Introduce Automatic Extension Priorities

Specify automatic dependencies as having low or high priority. Low priority auto dependencies are loaded first (before everything else). High priority auto dependencies are loaded last (after everything else).

Currently, the terminology and tools packages are low priority; the extensions package is high priority.

Author: cmoesel

src/utils/Processing.ts

@@ -34,10 +34,16 @@ const EXT_PKG_TO_FHIR_PKG_MAP: { [key: string]: string } = {
   'hl7.fhir.extensions.r5': 'hl7.fhir.r5.core#5.0.0'
 };
 
+export enum AutomaticDependencyPriority {
+  Low = 'Low', // load before configured dependencies / FHIR core (lowest resolution priority)
+  High = 'High' // load after configured dependencies / FHIR core (highest resolution priority)
+}
+
 type AutomaticDependency = {
   packageId: string;
   version: string;
   fhirVersions?: FHIRVersionName[];
+  priority: AutomaticDependencyPriority;
 };
 
 type FshFhirMapping = {
@@ -54,32 +60,38 @@ export const AUTOMATIC_DEPENDENCIES: AutomaticDependency[] = [
   {
     packageId: 'hl7.fhir.uv.tools.r4',
     version: 'latest',
-    fhirVersions: ['R4', 'R4B']
+    fhirVersions: ['R4', 'R4B'],
+    priority: AutomaticDependencyPriority.Low
   },
   {
     packageId: 'hl7.fhir.uv.tools.r5',
     version: 'latest',
-    fhirVersions: ['R5', 'R6']
+    fhirVersions: ['R5', 'R6'],
+    priority: AutomaticDependencyPriority.Low
   },
   {
     packageId: 'hl7.terminology.r4',
     version: 'latest',
-    fhirVersions: ['R4', 'R4B']
+    fhirVersions: ['R4', 'R4B'],
+    priority: AutomaticDependencyPriority.Low
   },
   {
     packageId: 'hl7.terminology.r5',
     version: 'latest',
-    fhirVersions: ['R5', 'R6']
+    fhirVersions: ['R5', 'R6'],
+    priority: AutomaticDependencyPriority.Low
   },
   {
     packageId: 'hl7.fhir.uv.extensions.r4',
     version: 'latest',
-    fhirVersions: ['R4', 'R4B']
+    fhirVersions: ['R4', 'R4B'],
+    priority: AutomaticDependencyPriority.High
   },
   {
     packageId: 'hl7.fhir.uv.extensions.r5',
     version: 'latest',
-    fhirVersions: ['R5', 'R6']
+    fhirVersions: ['R5', 'R6'],
+    priority: AutomaticDependencyPriority.High
   }
 ];
 
@@ -379,24 +391,42 @@ export async function loadExternalDependencies(
   }
   dependencies.push({ packageId: fhirVersionInfo.packageId, version: fhirVersionInfo.version });
 
-  // Load configured dependencies, with FHIR core last so it has higher priority in resolution
+  // First load automatic dependencies with the lowest priority (before configured dependencies and FHIR core)
+  await loadAutomaticDependencies(
+    fhirVersionInfo.version,
+    dependencies,
+    defs,
+    AutomaticDependencyPriority.Low
+  );
+
+  // Then load configured dependencies and FHIR core (FHIR core is last so it has higher priority in resolution)
   await loadConfiguredDependencies(dependencies, fhirVersionInfo.version, config.filePath, defs);
 
-  // Then load automatic dependencies since they have priority over the core dependencies
+  // Then load automatic dependencies with highest priority (taking precedence over even FHIR core)
   // See: https://chat.fhir.org/#narrow/channel/179239-tooling/topic/New.20Implicit.20Package/near/562477575
-  await loadAutomaticDependencies(fhirVersionInfo.version, dependencies, defs);
+  await loadAutomaticDependencies(
+    fhirVersionInfo.version,
+    dependencies,
+    defs,
+    AutomaticDependencyPriority.High
+  );
 }
 
 export async function loadAutomaticDependencies(
   fhirVersion: string,
   configuredDependencies: ImplementationGuideDependsOn[],
-  defs: FHIRDefinitions
+  defs: FHIRDefinitions,
+  priority: AutomaticDependencyPriority
 ): Promise<void> {
   const fhirVersionName = getFHIRVersionInfo(fhirVersion).name;
 
-  if (fhirVersionName === 'R4' || fhirVersionName === 'R4B') {
+  if (
+    priority === AutomaticDependencyPriority.Low &&
+    (fhirVersionName === 'R4' || fhirVersionName === 'R4B')
+  ) {
     // There are several R5 resources that are allowed for use in R4 and R4B.
-    // Add them first so they're always available.
+    // Add them first so they're always available (but are lower priority than
+    // any other version loaded from an official package).
     const R5forR4Map = new Map<string, any>();
     R5_DEFINITIONS_NEEDED_IN_R4.forEach(def => R5forR4Map.set(def.id, def));
     const virtualR5forR4Package = new InMemoryVirtualPackage(
@@ -411,20 +441,22 @@ export async function loadAutomaticDependencies(
     await defs.loadVirtualPackage(virtualR5forR4Package);
   }
 
-  // Gather all automatic dependencies, substituting matching configured dependencies where applicable
-  const automaticDependencies = AUTOMATIC_DEPENDENCIES.map(autoDep => {
-    const configuredDeps = configuredDependencies.filter(configuredDep =>
-      configuredDependencyMatchesAutomaticDependency(configuredDep, autoDep)
-    );
-    if (configuredDeps.length) {
-      // Prefer configured dependencies over automatic dependencies
-      return configuredDeps;
-    } else if (autoDep.fhirVersions && !autoDep.fhirVersions.includes(fhirVersionName)) {
-      // Skip automatic dependencies not intended for this version of FHIR
-      return [];
-    }
-    return autoDep;
-  }).flat();
+  // Gather all automatic dependencies matching this priority, substituting matching configured dependencies where applicable
+  const automaticDependencies = AUTOMATIC_DEPENDENCIES.filter(ad => ad.priority === priority)
+    .map(autoDep => {
+      const configuredDeps = configuredDependencies.filter(configuredDep =>
+        configuredDependencyMatchesAutomaticDependency(configuredDep, autoDep)
+      );
+      if (configuredDeps.length) {
+        // Prefer configured dependencies over automatic dependencies
+        return configuredDeps;
+      } else if (autoDep.fhirVersions && !autoDep.fhirVersions.includes(fhirVersionName)) {
+        // Skip automatic dependencies not intended for this version of FHIR
+        return [];
+      }
+      return autoDep;
+    })
+    .flat();
   // Load automatic dependencies serially so dependency loading order is predictable and repeatable
   for (const dep of automaticDependencies) {
     const isUserConfigured = !AUTOMATIC_DEPENDENCIES.some(