feat!: adds Node.js subpath exports (#75)

* feat: get a list of solutions

* feat: generate main barrel

* feat: adds exports

* chore: projen synth

* feat: add root export

* chore: projen synth

* refactor: use libdir

* refactor: into a component

* docs: use cases

* refactor: solutions prop

* refactor: generateBarrel

* refactor: generateSubPathExports

* docs: Construct Bootstrap

* refactor: rename for clarity

* refactor: rename for clarity

Author: moltar

.gitattributes

@@ -1,5 +1,6 @@
 import { ReleasableCommits, awscdk, github, javascript, release } from 'projen';
 import { ArrowParens, NodePackageManager } from 'projen/lib/javascript';
+import { SubPathExports } from './projenrc/sub-path-exports';
 
 let cdkVersion = '2.168.0';
 const project = new awscdk.AwsCdkConstructLibrary({
@@ -106,4 +107,6 @@ project.addTask('integ:update', {
   receiveArgs: true,
 });
 
+new SubPathExports(project);
+
 project.synth();

.gitignore

@@ -109,6 +109,19 @@ export class MyConstruct extends Resource {
   * Other import methods normally require access to the context API which is beyond the scope of these constructs. We'd like to address this in the future.
 * Constructs should implement an interface so that the import methods (e.g. `.fromSomethingAttributes()`) can return the interface type.
 
+## Construct Bootstrap
+
+To init a new construct, follow these steps:
+
+1. Create a new construct directory in `./src/${YOUR_CONSTRUCT_NAME}`
+2. Create an empty barrel file `./src/${YOUR_CONSTRUCT_NAME}/index.ts`
+3. Run `npm run default`
+
+This will produce the following changes:
+
+1. Updates to the root barrel file to export the construct.
+2. Update to the `package.json` to create Node.js subpath exports to allow subpath imports (`import * as cur from "@open-constructs/aws-cdk/aws-cur"`).
+
 ## Testing
 
 Tests are fundamental to building good constructs. The following testing guidelines should be followed:

.prettierignore

@@ -0,0 +1,56 @@
+import { readdirSync } from 'fs';
+import path from 'path';
+import { Component, SourceCode } from 'projen';
+import type { TypeScriptProject } from 'projen/lib/typescript';
+
+/**
+ * Dynamically generate Node.js subpath exports and root barrel file.
+ *
+ * @see https://nodejs.org/api/packages.html#subpath-patterns
+ */
+export class SubPathExports extends Component {
+  private readonly solutions: string[];
+
+  constructor(public readonly project: TypeScriptProject) {
+    super(project);
+
+    /**
+     * Gather all solution directories (e.g. `aws-codeartifact`, `aws-cur`).
+     */
+    this.solutions = readdirSync(path.join(project.outdir, project.srcdir), {
+      encoding: 'utf8',
+      withFileTypes: true,
+    })
+      .filter(entry => entry.isDirectory())
+      .map(entry => entry.name)
+      .sort((a, b) => a.localeCompare(b));
+
+    this.generateBarrel();
+    this.generateSubPathExports();
+  }
+
+  private generateBarrel() {
+    const sourceCode = new SourceCode(this.project, path.join(this.project.srcdir, 'index.ts'));
+
+    sourceCode.line('// ' + sourceCode.marker);
+
+    for (const solution of this.solutions) {
+      const exportedName = solution.split('-').join('_');
+      sourceCode.line(`export * as ${exportedName} from './${solution}';`);
+    }
+  }
+
+  private generateSubPathExports() {
+    const subPathExport = (...chunks: string[]) => './' + path.posix.join(this.project.libdir, ...chunks);
+
+    const subPathExports: Record<string, string> = {
+      '.': subPathExport('index.js'),
+    };
+
+    for (const solution of this.solutions) {
+      subPathExports[`./${solution}`] = subPathExport(solution, 'index.js');
+    }
+
+    this.project.package.addField('exports', subPathExports);
+  }
+}