import { powerMonitor, BrowserWindow } from 'electron'
import { IPC } from '@shared/ipc'
import type { Exercise, Tick, HistoryEntry } from '@shared/types'
import { isQuietAt } from '@shared/types'
import { getExercises, getHistory, getSettings, updateExercise } from './store'
import { fireReminder } from './notifications'
import { broadcastState } from './state-actions'
import { isMeetingActiveSync, refreshMeetingState } from './meeting-detect'
import { adjustNextFireAt } from './adaptive'

/**
 * Сколько reps пользователь сделал по упражнению `ex` за сегодня (local day).
 * Учитываем actualReps если задано (частичное выполнение), иначе planned reps.
 */
function repsDoneToday(ex: Exercise, history: HistoryEntry[]): number {
  const todayKey = new Date()
  todayKey.setHours(0, 0, 0, 0)
  const startMs = todayKey.getTime()
  let sum = 0
  for (const e of history) {
    if (e.action !== 'done') continue
    if (e.exerciseId !== ex.id) continue
    if (e.ts < startMs) continue
    sum += e.actualReps ?? ex.reps
  }
  return sum
}

/**
 * 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

  // Авто-пауза на встречах. Sync-чтение кеша (последнее значение); refresh
  // запускаем в фоне чтобы кеш «зрел» к следующему tick'у. На холодном
  // старте кеш false — первое срабатывание может прийти в момент митинга,
  // но 30 сек спустя система догонит и больше не будет fire'ить.
  if (settings.meetingAutoPause) {
    refreshMeetingState()
    if (isMeetingActiveSync()) return
  }

  const now = Date.now()
  const exercises = getExercises()
  // history запрашивается если у какого-нибудь упражнения есть
  // dailyGoal или adaptive: false — иначе экономим IPC-нагрузку.
  const needsHistory = exercises.some(
    (e) => e.dailyGoal !== undefined || e.adaptive
  )
  const history = needsHistory ? getHistory() : []
  let anyFired = false
  for (const ex of exercises) {
    if (!ex.enabled) continue
    if (ex.nextFireAt > now) continue
    // Soft cap: если dailyGoal задан и уже выполнен — переносим
    // следующий fire на «начало завтра» (без повторных проверок до утра).
    if (ex.dailyGoal !== undefined && ex.dailyGoal > 0) {
      const done = repsDoneToday(ex, history)
      if (done >= ex.dailyGoal) {
        const tomorrow = new Date()
        tomorrow.setHours(0, 0, 0, 0)
        tomorrow.setDate(tomorrow.getDate() + 1)
        updateExercise(ex.id, { nextFireAt: tomorrow.getTime() })
        continue
      }
    }
    // Базовый candidate. Если adaptive — сдвигаем на «хороший» час
    // по исторической статистике успеха/скипов.
    let nextFireAt = now + ex.intervalMinutes * 60_000
    if (ex.adaptive) {
      nextFireAt = adjustNextFireAt(ex, nextFireAt, history)
    }
    const updated = updateExercise(ex.id, { nextFireAt })
    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()
}