import datetime
import decimal
import logging
import sys

from django.core.exceptions import PermissionDenied, SuspiciousOperation
from django.http import Http404, HttpResponse, JsonResponse
from django.shortcuts import render
from django.template import TemplateDoesNotExist
from django.urls import get_resolver
from django.views import View
from django.views.debug import (
    SafeExceptionReporterFilter, technical_500_response,
)
from django.views.decorators.debug import (
    sensitive_post_parameters, sensitive_variables,
)


def index_page(request):
    """Dummy index page"""
    return HttpResponse('<html><body>Dummy page</body></html>')


def with_parameter(request, parameter):
    return HttpResponse('ok')


def raises(request):
    # Make sure that a callable that raises an exception in the stack frame's
    # local vars won't hijack the technical 500 response (#15025).
    def callable():
        raise Exception
    try:
        raise Exception
    except Exception:
        return technical_500_response(request, *sys.exc_info())


def raises500(request):
    # We need to inspect the HTML generated by the fancy 500 debug view but
    # the test client ignores it, so we send it explicitly.
    try:
        raise Exception
    except Exception:
        return technical_500_response(request, *sys.exc_info())


def raises400(request):
    raise SuspiciousOperation


def raises403(request):
    raise PermissionDenied("Insufficient Permissions")


def raises404(request):
    resolver = get_resolver(None)
    resolver.resolve('/not-in-urls')


def technical404(request):
    raise Http404("Testing technical 404.")


class Http404View(View):
    def get(self, request):
        raise Http404("Testing class-based technical 404.")


def template_exception(request):
    return render(request, 'debug/template_exception.html')


def jsi18n(request):
    return render(request, 'jsi18n.html')


def old_jsi18n(request):
    return render(request, 'old_jsi18n.html')


def jsi18n_multi_catalogs(request):
    return render(request, 'jsi18n-multi-catalogs.html')


def old_jsi18n_multi_catalogs(request):
    return render(request, 'old_jsi18n-multi-catalogs.html')


def raises_template_does_not_exist(request, path='i_dont_exist.html'):
    # We need to inspect the HTML generated by the fancy 500 debug view but
    # the test client ignores it, so we send it explicitly.
    try:
        return render(request, path)
    except TemplateDoesNotExist:
        return technical_500_response(request, *sys.exc_info())


def render_no_template(request):
    # If we do not specify a template, we need to make sure the debug
    # view doesn't blow up.
    return render(request, [], {})


def send_log(request, exc_info):
    logger = logging.getLogger('django')
    # The default logging config has a logging filter to ensure admin emails are
    # only sent with DEBUG=False, but since someone might choose to remove that
    # filter, we still want to be able to test the behavior of error emails
    # with DEBUG=True. So we need to remove the filter temporarily.
    admin_email_handler = [
        h for h in logger.handlers
        if h.__class__.__name__ == "AdminEmailHandler"
    ][0]
    orig_filters = admin_email_handler.filters
    admin_email_handler.filters = []
    admin_email_handler.include_html = True
    logger.error(
        'Internal Server Error: %s', request.path,
        exc_info=exc_info,
        extra={'status_code': 500, 'request': request},
    )
    admin_email_handler.filters = orig_filters


def non_sensitive_view(request):
    # Do not just use plain strings for the variables' values in the code
    # so that the tests don't return false positives when the function's source
    # is displayed in the exception report.
    cooked_eggs = ''.join(['s', 'c', 'r', 'a', 'm', 'b', 'l', 'e', 'd'])  # NOQA
    sauce = ''.join(['w', 'o', 'r', 'c', 'e', 's', 't', 'e', 'r', 's', 'h', 'i', 'r', 'e'])  # NOQA
    try:
        raise Exception
    except Exception:
        exc_info = sys.exc_info()
        send_log(request, exc_info)
        return technical_500_response(request, *exc_info)


@sensitive_variables('sauce')
@sensitive_post_parameters('bacon-key', 'sausage-key')
def sensitive_view(request):
    # Do not just use plain strings for the variables' values in the code
    # so that the tests don't return false positives when the function's source
    # is displayed in the exception report.
    cooked_eggs = ''.join(['s', 'c', 'r', 'a', 'm', 'b', 'l', 'e', 'd'])  # NOQA
    sauce = ''.join(['w', 'o', 'r', 'c', 'e', 's', 't', 'e', 'r', 's', 'h', 'i', 'r', 'e'])  # NOQA
    try:
        raise Exception
    except Exception:
        exc_info = sys.exc_info()
        send_log(request, exc_info)
        return technical_500_response(request, *exc_info)


@sensitive_variables()
@sensitive_post_parameters()
def paranoid_view(request):
    # Do not just use plain strings for the variables' values in the code
    # so that the tests don't return false positives when the function's source
    # is displayed in the exception report.
    cooked_eggs = ''.join(['s', 'c', 'r', 'a', 'm', 'b', 'l', 'e', 'd'])  # NOQA
    sauce = ''.join(['w', 'o', 'r', 'c', 'e', 's', 't', 'e', 'r', 's', 'h', 'i', 'r', 'e'])  # NOQA
    try:
        raise Exception
    except Exception:
        exc_info = sys.exc_info()
        send_log(request, exc_info)
        return technical_500_response(request, *exc_info)


def sensitive_args_function_caller(request):
    try:
        sensitive_args_function(''.join(['w', 'o', 'r', 'c', 'e', 's', 't', 'e', 'r', 's', 'h', 'i', 'r', 'e']))
    except Exception:
        exc_info = sys.exc_info()
        send_log(request, exc_info)
        return technical_500_response(request, *exc_info)


@sensitive_variables('sauce')
def sensitive_args_function(sauce):
    # Do not just use plain strings for the variables' values in the code
    # so that the tests don't return false positives when the function's source
    # is displayed in the exception report.
    cooked_eggs = ''.join(['s', 'c', 'r', 'a', 'm', 'b', 'l', 'e', 'd'])  # NOQA
    raise Exception


def sensitive_kwargs_function_caller(request):
    try:
        sensitive_kwargs_function(''.join(['w', 'o', 'r', 'c', 'e', 's', 't', 'e', 'r', 's', 'h', 'i', 'r', 'e']))
    except Exception:
        exc_info = sys.exc_info()
        send_log(request, exc_info)
        return technical_500_response(request, *exc_info)


@sensitive_variables('sauce')
def sensitive_kwargs_function(sauce=None):
    # Do not just use plain strings for the variables' values in the code
    # so that the tests don't return false positives when the function's source
    # is displayed in the exception report.
    cooked_eggs = ''.join(['s', 'c', 'r', 'a', 'm', 'b', 'l', 'e', 'd'])  # NOQA
    raise Exception


class UnsafeExceptionReporterFilter(SafeExceptionReporterFilter):
    """
    Ignores all the filtering done by its parent class.
    """

    def get_post_parameters(self, request):
        return request.POST

    def get_traceback_frame_variables(self, request, tb_frame):
        return tb_frame.f_locals.items()


@sensitive_variables()
@sensitive_post_parameters()
def custom_exception_reporter_filter_view(request):
    # Do not just use plain strings for the variables' values in the code
    # so that the tests don't return false positives when the function's source
    # is displayed in the exception report.
    cooked_eggs = ''.join(['s', 'c', 'r', 'a', 'm', 'b', 'l', 'e', 'd'])  # NOQA
    sauce = ''.join(['w', 'o', 'r', 'c', 'e', 's', 't', 'e', 'r', 's', 'h', 'i', 'r', 'e'])  # NOQA
    request.exception_reporter_filter = UnsafeExceptionReporterFilter()
    try:
        raise Exception
    except Exception:
        exc_info = sys.exc_info()
        send_log(request, exc_info)
        return technical_500_response(request, *exc_info)


class Klass:

    @sensitive_variables('sauce')
    def method(self, request):
        # Do not just use plain strings for the variables' values in the code
        # so that the tests don't return false positives when the function's
        # source is displayed in the exception report.
        cooked_eggs = ''.join(['s', 'c', 'r', 'a', 'm', 'b', 'l', 'e', 'd'])  # NOQA
        sauce = ''.join(['w', 'o', 'r', 'c', 'e', 's', 't', 'e', 'r', 's', 'h', 'i', 'r', 'e'])  # NOQA
        try:
            raise Exception
        except Exception:
            exc_info = sys.exc_info()
            send_log(request, exc_info)
            return technical_500_response(request, *exc_info)


def sensitive_method_view(request):
    return Klass().method(request)


@sensitive_variables('sauce')
@sensitive_post_parameters('bacon-key', 'sausage-key')
def multivalue_dict_key_error(request):
    cooked_eggs = ''.join(['s', 'c', 'r', 'a', 'm', 'b', 'l', 'e', 'd'])  # NOQA
    sauce = ''.join(['w', 'o', 'r', 'c', 'e', 's', 't', 'e', 'r', 's', 'h', 'i', 'r', 'e'])  # NOQA
    try:
        request.POST['bar']
    except Exception:
        exc_info = sys.exc_info()
        send_log(request, exc_info)
        return technical_500_response(request, *exc_info)


def json_response_view(request):
    return JsonResponse({
        'a': [1, 2, 3],
        'foo': {'bar': 'baz'},
        # Make sure datetime and Decimal objects would be serialized properly
        'timestamp': datetime.datetime(2013, 5, 19, 20),
        'value': decimal.Decimal('3.14'),
    })
