import * as fs from 'fs'
import * as path from 'path'

const DATA_DIR = fs.existsSync('/data') ? '/data' : '/tmp'
const TIMERS_PATH = path.join(DATA_DIR, 'tablet-timers.json')

export interface Timer {
  id: string
  label: string
  startedAt: string // ISO
  endsAt: string    // ISO
  agent?: 'cosmo' | 'lusya'
}

function load(): Timer[] {
  try {
    if (fs.existsSync(TIMERS_PATH)) {
      return JSON.parse(fs.readFileSync(TIMERS_PATH, 'utf-8'))
    }
  } catch {}
  return []
}

function save(list: Timer[]) {
  try {
    fs.writeFileSync(TIMERS_PATH, JSON.stringify(list, null, 2))
  } catch {}
}

// Mutative helpers, used by timer API route
export function listActive(): Timer[] {
  const now = Date.now()
  // Drop any that expired over 30 min ago — stale garbage
  const list = load().filter(t => new Date(t.endsAt).getTime() > now - 30 * 60 * 1000)
  save(list)
  return list
}

export function addTimer(t: Omit<Timer, 'id' | 'startedAt'>): Timer {
  const full: Timer = {
    id: Date.now().toString(36) + Math.random().toString(36).slice(2, 6),
    startedAt: new Date().toISOString(),
    ...t,
  }
  const list = load()
  list.push(full)
  save(list)
  return full
}

export function removeTimer(id: string): boolean {
  const list = load()
  const next = list.filter(t => t.id !== id)
  if (next.length === list.length) return false
  save(next)
  return true
}