import { FxGate, FxKind } from '../game/engine/kernel/fxqueue'
import { seasonOf } from '../game/data/season'

let gate: FxGate | null = null

export function fx(): FxGate | null {
  return gate
}

export function ensureFx(opts?: { onEmit?: (kind: FxKind, payload?: Record<string, number | string>) => void }): FxGate {
  if (gate) return gate
  gate = new FxGate({
    emit: (e) => {
      switch (e.kind) {
        case 'mist': {
          window.dispatchEvent(new CustomEvent('fx:mist'))
          break
        }
        case 'spark': {
          window.dispatchEvent(new CustomEvent('fx:spark'))
          break
        }
        case 'ripple': {
          window.dispatchEvent(new CustomEvent('fx:ripple', { detail: e.payload ?? {} }))
          break
        }
        case 'blade': {
          window.dispatchEvent(new CustomEvent('fx:blade'))
          break
        }
        case 'seasonShift': {
          window.dispatchEvent(new CustomEvent('fx:season', { detail: e.payload ?? {} }))
          break
        }
        case 'drift': {
          window.dispatchEvent(new CustomEvent('fx:drift', { detail: e.payload ?? {} }))
          break
        }
        case 'pulse': {
          window.dispatchEvent(new CustomEvent('fx:pulse', { detail: e.payload ?? {} }))
          break
        }
      }
      opts?.onEmit?.(e.kind, e.payload)
    }
  })
  if (typeof window !== 'undefined' && typeof window.matchMedia === 'function') {
    const mq = window.matchMedia('(prefers-reduced-motion: reduce)')
    gate.setReduced(mq.matches)
    mq.addEventListener('change', (ev) => gate?.setReduced(ev.matches))
  }
  return gate
}

/** store.advance 后调用：检测季节变化 → 季节脉动 + 季节色温 CSS 变量 */
export function fxSeason(prevMonth: number, nextMonth: number): void {
  const g = ensureFx()
  const prev = seasonOf(prevMonth)
  const next = seasonOf(nextMonth)
  if (prev !== next) {
    g.emit('seasonShift', { season: next, accent: labelOf(next) })
  }
  applySeason(next)
}

function labelOf(s: string): string {
  return { spring: '春', summer: '夏', autumn: '秋', winter: '冬' }[s] ?? s
}

export function seasonTintOf(month: number): string {
  const s = seasonOf(month)
  return labelOf(s)
}

/** 直接应用季节色温 CSS 变量（单源 data-season） */
export function applySeason(season: string): void {
  if (typeof document === 'undefined') return
  document.documentElement.setAttribute('data-season', season)
}

/** 慢帧保险：document.hidden 时自动停 particle（detail 在 canvas 端监听） */
export function fxVisibilityAutopause(): () => void {
  const onVis = () => {
    const g = ensureFx()
    if (document.hidden) {
      // hidden 时禁止未来发射
      g.setReduced(true)
    } else {
      const mq = window.matchMedia('(prefers-reduced-motion: reduce)')
      g.setReduced(mq.matches)
    }
  }
  document.addEventListener('visibilitychange', onVis)
  return () => document.removeEventListener('visibilitychange', onVis)
}