import { Router } from 'express'
import axios from 'axios'
import { githubRepos } from '../config/watchlist'

const router = Router()

/* ── Simple in-memory cache ── */
interface CacheEntry<T> { data: T; ts: number }
const cache: Record<string, CacheEntry<unknown>> = {}
function fromCache<T>(key: string, ttlMs: number): T | null {
  const entry = cache[key] as CacheEntry<T> | undefined
  if (entry && Date.now() - entry.ts < ttlMs) return entry.data
  return null
}
function toCache<T>(key: string, data: T) { cache[key] = { data, ts: Date.now() } }

/* ────────────────────────────────────────────────────────────────────────────
   Docker image updates
   ─────────────────────────────────────────────────────────────────────────── */
const DOCKER_SOCKET = '/var/run/docker.sock'
const HUB_TTL = 60 * 60 * 1000 // 1 hour

interface ContainerInfo {
  name: string
  image: string
  tag: string
  repoDigest: string | null
  upToDate: boolean | null  // null = couldn't determine
  registry: string
}

function parseImage(fullImage: string): { registry: string; name: string; tag: string } {
  // Strip digest if present
  const [imgPart] = fullImage.split('@')
  const colonIdx = imgPart.lastIndexOf(':')
  const slashIdx = imgPart.indexOf('/')

  let tag = 'latest'
  let img = imgPart
  if (colonIdx > slashIdx) {
    tag = imgPart.slice(colonIdx + 1)
    img = imgPart.slice(0, colonIdx)
  }

  // Detect registry
  const parts = img.split('/')
  const isCustomRegistry = parts[0].includes('.') || parts[0].includes(':')
  const registry = isCustomRegistry ? parts[0] : 'docker.io'

  // Normalise name for Docker Hub (no namespace → library/...)
  let name = isCustomRegistry ? parts.slice(1).join('/') : img
  if (registry === 'docker.io' && !name.includes('/')) name = `library/${name}`

  return { registry, name, tag }
}

async function getRegistryToken(image: string): Promise<string> {
  const res = await axios.get(
    `https://auth.docker.io/token?service=registry.docker.io&scope=repository:${image}:pull`,
    { timeout: 8000 }
  )
  return res.data.token as string
}

async function getLatestDigest(image: string, tag: string): Promise<string | null> {
  const cacheKey = `digest:${image}:${tag}`
  const cached = fromCache<string>(cacheKey, HUB_TTL)
  if (cached) return cached

  try {
    const token = await getRegistryToken(image)
    const res = await axios.head(
      `https://registry-1.docker.io/v2/${image}/manifests/${tag}`,
      {
        headers: {
          Authorization: `Bearer ${token}`,
          Accept: [
            'application/vnd.docker.distribution.manifest.v2+json',
            'application/vnd.docker.distribution.manifest.list.v2+json',
            'application/vnd.oci.image.index.v1+json',
          ].join(', '),
        },
        timeout: 10000,
      }
    )
    const digest = res.headers['docker-content-digest'] as string | undefined
    if (digest) toCache(cacheKey, digest)
    return digest ?? null
  } catch {
    return null
  }
}

router.get('/docker', async (_req, res) => {
  try {
    // List running containers
    const containersRes = await axios.get('http://localhost/v1.41/containers/json', {
      socketPath: DOCKER_SOCKET,
      timeout: 5000,
    })

    const containers: ContainerInfo[] = []

    for (const c of containersRes.data) {
      const rawImage: string = c.Image ?? ''
      const containerName: string = (c.Names?.[0] ?? '').replace(/^\//, '')

      // Get repo digests from image inspect
      let repoDigest: string | null = null
      try {
        const imgRes = await axios.get(`http://localhost/v1.41/images/${c.ImageID}/json`, {
          socketPath: DOCKER_SOCKET,
          timeout: 5000,
        })
        const digests: string[] = imgRes.data.RepoDigests ?? []
        const matched = digests.find(d => d.split('@')[0].includes(rawImage.split(':')[0]))
        repoDigest = matched?.split('@')[1] ?? digests[0]?.split('@')[1] ?? null
      } catch { /* ignore */ }

      const { registry, name, tag } = parseImage(rawImage)
      const isDockerHub = registry === 'docker.io'

      let upToDate: boolean | null = null
      if (isDockerHub && repoDigest) {
        const latest = await getLatestDigest(name, tag)
        if (latest) upToDate = latest === repoDigest
      }

      containers.push({
        name: containerName,
        image: rawImage.split(':')[0].split('/').slice(-1)[0], // short name
        tag: rawImage.includes(':') ? rawImage.split(':')[1].split('@')[0] : 'latest',
        repoDigest,
        upToDate,
        registry,
      })
    }

    res.json({ containers })
  } catch (err: unknown) {
    const msg = err instanceof Error ? err.message : 'Unknown error'
    res.status(500).json({ error: msg })
  }
})

/* ────────────────────────────────────────────────────────────────────────────
   GitHub release tracking
   ─────────────────────────────────────────────────────────────────────────── */
const GH_TTL = 15 * 60 * 1000 // 15 min

interface GithubRelease {
  repo: string
  version: string
  name: string
  publishedAt: string
  url: string
}

router.get('/github', async (_req, res) => {
  try {
    const token = process.env.GITHUB_TOKEN
    const headers: Record<string, string> = {
      Accept: 'application/vnd.github+json',
      'X-GitHub-Api-Version': '2022-11-28',
    }
    if (token) headers.Authorization = `Bearer ${token}`

    const releases: GithubRelease[] = await Promise.all(
      githubRepos.map(async repo => {
        const cacheKey = `gh:${repo}`
        const cached = fromCache<GithubRelease>(cacheKey, GH_TTL)
        if (cached) return cached

        const r = await axios.get(
          `https://api.github.com/repos/${repo}/releases/latest`,
          { headers, timeout: 8000 }
        )
        const release: GithubRelease = {
          repo,
          version:     r.data.tag_name,
          name:        r.data.name || r.data.tag_name,
          publishedAt: r.data.published_at,
          url:         r.data.html_url,
        }
        toCache(cacheKey, release)
        return release
      })
    )

    res.json({ releases })
  } catch (err: unknown) {
    const msg = err instanceof Error ? err.message : 'Unknown error'
    res.status(500).json({ error: msg })
  }
})

export default router