import { defineStore } from 'pinia'
import { ref, watch } from 'vue'
import { isAfterSunset, getMsUntilNextSwitch } from '../utils/sunset'

export const useThemeStore = defineStore('theme', () => {
  const STORAGE_KEY = 'onu-theme'
  const savedTheme = localStorage.getItem(STORAGE_KEY)
  // 无手动偏好时，根据广西日落时间自动选择
  const theme = ref(savedTheme || (isAfterSunset() ? 'dark' : 'light'))

  const applyTheme = (t) => {
    document.documentElement.setAttribute('data-theme', t)
  }

  let switchTimer = null

  // 初始化时立即应用
  applyTheme(theme.value)

  // 设置日落/日出自动切换定时器，仅在用户未手动选择时生效
  const scheduleAutoSwitch = () => {
    if (switchTimer) clearTimeout(switchTimer)
    // 始终在日落/日出时自动切换
    const delay = getMsUntilNextSwitch()
    switchTimer = setTimeout(() => {
      theme.value = isAfterSunset() ? 'dark' : 'light'
      scheduleAutoSwitch() // 递归调度下一次
    }, delay + 60000) // 加 1 分钟余量
  }
  scheduleAutoSwitch()

  // 切换
  const toggle = () => {
    theme.value = theme.value === 'dark' ? 'light' : 'dark'
  }

  // 监听变化：同步到 DOM + localStorage
  watch(theme, (t) => {
    applyTheme(t)
    localStorage.setItem(STORAGE_KEY, t)
  })

  return { theme, toggle }
})