diff --git a/‎packages/graphql/src/lib/type-utils.ts‎
Lines changed: 281 additions & 0 deletions b/‎packages/graphql/src/lib/type-utils.ts‎
Lines changed: 281 additions & 0 deletions
@@ -0,0 +1,281 @@
+import {
+  type ArrayModelType,
+  type Enum,
+  getDoc,
+  getTypeName,
+  type IndeterminateEntity,
+  isNeverType,
+  isTemplateInstance,
+  type Model,
+  type Program,
+  type RecordModelType,
+  type Scalar,
+  type Type,
+  type Union,
+  type Value,
+  walkPropertiesInherited,
+} from "@typespec/compiler";
+import {
+  type AliasStatementNode,
+  type IdentifierNode,
+  type ModelPropertyNode,
+  type ModelStatementNode,
+  type Node,
+  SyntaxKind,
+  type UnionStatementNode,
+} from "@typespec/compiler/ast";
+import { camelCase, constantCase, pascalCase, split, splitSeparateNumbers } from "change-case";
+
+/** Generate a GraphQL type name for a templated model (e.g., `ListOfString`). */
+export function getTemplatedModelName(model: Model): string {
+  const name = getTypeName(model, {});
+  const baseName = toTypeName(name.replace(/<[^>]*>/g, ""));
+  const templateString = getTemplateString(model);
+  return templateString ? `${baseName}Of${templateString}` : baseName;
+}
+
+function splitWithAcronyms(
+  split: (name: string) => string[],
+  skipStart: boolean,
+  name: string,
+): string[] {
+  const result = split(name);
+
+  if (name === name.toUpperCase()) {
+    return result;
+  }
+  // Preserve strings of capital letters, e.g. "API" should be treated as three words ["A", "P", "I"] instead of one word
+  return result.flatMap((part) => {
+    const result = !skipStart && part.match(/^[A-Z]+$/) ? part.split("") : part;
+    skipStart = false;
+    return result;
+  });
+}
+
+/** Convert a name to PascalCase for GraphQL type names. */
+export function toTypeName(name: string): string {
+  const sanitized = sanitizeNameForGraphQL(getNameWithoutNamespace(name));
+  // Preserve all-caps names (acronyms like API, HTTP, URL)
+  if (/^[A-Z]+$/.test(sanitized)) {
+    return sanitized;
+  }
+  return pascalCase(sanitized, {
+    split: splitWithAcronyms.bind(null, split, false),
+  });
+}
+
+/** Sanitize a name to be a valid GraphQL identifier. */
+export function sanitizeNameForGraphQL(name: string, prefix: string = ""): string {
+  name = name.replace("[]", "Array");
+  name = name.replaceAll(/\W/g, "_");
+  if (!name.match("^[_a-zA-Z]")) {
+    name = `${prefix}_${name}`;
+  }
+  return name;
+}
+
+/** Convert a name to CONSTANT_CASE for GraphQL enum members. */
+export function toEnumMemberName(enumName: string, name: string) {
+  return constantCase(sanitizeNameForGraphQL(name, enumName), {
+    split: splitSeparateNumbers,
+    prefixCharacters: "_",
+  });
+}
+
+/** Convert a name to camelCase for GraphQL field names. */
+export function toFieldName(name: string): string {
+  return camelCase(sanitizeNameForGraphQL(name), {
+    prefixCharacters: "_",
+    split: splitWithAcronyms.bind(null, split, true),
+  });
+}
+
+function getNameWithoutNamespace(name: string): string {
+  const parts = name.trim().split(".");
+  return parts[parts.length - 1];
+}
+
+/** Generate a GraphQL type name for a union, including anonymous unions. */
+export function getUnionName(union: Union, program: Program): string {
+  // SyntaxKind.UnionExpression: Foo | Bar
+  // SyntaxKind.UnionStatement: union FooBarUnion { Foo, Bar }
+  // SyntaxKind.TypeReference: FooBarUnion
+
+  const templateString = getTemplateString(union) ? "Of" + getTemplateString(union) : "";
+
+  switch (true) {
+    case !!union.name:
+      // The union is not anonymous, use its name
+      return union.name;
+
+    case isReturnType(union):
+      // The union is a return type, use the name of the operation
+      // e.g. op getBaz(): Foo | Bar => GetBazUnion
+      return `${getUnionNameForOperation(program, union)}${templateString}Union`;
+
+    case isModelProperty(union):
+      // The union is a model property, name it based on the model + property
+      // e.g. model Foo { bar: Bar | Baz } => FooBarUnion
+      const modelProperty = getModelProperty(union);
+      const propName = toTypeName(getNameForNode(modelProperty!));
+      const unionModel = union.node?.parent?.parent as ModelStatementNode;
+      const modelName = unionModel ? getNameForNode(unionModel) : "";
+      return `${modelName}${propName}${templateString}Union`;
+
+    case isAliased(union):
+      // The union is an alias, name it based on the alias name
+      // e.g. alias Baz = Foo<string> | Bar => Baz
+      const alias = getAlias(union);
+      const aliasName = getNameForNode(alias!);
+      return `${aliasName}${templateString}`;
+
+    default:
+      throw new Error("Unrecognized union construction.");
+  }
+}
+
+function isNamedType(type: Type | Value | IndeterminateEntity): type is { name: string } & Type {
+  return "name" in type && typeof (type as { name: unknown }).name === "string";
+}
+
+function isAliased(union: Union): boolean {
+  return union.node?.parent?.kind === SyntaxKind.AliasStatement;
+}
+
+function getAlias(union: Union): AliasStatementNode | undefined {
+  return isAliased(union) ? (union.node?.parent as AliasStatementNode) : undefined;
+}
+
+function isModelProperty(union: Union): boolean {
+  return union.node?.parent?.kind === SyntaxKind.ModelProperty;
+}
+
+function getModelProperty(union: Union): ModelPropertyNode | undefined {
+  return isModelProperty(union) ? (union.node?.parent as ModelPropertyNode) : undefined;
+}
+
+function isReturnType(type: Type): boolean {
+  return !!(
+    type.node &&
+    type.node.parent?.kind === SyntaxKind.OperationSignatureDeclaration &&
+    type.node.parent?.parent?.kind === SyntaxKind.OperationStatement
+  );
+}
+
+type NamedNode = Node & { id: IdentifierNode };
+
+function getNameForNode(node: NamedNode): string {
+  return "id" in node && node.id?.kind === SyntaxKind.Identifier ? node.id.sv : "";
+}
+
+function getUnionNameForOperation(program: Program, union: Union): string {
+  const operationNode = (union.node as UnionStatementNode).parent?.parent;
+  const operation = program.checker.getTypeForNode(operationNode!);
+
+  return toTypeName(getTypeName(operation));
+}
+
+/** Convert a namespaced name to a single name by replacing dots with underscores. */
+export function getSingleNameWithNamespace(name: string): string {
+  return name.trim().replace(/\./g, "_");
+}
+
+/**
+ * Check if a model is an array type.
+ */
+export function isArray(model: Model): model is ArrayModelType {
+  return Boolean(model.indexer && model.indexer.key.name === "integer");
+}
+
+/**
+ * Check if a model is a record/map type.
+ */
+export function isRecordType(type: Model): type is RecordModelType {
+  return Boolean(type.indexer && type.indexer.key.name === "string");
+}
+
+/** Check if a model is an array of scalars or enums. */
+export function isScalarOrEnumArray(type: Model): type is ArrayModelType {
+  return (
+    isArray(type) && (type.indexer?.value.kind === "Scalar" || type.indexer?.value.kind === "Enum")
+  );
+}
+
+/** Check if a model is an array of unions. */
+export function isUnionArray(type: Model): type is ArrayModelType {
+  return isArray(type) && type.indexer?.value.kind === "Union";
+}
+
+/** Extract the element type from an array model, or return the model itself. */
+export function unwrapModel(model: ArrayModelType): Model | Scalar | Enum | Union;
+export function unwrapModel(model: Exclude<Model, ArrayModelType>): Model;
+export function unwrapModel(model: Model): Model | Scalar | Enum | Union {
+  if (!isArray(model)) {
+    return model;
+  }
+
+  if (model.indexer?.value.kind) {
+    if (["Model", "Scalar", "Enum", "Union"].includes(model.indexer.value.kind)) {
+      return model.indexer.value as Model | Scalar | Enum | Union;
+    }
+    throw new Error(`Unexpected array type: ${model.indexer.value.kind}`);
+  }
+  return model;
+}
+
+/** Unwrap array types to get the inner element type. */
+export function unwrapType(type: Model): Model | Scalar | Enum | Union;
+export function unwrapType(type: Type): Type;
+export function unwrapType(type: Type): Type {
+  if (type.kind === "Model") {
+    return unwrapModel(type);
+  }
+  return type;
+}
+
+/** Get the GraphQL description for a type from its doc comments. */
+export function getGraphQLDoc(program: Program, type: Type): string | undefined {
+  // GraphQL uses CommonMark for descriptions
+  // https://spec.graphql.org/October2021/#sec-Descriptions
+  return getDoc(program, type);
+}
+
+/** Generate a string representation of template arguments (e.g., `StringAndInt`). */
+export function getTemplateString(
+  type: Type,
+  options: { conjunction: string } = { conjunction: "And" },
+): string {
+  if (isTemplateInstance(type)) {
+    const args = type.templateMapper.args.filter(isNamedType).map((arg) => getTypeName(arg));
+    return getTemplateStringInternal(args, options);
+  }
+  return "";
+}
+
+function getTemplateStringInternal(
+  args: string[],
+  options: { conjunction: string } = { conjunction: "And" },
+): string {
+  return args.length > 0 ? toTypeName(args.map(toTypeName).join(options.conjunction)) : "";
+}
+
+/** Check if a model should be emitted as a GraphQL object type (not an array, record, or never). */
+export function isTrueModel(model: Model): boolean {
+  /* eslint-disable no-fallthrough */
+  switch (true) {
+    // A scalar array is represented as a model with an indexer
+    // and a scalar type. We don't want to emit this as a model.
+    case isScalarOrEnumArray(model):
+    // A union array is represented as a model with an indexer
+    // and a union type. We don't want to emit this as a model.
+    case isUnionArray(model):
+    case isNeverType(model):
+    // If the model is purely a record, we don't want to emit it as a model.
+    // Instead, we will need to create a scalar
+    case isRecordType(model) && [...walkPropertiesInherited(model)].length === 0:
+      return false;
+    default:
+      return true;
+  }
+  /* eslint-enable no-fallthrough */
+}