from rest_framework import serializers
from apps.meetings.models import MeetingRequest, MeetingStatus
from apps.profiles.models import Institution, InstitutionMember
from apps.account.models import User


class InstitutionMeetingMinimalSerializer(serializers.ModelSerializer):
    class Meta:
        model = Institution
        fields = ['id', 'name', 'slug', 'type', 'avatar', 'city', 'country']


class MeetingUserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ['id', 'email', 'fullname', 'avatar']


class MeetingListSerializer(serializers.ModelSerializer):
    requester_institution = InstitutionMeetingMinimalSerializer(read_only=True)
    recipient_institution = InstitutionMeetingMinimalSerializer(read_only=True)
    created_by = MeetingUserSerializer(read_only=True)

    class Meta:
        model = MeetingRequest
        fields = [
            'id',
            'title',
            'requester_institution',
            'recipient_institution',
            'created_by',
            'status',
            'meeting_date',
            'meeting_time',
            'duration_minutes',
            'meeting_url',
            'rejection_reason',
            'created_at',
        ]


class MeetingDetailSerializer(serializers.ModelSerializer):
    requester_institution = InstitutionMeetingMinimalSerializer(read_only=True)
    recipient_institution = InstitutionMeetingMinimalSerializer(read_only=True)
    created_by = MeetingUserSerializer(read_only=True)

    class Meta:
        model = MeetingRequest
        fields = [
            'id',
            'title',
            'requester_institution',
            'recipient_institution',
            'created_by',
            'status',
            'meeting_date',
            'meeting_time',
            'duration_minutes',
            'meeting_url',
            'agenda',
            'admin_notes',
            'rejection_reason',
            'created_at',
            'updated_at',
        ]


class MeetingCreateSerializer(serializers.ModelSerializer):
    requester_institution_id = serializers.PrimaryKeyRelatedField(
        queryset=Institution.objects.all(),
        source='requester_institution',
        write_only=True
    )
    recipient_institution_id = serializers.PrimaryKeyRelatedField(
        queryset=Institution.objects.all(),
        source='recipient_institution',
        write_only=True
    )

    class Meta:
        model = MeetingRequest
        fields = [
            'id',
            'title',
            'requester_institution_id',
            'recipient_institution_id',
            'meeting_date',
            'meeting_time',
            'duration_minutes',
            'meeting_url',
            'agenda',
        ]

    def validate(self, attrs):
        requester = attrs.get('requester_institution')
        recipient = attrs.get('recipient_institution')
        if requester == recipient:
            raise serializers.ValidationError({"recipient_institution_id": "Requester and recipient institutions cannot be the same."})

        request = self.context.get('request')
        user = request.user if request else None

        if user and not (user.is_superuser or getattr(user, 'user_type', None) in ['super_admin', 'regional_admin']):
            is_member = InstitutionMember.objects.filter(
                institution=requester,
                user=user,
                role__in=['admin', 'editor']
            ).exists()
            if not is_member:
                raise serializers.ValidationError({"requester_institution_id": "You are not authorized to schedule meetings for this institution."})

        return attrs

    def create(self, validated_data):
        request = self.context.get('request')
        if request and request.user.is_authenticated:
            validated_data['created_by'] = request.user
        return super().create(validated_data)


class MeetingUpdateSerializer(serializers.ModelSerializer):
    rejection_reason = serializers.CharField(
        required=False,
        allow_blank=True,
        help_text="Required explanation when rejecting/declining a meeting request."
    )

    class Meta:
        model = MeetingRequest
        fields = [
            'status',
            'meeting_date',
            'meeting_time',
            'duration_minutes',
            'meeting_url',
            'agenda',
            'admin_notes',
            'rejection_reason',
        ]

    def validate(self, attrs):
        status_val = attrs.get('status')
        if status_val == MeetingStatus.DECLINED:
            reason = (attrs.get('rejection_reason') or attrs.get('admin_notes') or '').strip()
            if not reason:
                if self.instance and self.instance.rejection_reason:
                    reason = self.instance.rejection_reason
                else:
                    raise serializers.ValidationError({
                        "rejection_reason": "An explanation or reason is required when declining a meeting request."
                    })
            attrs['rejection_reason'] = reason
            if not attrs.get('admin_notes'):
                attrs['admin_notes'] = reason

        return attrs