/**
 * Vite dev middleware exposing the local doocus docs-output tree to the app.
 *
 * Runs in the dev server process (Node), so it can reach the original source
 * file by the absolute path stored in each doc's manifest.json — needed for the
 * package builder, which bundles the original alongside content.md + meta.json.
 * All reads are local; nothing leaves the machine.
 *
 * Routes:
 *   GET  /api/docs                 list extracted docs
 *   GET  /api/docs/:id             meta.json + content.md + thumb/original flags
 *   GET  /api/docs/:id/thumb       stream thumb.jpg
 *   GET  /api/docs/:id/original    stream the original source file
 */
import type { Plugin } from 'vite'
import type { IncomingMessage, ServerResponse } from 'node:http'
import fs from 'node:fs'
import fsp from 'node:fs/promises'
import path from 'node:path'

interface Options {
  outputDir: string
}

interface Manifest {
  source?: { name?: string; path?: string; sha256?: string }
  processed_at?: string
  outputs?: { content?: string; meta?: string; thumb?: string | null }
}

const ORIGINAL_MIME: Record<string, string> = {
  '.pdf': 'application/pdf',
  '.docx': 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
  '.pptx': 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
  '.xlsx': 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
  '.csv': 'text/csv',
  '.html': 'text/html',
  '.htm': 'text/html',
  '.json': 'application/json',
  '.md': 'text/markdown',
  '.txt': 'text/plain',
  '.yaml': 'text/yaml',
  '.yml': 'text/yaml',
  '.jpg': 'image/jpeg',
  '.jpeg': 'image/jpeg',
  '.png': 'image/png',
  '.mp4': 'video/mp4',
}

export function doocusApi(opts: Options): Plugin {
  const outputDir = path.resolve(opts.outputDir)
  const toPosix = (p: string) => p.split(path.sep).join('/')

  /** Resolve a doc id (possibly nested) to its directory, rejecting traversal. */
  function docDir(id: string): string | null {
    const dir = path.resolve(outputDir, id)
    if (dir !== outputDir && !dir.startsWith(outputDir + path.sep)) return null
    try {
      if (fs.statSync(dir).isDirectory()) return dir
    } catch { /* missing */ }
    return null
  }

  /** Find every doc run directory (one containing meta.json) under `base`. */
  async function findDocDirs(base: string, maxDepth = 8): Promise<string[]> {
    const found: string[] = []
    const walk = async (dir: string, depth: number): Promise<void> => {
      if (depth > maxDepth) return
      let ents
      try {
        ents = await fsp.readdir(dir, { withFileTypes: true })
      } catch { return }
      if (ents.some((e) => e.isFile() && e.name === 'meta.json')) {
        found.push(dir)
        return // a doc dir; don't descend into assets/
      }
      for (const e of ents) {
        if (!e.isDirectory()) continue
        if (e.name === 'assets' || e.name === 'node_modules' || e.name.startsWith('.')) continue
        await walk(path.join(dir, e.name), depth + 1)
      }
    }
    await walk(base, 0)
    return found
  }

  function readJson<T>(file: string): T | null {
    try {
      return JSON.parse(fs.readFileSync(file, 'utf-8')) as T
    } catch {
      return null
    }
  }

  return {
    name: 'doocus-api',
    configureServer(server) {
      server.config.logger.info(`[doocus-api] serving docs from: ${outputDir}`)
      server.middlewares.use('/api', (req, res, next) => {
        const url = new URL(req.url ?? '/', 'http://localhost')
        const parts = url.pathname.split('/').filter(Boolean)
        handle(req, res, parts).catch((err) => {
          server.config.logger.error(`[doocus-api] ${String(err)}`)
          sendJson(res, 500, { error: String(err) })
        }).then((handled) => {
          if (!handled) next()
        })
      })
    },
  }

  async function handle(req: IncomingMessage, res: ServerResponse, parts: string[]): Promise<boolean> {
    if (parts[0] !== 'docs') return false

    // GET /api/docs
    if (parts.length === 1 && req.method === 'GET') {
      await listDocs(res)
      return true
    }

    const id = parts[1] ? decodeURIComponent(parts[1]) : ''
    const dir = id ? docDir(id) : null
    if (!dir) { sendJson(res, 404, { error: 'doc not found' }); return true }

    // GET /api/docs/:id
    if (parts.length === 2 && req.method === 'GET') {
      await getDoc(res, id, dir)
      return true
    }
    // GET /api/docs/:id/thumb
    if (parts.length === 3 && parts[2] === 'thumb' && req.method === 'GET') {
      serveThumb(res, dir)
      return true
    }
    // GET /api/docs/:id/original
    if (parts.length === 3 && parts[2] === 'original' && req.method === 'GET') {
      serveOriginal(res, dir)
      return true
    }

    sendJson(res, 404, { error: 'not found' })
    return true
  }

  async function listDocs(res: ServerResponse): Promise<void> {
    const dirs = await findDocDirs(outputDir)
    const docs = []
    for (const dir of dirs) {
      const meta = readJson<Record<string, unknown>>(path.join(dir, 'meta.json'))
      if (!meta) continue
      const id = toPosix(path.relative(outputDir, dir))
      const source = (meta.source ?? {}) as { name?: string; bytes?: number }
      docs.push({
        id,
        name: source.name ?? id,
        type: meta.type ?? null,
        family: meta.family ?? null,
        title: meta.title ?? null,
        extractedAt: meta.extracted_at ?? null,
        wordCount: meta.word_count ?? 0,
        bytes: source.bytes ?? 0,
        hasThumb: fs.existsSync(path.join(dir, 'thumb.jpg')),
        warnings: Array.isArray(meta.warnings) ? meta.warnings.length : 0,
      })
    }
    docs.sort((a, b) =>
      String(b.extractedAt ?? '').localeCompare(String(a.extractedAt ?? '')) || a.id.localeCompare(b.id))
    sendJson(res, 200, { docs, outputDir })
  }

  async function getDoc(res: ServerResponse, id: string, dir: string): Promise<void> {
    const meta = readJson<Record<string, unknown>>(path.join(dir, 'meta.json'))
    if (!meta) { sendJson(res, 404, { error: 'meta missing' }); return }
    const manifest = readJson<Manifest>(path.join(dir, 'manifest.json'))

    let content = ''
    try {
      content = await fsp.readFile(path.join(dir, 'content.md'), 'utf-8')
    } catch { /* none */ }

    const hasThumb = fs.existsSync(path.join(dir, 'thumb.jpg'))
    const originalPath = manifest?.source?.path
    const hasOriginal = !!originalPath && isFile(originalPath)

    sendJson(res, 200, {
      id,
      meta,
      content,
      hasThumb,
      thumbUrl: hasThumb ? `/api/docs/${encodeURIComponent(id)}/thumb` : null,
      hasOriginal,
      originalUrl: hasOriginal ? `/api/docs/${encodeURIComponent(id)}/original` : null,
    })
  }

  function serveThumb(res: ServerResponse, dir: string): void {
    const full = path.join(dir, 'thumb.jpg')
    if (!fs.existsSync(full)) { sendJson(res, 404, { error: 'no thumb' }); return }
    res.setHeader('Content-Type', 'image/jpeg')
    res.setHeader('Cache-Control', 'no-cache')
    fs.createReadStream(full).pipe(res)
  }

  function serveOriginal(res: ServerResponse, dir: string): void {
    const manifest = readJson<Manifest>(path.join(dir, 'manifest.json'))
    const original = manifest?.source?.path
    if (!original || !isFile(original)) {
      sendJson(res, 404, { error: 'original source not reachable on this machine' })
      return
    }
    const mime = ORIGINAL_MIME[path.extname(original).toLowerCase()] ?? 'application/octet-stream'
    res.setHeader('Content-Type', mime)
    res.setHeader('Content-Disposition', `attachment; filename="${path.basename(original)}"`)
    fs.createReadStream(original).pipe(res)
  }
}

function sendJson(res: ServerResponse, status: number, obj: unknown): void {
  const body = JSON.stringify(obj)
  res.statusCode = status
  res.setHeader('Content-Type', 'application/json')
  res.setHeader('Content-Length', Buffer.byteLength(body))
  res.end(body)
}

function isFile(p: string): boolean {
  try { return fs.statSync(p).isFile() } catch { return false }
}