main.go

package main

import (
	"encoding/json"
	"log"
	"net/http"

	"golang.org/x/crypto/bcrypt"
)

type User struct {
	ID       int    `json:"id"`
	Username string `json:"username"`
	Email    string `json:"email"`
	Password string `json:"-"`
}

var users []User
var lastUserID int

func main() {
	http.HandleFunc("/signup", signUp)
	http.HandleFunc("/login", login)

	log.Fatal(http.ListenAndServe(":8080", nil))
}

func signUp(w http.ResponseWriter, r *http.Request) {
	var newUser User
	err := json.NewDecoder(r.Body).Decode(&newUser)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(newUser.Password), bcrypt.DefaultCost)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	newUser.Password = string(hashedPassword)

	lastUserID++
	newUser.ID = lastUserID
	users = append(users, newUser)

	w.WriteHeader(http.StatusOK)
}

func login(w http.ResponseWriter, r *http.Request) {
	var loginData struct {
		Username string `json:"username"`
		Password string `json:"password"`
	}
	err := json.NewDecoder(r.Body).Decode(&loginData)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	for _, user := range users {
		if user.Username == loginData.Username {
			err := bcrypt.CompareHashAndPassword([]byte(user.Password), []byte(loginData.Password))
			if err == nil {
				w.WriteHeader(http.StatusOK)
				return
			}
		}
	}

	http.Error(w, "Invalid username or password", http.StatusUnauthorized)
}