Add validation for input arguments

src/nativeMain/kotlin/Main.kt

@@ -5,13 +5,21 @@ import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
 import logger.Logger
 import logger.context
+import platform.posix.exit
 import userInput.Arguments
 import userInput.Keymap
 import userInput.Keymap.Actions
 
 @OptIn(ExperimentalCoroutinesApi::class, DelicateCoroutinesApi::class)
 fun main(args: Array<String>) {
-    Arguments.validate(args)
+    val appModule = AppModule()
+
+    try {
+        appModule.arguments.validate(args)
+    } catch (e: Arguments.ValidationException) {
+        println(e.message)
+        exit(1)
+    }
 
     val ui = newSingleThreadContext("UI")
 
@@ -24,8 +32,6 @@ fun main(args: Array<String>) {
         //he key takeaway is that if you call launch on a custom CoroutineScope, any CoroutineExceptionHandler provided
         // directly to the CoroutineScope constructor or to launch will be executed when an exception is thrown within the launched coroutine.
         val appJob = CoroutineScope(ui).launch(handler) {
-            val appModule = AppModule()
-
             with(appModule) {
                 Logger.set(fileLogger)
 

src/nativeMain/kotlin/di/AppModule.kt

@@ -5,7 +5,7 @@ import BuildConfig
 import FileLogger
 import InternalAppState
 import di.DogcatModule.dogcatModule
-import kotlinx.coroutines.CloseableCoroutineDispatcher
+import kotlinx.cli.ArgParser
 import logger.CanLog
 import logger.NoOpLogger
 import org.kodein.di.DI
@@ -14,6 +14,7 @@ import org.kodein.di.instance
 import ui.AppPresenter
 import ui.logLines.LogLinesPresenter
 import ui.status.StatusPresenter
+import userInput.Arguments
 import userInput.DefaultInput
 import userInput.Input
 
@@ -27,6 +28,7 @@ class AppModule {
                 NoOpLogger()
             }
         }
+        bindSingleton<Arguments> { Arguments(ArgParser("dogcat")) }
         bindSingleton<AppState> { InternalAppState() }
         bindSingleton<Input> { DefaultInput(instance()) }
         bindSingleton<AppPresenter> {
@@ -35,6 +37,7 @@ class AppModule {
                 instance(),
                 instance(),
                 instance(),
+                instance(),
                 instance()
             )
         }
@@ -47,6 +50,7 @@ class AppModule {
         }
         bindSingleton<LogLinesPresenter> {
             LogLinesPresenter(
+                instance(),
                 instance(),
                 instance(),
                 instance()
@@ -61,6 +65,8 @@ class AppModule {
 
     val fileLogger: CanLog by serviceLocator.instance()
 
+    val arguments: Arguments by serviceLocator.instance()
+
     val input: Input by serviceLocator.instance()
 
     val appPresenter: AppPresenter by serviceLocator.instance()

src/nativeMain/kotlin/ui/AppPresenter.kt

@@ -10,11 +10,13 @@ import dogcat.state.PublicState
 import dogcat.state.PublicState.Active
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.filter
+import kotlinx.coroutines.flow.filterIsInstance
+import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.launch
 import logger.Logger
 import logger.context
-import ui.Strings.INPUT_FILTER_PREFIX
 import ui.logLines.LogLinesPresenter
 import ui.status.StatusPresenter
 import userInput.Arguments
@@ -25,6 +27,7 @@ import kotlin.coroutines.coroutineContext
 
 class AppPresenter(
     private val dogcat: Dogcat,
+    private val arguments: Arguments,
     private val appState: AppState,
     private val input: Input,
     private val logLinesPresenter: LogLinesPresenter,
@@ -35,8 +38,8 @@ class AppPresenter(
 
     override suspend fun start() {
         when {
-            Arguments.packageName != null -> dogcat(PickAppPackage(Arguments.packageName!!))
-            Arguments.current == true -> dogcat(PickForegroundApp)
+            arguments.packageName != null -> dogcat(PickAppPackage(arguments.packageName!!))
+            arguments.current == true -> dogcat(PickForegroundApp)
             else -> dogcat(PickAllApps)
         }
 

src/nativeMain/kotlin/ui/logLines/LogLinesPresenter.kt

@@ -19,6 +19,7 @@ import kotlin.coroutines.coroutineContext
 
 class LogLinesPresenter(
     private val dogcat: Dogcat,
+    private val arguments: Arguments,
     private val appState: AppState,
     private val input: Input,
 ) : HasLifecycle {
@@ -55,7 +56,7 @@ class LogLinesPresenter(
                 .collect {
                     view.state = view.state.copy(
                         autoscroll = it.autoscroll,
-                        showLineNumbers = Arguments.lineNumbers ?: false,
+                        showLineNumbers = arguments.lineNumbers ?: false,
                         isCursorHeld = it.isCursorHeld,
                         cursorReturnLocation = it.inputFilterLocation
                     )

src/nativeMain/kotlin/userInput/Arguments.kt

@@ -4,18 +4,34 @@ import kotlinx.cli.ArgParser
 import kotlinx.cli.ArgType
 import kotlinx.cli.optional
 
-object Arguments {
+class Arguments(private val parser: ArgParser) {
 
-    private val parser = ArgParser("dogcat")
+    class ValidationException(override val message: String) : RuntimeException(message)
 
-    val packageName by parser.argument(ArgType.String, "package name", "description for p n").optional()
-    val current by parser.option(ArgType.Boolean, shortName = "c", description = "Filter by currently running program")
-    val lineNumbers by parser.option(ArgType.Boolean, shortName = "ln", description = "Show line numbers")
+    val packageName by parser.argument(
+        ArgType.String,
+        "package name",
+        "Show logs for a particular application specified by this package name. " +
+                "Example: 'com.google.android.apps.messaging'."
+    ).optional()
+
+    val current by parser.option(
+        ArgType.Boolean,
+        shortName = "c",
+        description = "Show logs for an application currently running in foreground"
+    )
+
+    val lineNumbers by parser.option(
+        ArgType.Boolean,
+        shortName = "ln",
+        description = "Show line numbers for log lines, embedded into message body"
+    )
 
     fun validate(args: Array<String>) {
         parser.parse(args)
         if (packageName != null && current != null) {
-            //can't have both at the same time
+            throw ValidationException("'Package name' and '--current' arguments are mutually exclusive and " +
+                    "can't be used at the same time.")
         }
     }
 }