import time
import hashlib
from demo import settings
from django.core import signing
from datetime import datetime, timedelta

HEADER = {'typ': 'JWP', 'alg': 'default'}
KEY = settings.SECRET_KEY
SALT = "ESS"

def encrypt(obj):
    """加密: signing 加密 and Base64 編碼"""
    value = signing.dumps(obj, key=KEY, salt=SALT)
    value = signing.b64_encode(value.encode()).decode()
    return value

def decrypt(src):
    """解密: Base64 解碼 and signing 解密"""
    src = signing.b64_decode(src.encode()).decode()
    raw = signing.loads(src, key=KEY, salt=SALT)
    return raw

def create_token(username):
    """生成token信息"""
    # 1. 加密頭信息
    header = encrypt(HEADER)
    # 2. 構造Payload(有效期31天)
    payload = {
        "username": username, 
        "iat": time.time(), 
        "exp": (datetime.utcnow() + timedelta(hours=8,days=31)).strftime("%Y-%m-%d")
        }
    payload = encrypt(payload)
    # 3. MD5 生成簽名
    md5 = hashlib.md5()
    md5.update(("%s.%s" % (header, payload)).encode())
    signature = md5.hexdigest()
    token = "%s.%s.%s" % (header, payload, signature)
    return token

def get_payload(token):
    """解析 token 獲取 payload 數(shù)據(jù)"""
    payload = str(token).split('.')[1]
    payload = decrypt(payload)
    return payload

def get_username(token):
    """解析 token 獲取 username"""
    payload = get_payload(token)
    return payload['username']

def get_exp_time(token):
    """解析 token 獲取過期時間"""
    payload = get_payload(token)
    return payload['exp']

def check_token(username, token):
    """驗證 token: 檢查 username 和 token 是否一致且未過期"""
    return get_username(token) == username and get_exp_time(token) > (datetime.utcnow() + timedelta(hours=8)).strftime('%Y-%m-%d')

from .token import check_token
from django.http import JsonResponse

try:
    from django.utils.deprecation import MiddlewareMixin  # Django 1.10.x
except ImportError:
    MiddlewareMixin = object

# 白名單，表示請求里面的路由時不驗證登錄信息
API_WHITELIST = ['/index/', '/index', 'index/']


class AuthorizeMiddleware(MiddlewareMixin):
    def process_request(self, request):
        print(request.path)
        print(request.path not in API_WHITELIST)
        if request.path not in API_WHITELIST:
            if "sites" in request.path:
                pass
            else:
                # 從請求頭中獲取 username 和 token
                username = request.META.get("HTTP_USERNAME")
                token = request.META.get("HTTP_AUTHORIZATION")
                if username is None or token is None:
                    return JsonResponse({"code": -2, "msg": "未查詢到登錄信息"})
                else:
                    # 調(diào)用 check_token 函數(shù)驗證
                    if check_token(username, token):
                        pass
                    else:
                        return JsonResponse({"code": -2, "msg": "登錄信息錯誤或已過期"})

from django.http import JsonResponse
from demo.utils.token import create_token

def index(request):
    return JsonResponse({'code': 0, 'message': 'Hello, world!'})

from django.urls import path
from demo import views

urlpatterns = [
    path('index/', views.index),
]

MIDDLEWARE = [
    'demo.utils.middleware.AuthorizeMiddleware', # 一定要放在最上面，有cors的話放cors下面
    '···',
]