Restructure files.

Author: davidhamill1-nhs

gateway-api/src/fhir/__init__.py

@@ -1,15 +1,13 @@
 """FHIR data types and resources."""
 
-from .elements import Issue, IssueCode, IssueSeverity
-from .resources import (
-    Bundle,
-    Device,
-    Endpoint,
-    OperationOutcome,
-    Parameters,
-    Patient,
-    Resource,
-)
+from .elements.issue import Issue, IssueCode, IssueSeverity
+from .resources.bundle import Bundle
+from .resources.device import Device
+from .resources.endpoint import Endpoint
+from .resources.operation_outcome import OperationOutcome
+from .resources.parameters import Parameters
+from .resources.patient import Patient
+from .resources.resource import Resource
 
 __all__ = [
     "Bundle",

gateway-api/src/fhir/elements.py

@@ -0,0 +1,50 @@
+import uuid
+from abc import ABC
+from dataclasses import dataclass
+from typing import ClassVar
+
+from pydantic import model_validator
+
+
+@dataclass(frozen=True)
+class Identifier(ABC):
+    """
+    A FHIR R4 Identifier element. See https://hl7.org/fhir/R4/datatypes.html#Identifier.
+    Attributes:
+        system: The namespace for the identifier value.
+        value: The value that is unique within the system.
+    """
+
+    _expected_system: ClassVar[str] = "__unknown__"
+
+    value: str
+    system: str
+
+    @model_validator(mode="after")
+    def validate_system(self) -> "Identifier":
+        if self.system != self._expected_system:
+            raise ValueError(
+                f"Identifier system '{self.system}' does not match expected "
+                f"system '{self._expected_system}'."
+            )
+        return self
+
+    @classmethod
+    def __init_subclass__(cls, expected_system: str) -> None:
+        cls._expected_system = expected_system
+
+
+class UUIDIdentifier(Identifier, expected_system="https://tools.ietf.org/html/rfc4122"):
+    """A UUID identifier utilising the standard RFC 4122 system."""
+
+    def __init__(self, value: uuid.UUID | None = None):
+        super().__init__(
+            value=str(value or uuid.uuid4()),
+            system=self._expected_system,
+        )
+
+
+class NHSNumberValueIdentifier(
+    Identifier, expected_system="https://fhir.nhs.uk/Id/nhs-number"
+):
+    """A valueIdentifier NHS numbers - used in Parameter"""

gateway-api/src/fhir/elements/__init__.py

@@ -0,0 +1,26 @@
+from abc import ABC
+from dataclasses import dataclass
+from enum import StrEnum
+
+
+class IssueSeverity(StrEnum):
+    FATAL = "fatal"
+    ERROR = "error"
+    WARNING = "warning"
+    INFORMATION = "information"
+
+
+class IssueCode(StrEnum):
+    INVALID = "invalid"
+    EXCEPTION = "exception"
+
+
+@dataclass(frozen=True)
+class Issue(ABC):
+    """
+    A FHIR R4 OperationOutcome Issue element. See https://hl7.org/fhir/R4/datatypes.html#OperationOutcome.
+    """
+
+    severity: IssueSeverity
+    code: IssueCode
+    diagnostics: str | None = None

gateway-api/src/fhir/elements/identifier.py

@@ -0,0 +1,31 @@
+import datetime
+from dataclasses import dataclass
+from typing import Annotated
+
+from pydantic import Field
+
+
+@dataclass(frozen=True)
+class Meta:
+    """
+    A FHIR R4 Meta element. See https://hl7.org/fhir/R4/datatypes.html#Meta.
+    Attributes:
+        version_id: The version id of the resource.
+        last_updated: The last updated timestamp of the resource.
+    """
+
+    last_updated: Annotated[datetime.datetime | None, Field(alias="lastUpdated")] = None
+    version_id: Annotated[str | None, Field(alias="versionId")] = None
+
+    @classmethod
+    def with_last_updated(cls, last_updated: datetime.datetime | None = None) -> "Meta":
+        """
+        Create a Meta instance with the provided last_updated timestamp.
+        Args:
+            last_updated: The last updated timestamp.
+        Returns:
+            A Meta instance with the specified last_updated.
+        """
+        return cls(
+            last_updated=last_updated or datetime.datetime.now(tz=datetime.timezone.utc)
+        )

gateway-api/src/fhir/elements/issue.py

@@ -0,0 +1,15 @@
+from typing import Any
+
+from pydantic import BaseModel, Field
+
+
+# TODO: convert this to dataclass/ABC like the other elements?
+class Reference(BaseModel):
+    """A FHIR R4 Reference base class."""
+
+    reference_type: str = Field(alias="type", frozen=True)
+
+    def __init_subclass__(
+        cls, reference_type: str, **kwargs: Any
+    ) -> None:  # TODO: Why is this necessary?
+        super().__init_subclass__(**kwargs)

gateway-api/src/fhir/elements/meta.py

@@ -4,7 +4,8 @@
 import pytest
 from pydantic import BaseModel
 
-from .elements import Identifier, Meta, UUIDIdentifier
+from fhir.elements.identifier import Identifier, UUIDIdentifier
+from fhir.elements.meta import Meta
 
 
 class TestMeta: