convert the implementation of the action to Dart

.gitattributes

@@ -0,0 +1 @@
+dist/** -diff linguist-generated=true

.github/dependabot.yaml

@@ -2,7 +2,12 @@
 version: 2
 
 updates:
-  - package-ecosystem: "github-actions"
-    directory: "/"
+  - package-ecosystem: github-actions
+    directory: /
     schedule:
-      interval: "weekly"
+      interval: monthly
+
+  - package-ecosystem: npm
+    directory: /
+    schedule:
+      interval: monthly

.github/workflows/build.yml

@@ -0,0 +1,18 @@
+# Validate that the compiled artifacts are up-to-date.
+
+name: Build
+
+on:
+  pull_request:
+    branches: [main]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ./
+        with:
+          sdk: beta
+      - run: dart pub get
+      - run: dart tool/sig.dart --verify

.github/workflows/dart.yml

@@ -1,3 +1,5 @@
+# Tests for general `setup-dart` configurations.
+
 name: Dart
 
 on:
@@ -6,7 +8,7 @@ on:
   pull_request:
     branches: [main]
   schedule:
-  - cron: "0 0 * * 0" # Run every Sunday at 00:00.
+    - cron: "0 0 * * 0" # Run every Sunday at 00:00.
 
 jobs:
 

.gitignore

@@ -1,3 +1,13 @@
-example/.packages
-example/pubspec.lock
-example/.dart_tool/
+# Dart files
+.dart_tool/
+pubspec.lock
+
+# node modules
+node_modules/
+
+# intermediary compilation artifacts
+lib/main.js
+lib/main.js.deps
+lib/main.js.map
+
+lib/sig.txt

CHANGELOG.md

@@ -1,3 +1,10 @@
+## v1.5.0-dev
+
+* Re-wrote the implementation of the action into Dart.
+* Auto-detect the platform architecture (`x64`, `ia32`, `arm`, `arm64`).
+* Improved the caching and download resilience of the sdk.
+* Added a new action output: `dart-version` - the installed version of the sdk.
+
 ## v1.4.0
 
 * Automatically create OIDC token for pub.dev.

CONTRIBUTING.md

@@ -1,8 +1,7 @@
-## How to Contribute
+# How to Contribute
 
-Prior to sending patches and contributions to this project, please file
-an issue in the issue tracker to ensure there is alignment with the overall
-goals of this project. Thanks!
+We'd love to accept your patches and contributions to this project. There are
+just a few small guidelines you need to follow.
 
 ## Contributor License Agreement
 
@@ -17,3 +16,46 @@ You generally only need to submit a CLA once, so if you've already submitted one
 (even if it was for a different project), you probably don't need to do it
 again.
 
+## Start with an issue
+
+Prior to sending patches and contributions to this project, please file an issue
+in the issue tracker to ensure there is alignment with the overall goals of this
+project. Thanks!
+
+## Code Reviews
+
+All submissions, including submissions by project members, require review. We
+use GitHub pull requests for this purpose. Consult
+[GitHub Help](https://help.github.com/articles/about-pull-requests/) for more
+information on using pull requests.
+
+## Coding style
+
+The Dart source code in this repo follows the:
+
+  * [Dart style guide](https://dart.dev/guides/language/effective-dart/style)
+
+You should familiarize yourself with those guidelines.
+
+## File headers
+
+All files in the Dart project must start with the following header; if you add a
+new file please also add this. The year should be a single number stating the
+year the file was created (don't use a range like "2011-2012"). Additionally, if
+you edit an existing file, you shouldn't update the year.
+
+    // Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+    // for details. All rights reserved. Use of this source code is governed by a
+    // BSD-style license that can be found in the LICENSE file.
+
+## Building and testing
+
+See the [DEVELOPING.md](DEVELOPING.md) file.
+
+## Community Guidelines
+
+This project follows
+[Google's Open Source Community Guidelines](https://opensource.google/conduct/).
+
+We pledge to maintain an open and welcoming environment. For details, see our
+[code of conduct](https://dart.dev/code-of-conduct).

DEVELOPING.md

@@ -0,0 +1,34 @@
+## Setting up
+
+1. Install node
+1. Install additional node tooling (`npm i -g @vercel/ncc`)
+1. Install the node package dependencies (`npm install`)
+
+## Development
+
+tldr: edit Dart source files; run `npm run all` to re-compile the action
+
+### Working on the action
+
+Generally, to work on the action, edit the Dart source code in `lib/` and
+re-compile the JavaScript code via `npm run all`. This will:
+
+- compile the Dart source (via dart2js) to `lib/main.js`; copy that file to
+  `dist/main.cjs`
+- package and minify the `lib/main.mjs` entrypoint point and referencd node
+  modules to `dist/index.mjs`
+
+### Files
+
+`lib/main.dart` - the Dart entry-point to the action.
+
+`lib/main.mjs` - the JavaScript wrapper; this sets up some important JS interop
+globals and bootstraps into `lib/main.dart`. 
+
+`dist/index.mjs` - the execution entry-point of the action.
+
+## Releasing
+
+See our
+[publishing](https://github.com/dart-lang/setup-dart/wiki/Publishing-procedure)
+wiki page.

README.md

@@ -36,8 +36,9 @@ The action takes the following inputs:
     * The available build flavors are `release` and `raw`.
     * The `release` flavor contains published builds.
     * The `raw` flavor contains unpublished builds; these can be used by
-      developers to test against SDK versions before a release. Note that the 
-      `main` release channel only supports `raw` build flavor.
+      developers to test against SDK versions before a signed release is
+      available. Note that the  `main` release channel only supports the `raw`
+      build flavor.
 
   * `architecture`: The CPU architecture to setup support for.
     * Valid options are `x64`, `ia32`, `arm`, and `arm64`.
@@ -46,7 +47,13 @@ The action takes the following inputs:
       [Dart system requirements](https://dart.dev/get-dart#system-requirements)
       for valid combinations.
 
-## Check static analysis, formatting, and run tests
+## Outputs
+
+The action produces the following output:
+
+  * `dart-version`: The version of the Dart SDK that was installed.
+
+## Checking static analysis, formatting, and running tests
 
 Various static checks:
 
@@ -171,4 +178,4 @@ Contributions are welcome! Please see [CONTRIBUTING.md.md](CONTRIBUTING.md.md).
 
 ## Version history
 
-Please see out [CHANGELOG.md](CHANGELOG.md) file.
+Please see our [CHANGELOG.md](CHANGELOG.md) file.

action.yml

@@ -1,26 +1,26 @@
 name: "Setup Dart SDK"
-description: "Setup the Dart SDK, and add it to the PATH"
+description: "Download and setup the Dart SDK."
 branding:
   icon: check-circle
   color: blue
 inputs:
   sdk:
     description: >-
       The channel, or a specific version from a channel to install ('stable',
-      'beta', 'dev', '2.7.2', '2.12.0-1.4.beta'). Using one of the three
+      'beta', 'dev', '2.7.2', '2.12.0-1.4.beta'). Using one of the named
       channels instead of a version will give you the latest version published
       to that channel.
     required: false
     default: "stable"
   architecture:
     description: "The CPU architecture ('x64', 'ia32', 'arm', or 'arm64')."
     required: false
-    default: "x64"
   flavor:
-    description: "The build flavor ('raw' or 'release')."
+    description: "The build flavor ('release' or 'raw')."
     required: false
+outputs:
+  dart-version:
+    description: 'The installed Dart version.'
 runs:
-  using: "composite"
-  steps:
-    - run: $GITHUB_ACTION_PATH/setup.sh ${{ inputs.sdk }} ${{ runner.os }} ${{ inputs.architecture }} ${{ inputs.flavor }}
-      shell: bash
+  using: "node16"
+  main: "dist/index.mjs"

analysis_options.yaml

@@ -0,0 +1,5 @@
+include: package:lints/recommended.yaml
+
+linter:
+  rules:
+    - unawaited_futures