fix: two clicks are needed to chenge the theme for the first time

src/hooks/theme.ts

@@ -1,33 +1,71 @@
 import {useSettingStore} from "@/stores/setting.ts";
 
+type Theme = "light" | "dark";
+// 获取系统主题
+function getSystemTheme(): Theme {
+  if (window.matchMedia('(prefers-color-scheme: dark)').matches) {
+     return 'dark';
+  } else if (window.matchMedia('(prefers-color-scheme: light)').matches) {
+      return 'light';
+  }
+  return 'light'; // 默认浅色模式
+}
+
+// 交换主题名称
+function swapTheme(theme: Theme): Theme {
+  return theme === 'light' ? 'dark' : 'light'
+}
+
+// 监听系统主题变化
+function listenToSystemThemeChange(call: (theme: Theme) => void) {
+    window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', e => {
+        if (e.matches) {
+            // console.log('系统已切换到深色模式');
+            call('dark');
+        }
+    });
+    window.matchMedia('(prefers-color-scheme: light)').addEventListener('change', e => {
+        if (e.matches) {
+            // console.log('系统已切换到浅色模式');
+            call('light');
+        }
+    });
+}
+
 export default function useTheme() {
   const settingStore = useSettingStore()
 
-// // 查询当前系统主题颜色
-//   const match: MediaQueryList = window.matchMedia("(prefers-color-scheme: dark)")
-// // 监听系统主题变化
-//   match.addEventListener('change', followSystem)
-//
-//   function followSystem() {
-//     document.documentElement.className = match.matches ? 'dark' : 'light'
-//   }
-
+  // 开启监听系统主题变更,后期可以通过用户配置来决定是否开启
+  listenToSystemThemeChange((theme: Theme) => {
+    // 如果系统主题变更后和当前的主题一致，则不需要再重新切换
+    if(settingStore.theme === theme){
+        return;
+    }
+    
+    settingStore.theme = theme;
+    setTheme(theme);
+  })
 
   function toggleTheme() {
-    if (settingStore.theme === 'auto') {
-      settingStore.theme = 'light'
-    } else {
-      settingStore.theme = settingStore.theme === 'light' ? 'dark' : 'light'
-    }
-    setTheme(settingStore.theme)
+    // auto模式下，默认是使用系统主题，切换时应该使用当前系统主题为基础进行切换
+    settingStore.theme = swapTheme(settingStore.theme === 'auto' ? getSystemTheme() : settingStore.theme as Theme);
+    setTheme(settingStore.theme);
   }
 
-  function setTheme(val) {
-    document.documentElement.className = val
+  function setTheme(val:string) {
+    // auto模式下，则通过查询系统主题来设置主题名称
+    document.documentElement.className = val === 'auto' ? getSystemTheme() : val;
+  }
+
+  // 获取当前具体的主题名称
+  function getTheme():Theme{
+    // auto模式下，则通过查询系统主题来获取当前具体的主题名称
+    return settingStore.theme === 'auto' ? getSystemTheme() : settingStore.theme as Theme;
   }
 
   return {
     toggleTheme,
-    setTheme
+    setTheme,
+    getTheme
   }
 }