import datetime

from dataclasses import dataclass
from smtplib import SMTPException
from typing import Optional
from urllib.parse import urljoin

from django.forms import ChoiceField, Field
from django.shortcuts import render, redirect
from django.http import HttpResponse, Http404
from django.urls import reverse
from django.utils.choices import flatten_choices
from django.utils.formats import date_format
from django.utils.functional import cached_property
from django.utils.http import url_has_allowed_host_and_scheme
from django.utils.safestring import mark_safe
from django.utils.text import get_text_list
from django.core.mail import BadHeaderError
from django.conf import settings
from django.contrib.auth.decorators import login_required
from django.views.generic import TemplateView
from django.views.generic.edit import FormView
from django.utils.html import strip_tags

from input.utils.admin import admin_url_name
from input.utils.mail import build_email, collect_and_attach

from .forms import (
    BaseApplicationForm,
    ProjectForm,
    LibraryForm,
    ELiteratureForm,
    SoftwareForm,
    IFGForm,
    LiteratureForm,
    TravelForm,
    EmailForm,
    ListForm,
    BusinessCardForm,
)
from .models import (
    MODELS,
    LIBRARY_TYPES,
    TYPE_CHOICES,
    TYPE_BIB,
    TYPE_ELIT,
    TYPE_IFG,
    TYPE_LIT,
    TYPE_LIST,
    TYPE_MAIL,
    TYPE_PROJ,
    TYPE_SOFT,
    TYPE_TRAV,
    TYPE_VIS,
    Project,
    ProductCategoryFormField,
)

HELP_TEXTS = {
    TYPE_IFG: {
        'notes': (
            'Bitte gib an, wie die gewonnenen Informationen den<br>'
            'Wikimedia-Projekten zugute kommen sollen.'
        )
    },
    TYPE_MAIL: {
        'domain': (
            'Mit welcher Domain, bzw. für welches Wikimedia-Projekt,<br>'
            'möchtest du eine Mailadresse beantragen?'
        )
    },
    TYPE_LIT: {
        'notes': 'Bitte gib an, wofür du die Literatur verwenden möchtest.'
    },
    TYPE_LIST: {
        'domain': (
            'Mit welcher Domain, bzw. für welches Wikimedia-Projekt,<br>'
            'möchtest du eine Mailingliste beantragen?'
        )
    },
}

@dataclass
class ApplicationType:
    code: str
    path: str
    form_class: type[BaseApplicationForm]
    link: str
    label: Optional[str] = None
    help_texts: Optional[dict] = None

    def __post_init__(self):
        if self.label is None:
            self.label = TYPE_CHOICES[self.code]

        if self.help_texts is None:  # pragma: no branch
            self.help_texts = HELP_TEXTS.get(self.code)

    @property
    def url(self):
        return f'https://de.wikipedia.org/wiki/Wikipedia:F%C3%B6rderung/{self.link}'


PROJECT_FUNDING = [
    ApplicationType(TYPE_PROJ, 'projektfoerderung', ProjectForm, 'Projektplanung',
                    'Projektförderung mit einer Gesamtsumme unter 1.000,— EUR'),
    ApplicationType(TYPE_PROJ, 'projektfoerderung-ab-1000', ProjectForm, 'Projektplanung',
                    'Projektförderung mit einer Gesamtsumme ab 1.000,— EUR'),
]

SERVICES = [
    ApplicationType(TYPE_BIB, 'bibliotheksstipendium', LibraryForm, 'Zugang_zu_Fachliteratur#Bibliotheksstipendium'),
    ApplicationType(TYPE_ELIT, 'eliteraturstipendium', ELiteratureForm, 'Zugang_zu_Fachliteratur#eLiteraturstipendium'),
    ApplicationType(TYPE_MAIL, 'email', EmailForm, 'E-Mail-Adressen_und_Visitenkarten#E-Mail-Adressen'),
    ApplicationType(TYPE_IFG, 'ifg', IFGForm, 'Geb%C3%BChrenerstattungen_f%C3%BCr_Beh%C3%B6rdenanfragen'),
    ApplicationType(TYPE_LIT, 'literaturstipendium', LiteratureForm, 'Zugang_zu_Fachliteratur#Literaturstipendium'),
    ApplicationType(TYPE_LIST, 'mailingliste', ListForm, 'E-Mail-Adressen_und_Visitenkarten#Mailinglisten'),
    ApplicationType(TYPE_TRAV, 'reisekosten', TravelForm, 'Reisekostenerstattungen'),
    ApplicationType(TYPE_SOFT, 'softwarestipendium', SoftwareForm, 'Software-Stipendien'),
    ApplicationType(TYPE_VIS, 'visitenkarten', BusinessCardForm, 'E-Mail-Adressen_und_Visitenkarten#Visitenkarten'),
]

APPLICATIONS = [
    ('Projektförderung', PROJECT_FUNDING),
    ('Serviceleistungen', SERVICES),
]

TYPES = {info.path: info for info in PROJECT_FUNDING + SERVICES}


def auth_deny(choice, pk, auth):
    if choice not in MODELS:
        return HttpResponse(f'ERROR! UNKNOWN CHOICE TYPE! {choice}')

    MODELS[choice].set_granted(pk, auth)


@login_required
def export(request):
    '''export the project database to a csv'''
    return HttpResponse('WE WANT CSV!')


@login_required
def authorize(request, choice, pk):
    '''If IF grant a support they click a link in a mail which leads here.
    We write the granted field in the database here and set a timestamp.'''

    if ret := auth_deny(choice, pk, True):
        return ret
    else:
        return HttpResponse(f'AUTHORIZED! choice: {choice}, pk: {pk}')


@login_required
def deny(request, choice, pk):
    '''If IF denies a support they click a link in a mail which leads here
    We write the granted field in the database here.'''

    if ret := auth_deny(choice, pk, False):
        return ret
    else:
        return HttpResponse(f'DENIED! choice: {choice}, pk: {pk}')


def done(request):
    return HttpResponse(
        'Deine Anfrage wurde gesendet. Du erhältst in Kürze eine E-Mail-Benachrichtigung mit deinen Angaben. Für alle Fragen kontaktiere bitte das Team Communitys und Engagement unter community@wikimedia.de.')


def index(request):
    return render(request, 'input/index.html')


class ApplicationStartView(TemplateView):
    template_name = 'input/forms/extern.html'
    extra_context = {'applications': APPLICATIONS}

    def post(self, request, *args, **kwargs):
        if url := request.POST.get('url'):
            if url_has_allowed_host_and_scheme(url, None):
                return redirect(url)

        return self.get(request, *args, **kwargs)


class ProjectFundingInfoView(TemplateView):
    template_name = 'input/info_project_funding_gt_1000.html'


class ApplicationView(FormView):
    """
    View for all application types.

    - Renders the generic form template.
    - Handles saving the submitted form to the database.
    - Adds extra fields from the session or request type if needed.
    - Applies optional help_text overrides for certain fields.
    - Sends confirmation mail to the applicant.
    - Sends notification mail to the internal IF address.
    - Returns the "done" response after successful processing.
    """

    template_name = 'input/forms/form_generic.html'

    @cached_property
    def type_info(self) -> ApplicationType:
        type_path = self.kwargs['type']

        if type_info := TYPES.get(type_path):
            return type_info

        raise Http404(f'"{type_path}" existiert nicht.')

    @property
    def type_code(self):
        return self.type_info.code

    @property
    def form_class(self):
        return self.type_info.form_class

    def get_context_data(self, **kwargs):
        return super().get_context_data(**kwargs, type_label=self.type_info.label)

    def get_form(self, form_class=None):
        """Return the form instance and inject custom help_texts if defined for this type."""
        form = super().get_form(form_class)

        # Apply help_text overrides if defined for this type_code
        if help_texts := self.type_info.help_texts:
            for field, text in help_texts.items():
                if field in form.fields:
                    form.fields[field].help_text = mark_safe(text)

        return form

    def form_valid(self, form):
        """
        Process a valid form submission:
        - Enrich form data (e.g., set type_code, handle special rules).
        - Save the model instance and related data.
        - Send confirmation and notification mails.
        - Return the "done" response.
        """

        data = self.prepare_data(form)
        obj = self.save_obj(form, data)

        if response := self.send_mail(obj, data):
            return response

        return done(self.request)

    def prepare_data(self, form):
        # Collect cleaned data and mark the current type
        return {**form.cleaned_data, 'choice': self.type_code}

    def save_obj(self, form, data):
        # Save model instance

        modell = form.save(commit=False)

        # Username from session if present
        if user := self.request.session.get('user'):
            modell.username = user.get('username')

        # Copy common fields if provided by the form
        if 'realname' in data:
            modell.realname = data['realname']

        if 'email' in data:
            modell.email = data['email']

        # Set model.type for specific request types
        if self.type_code in LIBRARY_TYPES:
            modell.type = self.type_code

        # Literature-specific extra field
        if self.type_code == TYPE_LIT and 'selfbuy_give_data' in data:
            modell.selfbuy_give_data = data['selfbuy_give_data']

        modell.save()

        if hasattr(form, 'save_m2m'):
            form.save_m2m()

        return modell

    def send_mail(self, obj, data):
        # Prepare minimal mail context and send mails

        context = self.get_email_context(obj, data)
        applicant_subject = 'Deine Förderanfrage bei Wikimedia Deutschland'
        staff_subject = 'Anfrage {type_label} von {applicant_name}'.format(**context)

        try:
            self.send_email('applicant', 'ifg_volunteer_mail', applicant_subject, data['email'], context)
            self.send_email('staff', 'if_mail', staff_subject, settings.IF_EMAIL, context)
        except BadHeaderError:
            obj.delete()
            return HttpResponse('Invalid header found. Data not saved!')
        except SMTPException:
            obj.delete()
            return HttpResponse('Error in sending mails (probably wrong address?). Data not saved!')

    def get_email_context(self, obj, data):
        return {
            'data': data,
            'urls': self.get_urls(obj),
            'form_data': self.get_form_data(obj, data),
            'applicant_name': self.get_recipient_name(obj, data),
            'type_label': self.sanitize_label(self.type_info.label),
        }

    def get_urls(self, obj, **urls):
        urls['admin'] = self.get_absolute_url(admin_url_name(obj, 'change'), obj.id)

        if isinstance(obj, Project):
            urls['authorize'] = urls['deny'] = None
        else:
            urls['authorize'] = self.get_absolute_url('authorize', self.type_info.code, obj.id)
            urls['deny'] = self.get_absolute_url('deny', self.type_info.code, obj.id)

        return urls

    @staticmethod
    def get_absolute_url(view, *args):
        return urljoin(settings.EMAIL_URL_PREFIX, reverse(view, args=args))

    def get_form_data(self, obj, data):
        return {
            self.sanitize_label(field.label): self.format_value(field.field, field.initial)
            for field in self.type_info.form_class(initial=data)
        }

    @staticmethod
    def sanitize_label(label: str):
        label = strip_tags(label)
        words = str.split(label)

        return ' '.join(words)

    @staticmethod
    def format_value(field: Field, value):
        if isinstance(field, ProductCategoryFormField):
            value = get_text_list(value, 'und')
        elif isinstance(field, ChoiceField):
            choices = flatten_choices(field.choices)
            value = dict(choices).get(value, value)
        elif isinstance(value, bool):
            value = '✓' if value else '✗'
        elif isinstance(value, datetime.date):
            value = date_format(value)
        elif value in field.empty_values:
            value = '–'

        return value

    def send_email(self, kind, template_name, subject, recipient, context, *, fail_silently=False):
        email = build_email(template_name, context, subject, recipient)

        collect_and_attach(email, kind, self.type_code)

        return email.send(fail_silently)

    @staticmethod
    def get_recipient_name(obj, data):
        for field in 'username', 'realname', 'email':
            if name := getattr(obj, field, None) or data.get(field):
                return name

        return 'Unbekannt'