client.go

package main

import (
	"bufio"
	"fmt"
	"io"
	"log"
	"os"
	"strconv"
	"strings"

	"golang.org/x/net/websocket"
)

func main() {
	ws, err := websocket.Dial("ws://localhost:8000/ws", "", "http://localhost/")
	if err != nil {
		log.Fatal("Dial error:", err)
	}
	defer ws.Close()

	consoleReader := bufio.NewReader(os.Stdin)

	// Send username
	log.Print("Enter username: ")
	username, err := consoleReader.ReadString('\n')
	if err != nil {
		fmt.Println("Error reading username:", err)
		return
	}
	websocket.Message.Send(ws, fmt.Sprintf(username))

	// Recieve Messages
	go func() {
		for {
			var msg string
			if err = websocket.Message.Receive(ws, &msg); err != nil {
				log.Println("Server closed connection")
				return
			}

			if strings.HasPrefix(msg, "FILE:") {
				parts := strings.Split(msg, ":")
				filename, sizeStr, recieverID := parts[1], parts[2], parts[3]
				size, _ := strconv.ParseInt(sizeStr, 10, 64)
				fmt.Printf("Recieving file from %s \n filename: %s, size: %d", recieverID, filename, size)

				fileData := make([]byte, size)
				if err := websocket.Message.Receive(ws, &fileData); err != nil {
					fmt.Printf("Error recieving file: %v", err)
					return
				}
				file, err := os.Create(recieverID + "-" + filename)
				if err != nil {
					fmt.Println("Error creating file:", err)
					return
				}
				file.Write(fileData)
				file.Close()
			} else {
				fmt.Println(msg)
			}
		}
	}()

	// Handle User Input
	for {
		text, err := consoleReader.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				log.Println("Input closed")
			} else {
				log.Println("Input error: ", err)
			}
			return
		}

		switch {
		case strings.HasPrefix(text, "/file"):
			// /file:filename:user -> FILE:filename:size:user
			parts := strings.Split(text, ":")
			filename, recieverID := parts[1], parts[2]

			// Read File
			file, err := os.Open(filename)
			if err != nil {
				log.Println("Error reading file:", err)
				continue
			}
			defer file.Close()

			// Inform the server
			size, _ := file.Stat()
			_, err = fmt.Fprintf(ws, "FILE:%s:%d:%s\n", filename, size.Size(), recieverID)
			if err != nil {
				log.Println("Write error:", err)
				return
			}

			// Send the File
			if _, err = io.Copy(ws, file); err != nil {
				fmt.Println("Error sending file:", err)
			}
		default:
			if err := websocket.Message.Send(ws, text); err != nil {
				fmt.Println("Write error:", err)
				continue
			}
		}
	}
}