package ui

import (
	"bytes"
	"embed"
	"encoding/json"
	"io/fs"
	"net/http"

	"code.thetadev.de/TSGRain/WebUI/src/server/middleware"
	"code.thetadev.de/TSGRain/WebUI/src/util"
	"github.com/gin-gonic/gin"
)

const distDir = "dist"

//go:embed dist/**
var assets embed.FS

type uiConfig struct {
	Version string `json:"version"`
	NZones  int32  `json:"n_zones"`
}

func subFS(fsys fs.FS, dir string) fs.FS {
	sub, err := fs.Sub(fsys, dir)
	if err != nil {
		panic(err)
	}
	return sub
}

func distFS() fs.FS {
	return subFS(assets, distDir)
}

func Register(r gin.IRouter, nZones int32) {
	indexHandler := getIndexHandler(nZones)

	uiAssets := r.Group("/assets", middleware.Cache)

	r.GET("/", indexHandler)
	r.GET("/index.html", indexHandler)

	uiAssets.StaticFS("/", http.FS(subFS(distFS(), "assets")))
}

func getIndexHandler(nZones int32) gin.HandlerFunc {
	content, err := fs.ReadFile(distFS(), "index.html")
	if err != nil {
		panic(err)
	}

	uiConfigBytes, err := json.Marshal(uiConfig{
		Version: util.Version(),
		NZones:  nZones,
	})
	if err != nil {
		panic(err)
	}
	content = bytes.ReplaceAll(content, []byte("\"%CONFIG%\""), uiConfigBytes)

	return func(c *gin.Context) {
		c.Data(200, "text/html", content)
	}
}