/**
 * Vite dev middleware exposing the local meetus output tree to the app.
 *
 * Runs in the dev server process (Node), so it can reach the source video by
 * the absolute path stored in each run's manifest.json — something a browser
 * cannot do. All reads are local; nothing leaves the machine.
 *
 * Routes:
 *   GET  /api/runs                    list runs
 *   GET  /api/runs/:id                manifest + segments + frames + review
 *   GET  /api/runs/:id/frames/:file   stream a frame JPEG
 *   GET  /api/runs/:id/video          stream the source video (Range support)
 *   PUT  /api/runs/:id/review         write sidecar review.json (atomic)
 */
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 {
  video?: { name?: string; path?: string }
  processed_at?: string
  outputs?: {
    frames?: string
    enhanced_transcript?: string
    whisper_transcript?: string | null
  }
}

const VIDEO_MIME: Record<string, string> = {
  '.mp4': 'video/mp4',
  '.m4v': 'video/mp4',
  '.webm': 'video/webm',
  '.mov': 'video/quicktime',
  '.mkv': 'video/x-matroska',
  '.avi': 'video/x-msvideo',
}

export function meetusApi(opts: Options): Plugin {
  const outputDir = path.resolve(opts.outputDir)

  /** Resolve a run id to its directory, rejecting traversal. */
  function runDir(id: string): string | null {
    const safe = path.basename(id)
    if (safe !== id || !safe || safe.startsWith('.')) return null
    const dir = path.join(outputDir, safe)
    if (!dir.startsWith(outputDir + path.sep)) return null
    try {
      if (fs.statSync(dir).isDirectory()) return dir
    } catch { /* missing */ }
    return null
  }

  function readManifest(dir: string): Manifest | null {
    try {
      return JSON.parse(fs.readFileSync(path.join(dir, 'manifest.json'), 'utf-8'))
    } catch {
      return null
    }
  }

  return {
    name: 'meetus-api',
    configureServer(server) {
      server.middlewares.use('/api', (req, res, next) => {
        const url = new URL(req.url ?? '/', 'http://localhost')
        const parts = url.pathname.split('/').filter(Boolean) // after /api strip
        // parts: ['runs', ...] (the '/api' prefix is stripped by `use('/api', ...)`)
        handle(req, res, parts, server.config.logger).catch((err) => {
          server.config.logger.error(`[meetus-api] ${String(err)}`)
          sendJson(res, 500, { error: String(err) })
        }).then((handled) => {
          if (!handled) next()
        })
      })
    },
  }

  async function handle(
    req: IncomingMessage,
    res: ServerResponse,
    parts: string[],
    logger: { warn: (m: string) => void },
  ): Promise<boolean> {
    if (parts[0] !== 'runs') return false

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

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

    // GET /api/runs/:id
    if (parts.length === 2 && req.method === 'GET') {
      await getRun(res, id, dir)
      return true
    }

    // GET /api/runs/:id/frames/:file
    if (parts.length === 4 && parts[2] === 'frames' && req.method === 'GET') {
      serveFrame(req, res, dir, decodeURIComponent(parts[3]))
      return true
    }

    // GET /api/runs/:id/video
    if (parts.length === 3 && parts[2] === 'video' && req.method === 'GET') {
      serveVideo(req, res, dir, logger)
      return true
    }

    // PUT /api/runs/:id/review
    if (parts.length === 3 && parts[2] === 'review' && req.method === 'PUT') {
      await saveReview(req, res, dir)
      return true
    }

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

  async function listRuns(res: ServerResponse): Promise<void> {
    let entries: string[] = []
    try {
      entries = (await fsp.readdir(outputDir, { withFileTypes: true }))
        .filter((e) => e.isDirectory())
        .map((e) => e.name)
    } catch {
      sendJson(res, 200, { runs: [], outputDir })
      return
    }
    const runs = []
    for (const name of entries.sort().reverse()) {
      const dir = path.join(outputDir, name)
      const manifest = readManifest(dir)
      if (!manifest) continue
      const framesRel = manifest.outputs?.frames ?? 'frames'
      let frameCount = 0
      try {
        frameCount = (await fsp.readdir(path.join(dir, framesRel)))
          .filter((f) => f.toLowerCase().endsWith('.jpg')).length
      } catch { /* no frames */ }
      runs.push({
        id: name,
        name: manifest.video?.name ?? name,
        processedAt: manifest.processed_at ?? null,
        frameCount,
        hasVideo: !!manifest.video?.path && fs.existsSync(manifest.video.path),
      })
    }
    sendJson(res, 200, { runs, outputDir })
  }

  async function getRun(res: ServerResponse, id: string, dir: string): Promise<void> {
    const manifest = readManifest(dir)
    if (!manifest) { sendJson(res, 404, { error: 'manifest missing' }); return }

    // Segments from the Whisper JSON. The manifest sometimes records
    // `whisper_transcript: null` even though `{stem}.json` exists on disk
    // (whisper run out-of-band), so fall back to probing for it by stem.
    const segments: Array<{ start: number; end: number; text: string; speaker: string | null }> = []
    let whisperName = manifest.outputs?.whisper_transcript ?? null
    if (!whisperName) {
      const stem = manifest.video?.name ? path.parse(manifest.video.name).name : null
      if (stem && fs.existsSync(path.join(dir, `${stem}.json`))) whisperName = `${stem}.json`
    }
    if (whisperName && fs.existsSync(path.join(dir, whisperName))) {
      try {
        const data = JSON.parse(await fsp.readFile(path.join(dir, whisperName), 'utf-8'))
        const segs = Array.isArray(data) ? data : data.segments ?? []
        for (const s of segs) {
          segments.push({
            start: Number(s.start ?? s.timestamp ?? 0),
            end: Number(s.end ?? s.start ?? 0),
            text: String(s.text ?? '').trim(),
            speaker: s.speaker ?? null,
          })
        }
      } catch { /* no/invalid transcript */ }
    }

    // Frame → time map from enhanced.txt (universal, MM:SS granularity).
    const framesRel = manifest.outputs?.frames ?? 'frames'
    const enhancedName = manifest.outputs?.enhanced_transcript
    const enhancedTimes = new Map<string, number>()
    let enhancedAvailable = false
    if (enhancedName) {
      try {
        const text = await fsp.readFile(path.join(dir, enhancedName), 'utf-8')
        enhancedAvailable = true
        let lastTs: number | null = null
        for (const line of text.split('\n')) {
          const ts = line.match(/^\[(\d+):(\d+)\]/)
          if (ts) lastTs = Number(ts[1]) * 60 + Number(ts[2])
          const fm = line.match(/Frame:\s*\S*?([^/\\\s]+\.jpg)/i)
          if (fm && lastTs != null) enhancedTimes.set(fm[1], lastTs)
        }
      } catch { /* none */ }
    }

    // Frame list with resolved times and byte sizes.
    const frames: Array<{ file: string; url: string; time: number | null; size: number }> = []
    try {
      const framesAbs = path.join(dir, framesRel)
      const files = (await fsp.readdir(framesAbs))
        .filter((f) => f.toLowerCase().endsWith('.jpg'))
        .sort()
      for (const file of files) {
        // Interval-mode filenames encode an exact float: `..._123.45s.jpg`.
        const fny = file.match(/_(\d+(?:\.\d+)?)s\.jpg$/i)
        const time = fny ? Number(fny[1])
          : enhancedTimes.has(file) ? enhancedTimes.get(file)!
            : null
        let size = 0
        try { size = (await fsp.stat(path.join(framesAbs, file))).size } catch { /* ignore */ }
        frames.push({
          file,
          url: `/api/runs/${encodeURIComponent(id)}/frames/${encodeURIComponent(file)}`,
          time,
          size,
        })
      }
    } catch { /* no frames dir */ }

    // Existing review sidecar, if any.
    let review: unknown = null
    try {
      review = JSON.parse(await fsp.readFile(path.join(dir, 'review.json'), 'utf-8'))
    } catch { /* none */ }

    sendJson(res, 200, {
      id,
      manifest,
      segments,
      frames,
      enhancedAvailable,
      hasVideo: !!manifest.video?.path && fs.existsSync(manifest.video.path),
      videoUrl: `/api/runs/${encodeURIComponent(id)}/video`,
      review,
    })
  }

  function serveFrame(req: IncomingMessage, res: ServerResponse, dir: string, file: string): void {
    const manifest = readManifest(dir)
    const framesRel = manifest?.outputs?.frames ?? 'frames'
    const safe = path.basename(file)
    const full = path.join(dir, framesRel, safe)
    if (safe !== file || !fs.existsSync(full)) { sendJson(res, 404, { error: 'frame not found' }); return }
    res.setHeader('Content-Type', 'image/jpeg')
    res.setHeader('Cache-Control', 'no-cache')
    fs.createReadStream(full).pipe(res)
  }

  function serveVideo(
    req: IncomingMessage,
    res: ServerResponse,
    dir: string,
    logger: { warn: (m: string) => void },
  ): void {
    const manifest = readManifest(dir)
    const videoPath = manifest?.video?.path
    if (!videoPath || !fs.existsSync(videoPath)) {
      logger.warn(`[meetus-api] source video missing for run: ${dir}`)
      sendJson(res, 404, { error: 'source video not available at manifest path' })
      return
    }
    const stat = fs.statSync(videoPath)
    const mime = VIDEO_MIME[path.extname(videoPath).toLowerCase()] ?? 'application/octet-stream'
    res.setHeader('Accept-Ranges', 'bytes')
    res.setHeader('Content-Type', mime)

    const range = req.headers.range
    if (range) {
      const m = range.match(/bytes=(\d*)-(\d*)/)
      if (m) {
        const start = m[1] ? parseInt(m[1], 10) : 0
        const end = m[2] ? parseInt(m[2], 10) : stat.size - 1
        if (start >= stat.size || end >= stat.size || start > end) {
          res.statusCode = 416
          res.setHeader('Content-Range', `bytes */${stat.size}`)
          res.end()
          return
        }
        res.statusCode = 206
        res.setHeader('Content-Range', `bytes ${start}-${end}/${stat.size}`)
        res.setHeader('Content-Length', String(end - start + 1))
        fs.createReadStream(videoPath, { start, end }).pipe(res)
        return
      }
    }
    res.statusCode = 200
    res.setHeader('Content-Length', String(stat.size))
    fs.createReadStream(videoPath).pipe(res)
  }

  async function saveReview(req: IncomingMessage, res: ServerResponse, dir: string): Promise<void> {
    const body = await readBody(req)
    let parsed: unknown
    try {
      parsed = JSON.parse(body || '{}')
    } catch {
      sendJson(res, 400, { error: 'invalid JSON' })
      return
    }
    if (typeof parsed !== 'object' || parsed === null) {
      sendJson(res, 400, { error: 'review must be an object' })
      return
    }
    const target = path.join(dir, 'review.json')
    const tmp = path.join(dir, `.review.${process.pid}.tmp`)
    await fsp.writeFile(tmp, JSON.stringify(parsed, null, 2), 'utf-8')
    await fsp.rename(tmp, target) // atomic; never touches source artifacts
    sendJson(res, 200, { ok: true })
  }
}

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 readBody(req: IncomingMessage): Promise<string> {
  return new Promise((resolve, reject) => {
    let data = ''
    req.on('data', (c) => { data += c; if (data.length > 5_000_000) reject(new Error('body too large')) })
    req.on('end', () => resolve(data))
    req.on('error', reject)
  })
}