package main

import (
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"text/template"

	_ "embed"
)

type Entry struct {
	Name  string
	IsDir bool
}

type Result struct {
	Err     string
	Entries []Entry
}

//go:embed index.html
var index string

var tpl = template.Must(template.New("index.html").Parse(index))

func Render(w http.ResponseWriter, data interface{}) {
	w.Header().Set("Content-Type", "text/html;charset=utf8")
	if err := tpl.Execute(w, data); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
}

func View(w http.ResponseWriter, r *http.Request) {
	log.Println(r.URL.Path)

	path := filepath.Join(*dir, filepath.Clean(r.URL.Path))

	if !strings.HasSuffix(r.URL.Path, "/") {
		w.Header().Add("Content-Disposition", fmt.Sprintf("attachment;filename=%s", filepath.Base(path)))
		http.ServeFile(w, r, path)
		return
	}

	entries, err := os.ReadDir(path)
	if err != nil {
		Render(w, &Result{Err: err.Error()})
		return
	}

	items := make([]Entry, 0)
	for _, entry := range entries {
		items = append(items, Entry{
			Name:  entry.Name(),
			IsDir: entry.IsDir(),
		})
	}
	Render(w, &Result{Entries: items})
}

var (
	dir    = flag.String("dir", "./", "server file directory")
	listen = flag.String("listen", ":3000", "listen address")
)

func main() {
	flag.Parse()

	http.HandleFunc("/", View)
	log.Printf("server listen at %s", *listen)
	log.Fatal(http.ListenAndServe(*listen, nil))
}