package funcs

import (
	"io"
	"io/fs"
	"net/http"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/rs/zerolog/log"
)

func headheader(f fs.File, c *gin.Context) (nocontent bool) {
	stats, err := f.Stat()
	if c.Request.Method == "HEAD" {
		nocontent = true
	}
	if err != nil {
		log.Error().Err(err).Msg("Cant get info of file")
		return
	}
	c.Writer.Header().Set("Last-Modified", stats.ModTime().Format(time.RFC1123))
	if t, err := time.Parse(time.RFC1123, c.GetHeader("If-Modified-Since")); stats.ModTime().After(t) && err == nil {
		c.Status(http.StatusNotModified)
		nocontent = true
	} else {
		c.Status(http.StatusOK)
	}
	return
}

func makeHandler(f fs.FS, name string) gin.HandlerFunc {
	return func(c *gin.Context) {
		content, err := f.Open(name)
		if err != nil {
			switch err {
			case fs.ErrNotExist:
				c.AbortWithStatus(404)
			default:
				c.AbortWithError(500, err)
			}
			return
		}
		if headheader(content, c) {
			return
		}
		c.Status(200)
		io.Copy(c.Writer, content)
	}
}

// StaticFS is an Handler for Staticfiles that doesn't use globs and uses a fs.FS
func StaticFS(r gin.IRouter, files fs.FS) {
	if files == nil {
		return
	}
	fns, err := fs.ReadDir(files, ".")
	if err != nil {
		log.Error().Err(err).Msg("Error while reading this file.")
		return
	}
	for _, fn := range fns {
		if fn.IsDir() {
			sub, _ := fs.Sub(files, fn.Name())
			StaticFS(r.Group("/"+fn.Name()), sub)
		} else {
			h := makeHandler(files, fn.Name())
			if fn.Name() == "index.html" {
				r.GET("/", h)
				r.HEAD("/", h)
			}
			r.GET("/"+fn.Name(), h)
			r.HEAD("/"+fn.Name(), h)
		}
	}
}