from rest_framework import serializers
from .models import Contact, Relation


class ContactSerializer(serializers.ModelSerializer):
    relations_count = serializers.SerializerMethodField()

    class Meta:
        model = Contact
        fields = [
            'id', 'name', 'email', 'phone',
            'organization', 'position', 'notes',
            'created_at', 'updated_at', 'relations_count',
        ]
        read_only_fields = ['id', 'created_at', 'updated_at', 'relations_count']

    def get_relations_count(self, obj):
        return (
            obj.relations_as_source.count() +
            obj.relations_as_target.count()
        )


class RelationSerializer(serializers.ModelSerializer):
    source_name = serializers.CharField(source='source.name', read_only=True)
    target_name = serializers.CharField(source='target.name', read_only=True)

    class Meta:
        model = Relation
        fields = [
            'id', 'source', 'source_name',
            'target', 'target_name',
            'relation_type', 'description', 'created_at',
        ]
        read_only_fields = ['id', 'created_at', 'source_name', 'target_name']

    def validate(self, data):
        if data.get('source') == data.get('target'):
            raise serializers.ValidationError(
                'Нельзя создать связь контакта с самим собой.'
            )
        return data


class GraphSerializer(serializers.Serializer):
    """Граф для vis.js: nodes + edges."""

    nodes = serializers.SerializerMethodField()
    edges = serializers.SerializerMethodField()

    def get_nodes(self, obj):
        contacts = Contact.objects.all()
        return [
            {
                'id': c.id,
                'label': c.name,
                'title': f'{c.organization}\n{c.position}'.strip() or c.name,
                'group': c.organization or 'default',
            }
            for c in contacts
        ]

    def get_edges(self, obj):
        relations = Relation.objects.select_related('source', 'target').all()
        return [
            {
                'id': r.id,
                'from': r.source_id,
                'to': r.target_id,
                'label': r.get_relation_type_display(),
                'title': r.description or r.get_relation_type_display(),
            }
            for r in relations
        ]