from rest_framework import serializers

from users.permissions import is_admin

from .models import Event, EventProfile


class EventSerializer(serializers.ModelSerializer):
    class Meta:
        model = Event
        fields = [
            'id', 'created_by', 'start_date', 'end_date',
            'start_time', 'end_time', 'color', 'name',
            'is_public', 'created_at', 'updated_at',
        ]
        read_only_fields = ['id', 'created_by', 'created_at', 'updated_at']


class EventCreateSerializer(serializers.ModelSerializer):
    color = serializers.RegexField(
        r'^#[0-9a-fA-F]{6}$', required=False,
        allow_null=True, allow_blank=True,
    )

    class Meta:
        model = Event
        fields = [
            'start_date', 'end_date', 'start_time', 'end_time',
            'color', 'name', 'is_public',
        ]

    def validate(self, attrs):
        request = self.context.get('request')
        if request is None or not is_admin(request.user):
            # En création comme en PATCH, les événements non-admin restent privés.
            attrs['is_public'] = False

        values = {
            field: attrs.get(field, getattr(self.instance, field, None))
            for field in ('start_date', 'end_date', 'start_time', 'end_time')
        }
        if values['start_date'] is None or values['end_date'] is None:
            raise serializers.ValidationError('Les dates de début et de fin sont requises.')
        if values['end_date'] < values['start_date']:
            raise serializers.ValidationError({'end_date': 'La fin doit suivre le début.'})
        if (
            values['start_date'] == values['end_date']
            and values['start_time'] is not None
            and values['end_time'] is not None
            and values['end_time'] <= values['start_time']
        ):
            raise serializers.ValidationError({'end_time': 'La fin doit suivre le début.'})
        return attrs


class EventUpdateSerializer(EventCreateSerializer):
    pass


class EventProfileSerializer(serializers.ModelSerializer):
    color = serializers.RegexField(
        r'^#[0-9a-fA-F]{6}$', required=False,
        allow_null=True, allow_blank=True,
    )

    class Meta:
        model = EventProfile
        fields = [
            'id', 'created_by', 'name',
            'start_time', 'end_time', 'color', 'is_public',
            'created_at', 'updated_at',
        ]
        read_only_fields = ['id', 'created_by', 'created_at', 'updated_at']

    def validate(self, attrs):
        request = self.context.get('request')
        if request is None or not is_admin(request.user):
            # Un utilisateur non-admin ne peut pas mémoriser un profil public.
            attrs['is_public'] = False
        # Les dates ne font volontairement pas partie d'un profil. On ne peut donc
        # pas conclure qu'une heure de fin plus petite correspond à une erreur :
        # le profil peut être utilisé pour un événement qui se termine le lendemain.
        return attrs