import { powerMonitor, BrowserWindow } from 'electron'
import { IPC } from '@shared/ipc'
import type { Tick } from '@shared/types'
import { isQuietAt } from '@shared/types'
import { getExercises, getSettings, updateExercise } from './store'
import { fireReminder } from './notifications'
import { broadcastState } from './state-actions'

/**
 * TICK_MS drives the per-second countdown UI; CHECK_MS gates the (cheaper)
 * "is anything due to fire?" pass so we don't iterate exercises every second.
 */
const TICK_MS = 1000
const CHECK_MS = 5000

let tickHandle: NodeJS.Timeout | null = null
let powerListenersArmed = false
let lastCheckAt = 0
let paused = false

function checkDueExercises(): void {
  if (paused) return
  const settings = getSettings()
  if (!settings.globalEnabled) return

  // Inside the quiet window: defer all due fires until it closes. The next
  // CHECK_MS pass after the window ends will pick them up.
  if (isQuietAt(settings.quietHours, new Date())) return

  const now = Date.now()
  const exercises = getExercises()
  let anyFired = false
  for (const ex of exercises) {
    if (!ex.enabled) continue
    if (ex.nextFireAt <= now) {
      const updated = updateExercise(ex.id, {
        nextFireAt: now + ex.intervalMinutes * 60_000
      })
      if (updated) {
        anyFired = true
        fireReminder(updated, settings.notificationMode)
      }
    }
  }
  // Push fresh state so the renderer's Dashboard/Exercises pages don't show
  // stale `nextFireAt` until the next state-changing IPC arrives.
  if (anyFired) broadcastState()
}

function broadcastTicks(): void {
  const now = Date.now()
  const ticks: Tick[] = getExercises().map((e) => ({
    exerciseId: e.id,
    msUntilFire: Math.max(0, e.nextFireAt - now),
    enabled: e.enabled
  }))
  for (const win of BrowserWindow.getAllWindows()) {
    if (!win.isDestroyed()) win.webContents.send(IPC.evtTick, ticks)
  }
}

function tick(): void {
  broadcastTicks()
  const now = Date.now()
  if (now - lastCheckAt >= CHECK_MS) {
    lastCheckAt = now
    checkDueExercises()
  }
}

export function startScheduler(): void {
  if (tickHandle) return
  lastCheckAt = 0
  tickHandle = setInterval(tick, TICK_MS)
  // Run an immediate tick so renderer hydrates quickly.
  tick()

  // Only attach powerMonitor listeners once per process — startScheduler may
  // be invoked again after stopScheduler in dev hot-reload paths and we don't
  // want the same handler firing N times after a resume.
  if (!powerListenersArmed) {
    powerListenersArmed = true
    powerMonitor.on('resume', () => {
      lastCheckAt = 0
      tick()
    })
    powerMonitor.on('unlock-screen', () => {
      lastCheckAt = 0
      tick()
    })
  }
}

export function stopScheduler(): void {
  if (tickHandle) {
    clearInterval(tickHandle)
    tickHandle = null
  }
}

export function setPaused(value: boolean): void {
  paused = value
}

export function isPaused(): boolean {
  return paused
}

export function forceCheck(): void {
  lastCheckAt = 0
  tick()
}