fileserver.go

package main

import (
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"io"
	"log"
	"mime/multipart"
	"net/http"
	"os"
)

const (
	PORT = 8080
)

type FileCreator interface {
	HashFileName(name string, size int64) string
	WriteFile(multipart.File, *multipart.FileHeader, string) error
}

type SimpleFileCreation struct{}

func (s SimpleFileCreation) HashFileName(name string, size int64) string {
	key := name + fmt.Sprint(size)
	h := md5.New()
	h.Write([]byte(key))
	return hex.EncodeToString(h.Sum(nil))
}

func (s SimpleFileCreation) WriteFile(file multipart.File, header *multipart.FileHeader, path string) error {

	filename := path + s.HashFileName(header.Filename, header.Size)

	dst, err := os.Create(filename)

	if err != nil {
		return err
	}

	defer dst.Close()

	// TODO1
	_, err = io.Copy(dst, file)

	if err != nil {
		return err
	}

	return nil
}

type FileHandler struct {
	path              string
	ServerFileHandler FileCreator
}

func NewFileHandler() *FileHandler {
	return &FileHandler{
		path:              "/tmp/",
		ServerFileHandler: SimpleFileCreation{},
	}
}

// TODO: Maybe a condition for data loss by checking if written bytes equal to uploaded byte -- GOTO TODO1

func (h *FileHandler) handelFile(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		http.Error(w, "ONLY POST METHOD IS ALLOWED", http.StatusBadRequest)
		return
	}

	file, header, err := r.FormFile("file")

	if err != nil {
		http.Error(w, "ERROR READING FILE", http.StatusBadRequest)
	}

	defer file.Close()

	log.Printf("Writing file %s to server\n", header.Filename)

	err = h.ServerFileHandler.WriteFile(file, header, h.path)

	if err != nil {
		http.Error(w, "ERROR SAVING FILE: "+err.Error(), http.StatusInternalServerError)
	}

	w.WriteHeader(http.StatusOK)
	w.Write([]byte("File uploaded succesfully"))
}

func main() {
	h := NewFileHandler()

	http.HandleFunc("/upload", h.handelFile)

	log.Printf("String the server at %d\n", PORT)

	if err := http.ListenAndServe(fmt.Sprintf(":%d", PORT), nil); err != nil {
		log.Fatal(err)
	}
}