import { Agent } from "@atproto/api"
import * as fs from "node:fs/promises"
import * as path from "node:path"
import mimeTypes from "mime-types"
import { BlogPost, BlobObject } from "../lib/types"

const LEXICON = "space.litenote.note"
const MAX_CONTENT = 10000

interface ImageRecord {
  image: BlobObject
  alt?: string
}

export interface NoteOptions {
  contentDir: string
  imagesDir?: string
  allPosts: BlogPost[]
}

async function fileExists(filePath: string): Promise<boolean> {
  try {
    await fs.access(filePath)
    return true
  } catch {
    return false
  }
}

export function isLocalPath(url: string): boolean {
  return (
    !url.startsWith("http://") &&
    !url.startsWith("https://") &&
    !url.startsWith("#") &&
    !url.startsWith("mailto:")
  )
}

function getImageCandidates(
  src: string,
  postFilePath: string,
  contentDir: string,
  imagesDir?: string,
): string[] {
  const candidates = [
    path.resolve(path.dirname(postFilePath), src),
    path.resolve(contentDir, src),
  ]
  if (imagesDir) {
    candidates.push(path.resolve(imagesDir, src))
    const baseName = path.basename(imagesDir)
    const idx = src.indexOf(baseName)
    if (idx !== -1) {
      const after = src.substring(idx + baseName.length).replace(/^[/\\]/, "")
      candidates.push(path.resolve(imagesDir, after))
    }
  }
  return candidates
}

async function uploadBlob(
  agent: Agent,
  candidates: string[],
): Promise<BlobObject | undefined> {
  for (const filePath of candidates) {
    if (!(await fileExists(filePath))) continue

    try {
      const imageBuffer = await fs.readFile(filePath)
      if (imageBuffer.byteLength === 0) continue
      const mimeType = mimeTypes.lookup(filePath) || "application/octet-stream"
      const response = await agent.com.atproto.repo.uploadBlob(
        new Uint8Array(imageBuffer),
        { encoding: mimeType },
      )
      return {
        $type: "blob",
        ref: { $link: response.data.blob.ref.toString() },
        mimeType,
        size: imageBuffer.byteLength,
      }
    } catch {}
  }
  return undefined
}

async function processImages(
  agent: Agent,
  content: string,
  postFilePath: string,
  contentDir: string,
  imagesDir?: string,
): Promise<{ content: string; images: ImageRecord[] }> {
  const images: ImageRecord[] = []
  const uploadCache = new Map<string, BlobObject>()
  let processedContent = content

  const imageRegex = /!\[([^\]]*)\]\(([^)]+)\)/g
  const matches = [...content.matchAll(imageRegex)]

  for (const match of matches) {
    const fullMatch = match[0]
    const alt = match[1] ?? ""
    const src = match[2]!
    if (!isLocalPath(src)) continue

    let blob = uploadCache.get(src)
    if (!blob) {
      const candidates = getImageCandidates(src, postFilePath, contentDir, imagesDir)
      blob = await uploadBlob(agent, candidates)
      if (!blob) continue
      uploadCache.set(src, blob)
    }

    images.push({ image: blob, alt: alt || undefined })
    processedContent = processedContent.replace(
      fullMatch,
      `![${alt}](${blob.ref.$link})`,
    )
  }

  return { content: processedContent, images }
}

export function resolveInternalLinks(
  content: string,
  allPosts: BlogPost[],
): string {
  const linkRegex = /(?<![!@])\[([^\]]+)\]\(([^)]+)\)/g

  return content.replace(linkRegex, (fullMatch, text, url) => {
    if (!isLocalPath(url)) return fullMatch

    // Normalize to a slug-like string for comparison
    const normalized = url
      .replace(/^\.?\/?/, "")
      .replace(/\/?$/, "")
      .replace(/\.mdx?$/, "")
      .replace(/\/index$/, "")

    const matchedPost = allPosts.find((p) => {
      if (!p.frontmatter.atUri) return false
      return (
        p.slug === normalized ||
        p.slug.endsWith(`/${normalized}`) ||
        normalized.endsWith(`/${p.slug}`)
      )
    })

    if (!matchedPost) return text

    const noteUri = matchedPost.frontmatter.atUri!.replace(
      /\/[^/]+\/([^/]+)$/,
      `/space.litenote.note/$1`,
    )
    return `[${text}](${noteUri})`
  })
}

async function processNoteContent(
  agent: Agent,
  post: BlogPost,
  options: NoteOptions,
): Promise<{ content: string; images: ImageRecord[] }> {
  let content = post.content.trim()

  content = resolveInternalLinks(content, options.allPosts)

  const result = await processImages(
    agent, content, post.filePath, options.contentDir, options.imagesDir,
  )

  return result
}

function parseRkey(atUri: string): string {
  const uriMatch = atUri.match(/^at:\/\/([^/]+)\/([^/]+)\/(.+)$/)
  if (!uriMatch) {
    throw new Error(`Invalid atUri format: ${atUri}`)
  }
  return uriMatch[3]!
}

export async function createNote(
  agent: Agent,
  post: BlogPost,
  atUri: string,
  options: NoteOptions,
): Promise<void> {
  const rkey = parseRkey(atUri)
  const publishDate = new Date(post.frontmatter.publishDate).toISOString()
  const trimmedContent = post.content.trim()
  const titleMatch = trimmedContent.match(/^# (.+)$/m)
  const title = titleMatch ? titleMatch[1] : post.frontmatter.title

  const { content, images } = await processNoteContent(agent, post, options)

  const record: Record<string, unknown> = {
    $type: LEXICON,
    title,
    content: content.slice(0, MAX_CONTENT),
    createdAt: publishDate,
    publishedAt: publishDate,
  }

  if (images.length > 0) {
    record.images = images
  }

  await agent.com.atproto.repo.createRecord({
    repo: agent.did!,
    collection: LEXICON,
    record,
    rkey,
    validate: false,
  })
}

export async function updateNote(
  agent: Agent,
  post: BlogPost,
  atUri: string,
  options: NoteOptions,
): Promise<void> {
  const rkey = parseRkey(atUri)
  const publishDate = new Date(post.frontmatter.publishDate).toISOString()
  const trimmedContent = post.content.trim()
  const titleMatch = trimmedContent.match(/^# (.+)$/m)
  const title = titleMatch ? titleMatch[1] : post.frontmatter.title

  const { content, images } = await processNoteContent(agent, post, options)

  const record: Record<string, unknown> = {
    $type: LEXICON,
    title,
    content: content.slice(0, MAX_CONTENT),
    createdAt: publishDate,
    publishedAt: publishDate,
  }

  if (images.length > 0) {
    record.images = images
  }

  await agent.com.atproto.repo.putRecord({
    repo: agent.did!,
    collection: LEXICON,
    rkey: rkey!,
    record,
    validate: false,
  })
}

export function findPostsWithStaleLinks(
  allPosts: BlogPost[],
  newSlugs: string[],
  excludeFilePaths: Set<string>,
): BlogPost[] {
  const linkRegex = /(?<![!@])\[([^\]]+)\]\(([^)]+)\)/g

  return allPosts.filter((post) => {
    if (excludeFilePaths.has(post.filePath)) return false
    if (!post.frontmatter.atUri) return false
    if (post.frontmatter.draft) return false

    const matches = [...post.content.matchAll(linkRegex)]
    return matches.some((match) => {
      const url = match[2]!
      if (!isLocalPath(url)) return false

      const normalized = url
        .replace(/^\.?\/?/, "")
        .replace(/\/?$/, "")
        .replace(/\.mdx?$/, "")
        .replace(/\/index$/, "")

      return newSlugs.some(
        (slug) =>
          slug === normalized ||
          slug.endsWith(`/${normalized}`) ||
          normalized.endsWith(`/${slug}`),
      )
    })
  })
}