exercise_tracker_api/app/Http/Controllers/UserController.php

<?php

namespace App\Http\Controllers;

use App\User;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Http\Response;
use Illuminate\Support\Facades\Auth;
use Illuminate\Support\Facades\Hash;
use Illuminate\Support\Facades\Validator;

class UserController extends Controller
{
    public function register(Request $request): JsonResponse {
        $validator = Validator::make($request->all(), [
            'username' => 'required|string|min:3|max:255|unique:users',
            'email' => 'required|string|email|max:255|unique:users',
            'password' => 'required|string|min:8|confirmed',
        ]);

        if ($validator->fails()) {
            return response()->json($validator->errors()->toArray(), 400);
        }

        $user = User::create([
            'username' => $request->get('username'),
            'email' => $request->get('email'),
            'password' => Hash::make($request->get('password')),
        ]);

        return response()->json($user,201);
    }

    public function login(Request $request): JsonResponse {
        $credentials = $request->only('email', 'password');

        if (! Auth::attempt($credentials)) {
            return response()->json(['error' => 'invalid_credentials'], 400);
        }

        return response()->json('yes');
    }
}