From 9aeeae54b0af3942a4ba24eeb4cb8ab60e513cfc Mon Sep 17 00:00:00 2001
From: Gabriela Britto <t-gaara@microsoft.com>
Date: Tue, 15 Jan 2019 16:56:53 -0800
Subject: [PATCH] create refactoring for converting to named parameters

---
 .../refactors/convertToNamedParameters.ts     | 94 +++++++++++++++++++
 src/services/tsconfig.json                    |  1 +
 2 files changed, 95 insertions(+)
 create mode 100644 src/services/refactors/convertToNamedParameters.ts

diff --git a/src/services/refactors/convertToNamedParameters.ts b/src/services/refactors/convertToNamedParameters.ts
new file mode 100644
index 00000000000..dd4e4326737
--- /dev/null
+++ b/src/services/refactors/convertToNamedParameters.ts
@@ -0,0 +1,94 @@
+/* @internal */
+namespace ts.refactor.convertToNamedParameters {
+    const refactorName = "Convert to named parameters";
+    const refactorDescription = "Convert to named parameters";
+    const actionNameNamedParameters = "Convert to named parameters";
+    const actionDescriptionNamedParameters = "Convert to named parameters";
+    const minimumParameterLength = 3;
+    const paramTypeNamePostfix = "Param";
+    registerRefactor(refactorName, { getEditsForAction, getAvailableActions });
+
+
+    function getAvailableActions(context: RefactorContext): ReadonlyArray<ApplicableRefactorInfo> {
+        const { file, startPosition } = context;
+        const func = getFunctionDeclarationAtPosition(file, startPosition);
+        if (!func) return emptyArray;
+
+        return [{
+            name: refactorName,
+            description: refactorDescription,
+            actions: [{
+                name: actionNameNamedParameters,
+                description: actionDescriptionNamedParameters
+            }]
+        }];
+    }
+
+    function getEditsForAction(context: RefactorContext, actionName: string): RefactorEditInfo | undefined {
+        Debug.assert(actionName === actionNameNamedParameters);
+        const { file, startPosition } = context;
+        const func = getFunctionDeclarationAtPosition(file, startPosition);
+        if (!func) return undefined;
+
+        const paramTypeDeclaration = createParamTypeDeclaration(func);
+        return undefined;
+    }
+
+    function getFunctionDeclarationAtPosition(file: SourceFile, startPosition: number): ValidFunctionDeclaration | undefined {
+        const node = getTokenAtPosition(file, startPosition);
+        const func = getContainingFunction(node);
+        if (!func || !isValidFunctionDeclaration(func)) return undefined;
+        return func;
+    }
+
+    function isValidFunctionDeclaration(func: SignatureDeclaration): func is ValidFunctionDeclaration {
+        switch (func.kind) {
+            case SyntaxKind.FunctionDeclaration:
+            case SyntaxKind.MethodDeclaration:
+                if (func.name && func.parameters && func.parameters.length > minimumParameterLength) {
+                    return true;
+                }
+                break;
+            default:
+        }
+        return false;
+    }
+
+    function createParamTypeDeclaration(func: ValidFunctionDeclaration): InterfaceDeclaration {
+        const paramTypeName = getFunctionName(func);
+        const paramTypeMembers =
+            ts.map(func.parameters,
+                (paramDecl, _i) => createPropertySignatureFromParameterDeclaration(paramDecl));
+        return createInterfaceDeclaration(
+            /* decorators */ undefined,
+            /* modifiers */ undefined,
+            createIdentifier(paramTypeName),
+            /* type parameters */ undefined,
+            /* heritage clauses */ undefined,
+            createNodeArray(paramTypeMembers));
+    }
+
+    function getFunctionName(func: ValidFunctionDeclaration): string {
+        return entityNameToString(func.name) + paramTypeNamePostfix;
+    }
+
+    function createPropertySignatureFromParameterDeclaration(paramDeclaration: ValidParameterDeclaration): PropertySignature {
+        return createPropertySignature(
+            /*modifiers*/ undefined,
+            paramDeclaration.name,
+            paramDeclaration.questionToken,
+            paramDeclaration.type,
+            paramDeclaration.initializer);
+    }
+
+    interface ValidFunctionDeclaration extends FunctionDeclaration {
+        name: Identifier;
+        body?: FunctionBody;
+        typeParameters?: NodeArray<TypeParameterDeclaration>;
+        parameters: NodeArray<ValidParameterDeclaration>;
+    }
+
+    interface ValidParameterDeclaration extends ParameterDeclaration {
+        name: Identifier;
+    }
+}
\ No newline at end of file
diff --git a/src/services/tsconfig.json b/src/services/tsconfig.json
index 21be663055a..793089e62c8 100644
--- a/src/services/tsconfig.json
+++ b/src/services/tsconfig.json
@@ -84,6 +84,7 @@
         "refactors/generateGetAccessorAndSetAccessor.ts",
         "refactors/moveToNewFile.ts",
         "refactors/addOrRemoveBracesToArrowFunction.ts",
+        "refactors/convertToNamedParameters.ts",
         "services.ts",
         "breakpoints.ts",
         "transform.ts",