import fs from 'node:fs'
import path from 'node:path'

/** "AITURK iş hattı" choice, stored in the Codex bridge's `bridge.json` under `aiturk_hat`.
 *  The bridge re-reads the field when the file changes, so no restart is needed. */
export type IsHattiSecim = 'onerilen' | 'buyuk' | 'kapali' | 'ozel'

export interface IsHattiSettings {
  secim: IsHattiSecim
  talimat: string
}

const SECIMLER: IsHattiSecim[] = ['onerilen', 'buyuk', 'kapali', 'ozel']
const MAX_TALIMAT = 20000

export function readIsHatti(raw: null | string): IsHattiSettings {
  try {
    const hat = raw ? JSON.parse(raw)?.aiturk_hat : null

    if (!hat || typeof hat !== 'object') {
      return { secim: 'onerilen', talimat: '' }
    }

    const talimat = typeof hat.talimat === 'string' ? hat.talimat : ''

    if (SECIMLER.includes(hat.secim)) {
      return { secim: hat.secim, talimat }
    }

    // Written before this screen existed: same meaning the bridge gives it.
    return { secim: hat.enabled === false ? 'kapali' : talimat.trim() ? 'ozel' : 'onerilen', talimat }
  } catch {
    return { secim: 'onerilen', talimat: '' }
  }
}

export function writeIsHatti(raw: null | string, value: unknown): string {
  const v = value as Partial<IsHattiSettings> | null

  if (!v || !SECIMLER.includes(v.secim as IsHattiSecim)) throw new Error('Invalid choice')
  const talimat = typeof v.talimat === 'string' ? v.talimat : ''

  if (talimat.length > MAX_TALIMAT) throw new Error('Instruction too long')
  if (v.secim === 'ozel' && !talimat.trim()) throw new Error('Custom instruction is empty')
  let config: Record<string, unknown> = {}

  try {
    const parsed = raw ? JSON.parse(raw) : {}
    config = parsed && typeof parsed === 'object' && !Array.isArray(parsed) ? parsed : {}
  } catch {
    throw new Error('bridge.json is not valid JSON')
  }

  const old = config.aiturk_hat && typeof config.aiturk_hat === 'object' ? (config.aiturk_hat as Record<string, unknown>) : {}
  const hat: Record<string, unknown> = { ...old, secim: v.secim, talimat }
  delete hat.enabled

  return `${JSON.stringify({ ...config, aiturk_hat: hat }, null, 2)}\n`
}

export function createIsHattiStore(directory: string) {
  const file = path.join(directory, 'bridge.json')
  const read = () => (fs.existsSync(file) ? fs.readFileSync(file, 'utf8') : null)

  return {
    get: (): IsHattiSettings => readIsHatti(read()),
    save(value: unknown): IsHattiSettings {
      const text = writeIsHatti(read(), value)
      fs.mkdirSync(directory, { recursive: true })
      const tmp = `${file}.${process.pid}.tmp`

      try {
        fs.writeFileSync(tmp, text, 'utf8')
        fs.renameSync(tmp, file)
      } finally {
        if (fs.existsSync(tmp)) fs.unlinkSync(tmp)
      }

      return readIsHatti(text)
    }
  }
}