import hashlib
import json
import os

# import shutil
import zipfile
from wsgiref.util import FileWrapper

from django.conf import settings
from django.db.models import Q
from django.http import StreamingHttpResponse

from account.decorators import problem_permission_required, ensure_created_by
from contest.models import Contest, ContestStatus
from submission.models import Submission
from utils.api import APIView, CSRFExemptAPIView, validate_serializer, APIError
from utils.shortcuts import rand_str, natural_sort_key
from ..models import Problem, ProblemRuleType, ProblemTag
from ..serializers import (
    CreateContestProblemSerializer,
    CreateProblemSerializer,
    EditProblemSerializer,
    EditContestProblemSerializer,
    ProblemAdminSerializer,
    ProblemAdminListSerializer,
    TestCaseUploadForm,
    ContestProblemMakePublicSerializer,
    AddContestProblemSerializer,
)


class TestCaseZipProcessor(object):
    def process_zip(self, uploaded_zip_file, dir=""):
        try:
            zip_file = zipfile.ZipFile(uploaded_zip_file, "r")
        except zipfile.BadZipFile:
            raise APIError("Bad zip file")
        name_list = zip_file.namelist()
        test_case_list = self.filter_name_list(name_list, dir=dir)
        if not test_case_list:
            raise APIError("Empty file")

        test_case_id = rand_str()
        test_case_dir = os.path.join(settings.TEST_CASE_DIR, test_case_id)
        os.mkdir(test_case_dir)
        os.chmod(test_case_dir, 0o710)

        size_cache = {}
        md5_cache = {}

        for item in test_case_list:
            with open(os.path.join(test_case_dir, item), "wb") as f:
                content = zip_file.read(f"{dir}{item}").replace(b"\r\n", b"\n")
                size_cache[item] = len(content)
                if item.endswith(".out"):
                    md5_cache[item] = hashlib.md5(content.rstrip()).hexdigest()
                f.write(content)
        test_case_info = {"test_cases": {}}

        info = []

        # ["1.in", "1.out", "2.in", "2.out"] => [("1.in", "1.out"), ("2.in", "2.out")]
        test_case_list = zip(*[test_case_list[i::2] for i in range(2)])
        for index, item in enumerate(test_case_list):
            data = {
                "stripped_output_md5": md5_cache[item[1]],
                "input_size": size_cache[item[0]],
                "output_size": size_cache[item[1]],
                "input_name": item[0],
                "output_name": item[1],
            }
            info.append(data)
            test_case_info["test_cases"][str(index + 1)] = data

        with open(os.path.join(test_case_dir, "info"), "w", encoding="utf-8") as f:
            f.write(json.dumps(test_case_info, indent=4))

        for item in os.listdir(test_case_dir):
            os.chmod(os.path.join(test_case_dir, item), 0o640)

        return info, test_case_id

    def filter_name_list(self, name_list, dir=""):
        ret = []
        prefix = 1
        while True:
            in_name = f"{prefix}.in"
            out_name = f"{prefix}.out"
            if f"{dir}{in_name}" in name_list and f"{dir}{out_name}" in name_list:
                ret.append(in_name)
                ret.append(out_name)
                prefix += 1
                continue
            else:
                return sorted(ret, key=natural_sort_key)


class TestCaseAPI(CSRFExemptAPIView, TestCaseZipProcessor):
    request_parsers = ()

    def get(self, request):
        problem_id = request.GET.get("problem_id")
        if not problem_id:
            return self.error("Parameter error, problem_id is required")
        try:
            problem = Problem.objects.get(id=problem_id)
        except Problem.DoesNotExist:
            return self.error("Problem does not exists")

        if problem.contest:
            ensure_created_by(problem.contest, request.user)
        else:
            ensure_created_by(problem, request.user)

        test_case_dir = os.path.join(settings.TEST_CASE_DIR, problem.test_case_id)
        if not os.path.isdir(test_case_dir):
            return self.error("Test case does not exists")
        name_list = self.filter_name_list(os.listdir(test_case_dir))
        name_list.append("info")
        file_name = os.path.join(test_case_dir, problem.test_case_id + ".zip")
        with zipfile.ZipFile(file_name, "w") as file:
            for test_case in name_list:
                file.write(f"{test_case_dir}/{test_case}", test_case)
        response = StreamingHttpResponse(
            FileWrapper(open(file_name, "rb")), content_type="application/octet-stream"
        )

        response["Content-Disposition"] = (
            f"attachment; filename=problem_{problem.id}_test_cases.zip"
        )
        response["Content-Length"] = os.path.getsize(file_name)
        return response

    def post(self, request):
        form = TestCaseUploadForm(request.POST, request.FILES)
        if form.is_valid():
            file = form.cleaned_data["file"]
        else:
            return self.error("Upload failed")
        zip_file = f"/tmp/{rand_str()}.zip"
        with open(zip_file, "wb") as f:
            for chunk in file:
                f.write(chunk)
        info, test_case_id = self.process_zip(zip_file)
        os.remove(zip_file)
        return self.success({"id": test_case_id, "info": info})


class ProblemBase(APIView):
    def common_checks(self, request):
        data = request.data
        if data["rule_type"] == ProblemRuleType.OI:
            total_score = 0
            for item in data["test_case_score"]:
                if item["score"] <= 0:
                    return "Invalid score"
                else:
                    total_score += item["score"]
            data["total_score"] = total_score
        data["languages"] = list(data["languages"])


class ProblemAPI(ProblemBase):
    @problem_permission_required
    @validate_serializer(CreateProblemSerializer)
    def post(self, request):
        data = request.data
        _id = data["_id"]
        if not _id:
            return self.error("Display ID is required")
        if Problem.objects.filter(_id=_id, contest_id__isnull=True).exists():
            return self.error("Display ID already exists")

        error_info = self.common_checks(request)
        if error_info:
            return self.error(error_info)

        # todo check filename and score info
        tags = data.pop("tags")
        data["created_by"] = request.user
        problem = Problem.objects.create(**data)

        for item in tags:
            try:
                tag = ProblemTag.objects.get(name=item)
            except ProblemTag.DoesNotExist:
                tag = ProblemTag.objects.create(name=item)
            problem.tags.add(tag)
        return self.success(ProblemAdminSerializer(problem).data)

    @problem_permission_required
    def get(self, request):
        problem_id = request.GET.get("id")
        user = request.user
        if problem_id:
            try:
                problem = Problem.objects.get(id=problem_id)
                ensure_created_by(problem, request.user)
                return self.success(ProblemAdminSerializer(problem).data)
            except Problem.DoesNotExist:
                return self.error("Problem does not exist")

        problems = Problem.objects.filter(contest_id__isnull=True).order_by(
            "-create_time"
        )

        author = request.GET.get("author", "")
        if author:
            problems = problems.filter(created_by__username=author)

        keyword = request.GET.get("keyword", "").strip()
        if keyword:
            problems = problems.filter(
                Q(title__icontains=keyword) | Q(_id__icontains=keyword)
            )
        if not user.can_mgmt_all_problem():
            problems = problems.filter(created_by=user)
        return self.success(
            self.paginate_data(request, problems, ProblemAdminListSerializer)
        )

    @problem_permission_required
    @validate_serializer(EditProblemSerializer)
    def put(self, request):
        data = request.data
        problem_id = data.pop("id")

        try:
            problem = Problem.objects.get(id=problem_id)
            ensure_created_by(problem, request.user)
        except Problem.DoesNotExist:
            return self.error("Problem does not exist")

        _id = data["_id"]
        if not _id:
            return self.error("Display ID is required")
        if (
            Problem.objects.exclude(id=problem_id)
            .filter(_id=_id, contest_id__isnull=True)
            .exists()
        ):
            return self.error("Display ID already exists")

        error_info = self.common_checks(request)
        if error_info:
            return self.error(error_info)
        # todo check filename and score info
        tags = data.pop("tags")
        data["languages"] = list(data["languages"])

        for k, v in data.items():
            setattr(problem, k, v)
        problem.save()

        problem.tags.remove(*problem.tags.all())
        for tag in tags:
            try:
                tag = ProblemTag.objects.get(name=tag)
            except ProblemTag.DoesNotExist:
                tag = ProblemTag.objects.create(name=tag)
            problem.tags.add(tag)

        return self.success()

    @problem_permission_required
    def delete(self, request):
        id = request.GET.get("id")
        if not id:
            return self.error("Invalid parameter, id is required")
        try:
            problem = Problem.objects.get(id=id, contest_id__isnull=True)
        except Problem.DoesNotExist:
            return self.error("Problem does not exists")
        ensure_created_by(problem, request.user)
        # d = os.path.join(settings.TEST_CASE_DIR, problem.test_case_id)
        # if os.path.isdir(d):
        #     shutil.rmtree(d, ignore_errors=True)
        problem.delete()
        return self.success()


class ContestProblemAPI(ProblemBase):
    @validate_serializer(CreateContestProblemSerializer)
    def post(self, request):
        data = request.data
        try:
            contest = Contest.objects.get(id=data.pop("contest_id"))
            ensure_created_by(contest, request.user)
        except Contest.DoesNotExist:
            return self.error("Contest does not exist")

        if data["rule_type"] != contest.rule_type:
            return self.error("Invalid rule type")

        _id = data["_id"]
        if not _id:
            return self.error("Display ID is required")

        if Problem.objects.filter(_id=_id, contest=contest).exists():
            return self.error("Duplicate Display id")

        error_info = self.common_checks(request)
        if error_info:
            return self.error(error_info)

        # todo check filename and score info
        data["contest"] = contest
        tags = data.pop("tags")
        data["created_by"] = request.user
        problem = Problem.objects.create(**data)

        for item in tags:
            try:
                tag = ProblemTag.objects.get(name=item)
            except ProblemTag.DoesNotExist:
                tag = ProblemTag.objects.create(name=item)
            problem.tags.add(tag)
        return self.success(ProblemAdminSerializer(problem).data)

    def get(self, request):
        problem_id = request.GET.get("id")
        contest_id = request.GET.get("contest_id")
        user = request.user
        if problem_id:
            try:
                problem = Problem.objects.get(id=problem_id)
                ensure_created_by(problem.contest, user)
            except Problem.DoesNotExist:
                return self.error("Problem does not exist")
            return self.success(ProblemAdminSerializer(problem).data)

        if not contest_id:
            return self.error("Contest id is required")
        try:
            contest = Contest.objects.get(id=contest_id)
            ensure_created_by(contest, user)
        except Contest.DoesNotExist:
            return self.error("Contest does not exist")
        problems = Problem.objects.filter(contest=contest).order_by("-create_time")
        if user.is_admin():
            problems = problems.filter(contest__created_by=user)
        keyword = request.GET.get("keyword")
        if keyword:
            problems = problems.filter(title__contains=keyword)
        return self.success(
            self.paginate_data(request, problems, ProblemAdminListSerializer)
        )

    @validate_serializer(EditContestProblemSerializer)
    def put(self, request):
        data = request.data
        user = request.user

        try:
            contest = Contest.objects.get(id=data.pop("contest_id"))
            ensure_created_by(contest, user)
        except Contest.DoesNotExist:
            return self.error("Contest does not exist")

        if data["rule_type"] != contest.rule_type:
            return self.error("Invalid rule type")

        problem_id = data.pop("id")

        try:
            problem = Problem.objects.get(id=problem_id, contest=contest)
        except Problem.DoesNotExist:
            return self.error("Problem does not exist")

        _id = data["_id"]
        if not _id:
            return self.error("Display ID is required")
        if (
            Problem.objects.exclude(id=problem_id)
            .filter(_id=_id, contest=contest)
            .exists()
        ):
            return self.error("Display ID already exists")

        error_info = self.common_checks(request)
        if error_info:
            return self.error(error_info)
        # todo check filename and score info
        tags = data.pop("tags")
        data["languages"] = list(data["languages"])

        for k, v in data.items():
            setattr(problem, k, v)
        problem.save()

        problem.tags.remove(*problem.tags.all())
        for tag in tags:
            try:
                tag = ProblemTag.objects.get(name=tag)
            except ProblemTag.DoesNotExist:
                tag = ProblemTag.objects.create(name=tag)
            problem.tags.add(tag)
        return self.success()

    def delete(self, request):
        id = request.GET.get("id")
        if not id:
            return self.error("Invalid parameter, id is required")
        try:
            problem = Problem.objects.get(id=id, contest_id__isnull=False)
        except Problem.DoesNotExist:
            return self.error("Problem does not exists")
        ensure_created_by(problem.contest, request.user)
        if Submission.objects.filter(problem=problem).exists():
            return self.error("Can't delete the problem as it has submissions")
        # d = os.path.join(settings.TEST_CASE_DIR, problem.test_case_id)
        # if os.path.isdir(d):
        #    shutil.rmtree(d, ignore_errors=True)
        problem.delete()
        return self.success()


class MakeContestProblemPublicAPIView(APIView):
    @validate_serializer(ContestProblemMakePublicSerializer)
    @problem_permission_required
    def post(self, request):
        data = request.data
        display_id = data.get("display_id")
        if Problem.objects.filter(_id=display_id, contest_id__isnull=True).exists():
            return self.error("Duplicate display ID")

        try:
            problem = Problem.objects.get(id=data["id"])
        except Problem.DoesNotExist:
            return self.error("Problem does not exist")

        if not problem.contest or problem.is_public:
            return self.error("Already be a public problem")
        problem.is_public = True
        problem.save()
        tags = problem.tags.all()
        problem.pk = None
        problem.contest = None
        problem._id = display_id
        problem.visible = False
        problem.submission_number = problem.accepted_number = 0
        problem.statistic_info = {}
        problem.save()
        problem.tags.set(tags)
        return self.success()


class AddContestProblemAPI(APIView):
    @validate_serializer(AddContestProblemSerializer)
    def post(self, request):
        data = request.data
        try:
            contest = Contest.objects.get(id=data["contest_id"])
            problem = Problem.objects.get(id=data["problem_id"])
        except (Contest.DoesNotExist, Problem.DoesNotExist):
            return self.error("Contest or Problem does not exist")

        if contest.status == ContestStatus.CONTEST_ENDED:
            return self.error("Contest has ended")
        if Problem.objects.filter(contest=contest, _id=data["display_id"]).exists():
            return self.error("Duplicate display id in this contest")

        tags = problem.tags.all()
        problem.pk = None
        problem.contest = contest
        problem.is_public = True
        problem.visible = True
        problem._id = request.data["display_id"]
        problem.submission_number = problem.accepted_number = 0
        problem.statistic_info = {}
        problem.save()
        problem.tags.set(tags)
        return self.success()


class ProblemVisibleAPI(APIView):
    @problem_permission_required
    def put(self, request):
        data = request.data
        try:
            problem = Problem.objects.get(id=data["id"])
        except Problem.DoesNotExist:
            self.error("problem does not exists")
        problem.visible = not problem.visible
        problem.save()
        return self.success()