change darwin impl to delegate to os_log_t (#348)

based on previous impl and https://blog.shipbook.io/ios-logs

looks like a better approach will be to just delegate logs to the os logger.

* change subsystem and category resolution based on #227
* add constant logger
* add constant constantOsDefaultLogger

build.gradle.kts

@@ -166,7 +166,7 @@ kotlin {
             dependsOn(nativeMain)
         }
         val darwinMain by creating {
-            dependsOn(nativeMain)
+            dependsOn(commonMain)
         }
         linuxTargets.forEach {
             getByName("${it.targetName}Main") {

src/darwinMain/kotlin/io/github/oshai/kotlinlogging/DarwinKLogger.kt

@@ -0,0 +1,42 @@
+package io.github.oshai.kotlinlogging
+
+import kotlinx.cinterop.ptr
+import platform.darwin.OS_LOG_TYPE_DEBUG
+import platform.darwin.OS_LOG_TYPE_DEFAULT
+import platform.darwin.OS_LOG_TYPE_ERROR
+import platform.darwin.OS_LOG_TYPE_INFO
+import platform.darwin.__dso_handle
+import platform.darwin._os_log_internal
+import platform.darwin.os_log_t
+import platform.darwin.os_log_type_enabled
+import platform.darwin.os_log_type_t
+
+public class DarwinKLogger(override val name: String, override val underlyingLogger: os_log_t) :
+  KLogger, DelegatingKLogger<os_log_t> {
+
+  override fun at(level: Level, marker: Marker?, block: KLoggingEventBuilder.() -> Unit) {
+    if (isLoggingEnabledFor(level, marker)) {
+      KLoggingEventBuilder().apply(block).run {
+        _os_log_internal(__dso_handle.ptr, underlyingLogger, level.toDarwinLevel(), message)
+      }
+    }
+  }
+
+  private fun Level.toDarwinLevel(): os_log_type_t {
+    return when (this) {
+      Level.TRACE -> OS_LOG_TYPE_DEBUG
+      Level.DEBUG -> OS_LOG_TYPE_DEBUG
+      Level.INFO -> OS_LOG_TYPE_INFO
+      Level.WARN -> OS_LOG_TYPE_DEFAULT
+      Level.ERROR -> OS_LOG_TYPE_ERROR
+      Level.OFF -> throw Exception("off level cannot be mapped to darwin level")
+    }
+  }
+
+  override fun isLoggingEnabledFor(level: Level, marker: Marker?): Boolean {
+    return when (level) {
+      Level.OFF -> false
+      else -> os_log_type_enabled(underlyingLogger, level.toDarwinLevel())
+    }
+  }
+}

src/darwinMain/kotlin/io/github/oshai/kotlinlogging/KotlinLoggingConfiguration.kt

@@ -1,3 +1,8 @@
 package io.github.oshai.kotlinlogging
 
-public actual val DefaultAppender: Appender = OSLogAppender()
+import kotlin.native.concurrent.AtomicReference
+
+public object KotlinLoggingConfiguration {
+  public var subsystem: AtomicReference<String?> = AtomicReference(null)
+  public var category: AtomicReference<String?> = AtomicReference(null)
+}

src/darwinMain/kotlin/io/github/oshai/kotlinlogging/internal/ErrorMessageProducer.kt

@@ -0,0 +1,3 @@
+package io.github.oshai.kotlinlogging.internal
+
+internal actual typealias ErrorMessageProducer = DefaultErrorMessageProducer

src/darwinMain/kotlin/io/github/oshai/kotlinlogging/internal/KLoggerFactory.kt

@@ -0,0 +1,42 @@
+package io.github.oshai.kotlinlogging.internal
+
+import io.github.oshai.kotlinlogging.DarwinKLogger
+import io.github.oshai.kotlinlogging.KLogger
+import io.github.oshai.kotlinlogging.KotlinLoggingConfiguration
+import kotlin.native.concurrent.AtomicReference
+import platform.darwin.OS_LOG_DEFAULT
+import platform.darwin.os_log_create
+
+/** factory methods to obtain a [KLogger] */
+internal actual object KLoggerFactory {
+
+  private val constantLogger: AtomicReference<KLogger?> = AtomicReference(null)
+  private val constantOsDefaultLogger: KLogger = DarwinKLogger("", OS_LOG_DEFAULT)
+
+  /** get logger by explicit name */
+  internal actual fun logger(name: String): KLogger {
+    val subsystemConfigured = KotlinLoggingConfiguration.subsystem.value
+    val categoryConfigured = KotlinLoggingConfiguration.category.value
+    return when {
+      subsystemConfigured != null && categoryConfigured != null -> {
+        constantLogger.value
+          ?: DarwinKLogger(name, os_log_create(subsystemConfigured, categoryConfigured)).also {
+            constantLogger.value = it
+          }
+      }
+      subsystemConfigured != null || categoryConfigured != null -> {
+        DarwinKLogger(name, os_log_create(subsystemConfigured ?: name, categoryConfigured ?: name))
+      }
+      name.isBlank() -> constantOsDefaultLogger
+      name.contains(".") -> {
+        DarwinKLogger(
+          name,
+          os_log_create(name.substringBeforeLast("."), name.substringAfterLast("."))
+        )
+      }
+      else -> {
+        DarwinKLogger(name, os_log_create(name, ""))
+      }
+    }
+  }
+}

src/darwinMain/kotlin/io/github/oshai/kotlinlogging/internal/KLoggerNameResolver.kt

@@ -0,0 +1,6 @@
+package io.github.oshai.kotlinlogging.internal
+
+internal actual object KLoggerNameResolver {
+
+  internal actual fun name(func: () -> Unit): String = func::class.qualifiedName ?: ""
+}