package main

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

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

// frontendFS 是构建时嵌入的前端生产资源。 // Logan.Li
//
//go:embed all:static
var frontendFS embed.FS

// setupEmbeddedFrontend 为单二进制模式提供前端静态资源和 SPA 回退。 // Logan.Li
func setupEmbeddedFrontend(r *gin.Engine) {
	staticFS, err := fs.Sub(frontendFS, "static")
	if err != nil {
		return
	}
	if _, err := fs.Stat(staticFS, "index.html"); err != nil {
		// 开发模式不复制 dist，后端仅提供 API。 // Logan.Li
		return
	}

	httpFS := http.FS(staticFS)
	r.NoRoute(func(c *gin.Context) {
		path := c.Request.URL.Path
		if strings.HasPrefix(path, "/api/") || strings.HasPrefix(path, "/ws/") {
			c.JSON(http.StatusNotFound, gin.H{"code": 404, "message": "接口不存在"})
			return
		}

		filePath := strings.TrimPrefix(path, "/")
		if filePath == "" {
			filePath = "index.html"
		}
		if _, err := staticFS.Open(filePath); err == nil {
			if strings.HasSuffix(filePath, ".html") {
				c.Header("Cache-Control", "no-store, no-cache, must-revalidate")
			}
			c.FileFromFS(path, httpFS)
			return
		}

		if strings.HasPrefix(filePath, "assets/") {
			c.String(http.StatusNotFound, "static asset not found")
			return
		}
		index, err := fs.ReadFile(staticFS, "index.html")
		if err != nil {
			c.String(http.StatusInternalServerError, "前端资源不可用")
			return
		}
		c.Header("Cache-Control", "no-store, no-cache, must-revalidate")
		c.Data(http.StatusOK, "text/html; charset=utf-8", index)
	})
}