from django import forms
from .models import Comment, Ticket
from django.core.exceptions import ValidationError


class CommentForm(forms.ModelForm):
    class Meta:
        model = Comment
        fields = ["text"]
        widgets = {
            "text": forms.Textarea(
                attrs={"rows": 3, "placeholder": "Kommentar schreiben..."}
            ),
        }


class TicketForm(forms.ModelForm):
    # Zentrale Definition der Status-Übergänge
    STATUS_TRANSITIONS = {
        'tutor': {
            'new': ['in_progress'],
            'in_progress': ['resolved', 'new'],
            'resolved': ['closed'],
            'closed': [],
        },
        'creator': {
            'new': [],
            'in_progress': [],
            'resolved': ['closed', 'new'],
            'closed': [],
        }
    }

    # Zentrale Definition welche Felder wann required sind
    REQUIRED_FIELDS_BY_STATUS = {
        'resolved': ['answer'],  # Answer required when resolving
    }

    class Meta:
        model = Ticket
        fields = ["title", "description", "status", "mistake", "course", "answer", "material"]
        widgets = {
            'answer': forms.Textarea(attrs={
                'rows': 4,
                'placeholder': 'Beschreibe die Lösung des Problems...'
            })
        }

    def __init__(self, *args, **kwargs):
        self.user = kwargs.pop('user', None)
        self.ticket = kwargs.pop('ticket', None)
        super().__init__(*args, **kwargs)

        if self.ticket and self.user:
            self._configure_form_based_on_permissions()

    def _configure_form_based_on_permissions(self):
        """Konfiguriert das Formular basierend auf Benutzerrechten"""
        is_creator = self.user == self.ticket.created_by
        is_tutor = self.user == self.ticket.assigned_to
        is_superuser = self.user.is_superuser

        # Status-Choices einschränken
        self._limit_status_choices(is_tutor, is_creator)

        # Feld-Berechtigungen setzen
        self._set_field_permissions(is_tutor, is_creator, is_superuser)

    def _set_field_permissions(self, is_tutor, is_creator, is_superuser):
        """Setzt welche Felder bearbeitet werden dürfen"""
        if self.ticket.status == 'resolved' and is_creator and not is_superuser:
            for field_name in self.fields:
                if field_name == "answer":
                    self.fields[field_name].disabled = True
        elif is_tutor and not is_superuser:
            # Tutor darf ändern:
            readonly_fields = ['title', 'description', 'material']
            for field_name in readonly_fields:
                if field_name in self.fields:
                    self.fields[field_name].disabled = True
        elif is_creator and not is_superuser and self.ticket.status != 'resolved':
            for field_name in self.fields:
                self.fields[field_name].disabled = True

    def _limit_status_choices(self, is_tutor, is_creator):
        """Beschränkt verfügbare Status-Optionen basierend auf der zentralen Logik"""
        current_status = self.ticket.status

        if is_tutor:
            role = 'tutor'
        elif is_creator:
            role = 'creator'
        else:
            role = None

        if role:
            allowed_statuses = self._get_allowed_transitions(current_status, role)
        else:
            # Andere User sehen nur aktuellen Status
            allowed_statuses = [current_status]

        # Status-Choices filtern
        all_choices = list(self.fields['status'].choices)
        self.fields['status'].choices = [
            choice for choice in all_choices
            if choice[0] in allowed_statuses
        ]

    def _get_allowed_transitions(self, from_status, role):
        """Gibt erlaubte Status-Übergänge zurück (zentrale Logik)"""
        transitions = self.STATUS_TRANSITIONS.get(role, {}).get(from_status, [])
        return [from_status] + transitions

    def _is_transition_allowed(self, from_status, to_status, role):
        """Prüft ob ein Status-Übergang erlaubt ist"""
        if from_status == to_status:
            return True
        return to_status in self.STATUS_TRANSITIONS.get(role, {}).get(from_status, [])

    def _get_required_fields_for_status(self, status):
        """Gibt zurück, welche Felder für einen Status required sind"""
        return self.REQUIRED_FIELDS_BY_STATUS.get(status, [])

    def clean(self):
        cleaned_data = super().clean()
        status = cleaned_data.get('status')

        if not self.ticket or not status:
            return cleaned_data

        # Prüfe Status-Übergang
        old_status = self.ticket.status
        is_tutor = self.user == self.ticket.assigned_to
        is_creator = self.user == self.ticket.created_by

        if is_tutor:
            role = 'tutor'
        elif is_creator:
            role = 'creator'
        else:
            role = None

        if role and not self._is_transition_allowed(old_status, status, role):
            raise ValidationError({
                'status': f'Übergang von "{self.ticket.get_status_display()}" zu "{dict(self.fields["status"].choices)[status]}" ist nicht erlaubt.'
            })

        # Prüfe required fields für neuen Status
        required_fields = self._get_required_fields_for_status(status)
        for field_name in required_fields:
            if not cleaned_data.get(field_name):
                field_label = self.fields[field_name].label
                raise ValidationError({
                    field_name: f'{field_label} ist erforderlich, wenn der Status auf "{dict(self.fields["status"].choices)[status]}" gesetzt wird.'
                })

        return cleaned_data

    def save(self, commit=True):
        ticket = super().save(commit=False)

        # Automatische Tutor-Zuweisung
        if ticket.course and ticket.course.tutor:
            ticket.assigned_to = ticket.course.tutor

        # Setze answered_at wenn eine Antwort gegeben wird
        if ticket.answer and not ticket.answered_at:
            from django.utils import timezone
            ticket.answered_at = timezone.now()

        if commit:
            ticket.save()
        return ticket