feat: update organization sales/supplied average to display sales if less than 3 years of supplied

[emi-hi]

-if less than 3 years of records exist for supplied, passes sales instead (dont just show 0)
-new @Property to display whether its a sales or supplied average
-updates frontend to display whether its sales or supplied

[tim738745]

@emi-hi, I think there are some references to get_avg_ldv_sales() in the backend that need to be addressed as well (line 173 in models/model_year_report.py, as well as line 181 in viewsets/model_year_report.py).

Also, I was thinking we don't need to update the frontend avgLdvSales references; maybe, in the OrganizationSerializer (line 23 of serializers/organization.py), we could do:

class OrganizationSerializer(serializers.ModelSerializer):
  ...
  avg_ldv_sales = serializers.SerializerMethodField()
  supplied_or_sales = serializers.SerializerMethodField()
  ...
  def get_avg_ldv_sales(self, obj):
        avg_sales, _ =  obj.get_avg_ldv_sales()
        return avg_sales

  def get_supplied_or_sales(self, obj):
        _ , supplied_or_sales = obj.get_avg_ldv_sales()
        return supplied_or_sales
  ...
  class Meta:
        model = Organization
        fields = (... "avg_ldv_sales", "supplied_or_sales",...)

And on the frontend, in the VehicleSupplierDetailsPage, just have what you had before:
<h4 className="d-inline">3 Year Average Vehicles {details.suppliedOrSales}: </h4>

Edit: Better yet, in order to avoid unnecessarily calling get_avg_ldv_sales() a second time for each use of the serializer, we can override the to_representation method of the serializer (https://www.django-rest-framework.org/api-guide/serializers/#overriding-serialization-and-deserialization-behavior).

So we can do:

class OrganizationSerializer(serializers.ModelSerializer):
    """
    Serializer for the Supplier
    Loads most of the fields and the balance for the Supplier
    """
    organization_address = serializers.SerializerMethodField()
    ldv_sales = OrganizationLDVSalesSerializer(many=True)
    first_model_year = serializers.SerializerMethodField()

    def get_organization_address(self, obj):
        """
        Loads the latest valid address for the organization
        """
        if obj.organization_address is None:
            return None

        serializer = OrganizationAddressSerializer(
            obj.organization_address, read_only=True, many=True
        )

        return serializer.data
    
    def get_first_model_year(self, obj):
        if obj.first_model_year is not None:
            return obj.first_model_year.name
        return None
    
    def to_representation(self, instance):
        ret = super().to_representation(instance)
        x, y = instance.get_avg_ldv_sales()
        ret["avg_ldv_sales"] = x
        ret["supplied_or_sales"] = y
        return ret

    class Meta:
        model = Organization
        fields = (
            'id', 'name', 'create_timestamp', 'organization_address',
            'balance', 'is_active', 'short_name', 'is_government',
            'supplier_class', 'ldv_sales',
            'has_submitted_report', 'first_model_year', 'has_report',
        )

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

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0.0% Coverage on New Code
0.0% Duplication on New Code

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