import os
from datetime import timedelta
from importlib import import_module

import qrcode
from django.conf import settings
from django.contrib import auth
from django.core.cache import cache
from django.db.models import Count, Q
from django.template.loader import render_to_string
from django.utils import timezone
from django.utils.decorators import method_decorator
from django.utils.timezone import now
from django.views.decorators.csrf import csrf_exempt, ensure_csrf_cookie
from otpauth import TOTP

from options.options import SysOptions
from problem.models import Problem
from submission.models import JudgeStatus, Submission
from utils.api import APIView, CSRFExemptAPIView, validate_serializer
from utils.captcha import Captcha
from utils.constants import CacheKey, ContestRuleType
from utils.shortcuts import datetime2str, img2base64, rand_str

from ..decorators import login_required
from ..models import AdminType, User, UserProfile
from ..serializers import (
    ApplyResetPasswordSerializer,
    EditUserProfileSerializer,
    ImageUploadForm,
    RankInfoSerializer,
    ResetPasswordSerializer,
    SSOSerializer,
    TwoFactorAuthCodeSerializer,
    UserChangeEmailSerializer,
    UserChangePasswordSerializer,
    UserLoginSerializer,
    UsernameOrEmailCheckSerializer,
    UserProfileSerializer,
    UserRegisterSerializer,
)
from ..tasks import send_email_async


def _totp(token):
    return TOTP(token.encode("utf-8"))


def _totp_uri(token, label, issuer):
    return _totp(token).to_uri(label, issuer)


def _valid_totp(token, code):
    try:
        code = int(code)
    except (TypeError, ValueError):
        return False
    return _totp(token).verify(code)


class UserProfileAPI(APIView):
    @method_decorator(ensure_csrf_cookie)
    def get(self, request, **kwargs):
        """
        判断是否登录， 若登录返回用户信息
        """
        user = request.user
        if not user.is_authenticated:
            return self.success()
        show_real_name = False
        username = request.GET.get("username")
        try:
            if username:
                user = User.objects.get(username=username, is_disabled=False)
            else:
                user = request.user
                # api返回的是自己的信息，可以返real_name
                show_real_name = True
        except User.DoesNotExist:
            return self.error("User does not exist")
        return self.success(
            UserProfileSerializer(user.userprofile, show_real_name=show_real_name).data
        )

    @validate_serializer(EditUserProfileSerializer)
    @login_required
    def put(self, request):
        data = request.data
        user_profile = request.user.userprofile
        for k, v in data.items():
            setattr(user_profile, k, v)
        user_profile.save()
        return self.success(
            UserProfileSerializer(user_profile, show_real_name=True).data
        )


class Metrics(APIView):
    def get(self, request):
        userid = request.GET.get("userid")
        submissions = Submission.objects.filter(user_id=userid, contest_id__isnull=True)
        if submissions.count() == 0:
            return self.error("暂无提交")
        else:
            latest_submission = submissions.first()
            last_submission = submissions.last()
            if last_submission and latest_submission:
                return self.success(
                    {
                        "now": datetime2str(timezone.now()),
                        "latest": datetime2str(latest_submission.create_time),
                        "first": datetime2str(last_submission.create_time),
                    }
                )
            else:
                return self.error("暂无提交")


class AvatarUploadAPI(APIView):
    request_parsers = ()

    @login_required
    def post(self, request):
        form = ImageUploadForm(request.POST, request.FILES)
        if form.is_valid():
            avatar = form.cleaned_data["image"]
        else:
            return self.error("Invalid file content")
        if avatar.size > 2 * 1024 * 1024:
            return self.error("Picture is too large")
        suffix = os.path.splitext(avatar.name)[-1].lower()
        if suffix not in [".gif", ".jpg", ".jpeg", ".bmp", ".png"]:
            return self.error("Unsupported file format")

        name = rand_str(10) + suffix
        with open(os.path.join(settings.AVATAR_UPLOAD_DIR, name), "wb") as img:
            for chunk in avatar:
                img.write(chunk)
        user_profile = request.user.userprofile

        user_profile.avatar = f"{settings.AVATAR_URI_PREFIX}/{name}"
        user_profile.save()
        return self.success("Succeeded")


class TwoFactorAuthAPI(APIView):
    @login_required
    def get(self, request):
        """
        Get QR code
        """
        user = request.user
        if user.two_factor_auth:
            return self.error("2FA is already turned on")
        token = rand_str()
        user.tfa_token = token
        user.save()

        label = f"{SysOptions.website_name_shortcut}:{user.username}"
        image = qrcode.make(
            _totp_uri(token, label, SysOptions.website_name.replace(" ", ""))
        )
        return self.success(img2base64(image))

    @login_required
    @validate_serializer(TwoFactorAuthCodeSerializer)
    def post(self, request):
        """
        Open 2FA
        """
        code = request.data["code"]
        user = request.user
        if _valid_totp(user.tfa_token, code):
            user.two_factor_auth = True
            user.save()
            return self.success("Succeeded")
        else:
            return self.error("Invalid code")

    @login_required
    @validate_serializer(TwoFactorAuthCodeSerializer)
    def put(self, request):
        code = request.data["code"]
        user = request.user
        if not user.two_factor_auth:
            return self.error("2FA is already turned off")
        if _valid_totp(user.tfa_token, code):
            user.two_factor_auth = False
            user.save()
            return self.success("Succeeded")
        else:
            return self.error("Invalid code")


class CheckTFARequiredAPI(APIView):
    @validate_serializer(UsernameOrEmailCheckSerializer)
    def post(self, request):
        """
        Check TFA is required
        """
        data = request.data
        result = False
        if data.get("username"):
            try:
                user = User.objects.get(username=data["username"])
                result = user.two_factor_auth
            except User.DoesNotExist:
                pass
        return self.success({"result": result})


class UserLoginAPI(APIView):
    @validate_serializer(UserLoginSerializer)
    def post(self, request):
        """
        User login api
        """
        data = request.data
        user = auth.authenticate(username=data["username"], password=data["password"])
        # None is returned if username or password is wrong
        if user:
            if user.is_disabled:
                return self.error("Your account has been disabled")
            if not user.two_factor_auth:
                prev_login = user.last_login
                auth.login(request, user)
                request.session["prev_login"] = (
                    datetime2str(prev_login) if prev_login else ""
                )
                return self.success("Succeeded")

            # `tfa_code` not in post data
            if user.two_factor_auth and "tfa_code" not in data:
                return self.error("tfa_required")

            if _valid_totp(user.tfa_token, data["tfa_code"]):
                prev_login = user.last_login
                auth.login(request, user)
                request.session["prev_login"] = (
                    datetime2str(prev_login) if prev_login else ""
                )
                return self.success("Succeeded")
            else:
                return self.error("Invalid two factor verification code")
        else:
            return self.error("Invalid username or password")


class UserLogoutAPI(APIView):
    def get(self, request):
        auth.logout(request)
        return self.success()


class UsernameOrEmailCheck(APIView):
    @validate_serializer(UsernameOrEmailCheckSerializer)
    def post(self, request):
        """
        check username or email is duplicate
        """
        data = request.data
        # True means already exist.
        result = {"username": False, "email": False}
        if data.get("username"):
            result["username"] = User.objects.filter(
                username=data["username"].lower()
            ).exists()
        if data.get("email"):
            result["email"] = User.objects.filter(email=data["email"].lower()).exists()
        return self.success(result)


class UserRegisterAPI(APIView):
    @validate_serializer(UserRegisterSerializer)
    def post(self, request):
        """
        User register api
        """
        if not SysOptions.allow_register:
            return self.error("Register function has been disabled by admin")

        data = request.data
        data["username"] = data["username"].lower()
        data["email"] = data["email"].lower()
        captcha = Captcha(request)
        if not captcha.check(data["captcha"]):
            return self.error("Invalid captcha")
        if User.objects.filter(username=data["username"]).exists():
            return self.error("Username already exists")
        if User.objects.filter(email=data["email"]).exists():
            return self.error("Email already exists")
        user = User.objects.create(username=data["username"], email=data["email"])
        user.set_password(data["password"])
        user.save()
        UserProfile.objects.create(user=user)
        return self.success("Succeeded")


class UserChangeEmailAPI(APIView):
    @validate_serializer(UserChangeEmailSerializer)
    @login_required
    def post(self, request):
        data = request.data
        user = auth.authenticate(
            username=request.user.username, password=data["password"]
        )
        if user:
            if user.two_factor_auth:
                if "tfa_code" not in data:
                    return self.error("tfa_required")
                if not _valid_totp(user.tfa_token, data["tfa_code"]):
                    return self.error("Invalid two factor verification code")
            data["new_email"] = data["new_email"].lower()
            if User.objects.filter(email=data["new_email"]).exists():
                return self.error("The email is owned by other account")
            user.email = data["new_email"]
            user.save()
            return self.success("Succeeded")
        else:
            return self.error("Wrong password")


class UserChangePasswordAPI(APIView):
    @validate_serializer(UserChangePasswordSerializer)
    @login_required
    def post(self, request):
        """
        User change password api
        """
        data = request.data
        username = request.user.username
        user = auth.authenticate(username=username, password=data["old_password"])
        if user:
            if user.two_factor_auth:
                if "tfa_code" not in data:
                    return self.error("tfa_required")
                if not _valid_totp(user.tfa_token, data["tfa_code"]):
                    return self.error("Invalid two factor verification code")
            user.set_password(data["new_password"])
            user.save()
            return self.success("Succeeded")
        else:
            return self.error("Invalid old password")


class ApplyResetPasswordAPI(APIView):
    @validate_serializer(ApplyResetPasswordSerializer)
    def post(self, request):
        if request.user.is_authenticated:
            return self.error("You have already logged in, are you kidding me? ")
        data = request.data
        captcha = Captcha(request)
        if not captcha.check(data["captcha"]):
            return self.error("Invalid captcha")
        try:
            user = User.objects.get(email__iexact=data["email"])
        except User.DoesNotExist:
            return self.error("User does not exist")
        if (
            user.reset_password_token_expire_time
            and 0
            < int((user.reset_password_token_expire_time - now()).total_seconds())
            < 20 * 60
        ):
            return self.error("You can only reset password once per 20 minutes")
        user.reset_password_token = rand_str()
        user.reset_password_token_expire_time = now() + timedelta(minutes=20)
        user.save()
        render_data = {
            "username": user.username,
            "website_name": SysOptions.website_name,
            "link": f"{SysOptions.website_base_url}/reset-password/{user.reset_password_token}",
        }
        email_html = render_to_string("reset_password_email.html", render_data)
        send_email_async.send(
            from_name=SysOptions.website_name_shortcut,
            to_email=user.email,
            to_name=user.username,
            subject="Reset your password",
            content=email_html,
        )
        return self.success("Succeeded")


class ResetPasswordAPI(APIView):
    @validate_serializer(ResetPasswordSerializer)
    def post(self, request):
        data = request.data
        captcha = Captcha(request)
        if not captcha.check(data["captcha"]):
            return self.error("Invalid captcha")
        try:
            user = User.objects.get(reset_password_token=data["token"])
        except User.DoesNotExist:
            return self.error("Token does not exist")
        if user.reset_password_token_expire_time < now():
            return self.error("Token has expired")
        user.reset_password_token = None
        user.two_factor_auth = False
        user.set_password(data["password"])
        user.save()
        return self.success("Succeeded")


class SessionManagementAPI(APIView):
    @login_required
    def get(self, request):
        engine = import_module(settings.SESSION_ENGINE)
        session_store = engine.SessionStore
        current_session = request.session.session_key
        session_keys = request.user.session_keys
        result = []
        modified = False
        for key in session_keys[:]:
            session = session_store(key)
            # session does not exist or is expiry
            if not session._session:
                session_keys.remove(key)
                modified = True
                continue

            s = {}
            if current_session == key:
                s["current_session"] = True
            s["ip"] = session["ip"]
            s["user_agent"] = session["user_agent"]
            s["last_activity"] = datetime2str(session["last_activity"])
            s["session_key"] = key
            result.append(s)
        if modified:
            request.user.save()
        return self.success(result)

    @login_required
    def delete(self, request):
        session_key = request.GET.get("session_key")
        if not session_key:
            return self.error("Parameter Error")
        request.session.delete(session_key)
        if session_key in request.user.session_keys:
            request.user.session_keys.remove(session_key)
            request.user.save()
            return self.success("Succeeded")
        else:
            return self.error("Invalid session_key")


class UserRankAPI(APIView):
    def get(self, request):
        rule_type = request.GET.get("rule")
        username = request.GET.get("username", "")
        try:
            n = int(request.GET.get("n", "0"))
        except ValueError:
            n = 0
        if rule_type not in ContestRuleType.choices():
            rule_type = ContestRuleType.ACM

        profiles = UserProfile.objects.filter(
            user__admin_type__in=[AdminType.REGULAR_USER, AdminType.ADMIN],
            user__is_disabled=False,
            user__username__icontains=username,
        ).select_related("user")
        if rule_type == ContestRuleType.ACM:
            profiles = profiles.filter(accepted_number__gte=0).order_by(
                "-accepted_number", "submission_number"
            )
        else:
            profiles = profiles.filter(total_score__gt=0).order_by("-total_score")
        if n > 0:
            profiles = profiles[:n]
        return self.success(self.paginate_data(request, profiles, RankInfoSerializer))


class UserActivityRankAPI(APIView):
    def get(self, request):
        start = request.GET.get("start")
        if not start:
            return self.error("start time is required")
        cache_key = f"{CacheKey.user_activity_rank}:{start}"
        cached = cache.get(cache_key)
        if cached is not None:
            return self.success(cached)

        hidden_names = User.objects.filter(
            Q(admin_type=AdminType.SUPER_ADMIN) | Q(is_disabled=True)
        ).values_list("username", flat=True)
        submissions = Submission.objects.filter(
            contest_id__isnull=True,
            create_time__gte=start,
            result=JudgeStatus.ACCEPTED,
        ).exclude(username__in=hidden_names)
        data = list(
            submissions.values("username")
            .annotate(count=Count("problem_id", distinct=True))
            .order_by("-count")[:10]
        )
        cache.set(cache_key, data, 600)
        return self.success(data)


class UserProblemRankAPI(APIView):
    def get(self, request):
        problem_id = request.GET.get("problem_id")
        user = request.user
        if not user.is_authenticated:
            return self.error("User is not authenticated")

        problem = Problem.objects.get(
            _id=problem_id, contest_id__isnull=True, visible=True
        )
        submissions = Submission.objects.filter(
            problem=problem, result=JudgeStatus.ACCEPTED
        )

        all_ac_count = submissions.values("user_id").distinct().count()

        class_name = user.class_name or ""
        class_ac_count = 0

        if class_name:
            users = User.objects.filter(
                class_name=user.class_name, is_disabled=False
            ).values_list("id", flat=True)
            user_ids = list(users)
            submissions = submissions.filter(user_id__in=user_ids)
            class_ac_count = submissions.values("user_id").distinct().count()

        my_submissions = submissions.filter(user_id=user.id)

        if len(my_submissions) == 0:
            return self.success(
                {
                    "class_name": class_name,
                    "rank": -1,
                    "class_ac_count": class_ac_count,
                    "all_ac_count": all_ac_count,
                }
            )

        my_first_submission = my_submissions.order_by("create_time").first()
        rank = submissions.filter(
            create_time__lte=my_first_submission.create_time
        ).count()
        return self.success(
            {
                "class_name": class_name,
                "rank": rank,
                "class_ac_count": class_ac_count,
                "all_ac_count": all_ac_count,
            }
        )


class ProfileProblemDisplayIDRefreshAPI(APIView):
    @login_required
    def get(self, request):
        profile = request.user.userprofile
        acm_problems = profile.acm_problems_status.get("problems", {})
        oi_problems = profile.oi_problems_status.get("problems", {})
        ids = list(acm_problems.keys()) + list(oi_problems.keys())
        if not ids:
            return self.success()
        display_ids = Problem.objects.filter(id__in=ids, visible=True).values_list(
            "_id", flat=True
        )
        id_map = dict(zip(ids, display_ids))
        for k, v in acm_problems.items():
            v["_id"] = id_map[k]
        for k, v in oi_problems.items():
            v["_id"] = id_map[k]
        profile.save(update_fields=["acm_problems_status", "oi_problems_status"])
        return self.success()


class OpenAPIAppkeyAPI(APIView):
    @login_required
    def post(self, request):
        user = request.user
        if not user.open_api:
            return self.error("OpenAPI function is truned off for you")
        api_appkey = rand_str()
        user.open_api_appkey = api_appkey
        user.save()
        return self.success({"appkey": api_appkey})


class SSOAPI(CSRFExemptAPIView):
    @login_required
    def get(self, request):
        token = rand_str()
        request.user.auth_token = token
        request.user.save()
        return self.success({"token": token})

    @method_decorator(csrf_exempt)
    @validate_serializer(SSOSerializer)
    def post(self, request):
        try:
            user = User.objects.get(auth_token=request.data["token"])
        except User.DoesNotExist:
            return self.error("User does not exist")
        return self.success(
            {
                "username": user.username,
                "avatar": user.userprofile.avatar,
                "admin_type": user.admin_type,
            }
        )