeadings(
  node: any,
  headings: { id: string; text: string; level: number }[] = [],
): { id: string; text: string; level: number }[] {
  if (!node) return headings;

  if (node.type === 'heading' && node.tag) {
    const level = parseInt(node.tag.replace('h', ''));
    const text = getTextContentFromLexical(node);
    if (text) {
      headings.push({
        id: generateHeadingId(text),
        text,
        level,
      });
    }
  }

  if (node.children && Array.isArray(node.children)) {
    node.children.forEach((child: any) => extractLexicalHeadings(child, headings));
  }

  return headings;
}

function getTextContentFromLexical(node: any): string {
  if (node.type === 'text') {
    return node.text || '';
  }
  if (node.children && Array.isArray(node.children)) {
    return node.children.map(getTextContentFromLexical).join('');
  }
  return '';
}