set up convention plugins

- tidy up build scripts to use convention plugins
- use centralised repo definition
- tidy up some of the build config

buildSrc/src/main/kotlin/buildsrc/conventions/lang/kotlin-multiplatform-base.gradle.kts

@@ -0,0 +1,45 @@
+package buildsrc.conventions.lang
+
+import org.jetbrains.kotlin.gradle.targets.jvm.KotlinJvmTarget
+
+
+/**
+ * Base configuration for all Kotlin/Multiplatform conventions.
+ *
+ * This plugin does not enable any Kotlin target. To enable a target in a subproject, prefer applying specific Kotlin
+ * target convention plugins.
+ */
+
+plugins {
+    id("buildsrc.conventions.base")
+    kotlin("multiplatform")
+}
+
+
+kotlin {
+    jvmToolchain(11)
+
+    targets.configureEach {
+        compilations.configureEach {
+            kotlinOptions {
+                // nothin' yet
+            }
+        }
+    }
+
+    // configure all Kotlin/JVM Tests to use JUnit
+    targets.withType<KotlinJvmTarget>().configureEach {
+        testRuns.configureEach {
+            executionTask.configure {
+                useJUnitPlatform()
+            }
+        }
+    }
+
+    sourceSets.configureEach {
+        languageSettings {
+//         languageVersion =
+//         apiVersion =
+        }
+    }
+}

buildSrc/src/main/kotlin/buildsrc/conventions/lang/kotlin-multiplatform-js.gradle.kts

@@ -0,0 +1,18 @@
+package buildsrc.conventions.lang
+
+/** conventions for a Kotlin/JS subproject */
+
+plugins {
+    id("buildsrc.conventions.lang.kotlin-multiplatform-base")
+}
+
+kotlin {
+    targets {
+        js(IR) {
+            browser()
+            nodejs()
+        }
+    }
+}
+
+relocateKotlinJsStore()

buildSrc/src/main/kotlin/buildsrc/conventions/lang/kotlin-multiplatform-jvm.gradle.kts

@@ -0,0 +1,11 @@
+package buildsrc.conventions.lang
+
+plugins {
+    id("buildsrc.conventions.lang.kotlin-multiplatform-base")
+}
+
+kotlin {
+    jvm {
+        withJava()
+    }
+}

buildSrc/src/main/kotlin/buildsrc/conventions/lang/kotlin-multiplatform-native.gradle.kts

@@ -0,0 +1,102 @@
+package buildsrc.conventions.lang
+
+/** conventions for a Kotlin/Native subproject */
+
+plugins {
+    id("buildsrc.conventions.lang.kotlin-multiplatform-base")
+}
+
+kotlin {
+
+    // Native targets all extend commonMain and commonTest.
+    //
+    // Some targets (ios, tvos, watchos) are shortcuts provided by the Kotlin DSL, that
+    // provide additional targets, except for 'simulators' which must be defined manually.
+    // https://kotlinlang.org/docs/multiplatform-share-on-platforms.html#use-target-shortcuts
+    //
+    // common/
+    // └── native/
+    //     ├── linuxX64
+    //     ├── mingwX64
+    //     ├── macosX64
+    //     ├── macosArm64
+    //     ├── ios/ (shortcut)
+    //     │   ├── iosArm64
+    //     │   ├── iosX64
+    //     │   └── iosSimulatorArm64
+    //     ├── tvos/ (shortcut)
+    //     │   ├── tvosArm64
+    //     │   ├── tvosX64
+    //     │   └── tvosSimulatorArm64Main
+    //     └── watchos/ (shortcut)
+    //         ├── watchosArm32
+    //         ├── watchosArm64
+    //         ├── watchosX64
+    //         └── watchosSimulatorArm64Main
+
+    targets {
+        linuxX64()
+
+        mingwX64()
+
+        macosX64()
+        macosArm64()
+
+        // https://kotlinlang.org/docs/multiplatform-share-on-platforms.html#use-target-shortcuts
+        ios()     // iosArm64, iosX64
+        watchos() // watchosArm32, watchosArm64, watchosX64
+        tvos()    // tvosArm64, tvosX64
+
+        iosSimulatorArm64()
+        tvosSimulatorArm64()
+        watchosSimulatorArm64()
+    }
+
+    @Suppress("UNUSED_VARIABLE")
+    sourceSets {
+        val commonMain by getting {}
+        val commonTest by getting {}
+
+        val nativeMain by creating { dependsOn(commonMain) }
+        val nativeTest by creating { dependsOn(commonTest) }
+
+        // Linux
+        val linuxX64Main by getting { dependsOn(nativeMain) }
+        val linuxX64Test by getting { dependsOn(nativeTest) }
+
+        // Windows - MinGW
+        val mingwX64Main by getting { dependsOn(nativeMain) }
+        val mingwX64Test by getting { dependsOn(nativeTest) }
+
+        // Apple - macOS
+        val macosArm64Main by getting { dependsOn(nativeMain) }
+        val macosArm64Test by getting { dependsOn(nativeTest) }
+
+        val macosX64Main by getting { dependsOn(nativeMain) }
+        val macosX64Test by getting { dependsOn(nativeTest) }
+
+        // Apple - iOS
+        val iosMain by getting { dependsOn(nativeMain) }
+        val iosTest by getting { dependsOn(nativeTest) }
+
+//         val iosSimulatorArm64Main by getting { dependsOn(iosMain) }
+//         val iosSimulatorArm64Test by getting { dependsOn(iosTest) }
+
+//         // Apple - tvOS
+//         val tvosMain by getting { dependsOn(nativeMain) }
+//         val tvosTest by getting { dependsOn(nativeTest) }
+//
+//         val tvosSimulatorArm64Main by getting { dependsOn(tvosMain) }
+//         val tvosSimulatorArm64Test by getting { dependsOn(tvosTest) }
+//
+//         // Apple - watchOS
+//         val watchosMain by getting { dependsOn(nativeMain) }
+//         val watchosTest by getting { dependsOn(nativeTest) }
+//
+//         val watchosSimulatorArm64Main by getting { dependsOn(watchosMain) }
+//         val watchosSimulatorArm64Test by getting { dependsOn(watchosTest) }
+
+        // val iosArm32Main by getting { dependsOn(desktopMain) }
+        // val iosArm32Test by getting { dependsOn(nativeTest) }
+    }
+}

buildSrc/src/main/kotlin/buildsrc/conventions/lang/kotlinJsExtensions.kt

@@ -0,0 +1,18 @@
+package buildsrc.conventions.lang
+
+import org.gradle.api.Project
+import org.gradle.kotlin.dsl.configure
+import org.jetbrains.kotlin.gradle.targets.js.yarn.YarnRootExtension
+
+/**
+ * `kotlin-js` and `kotlin-multiplatform` plugins adds a directory in the root-dir for the Yarn
+ * lockfile. That's a bit annoying. It's a little neater if it's in the Gradle dir, next to the
+ * version catalog.
+ */
+internal fun Project.relocateKotlinJsStore() {
+   afterEvaluate {
+      rootProject.extensions.configure<YarnRootExtension> {
+         lockFileDirectory = project.rootDir.resolve("gradle/kotlin-js-store")
+      }
+   }
+}