/**
 * Lightweight scheduled Docker maintenance jobs on the peardock server.
 * Not a full webhook platform — interval tasks for prune / health checks.
 */
import { docker } from './docker.js'
import logger from '../utils/logger.js'
import fs from 'fs'
import path from 'path'
import { randomBytes } from 'crypto'

const FILE =
  process.env.PEARDOCK_SCHEDULES_PATH ||
  path.join(process.cwd(), 'peardock-schedules.json')

/** @type {Map<string, { id: string, kind: string, intervalMs: number, enabled: boolean, lastRun?: string, lastError?: string, options?: object, timer?: NodeJS.Timeout }>} */
const jobs = new Map()

function loadDisk() {
  try {
    if (!fs.existsSync(FILE)) return []
    const raw = JSON.parse(fs.readFileSync(FILE, 'utf8'))
    return Array.isArray(raw?.jobs) ? raw.jobs : Array.isArray(raw) ? raw : []
  } catch (err) {
    logger.warn('Failed to load schedules', { error: err.message })
    return []
  }
}

function saveDisk() {
  try {
    const payload = {
      version: 1,
      updatedAt: new Date().toISOString(),
      jobs: [...jobs.values()].map((j) => ({
        id: j.id,
        kind: j.kind,
        intervalMs: j.intervalMs,
        enabled: j.enabled,
        lastRun: j.lastRun || null,
        lastError: j.lastError || null,
        options: j.options || {},
      })),
    }
    const tmp = `${FILE}.${process.pid}.tmp`
    fs.writeFileSync(tmp, JSON.stringify(payload, null, 2), { mode: 0o600 })
    fs.renameSync(tmp, FILE)
  } catch (err) {
    logger.warn('Failed to save schedules', { error: err.message })
  }
}

async function runJob(job) {
  if (!job.enabled) return
  try {
    if (job.kind === 'systemPrune') {
      const volumes = Boolean(job.options?.volumes)
      if (typeof docker.pruneSystem === 'function') {
        await docker.pruneSystem({ volumes })
      } else {
        await docker.pruneContainers({})
        await docker.pruneImages({})
        await docker.pruneNetworks({})
        if (volumes) await docker.pruneVolumes({})
      }
    } else if (job.kind === 'pruneImages') {
      await docker.pruneImages({})
    } else if (job.kind === 'pruneContainers') {
      await docker.pruneContainers({})
    } else if (job.kind === 'dockerPing') {
      await docker.ping()
    } else {
      throw new Error(`Unknown schedule kind: ${job.kind}`)
    }
    job.lastRun = new Date().toISOString()
    job.lastError = null
    logger.info('Scheduled job ok', { id: job.id, kind: job.kind })
  } catch (err) {
    job.lastError = err.message || String(err)
    job.lastRun = new Date().toISOString()
    logger.warn('Scheduled job failed', { id: job.id, kind: job.kind, error: job.lastError })
  }
  saveDisk()
}

function arm(job) {
  if (job.timer) {
    clearInterval(job.timer)
    job.timer = null
  }
  if (!job.enabled || job.intervalMs < 60_000) return
  job.timer = setInterval(() => {
    runJob(job)
  }, job.intervalMs)
  if (typeof job.timer.unref === 'function') job.timer.unref()
}

export function listSchedules() {
  return [...jobs.values()].map((j) => ({
    id: j.id,
    kind: j.kind,
    intervalMs: j.intervalMs,
    enabled: j.enabled,
    lastRun: j.lastRun || null,
    lastError: j.lastError || null,
    options: j.options || {},
  }))
}

/**
 * @param {{ id?: string, kind: string, intervalMs: number, enabled?: boolean, options?: object }} input
 */
export function upsertSchedule(input) {
  const kind = String(input.kind || '').trim()
  const allowed = new Set(['systemPrune', 'pruneImages', 'pruneContainers', 'dockerPing'])
  if (!allowed.has(kind)) throw Object.assign(new Error('Invalid schedule kind'), { code: 'INVALID_ARGS' })
  const intervalMs = Math.max(60_000, Number(input.intervalMs) || 3_600_000)
  const id =
    input.id && String(input.id).startsWith('sch_')
      ? String(input.id)
      : `sch_${Date.now().toString(36)}_${randomBytes(3).toString('hex')}`
  const prev = jobs.get(id)
  if (prev?.timer) clearInterval(prev.timer)
  const job = {
    id,
    kind,
    intervalMs,
    enabled: input.enabled !== false,
    lastRun: prev?.lastRun,
    lastError: prev?.lastError,
    options: input.options && typeof input.options === 'object' ? input.options : {},
  }
  jobs.set(id, job)
  arm(job)
  saveDisk()
  return listSchedules().find((j) => j.id === id)
}

export function deleteSchedule(id) {
  const job = jobs.get(id)
  if (!job) return false
  if (job.timer) clearInterval(job.timer)
  jobs.delete(id)
  saveDisk()
  return true
}

export function restoreSchedules() {
  for (const def of loadDisk()) {
    if (!def?.kind || !def?.id) continue
    const job = {
      id: def.id,
      kind: def.kind,
      intervalMs: Math.max(60_000, Number(def.intervalMs) || 3_600_000),
      enabled: def.enabled !== false,
      lastRun: def.lastRun,
      lastError: def.lastError,
      options: def.options || {},
    }
    jobs.set(job.id, job)
    arm(job)
  }
  logger.info('Schedules restored', { count: jobs.size })
}

export default {
  listSchedules,
  upsertSchedule,
  deleteSchedule,
  restoreSchedules,
}