Implement GradleProjectFlattenerCli (#65)

* Implement GradleProjectFlattenerCli

* Spotless

* Final touchups

* More flags + error handling

* Suppression

* More flags and fixes from testing

Author: ZacSweers

api/kotlin-cli-util.api

@@ -37,6 +37,11 @@ public final class slack/cli/Toml {
 	public final fun parseVersion (Ljava/io/File;)Ljava/util/Map;
 }
 
+public final class slack/cli/gradle/GradleProjectFlattenerCli : com/github/ajalt/clikt/core/CliktCommand {
+	public fun <init> ()V
+	public fun run ()V
+}
+
 public final class slack/cli/lint/LintBaselineMergerCli : com/github/ajalt/clikt/core/CliktCommand {
 	public fun <init> ()V
 	public fun run ()V

src/main/kotlin/slack/cli/gradle/GradleProjectFlattenerCli.kt

@@ -0,0 +1,145 @@
+/*
+ * Copyright (C) 2023 Slack Technologies, LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package slack.cli.gradle
+
+import com.github.ajalt.clikt.core.CliktCommand
+import com.github.ajalt.clikt.parameters.options.default
+import com.github.ajalt.clikt.parameters.options.flag
+import com.github.ajalt.clikt.parameters.options.option
+import com.github.ajalt.clikt.parameters.options.required
+import com.github.ajalt.clikt.parameters.types.path
+import java.io.File
+import kotlin.io.path.ExperimentalPathApi
+import kotlin.io.path.appendLines
+import kotlin.io.path.appendText
+import kotlin.io.path.copyToRecursively
+import kotlin.io.path.exists
+import kotlin.io.path.isDirectory
+import kotlin.io.path.readText
+import kotlin.io.path.relativeTo
+import slack.cli.dryRunOption
+import slack.cli.projectDirOption
+
+/**
+ * A CLI that flattens all gradle projects in a given directory to be top level while preserving
+ * their original project paths.
+ *
+ * This is useful for flattening nested projects that use Dokka, which does not currently support
+ * easy doc gen for nested projects and end up with colliding names.
+ *
+ * It's recommended to run `./gradlew clean` first before running this script to minimize work.
+ */
+public class GradleProjectFlattenerCli :
+  CliktCommand(
+    help =
+      "A CLI that flattens all gradle projects in a given directory to be top level while " +
+        "preserving their original project paths."
+  ) {
+
+  private val projectDir by projectDirOption()
+
+  private val settingsFile by
+    option(
+        "--settings-file",
+        "-s",
+        help =
+          "The settings.gradle file to use. Note this file _must_ only have a single, top-level `include()` call " +
+            "with vararg project args."
+      )
+      .path(mustExist = true, canBeDir = false)
+      .required()
+
+  private val projectDelimiter by option().default("--")
+
+  private val dryRun by dryRunOption()
+
+  private val strict by
+    option("--strict", help = "If true, will fail if any of the projects to flatten don't exist.")
+      .flag()
+
+  private val verbose by
+    option("--verbose", "-v", help = "If true, will print out more information.").flag()
+
+  private val force by
+    option("--force", "-f", help = "If true, force overwrite new projects.").flag()
+
+  @ExperimentalPathApi
+  override fun run() {
+    val projectPaths =
+      settingsFile
+        .readText()
+        .trim()
+        .lines()
+        // Filter out commented lines
+        .filterNot { it.trimStart().startsWith("//") }
+        .joinToString("\n")
+        .removePrefix("include(")
+        .removeSuffix(")")
+        .split(",")
+        .map { it.trim().removeSurrounding("\"") }
+
+    val newPathMapping = mutableMapOf<String, String>()
+    @Suppress("LoopWithTooManyJumpStatements")
+    for (path in projectPaths) {
+      val realPath =
+        projectDir.resolve(path.removePrefix(":").removeSuffix(":").replace(":", File.separator))
+      if (strict) {
+        check(!path.endsWith(":")) { "Project paths cannot end with ':'" }
+        check(realPath.exists()) { "Expected $realPath to exist." }
+        check(realPath.isDirectory()) { "Expected $realPath to be a directory." }
+      } else if (!realPath.exists()) {
+        echo("Skipping $path as it doesn't exist", err = true)
+        continue
+      }
+      val newPath =
+        projectDir.resolve(path.removePrefix(":").removeSuffix(":").replace(":", projectDelimiter))
+      if (newPath == realPath) {
+        // Already top-level, move on
+        continue
+      }
+      newPathMapping[path] = newPath.relativeTo(projectDir).toString()
+      if (verbose) {
+        echo("Flattening $realPath to $newPath")
+      }
+      if (!dryRun) {
+        realPath.copyToRecursively(newPath, followLinks = false, overwrite = force)
+      }
+    }
+
+    if (verbose) {
+      echo("Finished flattening projects. Updating settings file")
+    }
+    val newPaths =
+      projectPaths.mapNotNull { path ->
+        // Point at their new paths
+        // Example:
+        //   project(":libraries:compose-extensions:pull-refresh").projectDir =
+        //     file("libraries--compose-extensions--pull-refresh")
+        val newPath = newPathMapping[path] ?: return@mapNotNull null
+        "project(\"$path\").projectDir = file(\"$newPath\")"
+          .also {
+            if (verbose) {
+              echo("+  $it")
+            }
+          }
+      }
+
+    if (!dryRun) {
+      settingsFile.appendText("\n\n")
+      settingsFile.appendLines(newPaths)
+    }
+  }
+}