import { readFileSync } from 'node:fs'
import { dirname, join } from 'node:path'
import { fileURLToPath } from 'node:url'
import type { Db } from '@evofw/db'
import { repos } from '@evofw/db'
import { AppError } from '../plugins/error-handler.js'

const __dirname = dirname(fileURLToPath(import.meta.url))
const scriptsDir = join(__dirname, '../agent-scripts')

const ID_ALPHABET =
  'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'

export function randomToken(length: number): string {
  const bytes = crypto.getRandomValues(new Uint8Array(length))
  let out = ''
  for (const b of bytes) {
    out += ID_ALPHABET[b % ID_ALPHABET.length]
  }
  return out
}

/** Root path segments that must never be treated as install slugs. */
export const RESERVED_ROOT_SEGMENTS = new Set([
  'api',
  'v1',
  'assets',
  'health',
  'ready',
  'favicon.ico',
  'index.html',
  'robots.txt',
  'agent-install',
  'static',
])

const SLUG_RE = /^[A-Za-z0-9_-]{8,64}$/

export function isValidInstallSlug(segment: string): boolean {
  if (!segment || segment.includes('/') || segment.includes('.')) return false
  if (RESERVED_ROOT_SEGMENTS.has(segment.toLowerCase())) return false
  return SLUG_RE.test(segment)
}

export type InstallPlatform = 'linux' | 'mikrotik'

function mikrotikFetchImport(url: string): string {
  return `/tool fetch url="${url}" dst-path=evofw-install.rsc; /import file-name=evofw-install.rsc`
}

export function buildInstallUrls(
  baseUrl: string,
  id: string,
  slug: string,
  platform: InstallPlatform = 'linux',
) {
  const base = baseUrl.replace(/\/$/, '')
  const byId = `${base}/agent-install/${id}`
  const bySlug = `${base}/${slug}`
  if (platform === 'mikrotik') {
    return {
      by_id: byId,
      by_slug: bySlug,
      curl: {
        by_id: mikrotikFetchImport(byId),
        by_slug: mikrotikFetchImport(bySlug),
      },
    }
  }
  return {
    by_id: byId,
    by_slug: bySlug,
    curl: {
      by_id: `curl -fsSL ${byId} | bash`,
      by_slug: `curl -fsSL ${bySlug} | bash`,
    },
  }
}

export function mapInstallLink(
  row: NonNullable<ReturnType<typeof repos.getInstallLink>>,
  baseUrl: string,
) {
  const platform = (row.platform === 'mikrotik' ? 'mikrotik' : 'linux') as InstallPlatform
  const urls = buildInstallUrls(baseUrl, row.id, row.slug, platform)
  return {
    id: row.id,
    slug: row.slug,
    client_name: row.clientName,
    platform,
    agent_id: row.agentId ?? null,
    created_at: row.createdAt,
    revoked_at: row.revokedAt,
    last_used_at: row.lastUsedAt,
    use_count: row.useCount,
    urls: { by_id: urls.by_id, by_slug: urls.by_slug },
    curl: urls.curl,
  }
}

function loadInstallSh(): string {
  return readFileSync(join(scriptsDir, 'install.sh'), 'utf-8')
}

function loadMikrotikInstallRsc(): string {
  return readFileSync(join(scriptsDir, 'mikrotik-install.rsc'), 'utf-8')
}

function escapeRosString(s: string): string {
  return s.replace(/\\/g, '\\\\').replace(/"/g, '\\"')
}

/**
 * Self-contained install script: env exports + full install.sh body.
 */
export function renderInstallScript(opts: {
  cpUrl: string
  seed: string
  clientName: string
  platform: string
  installLinkId: string
}): string {
  const cp = opts.cpUrl.replace(/\/$/, '')
  const escape = (s: string) => s.replace(/'/g, `'\\''`)
  const header = [
    '#!/usr/bin/env bash',
    '# EvoFirewall short install link — env pre-set',
    'set -euo pipefail',
    `export EVOFW_CP_URL='${escape(cp)}'`,
    `export EVOFW_SEED='${escape(opts.seed)}'`,
    `export EVOFW_CLIENT_NAME='${escape(opts.clientName)}'`,
    `export EVOFW_PLATFORM='${escape(opts.platform)}'`,
    `export EVOFW_INSTALL_LINK_ID='${escape(opts.installLinkId)}'`,
    '',
  ].join('\n')

  // Drop the shebang from install.sh to avoid double shebang.
  const body = loadInstallSh().replace(/^#!\/usr\/bin\/env bash\r?\n/, '')
  return `${header}${body}`
}

/**
 * Personalized MikroTik RSC: globals + mikrotik-install.rsc body.
 */
export function renderMikrotikInstallScript(opts: {
  cpUrl: string
  seed: string
  clientName: string
  installLinkId: string
}): string {
  const cp = opts.cpUrl.replace(/\/$/, '')
  const header = [
    '# EvoFirewall short install link — globals pre-set (RouterOS 7.21+)',
    `:global EvofwCpUrl "${escapeRosString(cp)}"`,
    `:global EvofwSeed "${escapeRosString(opts.seed)}"`,
    `:global EvofwName "${escapeRosString(opts.clientName)}"`,
    `:global EvofwInstallLinkId "${escapeRosString(opts.installLinkId)}"`,
    '',
  ].join('\n')
  return `${header}${loadMikrotikInstallRsc()}`
}

export type ResolvedInstall = {
  body: string
  contentType: string
}

/** @deprecated use resolveAndRenderInstall */
export function resolveAndRenderInstallScript(
  db: Db,
  link: NonNullable<ReturnType<typeof repos.getInstallLink>>,
  publicBaseUrl: string,
  enrollSeedFallback: string,
): string {
  return resolveAndRenderInstall(db, link, publicBaseUrl, enrollSeedFallback)
    .body
}

export function resolveAndRenderInstall(
  db: Db,
  link: NonNullable<ReturnType<typeof repos.getInstallLink>>,
  publicBaseUrl: string,
  enrollSeedFallback: string,
): ResolvedInstall {
  if (link.revokedAt) {
    throw new AppError('GONE', 'Install link revoked', 410)
  }
  const seed = repos.getSetting(db, 'enroll_seed') || enrollSeedFallback
  repos.touchInstallLink(db, link.id)
  if (link.platform === 'mikrotik') {
    return {
      body: renderMikrotikInstallScript({
        cpUrl: publicBaseUrl,
        seed,
        clientName: link.clientName,
        installLinkId: link.id,
      }),
      contentType: 'text/plain',
    }
  }
  return {
    body: renderInstallScript({
      cpUrl: publicBaseUrl,
      seed,
      clientName: link.clientName,
      platform: link.platform,
      installLinkId: link.id,
    }),
    contentType: 'text/x-shellscript',
  }
}