Add utility to remove unused modules (#793)

Author: trivikr

.changeset/shiny-dogs-confess.md

@@ -0,0 +1,5 @@
+---
+"aws-sdk-js-codemod": patch
+---
+
+Add utility to remove unused modules

src/transforms/v2-to-v3/__fixtures__/misc/import-over-require.input.ts

@@ -1,3 +1,4 @@
 export * from "./addNamedModule";
 export * from "./getImportSpecifiers";
 export * from "./getImportEqualsDeclarations";
+export * from "./removeImportEquals";

src/transforms/v2-to-v3/__fixtures__/misc/import-over-require.output.ts

@@ -0,0 +1,18 @@
+import { Collection, JSCodeshift } from "jscodeshift";
+import { removeDeclaration } from "../removeDeclaration";
+import { getImportEqualsDeclarations } from "./getImportEqualsDeclarations";
+
+const isAnotherSpecifier = (j: JSCodeshift, source: Collection<unknown>, localName: string) =>
+  source.find(j.TSImportEqualsDeclaration, { id: { name: localName } }).size() > 1;
+
+export const removeImportEquals = (j: JSCodeshift, source: Collection<unknown>) =>
+  getImportEqualsDeclarations(j, source).forEach((importEqualsDeclaration) => {
+    const localName = importEqualsDeclaration.value.id.name;
+    const identifiers = source.find(j.Identifier, { name: localName });
+
+    // Either the identifier is the only occurence on the page.
+    // Or there is another specifier with the same name imported from JS SDK v3.
+    if (identifiers.size() === 1 || isAnotherSpecifier(j, source, localName)) {
+      removeDeclaration(j, source, importEqualsDeclaration.get());
+    }
+  });

src/transforms/v2-to-v3/modules/getRequireDeclaratorsWithIdentifier.ts

@@ -1,3 +1,4 @@
 export * from "./addNamedModule";
 export * from "./getImportSpecifiers";
 export * from "./getImportDeclarations";
+export * from "./removeImport";

src/transforms/v2-to-v3/modules/importEqualsModule/index.ts

@@ -0,0 +1,42 @@
+import { Collection, JSCodeshift } from "jscodeshift";
+import { removeDeclaration } from "../removeDeclaration";
+import { getImportDeclarations } from "./getImportDeclarations";
+
+const isAnotherSpecifier = (j: JSCodeshift, source: Collection<unknown>, localName: string) =>
+  source
+    .find(j.ImportDeclaration, { specifiers: [{ local: { name: localName } }] })
+    .filter((importDeclaration) => {
+      const sourceValue = importDeclaration.value.source.value;
+      if (typeof sourceValue !== "string") {
+        return false;
+      }
+      return sourceValue.startsWith("@aws-sdk/");
+    })
+    .size() > 0;
+
+export const removeImport = (j: JSCodeshift, source: Collection<unknown>) =>
+  getImportDeclarations(j, source).forEach((importDeclaration) => {
+    importDeclaration.value.specifiers = (importDeclaration.value.specifiers || []).filter(
+      (specifier) => {
+        const localName = specifier.local?.name;
+        if (!localName) {
+          return true;
+        }
+        const identifiers = source.find(j.Identifier, { name: localName });
+        const importedName = specifier.type === "ImportSpecifier" && specifier.imported?.name;
+
+        // For default or namespace import, there's only one occurrence of local identifier.
+        // For named import, there can be two occurrences: one imported identifier and one local identifier.
+        const identifierNum = importedName && importedName === localName ? 2 : 1;
+
+        // Either the identifiers are the only occurences on the page.
+        // Or there's another specifier with the same name imported from JS SDK v3.
+        return !(identifiers.size() === identifierNum || isAnotherSpecifier(j, source, localName));
+      }
+    );
+
+    // Remove ImportDeclaration if there are no import specifiers.
+    if (importDeclaration.value.specifiers.length === 0) {
+      removeDeclaration(j, source, importDeclaration);
+    }
+  });

src/transforms/v2-to-v3/modules/importEqualsModule/removeImportEquals.ts

@@ -3,6 +3,5 @@ export * from "./addNamedModule";
 export * from "./getGlobalNameFromModule";
 export * from "./getImportType";
 export * from "./getRequireDeclaratorsWithProperty";
-export * from "./removeClientModule";
-export * from "./removeGlobalModule";
+export * from "./removeModules";
 export * from "./types";

src/transforms/v2-to-v3/modules/importModule/index.ts

@@ -0,0 +1,26 @@
+import { Collection, JSCodeshift } from "jscodeshift";
+import { removeImportEquals } from "./importEqualsModule";
+import { removeImport } from "./importModule";
+import { removeRequire } from "./requireModule";
+import { ImportType } from "./types";
+
+export const removeModules = (
+  j: JSCodeshift,
+  source: Collection<unknown>,
+  importType: ImportType
+) => {
+  switch (importType) {
+    case ImportType.REQUIRE: {
+      removeRequire(j, source);
+      break;
+    }
+    case ImportType.IMPORT_EQUALS: {
+      removeImportEquals(j, source);
+      break;
+    }
+    case ImportType.IMPORT: {
+      removeImport(j, source);
+      break;
+    }
+  }
+};