import { join } from 'path'
import { loadAppEnv } from '@because/toes/tools'
import type { CronJob } from './schedules'
import { getNextRun } from './scheduler'

const APPS_DIR = process.env.APPS_DIR!
const TOES_DIR = process.env.TOES_DIR!
const RUNNER = join(import.meta.dir, 'runner.ts')

async function readStream(stream: ReadableStream<Uint8Array>, append: (text: string) => void) {
  const reader = stream.getReader()
  const decoder = new TextDecoder()
  while (true) {
    const { done, value } = await reader.read()
    if (done) break
    append(decoder.decode(value, { stream: true }))
  }
}

export async function executeJob(job: CronJob, onUpdate: () => void): Promise<void> {
  if (job.state === 'disabled') return

  job.state = 'running'
  job.lastRun = Date.now()
  job.lastOutput = undefined
  job.lastError = undefined
  job.lastExitCode = undefined
  job.lastDuration = undefined
  onUpdate()

  const cwd = join(APPS_DIR, job.app, 'current')

  try {
    const proc = Bun.spawn(['bun', 'run', RUNNER, job.file], {
      cwd,
      env: { ...process.env, ...loadAppEnv(job.app), DATA_DIR: join(TOES_DIR, job.app) },
      stdout: 'pipe',
      stderr: 'pipe',
    })

    // Stream output incrementally into job fields
    await Promise.all([
      readStream(proc.stdout as ReadableStream<Uint8Array>, text => {
        job.lastOutput = (job.lastOutput || '') + text
      }),
      readStream(proc.stderr as ReadableStream<Uint8Array>, text => {
        job.lastError = (job.lastError || '') + text
      }),
    ])

    const code = await proc.exited

    job.lastDuration = Date.now() - job.lastRun
    job.lastExitCode = code
    if (!job.lastError && code !== 0) job.lastError = 'Non-zero exit'
    if (code === 0) job.lastError = undefined
    if (!job.lastOutput) job.lastOutput = undefined
    job.state = 'idle'
    job.nextRun = getNextRun(job.id)

    // Log result
    console.log(`[cron] ${job.id} finished: code=${code} duration=${job.lastDuration}ms`)
    if (job.lastOutput) console.log(job.lastOutput)
    if (job.lastError) console.error(job.lastError)
  } catch (e) {
    job.lastDuration = Date.now() - job.lastRun
    job.lastExitCode = 1
    job.lastError = e instanceof Error ? e.message : String(e)
    job.state = 'idle'
    console.error(`[cron] ${job.id} failed:`, e)
  }

  onUpdate()
}