import { readFile, writeFile } from 'node:fs/promises'
import vpsConfig from '#config/vps'
import dockerService from '#services/docker_service'
import CaddyfileVersion from '#models/caddyfile_version'

export interface CaddySite {
  /**
   * Addresses as written in the Caddyfile ("a.fr, www.a.fr").
   */
  addresses: string[]

  /**
   * Domains that can be checked over HTTPS (no wildcard, no port-only address).
   */
  domains: string[]
  kind: 'proxy' | 'static' | 'other'

  /**
   * "container:port" for a reverse proxy, the root folder for a static site.
   */
  upstream: string | null
  line: number
}

export interface ReloadResult {
  ok: boolean
  output: string
}

const LINE_BREAK = /\r?\n/

/**
 * Extracts the site blocks of a Caddyfile. This is not a full parser:
 * it only needs the addresses and what each site serves.
 */
export function parseCaddyfile(content: string): CaddySite[] {
  const sites: CaddySite[] = []
  let depth = 0
  let current: CaddySite | null = null
  let currentDepth = 0

  content.split(LINE_BREAK).forEach((rawLine, index) => {
    const line = rawLine.replace(/(^|\s)#.*$/, '').trim()
    if (!line) return

    const opens = (line.match(/{/g) ?? []).length
    const closes = (line.match(/}/g) ?? []).length

    /**
     * A site block starts at the top level, with the addresses before "{".
     * "{" alone is the global options block and "(name) {" a snippet.
     */
    if (depth === 0 && line.endsWith('{') && line !== '{' && !line.startsWith('(')) {
      const addresses = line
        .slice(0, -1)
        .split(/[,\s]+/)
        .map((address) => address.trim())
        .filter(Boolean)
      current = {
        addresses,
        domains: addresses.map(toDomain).filter((domain): domain is string => domain !== null),
        kind: 'other',
        upstream: null,
        line: index + 1,
      }
      currentDepth = depth + opens - closes
      sites.push(current)
      depth = currentDepth
      /**
       * Block opened and closed on the same line.
       */
      if (currentDepth === 0) current = null
      return
    }

    if (current) {
      const [directive, ...args] = line.split(/\s+/)
      if (directive === 'reverse_proxy' && current.kind !== 'proxy') {
        const upstream = args.find(
          (arg) => !arg.startsWith('/') && !arg.startsWith('@') && arg !== '{' && arg !== '*'
        )
        current.kind = 'proxy'
        current.upstream = upstream?.replace(/^https?:\/\//, '') ?? null
      } else if (directive === 'root' && current.kind === 'other') {
        current.kind = 'static'
        current.upstream = args.at(-1) ?? null
      } else if (directive === 'file_server' && current.kind === 'other') {
        current.kind = 'static'
      }
    }

    depth += opens - closes
    if (current && depth < currentDepth) current = null
  })

  return sites
}

/**
 * "https://a.fr:443" -> "a.fr". Null when the address cannot be checked.
 */
function toDomain(address: string): string | null {
  const host = address
    .replace(/^https?:\/\//, '')
    .replace(/\/.*$/, '')
    .replace(/:\d+$/, '')
  if (!host || host.includes('*') || host.includes('{') || host === 'localhost') return null
  if (/^[\d.]+$/.test(host) || host.includes(':')) return null
  return host.toLowerCase()
}

/**
 * Caddy logs JSON lines: keep the level, the message and the error.
 */
function readableCaddyLog(output: string) {
  return output
    .split(LINE_BREAK)
    .filter((line) => line.trim())
    .map((line) => {
      try {
        const entry = JSON.parse(line) as { level?: string; msg?: string; error?: string }
        return [entry.level?.toUpperCase(), entry.msg, entry.error].filter(Boolean).join(' · ')
      } catch {
        return line
      }
    })
    .join('\n')
}

class CaddyService {
  read() {
    return readFile(vpsConfig.caddy.caddyfilePath, 'utf8')
  }

  async sites() {
    return parseCaddyfile(await this.read())
  }

  /**
   * Writes in place: the Caddyfile is often mounted as a single file in
   * the Caddy container, and replacing the file (write + rename) would leave
   * the container on the old version.
   */
  #write(content: string) {
    return writeFile(vpsConfig.caddy.caddyfilePath, content, 'utf8')
  }

  async reload(): Promise<ReloadResult> {
    const result = await dockerService.exec(vpsConfig.caddy.container, [
      'caddy',
      'reload',
      '--config',
      vpsConfig.caddy.configPath,
      '--adapter',
      'caddyfile',
    ])
    return {
      ok: result.exitCode === 0,
      output: readableCaddyLog(`${result.stdout}${result.stderr}`),
    }
  }

  /**
   * Saves the new Caddyfile and reloads Caddy. When Caddy refuses the new
   * configuration, the previous file is put back (Caddy keeps running with
   * the previous configuration anyway).
   */
  async saveAndReload(
    content: string,
    meta: { username: string | null; reason: string }
  ): Promise<ReloadResult> {
    const previous = await this.read()
    const normalized = content.replace(/\r\n/g, '\n')
    if (normalized === previous) return { ok: true, output: 'Aucun changement.' }

    await this.#write(normalized)

    let result: ReloadResult
    try {
      result = await this.reload()
    } catch (error) {
      result = { ok: false, output: error instanceof Error ? error.message : String(error) }
    }

    if (!result.ok) {
      await this.#write(previous)
      return result
    }

    await CaddyfileVersion.create({
      content: previous,
      username: meta.username,
      reason: meta.reason,
    })
    await this.#pruneVersions()
    return result
  }

  async appendBlock(block: string, meta: { username: string | null; reason: string }) {
    const current = await this.read()
    return this.saveAndReload(`${current.trimEnd()}\n\n${block.trim()}\n`, meta)
  }

  /**
   * Keeps the last 50 versions.
   */
  async #pruneVersions() {
    const kept = await CaddyfileVersion.query().select('id').orderBy('id', 'desc').limit(50)
    if (kept.length < 50) return
    await CaddyfileVersion.query().where('id', '<', kept.at(-1)!.id).delete()
  }
}

const caddyService = new CaddyService()
export default caddyService