feat: support windows and projects with no mill

.github/workflows/ci.yml

@@ -32,11 +32,12 @@ jobs:
         ./mill -i __.fix --check
 
   test:
-    runs-on: 'ubuntu-latest'
+    runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
       matrix:
         java: ['8', '17']
+        os: ['ubuntu-latest', 'windows-latest']
 
     steps:
     - uses: actions/checkout@v3
@@ -46,13 +47,24 @@ jobs:
         distribution: 'temurin'
         java-version: ${{ matrix.java }}
 
-    - name: Compile
+    - name: Compile Ubuntu
       run:
         ./mill -i __.compile
+      if: matrix.os == 'ubuntu-latest'
 
-    - name: Test
+    - name: Compile Windows
+      run: ./millw.bat -i __.compile
+      if: matrix.os == 'windows-latest'
+
+    - name: Test Ubuntu
       run:
         ./mill -i --debug itest
+      if: matrix.os == 'ubuntu-latest'
+
+    - name: Test Windows
+      run:
+        ./millw.bat -i --debug itest
+      if: matrix.os == 'windows-latest'
 
   publish-sonatype:
     if: github.repository == 'ckipp01/mill-giter8' && contains(github.ref, 'refs/tags/')

build.sc

@@ -68,13 +68,18 @@ object itest extends MillIntegrationTestModule {
 
   override def pluginsUnderTest = Seq(plugin)
 
+  override def perTestResources = T.sources { millSourcePath / "shared" }
+
   def testBase = millSourcePath / "src"
 
   override def testInvocations: T[Seq[(PathRef, Seq[TestInvocation.Targets])]] =
     T {
       Seq(
         PathRef(testBase / "minimal") -> Seq(
           TestInvocation.Targets(Seq("g8.validate"), noServer = true)
+        ),
+        PathRef(testBase / "no-mill") -> Seq(
+          TestInvocation.Targets(Seq("g8.validate"), noServer = true)
         )
       )
     }

millw.bat

@@ -0,0 +1,115 @@
+@echo off
+
+rem This is a wrapper script, that automatically download mill from GitHub release pages
+rem You can give the required mill version with --mill-version parameter
+rem If no version is given, it falls back to the value of DEFAULT_MILL_VERSION
+rem
+rem Project page: https://github.com/lefou/millw
+rem Script Version: 0.4.2
+rem
+rem If you want to improve this script, please also contribute your changes back!
+rem
+rem Licensed under the Apache License, Version 2.0
+
+rem setlocal seems to be unavailable on Windows 95/98/ME
+rem but I don't think we need to support them in 2019
+setlocal enabledelayedexpansion
+
+set "DEFAULT_MILL_VERSION=0.10.0"
+
+set "MILL_REPO_URL=https://github.com/com-lihaoyi/mill"
+
+rem %~1% removes surrounding quotes
+if [%~1%]==[--mill-version] (
+    rem shift command doesn't work within parentheses
+    if not [%~2%]==[] (
+        set MILL_VERSION=%~2%
+        set "STRIP_VERSION_PARAMS=true"
+    ) else (
+        echo You specified --mill-version without a version. 1>&2
+        echo Please provide a version that matches one provided on 1>&2
+        echo %MILL_REPO_URL%/releases 1>&2
+        exit /b 1
+    )
+)
+
+if [!MILL_VERSION!]==[] (
+  if exist .mill-version (
+      set /p MILL_VERSION=<.mill-version
+  )
+)
+
+if [!MILL_VERSION!]==[] (
+    set MILL_VERSION=%DEFAULT_MILL_VERSION%
+)
+
+set MILL_DOWNLOAD_PATH=%USERPROFILE%\.mill\download
+
+rem without bat file extension, cmd doesn't seem to be able to run it
+set MILL=%MILL_DOWNLOAD_PATH%\!MILL_VERSION!.bat
+
+if not exist "%MILL%" (
+    set VERSION_PREFIX=%MILL_VERSION:~0,4%
+    set DOWNLOAD_SUFFIX=-assembly
+    if [!VERSION_PREFIX!]==[0.0.] set DOWNLOAD_SUFFIX=
+    if [!VERSION_PREFIX!]==[0.1.] set DOWNLOAD_SUFFIX=
+    if [!VERSION_PREFIX!]==[0.2.] set DOWNLOAD_SUFFIX=
+    if [!VERSION_PREFIX!]==[0.3.] set DOWNLOAD_SUFFIX=
+    if [!VERSION_PREFIX!]==[0.4.] set DOWNLOAD_SUFFIX=
+    set VERSION_PREFIX=
+
+    for /F "delims=- tokens=1" %%A in ("!MILL_VERSION!") do set MILL_VERSION_BASE=%%A
+    for /F "delims=- tokens=2" %%A in ("!MILL_VERSION!") do set MILL_VERSION_MILESTONE=%%A
+	set VERSION_MILESTONE_START=!MILL_VERSION_MILESTONE:~0,1!
+    if [!VERSION_MILESTONE_START!]==[M] (
+        set MILL_VERSION_TAG="!MILL_VERSION_BASE!-!MILL_VERSION_MILESTONE!"
+    ) else (
+        set MILL_VERSION_TAG=!MILL_VERSION_BASE!
+    )
+
+    rem there seems to be no way to generate a unique temporary file path (on native Windows)
+    set DOWNLOAD_FILE=%MILL%.tmp
+
+    set DOWNLOAD_URL=%MILL_REPO_URL%/releases/download/!MILL_VERSION_TAG!/!MILL_VERSION!!DOWNLOAD_SUFFIX!
+
+    echo Downloading mill %MILL_VERSION% from %MILL_REPO_URL%/releases ... 1>&2
+
+    if not exist "%MILL_DOWNLOAD_PATH%" mkdir "%MILL_DOWNLOAD_PATH%"
+    rem curl is bundled with recent Windows 10
+    rem but I don't think we can expect all the users to have it in 2019
+    where /Q curl
+    if %ERRORLEVEL% EQU 0 (
+        curl -f -L "!DOWNLOAD_URL!" -o "!DOWNLOAD_FILE!"
+    ) else (
+        rem bitsadmin seems to be available on Windows 7
+        rem without /dynamic, github returns 403
+        rem bitsadmin is sometimes needlessly slow but it looks better with /priority foreground
+        bitsadmin /transfer millDownloadJob /dynamic /priority foreground "!DOWNLOAD_URL!" "!DOWNLOAD_FILE!"
+    )
+    if not exist "!DOWNLOAD_FILE!" (
+        echo Could not download mill %MILL_VERSION% 1>&2
+        exit /b 1
+    )
+
+    move /y "!DOWNLOAD_FILE!" "%MILL%"
+
+    set DOWNLOAD_FILE=
+    set DOWNLOAD_SUFFIX=
+)
+
+set MILL_DOWNLOAD_PATH=
+set MILL_VERSION=
+set MILL_REPO_URL=
+
+set MILL_PARAMS=%*
+
+if defined STRIP_VERSION_PARAMS (
+    for /f "tokens=1-2*" %%a in ("%*") do (
+        rem strip %%a - It's the "--mill-version" option.
+        rem strip %%b - it's the version number that comes after the option.
+        rem keep  %%c - It's the remaining options.
+        set MILL_PARAMS=%%c
+    )
+)
+
+"%MILL%" %MILL_PARAMS%

plugin/src/io/kipp/mill/giter8/G8Module.scala

@@ -7,6 +7,7 @@ import mill.define.Target
 import mill.define.TaskModule
 import os.Path
 
+import java.nio.file.attribute.PosixFilePermission
 import scala.util.Failure
 import scala.util.Success
 import scala.util.Using
@@ -46,6 +47,55 @@ trait G8Module extends TaskModule {
     */
   def validationTargets: Target[Seq[String]] = T { Seq.empty[String] }
 
+  /** If no mill is detected in the template in order to run the
+    * [[io.kipp.mill.giter8.G8Module.validationTargets]] aginst it we need Mill.
+    * To make this easier, we just download millw, cache it, and use it.
+    *
+    * @return
+    *   the PathRef to millw
+    */
+  private def downloadMill: T[PathRef] = T.task {
+    val log = T.log
+    val exeSuffix = if (scala.util.Properties.isWin) ".bat" else ""
+    log.info(
+      s"No mill found in template root, so falling back to millw${exeSuffix} to validate targets."
+    )
+
+    val url =
+      s"https://raw.githubusercontent.com/lefou/millw/main/millw${exeSuffix}"
+
+    val cacheDir = T.env
+      .get("XDG_CACHE_HOME")
+      .map(os.Path(_))
+      .getOrElse(
+        os.home / ".cache"
+      ) / "mill-giter8"
+
+    val cacheTarget = cacheDir / s"millw${exeSuffix}"
+
+    os.makeDir.all(cacheDir)
+
+    if (!os.exists(cacheTarget)) {
+      log.info(
+        s"No millw${exeSuffix} found in cache so downloading one for you"
+      )
+
+      val r = requests.get(url)
+      if (r.is2xx) {
+        os.write(cacheTarget, r.bytes)
+        if (!scala.util.Properties.isWin) {
+          os.perms.set(
+            cacheTarget,
+            os.perms(cacheTarget) + PosixFilePermission.OWNER_EXECUTE
+          )
+        }
+      } else {
+        Result.Failure(s"Unable to download millw${exeSuffix} when needed.")
+      }
+    }
+    PathRef(cacheTarget)
+  }
+
   /** The main target that you'll want to use. This will first ensure that
     * [[io.kipp.mill.giter8.G8Module.generate]] runs to ensure your project can
     * actually be generated with g8 and then run the
@@ -59,16 +109,26 @@ trait G8Module extends TaskModule {
     val targets = validationTargets()
     val log = T.log
 
+    val exeSuffix = if (scala.util.Properties.isWin) ".bat" else ""
+
+    val mill = if (os.exists(projectPath / s"mill${exeSuffix}")) {
+      s"./mill${exeSuffix}"
+    } else if (os.exists(projectPath / s"millw${exeSuffix}")) {
+      s"./millw${exeSuffix}"
+    } else {
+      downloadMill().path.toString()
+    }
+
+    val d = downloadMill()
+    log.info(d.toString())
     val results: Seq[(String, Int)] = targets.zipWithIndex.map {
       case (command, id) =>
         log.info(
           s"""[${id + 1}/${targets.size}] attempting to run "${command}""""
         )
-        // TODO right now we assume this is here, but we should download it if it's not
-        // TODO we assume non-windows -- we'll need to account for .bat
         // TODO do we want --no-server to be configurable?
         val cmd = os
-          .proc("./mill", "--no-server", command)
+          .proc(mill, "--no-server", command)
           .call(cwd = projectPath)
 
         (command, cmd.exitCode)
@@ -78,7 +138,7 @@ trait G8Module extends TaskModule {
       true
     }
 
-    // TODO this assumes we want everything to suceed. Add in the ability to fail
+    // TODO right now we assume that we want everythign to succeed. Should we?
     if (failed.isEmpty) {
       val msg = "All targets ran successfully!"
       log.info(msg)