buildSrc: introduce versioning plugin

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

app/build.gradle.kts

@@ -4,6 +4,7 @@ plugins {
   kotlin("kapt")
   kotlin("plugin.serialization") version "1.4.21"
   id("dagger.hilt.android.plugin")
+  `versioning-plugin`
   `lobsters-plugin`
   `core-library-desugaring`
 }
@@ -11,8 +12,6 @@ plugins {
 android {
   defaultConfig {
     applicationId = "dev.msfjarvis.lobsters"
-    versionCode = 1
-    versionName = "1.0"
     testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     javaCompileOptions.annotationProcessorOptions {
       argument("room.schemaLocation", "${projectDir}/schemas")

app/version.properties

@@ -0,0 +1,6 @@
+#
+#This file was automatically generated by 'versioning-plugin'. DO NOT EDIT MANUALLY.
+#
+#Mon Jan 18 18:42:38 IST 2021
+versioning-plugin.versionCode=10000
+versioning-plugin.versionName=1.0.0

buildSrc/build.gradle.kts

@@ -24,6 +24,10 @@ gradlePlugin {
       id = "core-library-desugaring"
       implementationClass = "CoreLibraryDesugaringPlugin"
     }
+    register("versioning") {
+      id = "versioning-plugin"
+      implementationClass = "VersioningPlugin"
+    }
   }
 }
 
@@ -34,4 +38,5 @@ dependencies {
   implementation(build.getValue("androidGradlePlugin_builder"))
   implementation(build.getValue("androidGradlePlugin_builderModel"))
   implementation(build.getValue("androidGradlePlugin_lintModel"))
+  implementation(build.getValue("jsemver"))
 }

buildSrc/buildDependencies.gradle

@@ -3,6 +3,7 @@ rootProject.ext.versions = [
   daggerHilt: '2.30.1-alpha',
   kotlin: '1.4.21',
   lint: '27.3.0-alpha04',
+  semver: '0.9.0',
 ]
 
 rootProject.ext.build = [
@@ -12,4 +13,5 @@ rootProject.ext.build = [
   androidGradlePlugin_lintModel: "com.android.tools.lint:lint-model:${versions.lint}",
   daggerGradlePlugin: "com.google.dagger:hilt-android-gradle-plugin:${versions.daggerHilt}",
   kotlinGradlePlugin: "org.jetbrains.kotlin:kotlin-gradle-plugin:${versions.kotlin}",
+  jsemver: "com.github.zafarkhaja:java-semver:${versions.semver}",
 ]

buildSrc/src/main/java/VersioningPlugin.kt

@@ -0,0 +1,115 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+
+import com.android.build.gradle.internal.plugins.AppPlugin
+import com.github.zafarkhaja.semver.Version
+import java.io.OutputStream
+import java.util.Properties
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+
+private const val VERSIONING_PROP_FILE = "version.properties"
+private const val VERSIONING_PROP_VERSION_NAME = "versioning-plugin.versionName"
+private const val VERSIONING_PROP_VERSION_CODE = "versioning-plugin.versionCode"
+private const val VERSIONING_PROP_COMMENT = """
+This file was automatically generated by 'versioning-plugin'. DO NOT EDIT MANUALLY.
+"""
+
+/**
+ * A Gradle [Plugin] that takes a [Project] with the [AppPlugin] applied and dynamically sets the
+ * versionCode and versionName properties based on values read from a [VERSIONING_PROP_FILE] file in
+ * the [Project.getBuildDir] directory. It also adds Gradle tasks to bump the major, minor, and patch
+ * versions along with one to prepare the next snapshot.
+ */
+@Suppress(
+  "UnstableApiUsage",
+  "NAME_SHADOWING"
+)
+class VersioningPlugin : Plugin<Project> {
+
+  /**
+   * Generate the Android 'versionCode' property
+   */
+  private fun Version.androidCode(): Int {
+    return majorVersion * 1_00_00 +
+      minorVersion * 1_00 +
+      patchVersion
+  }
+
+  /**
+   * Write an Android-specific variant of [this] to [stream]
+   */
+  private fun Version.writeForAndroid(stream: OutputStream) {
+    val newVersionCode = androidCode()
+    val props = Properties()
+    props.setProperty(VERSIONING_PROP_VERSION_CODE, "$newVersionCode")
+    props.setProperty(VERSIONING_PROP_VERSION_NAME, toString())
+    props.store(stream, VERSIONING_PROP_COMMENT)
+  }
+
+  /**
+   * Returns the same [Version], but with build metadata stripped.
+   */
+  private fun Version.clearPreRelease(): Version {
+    return Version.forIntegers(majorVersion, minorVersion, patchVersion)
+  }
+
+  override fun apply(project: Project) {
+    with(project) {
+      val appPlugin = requireNotNull(plugins.findPlugin(AppPlugin::class.java)) {
+        "Plugin 'com.android.application' must be applied to use this plugin"
+      }
+      val propFile = layout.projectDirectory.file(VERSIONING_PROP_FILE)
+      require(propFile.asFile.exists()) {
+        "A 'version.properties' file must exist in the project subdirectory to use this plugin"
+      }
+      val contents = providers.fileContents(propFile).asText.forUseAtConfigurationTime()
+      val versionProps = Properties().also { it.load(contents.get().byteInputStream()) }
+      val versionName = requireNotNull(versionProps.getProperty(VERSIONING_PROP_VERSION_NAME)) {
+        "version.properties must contain a '$VERSIONING_PROP_VERSION_NAME' property"
+      }
+      val versionCode = requireNotNull(versionProps.getProperty(VERSIONING_PROP_VERSION_CODE).toInt()) {
+        "version.properties must contain a '$VERSIONING_PROP_VERSION_CODE' property"
+      }
+      appPlugin.extension.defaultConfig.versionName = versionName
+      appPlugin.extension.defaultConfig.versionCode = versionCode
+      afterEvaluate {
+        val version = Version.valueOf(versionName)
+        tasks.register("clearPreRelease") {
+          doLast {
+            version.clearPreRelease()
+              .writeForAndroid(propFile.asFile.outputStream())
+          }
+        }
+        tasks.register("bumpMajor") {
+          doLast {
+            version.incrementMajorVersion()
+              .writeForAndroid(propFile.asFile.outputStream())
+          }
+        }
+        tasks.register("bumpMinor") {
+          doLast {
+            version.incrementMinorVersion()
+              .writeForAndroid(propFile.asFile.outputStream())
+          }
+        }
+        tasks.register("bumpPatch") {
+          doLast {
+            version.incrementPatchVersion()
+              .writeForAndroid(propFile.asFile.outputStream())
+          }
+        }
+        tasks.register("bumpSnapshot") {
+          doLast {
+            version.incrementMinorVersion()
+              .setPreReleaseVersion("SNAPSHOT")
+              .writeForAndroid(propFile.asFile.outputStream())
+          }
+        }
+      }
+    }
+  }
+}