//go:build web

package ext

import (
	"crypto/md5"
	"demo-server/pkg/str"
	"embed"
	"fmt"
	"github.com/gin-gonic/gin"
	"github.com/vearutop/statigz"
	"go.uber.org/zap"
	"io"
	"io/fs"
	"net/http"
	"strings"
)

/*
	embed static web learn insp opensource license MIT
	see "github.com/v2rayA/v2rayA/server/router/index.go"
*/

func init() {
	initEngQueue = append(initEngQueue, initGUI)
}

// webRootFS 嵌入静态文件
//
//go:embed web
var webRootFS embed.FS

func initGUI(r *gin.Engine) {
	webFS, err := fs.Sub(webRootFS, "web")
	if err != nil {
		zap.S().Panic("init gui err, cause: ", err)
	}

	guiStaticResource(r, webFS)
	guiIndexHTML(r, webFS)
}

// html 缓存 HTML 页面
func html(html []byte) func(ctx *gin.Context) {
	etag := fmt.Sprintf("W/%x", md5.Sum(html))
	h := str.B2S(html)
	return func(ctx *gin.Context) {
		if ctx.IsAborted() {
			return
		}
		ctx.Header("Content-Type", "text/html; charset=utf-8")
		ctx.Header("Cache-Control", "public, must-revalidate")
		ctx.Header("ETag", etag)
		if match := ctx.GetHeader("If-None-Match"); match != "" {
			if strings.Contains(match, etag) {
				ctx.Status(http.StatusNotModified)
				return
			}
		}
		ctx.String(http.StatusOK, h)
	}
}

func guiStaticResource(r *gin.Engine, sfs fs.FS) {

	const (
		assetsPrefix = "/assets"
		staticPrefix = "/static"

		stripPrefix = ""
	)

	staticResource := http.StripPrefix(stripPrefix, statigz.FileServer(sfs.(fs.ReadDirFS)))
	r.GET(assetsPrefix+"/*w", func(c *gin.Context) {
		staticResource.ServeHTTP(c.Writer, c.Request)
	})
	r.GET(staticPrefix+"/*w", func(c *gin.Context) {
		staticResource.ServeHTTP(c.Writer, c.Request)
	})
	r.GET("/favicon.ico", func(c *gin.Context) {
		staticResource.ServeHTTP(c.Writer, c.Request)
	})
}

func guiIndexHTML(r *gin.Engine, sfs fs.FS) {
	var indexHTML []byte
	{
		const indexFileName = "index.html"
		index, err := sfs.Open(indexFileName)
		if err != nil {
			zap.S().Panicf("open [%s] err! cause: %e", indexFileName, err)
		}
		indexHTML, err = io.ReadAll(index)
		if err != nil {
			zap.S().Panicf("read [%s] err! cause: %e", indexFileName, err)
		}
	}

	r.GET("/", html(indexHTML))
	r.NoRoute(html(indexHTML))
}