import fs from 'fs'
import path from 'path'
import matter from 'gray-matter'
import { cache } from 'react'

const postsDirectory = path.join(process.cwd(), 'content/posts')

export interface PostMeta {
  slug: string
  title: string
  date: string
  excerpt: string
  tags: string[]
  author: string | null
  coverImage: string | null
  readingTime: number
}

export interface Post extends PostMeta {}

const getMdxFiles = cache(async () => {
  try {
    const files = await fs.promises.readdir(postsDirectory)
    return files.filter((f) => f.endsWith('.mdx') || f.endsWith('.md'))
  } catch {
    return []
  }
})

export const getPosts = cache(async (): Promise<PostMeta[]> => {
  const files = await getMdxFiles()
  return Promise.all(
    files.map(async (file) => {
      const filePath = path.join(postsDirectory, file)
      const raw = await fs.promises.readFile(filePath, 'utf-8')
      const { data } = matter(raw)
      const slug = file.replace(/\.(mdx|md)$/, '')
      // Compute reading time from content (everything after frontmatter)
      const content = raw.split(/---\n*\n*/).slice(2).join('\n')
      const readingTime = Math.max(1, Math.ceil(content.split(/\s+/).length / 200))

      return {
        slug,
        title: data.title ?? slug,
        date: data.date ?? 'Unknown',
        excerpt: data.excerpt ?? '',
        tags: data.tags ?? [],
        author: data.author ?? null,
        coverImage: data.coverImage ?? null,
        readingTime,
      }
    })
  ).then((posts) =>
    posts.sort((a, b) => new Date(b.date).getTime() - new Date(a.date).getTime())
  )
})

export const getPost = async (slug: string): Promise<Post | null> => {
  const files = await getMdxFiles()
  const file = files.find((f) => f.replace(/\.(mdx|md)$/, '') === slug)
  if (!file) return null

  const filePath = path.join(postsDirectory, file)
  const raw = await fs.promises.readFile(filePath, 'utf8')
  const { data } = matter(raw)

  const contentForReadingTime = raw.replace(/^---[\s\S]*?---\s*?/, '')
  const readingTime = Math.max(1, Math.ceil(contentForReadingTime.split(/\s+/).filter(Boolean).length / 200))

  return {
    slug,
    title: data.title ?? slug,
    date: data.date ?? 'Unknown',
    excerpt: data.excerpt ?? '',
    tags: data.tags ?? [],
    author: data.author ?? null,
    coverImage: data.coverImage ?? null,
    readingTime,
  } satisfies Post
}

export const getReadingTime = (content: string): number => {
  const words = content.replace(/<[^>]*>/g, '').trim().split(/\s+/).filter(Boolean).length
  return Math.max(1, Math.ceil(words / 200))
}