cmp-observe-metadata.gradle.kts

/*
 * Copyright 2026 MobileByteLabs
 *
 * 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
 */

// ============================================================================
// cmp-observe-metadata.gradle.kts — shared Gradle task generating CmpMetadata.kt
// from CMP_LIBRARY_METADATA.gradle's `extra["..."]` properties at compile time.
//
// Authored 2026-05-30 by library-runtime-observability epic Phase 02 T3 (AC #10).
//
// Each cmp-* module that consumes cmp-observe applies this script:
//
//     // In cmp-share/build.gradle.kts (or any cmp-*):
//     apply(from = "$rootDir/cmp-observe-metadata.gradle.kts")
//
// At every `:cmp-share:compileKotlinCommon`, generates:
//
//     cmp-share/build/generated/observability/io/github/mobilebytelabs/kmptoolkit/share/CmpMetadata.kt
//
// containing compile-time constants:
//
//     internal object CmpMetadata {
//         const val NAME = "cmp-share"
//         const val VERSION = "3.2.11"
//         const val ARTIFACT = "io.github.mobilebytelabs:cmp-share"
//     }
//
// Module init paths read these constants when calling
// `LibraryObservation.notifyInit(CmpMetadata(NAME, VERSION, ARTIFACT))`.
//
// The generated file is automatically added to commonMain.kotlin.srcDirs.
// ============================================================================

// Read CMP_LIBRARY_METADATA.gradle if it exists (top-level umbrella defaults).
val metadataFile = rootProject.file("CMP_LIBRARY_METADATA.gradle.kts")
if (metadataFile.exists()) {
    apply(from = metadataFile)
}

// Module name = the project's directory name (cmp-share, cmp-network-monitor, etc.)
val moduleName: String = project.name
val moduleKey: String = moduleName.replace('-', '_')

// Resolve version + artifact from rootProject.extra; fall back to UNKNOWN.
val moduleVersion: String =
    try {
        rootProject.extra["${moduleKey}_version"] as String
    } catch (_: Exception) {
        "UNKNOWN"
    }
val moduleArtifact: String =
    try {
        rootProject.extra["${moduleKey}_artifact"] as String
    } catch (_: Exception) {
        "io.github.mobilebytelabs:$moduleName"
    }

// Derive Kotlin package: cmp-share → com.mobilebytelabs.kmptoolkit.share
val modulePackage: String =
    run {
        // Mirror the actual source package convention used across cmp-* modules:
        // cmp-network-monitor → io.github.mobilebytelabs.kmptoolkit.networkmonitor
        // cmp-deep-link       → io.github.mobilebytelabs.kmptoolkit.deeplink
        // cmp-share           → io.github.mobilebytelabs.kmptoolkit.share
        // (hyphens are DROPPED, not converted to dots — the existing source tree uses
        // squashed concatenation, e.g. `package …kmptoolkit.networkmonitor`.)
        val short = moduleName.removePrefix("cmp-").replace("-", "")
        "io.github.mobilebytelabs.kmptoolkit.$short"
    }

abstract class CmpMetadataGenTask : org.gradle.api.DefaultTask() {
    @get:org.gradle.api.tasks.Input
    abstract val moduleName: org.gradle.api.provider.Property<String>

    @get:org.gradle.api.tasks.Input
    abstract val moduleVersion: org.gradle.api.provider.Property<String>

    @get:org.gradle.api.tasks.Input
    abstract val moduleArtifact: org.gradle.api.provider.Property<String>

    @get:org.gradle.api.tasks.Input
    abstract val modulePackage: org.gradle.api.provider.Property<String>

    @get:org.gradle.api.tasks.OutputDirectory
    abstract val outputDir: org.gradle.api.file.DirectoryProperty

    @org.gradle.api.tasks.TaskAction
    fun generate() {
        val pkgDir = outputDir.get().asFile.resolve(modulePackage.get().replace('.', '/'))
        pkgDir.mkdirs()
        pkgDir.resolve("CmpMetadata.kt").writeText(
            """
            /*
             * Auto-generated by cmp-observe-metadata.gradle.kts. DO NOT EDIT.
             *
             * Source: CMP_LIBRARY_METADATA.gradle (regenerated post-publish by mbl-actionhub).
             * Per library-runtime-observability epic Phase 02 T4 (AC #10).
             */
            package ${modulePackage.get()}

            internal object CmpMetadata {
                const val NAME: String = "${moduleName.get()}"
                const val VERSION: String = "${moduleVersion.get()}"
                const val ARTIFACT: String = "${moduleArtifact.get()}"
            }
            """.trimIndent(),
        )
    }
}

// Capture script-level vars before they are shadowed by the task's same-named abstract properties.
val capturedModuleName = moduleName
val capturedModuleVersion = moduleVersion
val capturedModuleArtifact = moduleArtifact
val capturedModulePackage = modulePackage

val genTask =
    tasks.register<CmpMetadataGenTask>("generateCmpMetadata") {
        moduleName.set(capturedModuleName)
        moduleVersion.set(capturedModuleVersion)
        moduleArtifact.set(capturedModuleArtifact)
        modulePackage.set(capturedModulePackage)
        outputDir.set(layout.buildDirectory.dir("generated/observability"))
    }

// Wire generated file into commonMain so compileKotlinCommon picks it up.
// KotlinMultiplatformExtension is NOT on the buildscript compilation classpath of an applied
// script — only on the plugin classpath resolved at runtime. We use reflection so this script
// compiles with only Gradle-core types (always available), and defers the KGP type lookup to
// the configuration phase when the plugin is already applied.
afterEvaluate {
    val ext = project.extensions.findByName("kotlin") ?: return@afterEvaluate
    try {
        @Suppress("UNCHECKED_CAST")
        val sourceSets =
            ext.javaClass.getMethod("getSourceSets").invoke(ext)
                as? org.gradle.api.NamedDomainObjectContainer<Any>
                ?: return@afterEvaluate
        val commonMain = sourceSets.findByName("commonMain") ?: return@afterEvaluate
        val kotlinSrcSet =
            commonMain.javaClass.getMethod("getKotlin").invoke(commonMain)
                as? org.gradle.api.file.SourceDirectorySet
                ?: return@afterEvaluate
        // Wire srcDir to the TaskProvider (not the static path) — Gradle then
        // auto-derives the task dependency for EVERY consumer of this source
        // set (compileKotlinX, androidSourcesJar, X64SourcesJar, etc.). Avoids
        // the brittle task-name-pattern approach that previously missed
        // *SourcesJar publish-time tasks and broke the publish workflow.
        kotlinSrcSet.srcDir(genTask.map { it.outputDir })
    } catch (e: Exception) {
        logger.warn("cmp-observe-metadata: failed to register generated sources in commonMain: ${e.message}")
    }
}

// Belt-and-suspenders: also wire an explicit dependsOn on every consumer task
// pattern we know about. The srcDir(taskProvider) registration above should be
// sufficient on its own, but this guard catches any task that reads the source
// dir via a path other than the kotlinSrcSet API.
//
// Pattern coverage:
//   - compileKotlin{TargetName}            (KMP standard targets)
//   - compileCommonMainKotlinMetadata      (KMP metadata)
//   - compileAndroidMain                   (Android KMP Library plugin)
//   - compile{Variant}KotlinAndroid        (legacy android plugin paths)
//   - {target}SourcesJar / androidSourcesJar / sourcesJar  (publish-time)
tasks
    .matching {
        it.name.startsWith("compileKotlin") ||
            it.name.startsWith("compileCommonMainKotlinMetadata") ||
            it.name.startsWith("compileAndroid") ||
            it.name.endsWith("SourcesJar") ||
            it.name == "sourcesJar"
    }.configureEach { dependsOn(genTask) }