server.go

// Copyright 2019 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//go:build ignore

package main

import (
	"errors"
	"flag"
	"io"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"strings"
)

var (
	httpAddr = flag.String("http", ":8000", "HTTP address")
)

var rootPath = ""

func init() {
	flag.Parse()
	dir := flag.Arg(0)
	if dir == "" {
		dir = "."
	}
	rootPath = dir
}

type handler struct{}

func (handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	path := filepath.Join(rootPath, r.URL.Path[1:])
	f, err := os.Stat(path)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			notFound(w, r)
			return
		}
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	if f.IsDir() {
		if !strings.HasSuffix(r.URL.Path, "/") {
			http.Redirect(w, r, r.URL.Path+"/", http.StatusMovedPermanently)
			return
		}

		path = filepath.Join(path, "index.html")
		if _, err := os.Stat(path); err != nil {
			if errors.Is(err, os.ErrNotExist) {
				notFound(w, r)
				return
			}
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
	}

	w.Header().Set("Access-Control-Allow-Origin", "*")
	http.ServeFile(w, r, path)
}

func notFound(w http.ResponseWriter, r *http.Request) {
	w.WriteHeader(http.StatusNotFound)

	f, err := os.Open(filepath.Join(rootPath, "404.html"))
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer f.Close()

	io.Copy(w, f)
}

func main() {
	http.Handle("/", handler{})
	log.Fatal(http.ListenAndServe(*httpAddr, nil))
}