package admin

import (
	"embed"
	"io/fs"
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
)

//go:embed all:dist
var distFS embed.FS

// Register 把内嵌的后台 SPA 挂到 /admin 下，index.html 做 SPA fallback
func Register(r *gin.Engine) {
	sub, err := fs.Sub(distFS, "dist")
	if err != nil {
		panic(err)
	}
	fileServer := http.FileServer(http.FS(sub))

	handler := func(c *gin.Context) {
		// 去掉前缀 /admin，交给内嵌文件服务器
		reqPath := strings.TrimPrefix(c.Request.URL.Path, "/admin")
		reqPath = strings.TrimPrefix(reqPath, "/")

		// 若请求的是真实存在的静态资源，直出；否则回退 index.html（前端路由）
		if reqPath != "" {
			if f, err := sub.Open(reqPath); err == nil {
				_ = f.Close()
				c.Request.URL.Path = "/" + reqPath
				fileServer.ServeHTTP(c.Writer, c.Request)
				return
			}
		}
		// SPA fallback
		data, err := fs.ReadFile(sub, "index.html")
		if err != nil {
			c.String(http.StatusInternalServerError, "admin dist missing")
			return
		}
		c.Data(http.StatusOK, "text/html; charset=utf-8", data)
	}

	r.GET("/admin", func(c *gin.Context) { c.Redirect(http.StatusFound, "/admin/") })
	r.GET("/admin/*filepath", handler)
}