package main

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

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

//go:embed all:static
var frontendFS embed.FS

// setupFrontend 配置前端静态文件服务（go:embed 模式） // Logan.Li
// 前端构建产物放在 backend/static/ 目录，编译时嵌入二进制
func setupFrontend(r *gin.Engine) {
	// 获取 static 子目录的 fs.FS
	staticFS, err := fs.Sub(frontendFS, "static")
	if err != nil {
		// static 目录不存在（开发模式或未构建前端），跳过
		return
	}
	httpFS := http.FS(staticFS)

	// 静态资源文件（js/css/图片等）直接返回
	r.Use(func(c *gin.Context) {
		// API 和 WebSocket 路径不走静态文件
		path := c.Request.URL.Path
		if strings.HasPrefix(path, "/api/") ||
			strings.HasPrefix(path, "/ws/") ||
			strings.HasPrefix(path, "/agent/") ||
			strings.HasPrefix(path, "/health") ||
			strings.HasPrefix(path, "/version") {
			c.Next()
			return
		}
		c.Next()
	})

	// NoRoute: SPA fallback — 非 API 请求尝试静态文件，找不到则返回 index.html
	r.NoRoute(func(c *gin.Context) {
		path := c.Request.URL.Path

		// API/WS 路径返回 JSON 404
		if strings.HasPrefix(path, "/api/") || strings.HasPrefix(path, "/ws/") || strings.HasPrefix(path, "/agent/") {
			c.JSON(http.StatusNotFound, gin.H{"code": 404, "message": "接口不存在"})
			return
		}

		// 尝试打开静态文件
		cleanPath := strings.TrimPrefix(path, "/")
		if cleanPath == "" {
			cleanPath = "index.html"
		}

		f, err := staticFS.Open(cleanPath)
		if err == nil {
			f.Close()
			if cleanPath == "index.html" || strings.HasSuffix(cleanPath, ".html") {
				// HTML 入口必须每次校验，避免浏览器长期执行旧版前端 bundle。// Logan.Li
				c.Header("Cache-Control", "no-store, no-cache, must-revalidate")
			} else {
				// 当前内嵌构建在本地验证阶段需要强制校验，避免旧 bundle 残留。// Logan.Li
				c.Header("Cache-Control", "no-cache")
			}
			c.FileFromFS(path, httpFS)
			return
		}

		if strings.HasPrefix(cleanPath, "assets/") {
			// 构建哈希资源缺失时返回真实 404，避免 SPA fallback 把 index.html 当 JS 模块返回。 // Logan.Li
			c.Header("Cache-Control", "no-store, no-cache, must-revalidate")
			c.String(http.StatusNotFound, "static asset not found")
			return
		}

		// SPA fallback → 直接返回 index.html 字节（避免 http.FileServer 的 301 redirect）
		indexBytes, err := fs.ReadFile(staticFS, "index.html")
		if err != nil {
			c.String(http.StatusInternalServerError, "前端文件缺失")
			return
		}
		c.Header("Cache-Control", "no-store, no-cache, must-revalidate")
		c.Data(http.StatusOK, "text/html; charset=utf-8", indexBytes)
	})
}