# accounts/models.py
from django.contrib.auth.models import AbstractUser
from django.db import models


class User(AbstractUser):
    kakao_id = models.BigIntegerField(null=True, blank=True, unique=True)
    nickname = models.CharField(max_length=50, blank=True)
    profile_image = models.URLField(blank=True)

    def __str__(self):
        return self.nickname or self.username

# settings.py
AUTH_USER_MODEL = 'accounts.User'

[브라우저] --(1)-- /accounts/kakao/login/ --> [내 서버]
[내 서버] --(2) redirect--> https://kauth.kakao.com/oauth/authorize
[카카오]  --(3) 사용자 동의 후 code로 redirect--> /accounts/kakao/callback/?code=...
[내 서버] --(4) code + client_secret으로 access_token 요청--> [카카오 토큰 서버]
[내 서버] --(5) access_token으로 프로필 조회--> [카카오 API]
[내 서버] --(6) User 생성/조회 후 login()--> [브라우저]

# accounts/views.py
from django.conf import settings
from django.shortcuts import redirect
from urllib.parse import urlencode


def kakao_login(request):
    params = {
        'client_id': settings.KAKAO_REST_API_KEY,
        'redirect_uri': settings.KAKAO_REDIRECT_URI,
        'response_type': 'code',
    }
    url = f'https://kauth.kakao.com/oauth/authorize?{urlencode(params)}'
    return redirect(url)

# accounts/views.py
import requests
from django.contrib.auth import login
from django.shortcuts import redirect
from django.conf import settings

from .models import User


def kakao_callback(request):
    code = request.GET.get('code')
    if not code:
        return redirect('accounts:login')

    # (4) access_token 교환
    token_res = requests.post(
        'https://kauth.kakao.com/oauth/token',
        data={
            'grant_type': 'authorization_code',
            'client_id': settings.KAKAO_REST_API_KEY,
            'client_secret': settings.KAKAO_CLIENT_SECRET,
            'redirect_uri': settings.KAKAO_REDIRECT_URI,
            'code': code,
        },
        timeout=5,
    )
    token_res.raise_for_status()
    access_token = token_res.json()['access_token']

    # (5) 프로필 조회
    profile_res = requests.get(
        'https://kapi.kakao.com/v2/user/me',
        headers={'Authorization': f'Bearer {access_token}'},
        timeout=5,
    )
    profile_res.raise_for_status()
    profile = profile_res.json()

    kakao_id = profile['id']
    kakao_account = profile.get('kakao_account', {})
    kakao_profile = kakao_account.get('profile', {})
    nickname = kakao_profile.get('nickname', '')
    profile_image = kakao_profile.get('profile_image_url', '')

    # (6) 유저 조회/생성
    user, created = User.objects.get_or_create(
        kakao_id=kakao_id,
        defaults={
            'username': f'kakao_{kakao_id}',
            'nickname': nickname,
            'profile_image': profile_image,
        },
    )
    if not created:
        # 닉네임/프로필 이미지가 바뀌었을 수도 있으니 갱신
        user.nickname = nickname
        user.profile_image = profile_image
        user.save(update_fields=['nickname', 'profile_image'])

    login(request, user)
    return redirect('cafe:list')

# accounts/forms.py
class LoginForm(forms.Form):
    username = forms.CharField()
    password = forms.CharField(widget=forms.PasswordInput)

    def clean(self):
        data = super().clean()
        user = authenticate(
            username=data.get('username'),
            password=data.get('password'),
        )
        if user is None:
            # 카카오 유저는 username에 'kakao_' 프리픽스가 있어서
            # 여기서 혼란스럽지 않게 안내를 분리
            try:
                u = User.objects.get(username=data.get('username'))
                if u.kakao_id:
                    raise forms.ValidationError('카카오 로그인으로 가입된 계정입니다.')
            except User.DoesNotExist:
                pass
            raise forms.ValidationError('아이디 또는 비밀번호가 올바르지 않습니다.')
        data['user'] = user
        return data