import logging
import secrets
from typing import List, Optional, Tuple

from django.conf import settings
from django.http import HttpRequest, HttpResponse
from django.shortcuts import redirect, render
from django.urls import reverse
from django.utils.cache import patch_cache_control

from zerver.actions.user_settings import do_change_tos_version, do_change_user_setting
from zerver.context_processors import get_realm_from_request, get_valid_realm_from_request
from zerver.decorator import web_public_view, zulip_login_required
from zerver.forms import ToSForm
from zerver.lib.compatibility import is_outdated_desktop_app, is_unsupported_browser
from zerver.lib.home import build_page_params_for_home_page_load, get_user_permission_info
from zerver.lib.narrow_helpers import NarrowTerm
from zerver.lib.request import RequestNotes
from zerver.lib.streams import access_stream_by_name
from zerver.lib.subdomains import get_subdomain
from zerver.lib.user_counts import realm_user_count
from zerver.models import PreregistrationUser, Realm, RealmUserDefault, Stream, UserProfile


def need_accept_tos(user_profile: Optional[UserProfile]) -> bool:
    if user_profile is None:
        return False

    if user_profile.tos_version == UserProfile.TOS_VERSION_BEFORE_FIRST_LOGIN:
        return True

    if settings.TERMS_OF_SERVICE_VERSION is None:
        return False

    return int(settings.TERMS_OF_SERVICE_VERSION.split(".")[0]) > user_profile.major_tos_version()


@zulip_login_required
def accounts_accept_terms(request: HttpRequest) -> HttpResponse:
    assert request.user.is_authenticated

    if request.method == "POST":
        form = ToSForm(request.POST)
        if form.is_valid():
            assert (
                settings.TERMS_OF_SERVICE_VERSION is not None
                or request.user.tos_version == UserProfile.TOS_VERSION_BEFORE_FIRST_LOGIN
            )
            do_change_tos_version(request.user, settings.TERMS_OF_SERVICE_VERSION)

            email_address_visibility = form.cleaned_data["email_address_visibility"]
            if (
                email_address_visibility is not None
                and email_address_visibility != request.user.email_address_visibility
            ):
                do_change_user_setting(
                    request.user,
                    "email_address_visibility",
                    email_address_visibility,
                    acting_user=request.user,
                )
            return redirect(home)
    else:
        form = ToSForm()

    default_email_address_visibility = None
    first_time_login = request.user.tos_version == UserProfile.TOS_VERSION_BEFORE_FIRST_LOGIN
    if first_time_login:
        realm_user_default = RealmUserDefault.objects.get(realm=request.user.realm)
        default_email_address_visibility = realm_user_default.email_address_visibility

    context = {
        "form": form,
        "email": request.user.delivery_email,
        # Text displayed when updating TERMS_OF_SERVICE_VERSION.
        "terms_of_service_message": settings.TERMS_OF_SERVICE_MESSAGE,
        "terms_of_service_version": settings.TERMS_OF_SERVICE_VERSION,
        # HTML template used when agreeing to terms of service the
        # first time, e.g. after data import.
        "first_time_terms_of_service_message_template": None,
        "first_time_login": first_time_login,
        "default_email_address_visibility": default_email_address_visibility,
        "email_address_visibility_options_dict": UserProfile.EMAIL_ADDRESS_VISIBILITY_ID_TO_NAME_MAP,
        "email_address_visibility_admins_only": UserProfile.EMAIL_ADDRESS_VISIBILITY_ADMINS,
        "email_address_visibility_moderators": UserProfile.EMAIL_ADDRESS_VISIBILITY_MODERATORS,
        "email_address_visibility_nobody": UserProfile.EMAIL_ADDRESS_VISIBILITY_NOBODY,
    }

    if (
        request.user.tos_version == UserProfile.TOS_VERSION_BEFORE_FIRST_LOGIN
        and settings.FIRST_TIME_TERMS_OF_SERVICE_TEMPLATE is not None
    ):
        context["first_time_terms_of_service_message_template"] = (
            settings.FIRST_TIME_TERMS_OF_SERVICE_TEMPLATE
        )

    return render(
        request,
        "zerver/accounts_accept_terms.html",
        context,
    )


def detect_narrowed_window(
    request: HttpRequest, user_profile: Optional[UserProfile]
) -> Tuple[List[NarrowTerm], Optional[Stream], Optional[str]]:
    """This function implements Zulip's support for a mini Zulip window
    that just handles messages from a single narrow"""
    if user_profile is None:
        return [], None, None

    narrow: List[NarrowTerm] = []
    narrow_stream = None
    narrow_topic_name = request.GET.get("topic")

    if "stream" in request.GET:
        try:
            # TODO: We should support stream IDs and direct messages here as well.
            narrow_stream_name = request.GET.get("stream")
            assert narrow_stream_name is not None
            (narrow_stream, ignored_sub) = access_stream_by_name(user_profile, narrow_stream_name)
            narrow = [NarrowTerm(operator="stream", operand=narrow_stream.name)]
        except Exception:
            logging.warning("Invalid narrow requested, ignoring", extra=dict(request=request))
        if narrow_stream is not None and narrow_topic_name is not None:
            narrow.append(NarrowTerm(operator="topic", operand=narrow_topic_name))
    return narrow, narrow_stream, narrow_topic_name


def update_last_reminder(user_profile: Optional[UserProfile]) -> None:
    """Reset our don't-spam-users-with-email counter since the
    user has since logged in
    """
    if user_profile is None:
        return

    if user_profile.last_reminder is not None:  # nocoverage
        # TODO: Look into the history of last_reminder; we may have
        # eliminated that as a useful concept for non-bot users.
        user_profile.last_reminder = None
        user_profile.save(update_fields=["last_reminder"])


def home(request: HttpRequest) -> HttpResponse:
    subdomain = get_subdomain(request)

    # If settings.ROOT_DOMAIN_LANDING_PAGE and this is the root
    # domain, send the user the landing page.
    if (
        settings.ROOT_DOMAIN_LANDING_PAGE
        and subdomain == Realm.SUBDOMAIN_FOR_ROOT_DOMAIN
        and settings.CORPORATE_ENABLED
    ):
        from corporate.views.portico import hello_view

        return hello_view(request)

    if subdomain == settings.SOCIAL_AUTH_SUBDOMAIN:
        return redirect(settings.ROOT_DOMAIN_URI)
    elif subdomain == settings.SELF_HOSTING_MANAGEMENT_SUBDOMAIN:
        return redirect(reverse("remote_billing_legacy_server_login"))
    realm = get_realm_from_request(request)
    if realm is None:
        return render(request, "zerver/invalid_realm.html", status=404)
    if realm.allow_web_public_streams_access():
        return web_public_view(home_real)(request)
    return zulip_login_required(home_real)(request)


def home_real(request: HttpRequest) -> HttpResponse:
    # Before we do any real work, check if the app is banned.
    client_user_agent = request.headers.get("User-Agent", "")
    (insecure_desktop_app, banned_desktop_app, auto_update_broken) = is_outdated_desktop_app(
        client_user_agent
    )
    if banned_desktop_app:
        return render(
            request,
            "zerver/insecure_desktop_app.html",
            context={
                "auto_update_broken": auto_update_broken,
            },
        )
    (unsupported_browser, browser_name) = is_unsupported_browser(client_user_agent)
    if unsupported_browser:
        return render(
            request,
            "zerver/unsupported_browser.html",
            context={
                "browser_name": browser_name,
            },
        )

    # We need to modify the session object every two weeks or it will expire.
    # This line makes reloading the page a sufficient action to keep the
    # session alive.
    request.session.modified = True

    if request.user.is_authenticated:
        user_profile = request.user
        realm = user_profile.realm
    else:
        realm = get_valid_realm_from_request(request)
        # We load the spectator experience.  We fall through to the shared code
        # for loading the application, with user_profile=None encoding
        # that we're a spectator, not a logged-in user.
        user_profile = None

    update_last_reminder(user_profile)

    # If a user hasn't signed the current Terms of Service, send them there
    if need_accept_tos(user_profile):
        return accounts_accept_terms(request)

    narrow, narrow_stream, narrow_topic_name = detect_narrowed_window(request, user_profile)

    if user_profile is not None:
        first_in_realm = realm_user_count(user_profile.realm) == 1
        # If you are the only person in the realm and you didn't invite
        # anyone, we'll continue to encourage you to do so on the frontend.
        prompt_for_invites = (
            first_in_realm
            and not PreregistrationUser.objects.filter(referred_by=user_profile).count()
        )
        needs_tutorial = user_profile.tutorial_status == UserProfile.TUTORIAL_WAITING

    else:
        first_in_realm = False
        prompt_for_invites = False
        # The current tutorial doesn't super make sense for logged-out users.
        needs_tutorial = False

    queue_id, page_params = build_page_params_for_home_page_load(
        request=request,
        user_profile=user_profile,
        realm=realm,
        insecure_desktop_app=insecure_desktop_app,
        narrow=narrow,
        narrow_stream=narrow_stream,
        narrow_topic_name=narrow_topic_name,
        first_in_realm=first_in_realm,
        prompt_for_invites=prompt_for_invites,
        needs_tutorial=needs_tutorial,
    )

    log_data = RequestNotes.get_notes(request).log_data
    assert log_data is not None
    log_data["extra"] = f"[{queue_id}]"

    csp_nonce = secrets.token_hex(24)

    user_permission_info = get_user_permission_info(user_profile)

    response = render(
        request,
        "zerver/app/index.html",
        context={
            "user_profile": user_profile,
            "page_params": page_params,
            "csp_nonce": csp_nonce,
            "color_scheme": user_permission_info.color_scheme,
        },
    )
    patch_cache_control(response, no_cache=True, no_store=True, must_revalidate=True)
    return response


@zulip_login_required
def desktop_home(request: HttpRequest) -> HttpResponse:
    return redirect(home)