import { defineStore } from 'pinia'
import { ref, watch } from 'vue'

export const useThemeStore = defineStore('theme', () => {
  // State
  const theme = ref('dark') // 'dark' | 'light'

  // Load persisted theme on init
  function init() {
    try {
      const saved = uni.getStorageSync('theme')
      if (saved === 'light' || saved === 'dark') {
        theme.value = saved
      } else {
        // Follow system preference if available
        try {
          const sysInfo = uni.getSystemInfoSync()
          if (sysInfo.theme && sysInfo.theme === 'light') {
            theme.value = 'light'
          }
        } catch (e) {
          // Default to dark (brand identity)
        }
      }
    } catch (e) {
      theme.value = 'dark'
    }
    applyTheme(theme.value)
  }

  // Toggle theme
  function toggle() {
    theme.value = theme.value === 'dark' ? 'light' : 'dark'
    applyTheme(theme.value)
    persistTheme(theme.value)
  }

  // Set specific theme
  function setTheme(t) {
    if (t !== 'dark' && t !== 'light') return
    theme.value = t
    applyTheme(t)
    persistTheme(t)
  }

  // Apply to DOM
  function applyTheme(t) {
    // Update page data-theme (CSS fallback)
    try {
      const pages = getCurrentPages()
      const curPage = pages[pages.length - 1]
      if (curPage && curPage.$page && curPage.$page.$el) {
        curPage.$page.$el.setAttribute('data-theme', t)
      }
    } catch (e) {
      // Silent fallback
    }

    // Update the native bottom tab bar (outside Vue component tree)
    try {
      uni.setTabBarStyle({
        color: t === 'light' ? '#4A5568' : '#A0AEC0',
        selectedColor: '#C9A84C',
        backgroundColor: t === 'light' ? '#FFFFFF' : '#1E3A5F',
        borderStyle: t === 'light' ? 'black' : 'white',
      })
    } catch (e) {
      // Tab bar not configured — skip
    }
  }

  // Persist to storage
  function persistTheme(t) {
    try {
      uni.setStorageSync('theme', t)
    } catch (e) {
      // Silent
    }
  }

  // Listen for system theme changes
  function watchSystemTheme() {
    try {
      uni.onThemeChange((res) => {
        // Optional: auto-follow system
        // theme.value = res.theme
        // applyTheme(res.theme)
      })
    } catch (e) {
      // onThemeChange not supported on this platform
    }
  }

  return {
    theme,
    init,
    toggle,
    setTheme,
    watchSystemTheme
  }
})