use pigeon to generate platform channels

android/app/src/main/kotlin/io/chaldeaprjkt/boorusphere/AndroidStorageUtil.kt

@@ -0,0 +1,16 @@
+package io.chaldeaprjkt.boorusphere
+
+import StorageUtil
+import android.os.Environment
+
+class AndroidStorageUtil : StorageUtil {
+    override fun getStoragePath(): String {
+        val file = Environment.getExternalStorageDirectory()
+        return file.absolutePath
+    }
+
+    override fun getDownloadPath(): String {
+        val file = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
+        return file.absolutePath
+    }
+}

android/app/src/main/kotlin/io/chaldeaprjkt/boorusphere/MainActivity.kt

@@ -1,28 +1,13 @@
 package io.chaldeaprjkt.boorusphere
 
-import android.os.Environment
-import androidx.annotation.NonNull
+import StorageUtil
 import io.flutter.embedding.android.FlutterActivity
 import io.flutter.embedding.engine.FlutterEngine
-import io.flutter.plugin.common.MethodChannel
 
 class MainActivity : FlutterActivity() {
-    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
+    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
         super.configureFlutterEngine(flutterEngine)
-        val channelPath = "${BuildConfig.APPLICATION_ID}/path"
-        MethodChannel(
-            flutterEngine.dartExecutor.binaryMessenger,
-            channelPath
-        ).setMethodCallHandler { call, result ->
-            if (call.method == "getDownload") {
-                result.success(downloadPath.absolutePath)
-            } else {
-                result.notImplemented()
-            }
-        }
-    }
 
-    @Suppress("DEPRECATION")
-    private val downloadPath get() =
-        Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
+        StorageUtil.setUp(flutterEngine.dartExecutor.binaryMessenger, AndroidStorageUtil())
+    }
 }

android/app/src/main/kotlin/io/chaldeaprjkt/boorusphere/pigeon/StorageUtil.pi.kt

@@ -0,0 +1,91 @@
+// Autogenerated from Pigeon (v9.2.5), do not edit directly.
+// See also: https://pub.dev/packages/pigeon
+
+
+import android.util.Log
+import io.flutter.plugin.common.BasicMessageChannel
+import io.flutter.plugin.common.BinaryMessenger
+import io.flutter.plugin.common.MessageCodec
+import io.flutter.plugin.common.StandardMessageCodec
+import java.io.ByteArrayOutputStream
+import java.nio.ByteBuffer
+
+private fun wrapResult(result: Any?): List<Any?> {
+  return listOf(result)
+}
+
+private fun wrapError(exception: Throwable): List<Any?> {
+  if (exception is FlutterError) {
+    return listOf(
+      exception.code,
+      exception.message,
+      exception.details
+    )
+  } else {
+    return listOf(
+      exception.javaClass.simpleName,
+      exception.toString(),
+      "Cause: " + exception.cause + ", Stacktrace: " + Log.getStackTraceString(exception)
+    )
+  }
+}
+
+/**
+ * Error class for passing custom error details to Flutter via a thrown PlatformException.
+ * @property code The error code.
+ * @property message The error message.
+ * @property details The error details. Must be a datatype supported by the api codec.
+ */
+class FlutterError (
+  val code: String,
+  override val message: String? = null,
+  val details: Any? = null
+) : Throwable()
+/** Generated interface from Pigeon that represents a handler of messages from Flutter. */
+interface StorageUtil {
+  fun getStoragePath(): String
+  fun getDownloadPath(): String
+
+  companion object {
+    /** The codec used by StorageUtil. */
+    val codec: MessageCodec<Any?> by lazy {
+      StandardMessageCodec()
+    }
+    /** Sets up an instance of `StorageUtil` to handle messages through the `binaryMessenger`. */
+    @Suppress("UNCHECKED_CAST")
+    fun setUp(binaryMessenger: BinaryMessenger, api: StorageUtil?) {
+      run {
+        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.StorageUtil.getStoragePath", codec)
+        if (api != null) {
+          channel.setMessageHandler { _, reply ->
+            var wrapped: List<Any?>
+            try {
+              wrapped = listOf<Any?>(api.getStoragePath())
+            } catch (exception: Throwable) {
+              wrapped = wrapError(exception)
+            }
+            reply.reply(wrapped)
+          }
+        } else {
+          channel.setMessageHandler(null)
+        }
+      }
+      run {
+        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.StorageUtil.getDownloadPath", codec)
+        if (api != null) {
+          channel.setMessageHandler { _, reply ->
+            var wrapped: List<Any?>
+            try {
+              wrapped = listOf<Any?>(api.getDownloadPath())
+            } catch (exception: Throwable) {
+              wrapped = wrapError(exception)
+            }
+            reply.reply(wrapped)
+          }
+        } else {
+          channel.setMessageHandler(null)
+        }
+      }
+    }
+  }
+}

lib/pigeon/storage_util.pi.dart

@@ -0,0 +1,74 @@
+// Autogenerated from Pigeon (v9.2.5), do not edit directly.
+// See also: https://pub.dev/packages/pigeon
+// ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import
+
+import 'dart:async';
+import 'dart:typed_data' show Float64List, Int32List, Int64List, Uint8List;
+
+import 'package:flutter/foundation.dart' show ReadBuffer, WriteBuffer;
+import 'package:flutter/services.dart';
+
+class StorageUtil {
+  /// Constructor for [StorageUtil].  The [binaryMessenger] named argument is
+  /// available for dependency injection.  If it is left null, the default
+  /// BinaryMessenger will be used which routes to the host platform.
+  StorageUtil({BinaryMessenger? binaryMessenger})
+      : _binaryMessenger = binaryMessenger;
+  final BinaryMessenger? _binaryMessenger;
+
+  static const MessageCodec<Object?> codec = StandardMessageCodec();
+
+  Future<String> getStoragePath() async {
+    final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
+        'dev.flutter.pigeon.StorageUtil.getStoragePath', codec,
+        binaryMessenger: _binaryMessenger);
+    final List<Object?>? replyList =
+        await channel.send(null) as List<Object?>?;
+    if (replyList == null) {
+      throw PlatformException(
+        code: 'channel-error',
+        message: 'Unable to establish connection on channel.',
+      );
+    } else if (replyList.length > 1) {
+      throw PlatformException(
+        code: replyList[0]! as String,
+        message: replyList[1] as String?,
+        details: replyList[2],
+      );
+    } else if (replyList[0] == null) {
+      throw PlatformException(
+        code: 'null-error',
+        message: 'Host platform returned null value for non-null return value.',
+      );
+    } else {
+      return (replyList[0] as String?)!;
+    }
+  }
+
+  Future<String> getDownloadPath() async {
+    final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
+        'dev.flutter.pigeon.StorageUtil.getDownloadPath', codec,
+        binaryMessenger: _binaryMessenger);
+    final List<Object?>? replyList =
+        await channel.send(null) as List<Object?>?;
+    if (replyList == null) {
+      throw PlatformException(
+        code: 'channel-error',
+        message: 'Unable to establish connection on channel.',
+      );
+    } else if (replyList.length > 1) {
+      throw PlatformException(
+        code: replyList[0]! as String,
+        message: replyList[1] as String?,
+        details: replyList[2],
+      );
+    } else if (replyList[0] == null) {
+      throw PlatformException(
+        code: 'null-error',
+        message: 'Host platform returned null value for non-null return value.',
+      );
+    } else {
+      return (replyList[0] as String?)!;
+    }
+  }
+}

lib/presentation/provider/shared_storage_handle.dart

@@ -1,6 +1,6 @@
 import 'dart:io';
 
-import 'package:flutter/services.dart';
+import 'package:boorusphere/pigeon/storage_util.pi.dart';
 import 'package:media_scanner/media_scanner.dart';
 import 'package:path/path.dart' as p;
 import 'package:permission_handler/permission_handler.dart';
@@ -14,8 +14,7 @@ SharedStorageHandle sharedStorageHandle(SharedStorageHandleRef ref) {
 }
 
 Future<SharedStorageHandle> provideSharedStorageHandle() async {
-  const channel = MethodChannel('io.chaldeaprjkt.boorusphere/path');
-  final downloadPath = await channel.invokeMethod('getDownload');
+  final downloadPath = await StorageUtil().getDownloadPath();
   return SharedStorageHandle(downloadPath: downloadPath);
 }
 

pigeons/storage_util.pi.dart

@@ -0,0 +1,15 @@
+import 'package:pigeon/pigeon.dart';
+
+@ConfigurePigeon(
+  PigeonOptions(
+    dartOut: 'lib/pigeon/storage_util.pi.dart',
+    kotlinOut:
+        'android/app/src/main/kotlin/io/chaldeaprjkt/boorusphere/pigeon/StorageUtil.pi.kt',
+    kotlinOptions: KotlinOptions(errorClassName: 'StorageUtilException'),
+  ),
+)
+@HostApi()
+abstract class StorageUtil {
+  String getStoragePath();
+  String getDownloadPath();
+}

pubspec.lock

@@ -885,6 +885,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "5.4.0"
+  pigeon:
+    dependency: "direct dev"
+    description:
+      name: pigeon
+      sha256: "6b270420d0808903f4c2d848aa96f8c12e6275b15989270f24e552939642212f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "9.2.5"
   pigment:
     dependency: transitive
     description:

pubspec.yaml

@@ -97,6 +97,7 @@ dev_dependencies:
   json_serializable: ^6.7.0
   mocktail: ^0.3.0
   riverpod_generator: ^2.0.0
+  pigeon: ^9.2.5
 
 flutter_icons:
   android: true

tool/grind.dart

@@ -73,6 +73,21 @@ Future<void> genlang() async {
   await Pub.runAsync('slang', runOptions: utf8Opt);
 }
 
+@Task('Generate pigeon bindings')
+Future<void> pigeons() async {
+  final files = Directory('pigeons')
+      .listSync(recursive: true)
+      .where((x) => x is File && x.path.endsWith('.pi.dart'))
+      .map((x) => x.path);
+
+  await Pub.runAsync('pigeon',
+      arguments: [
+        '--input',
+        ...files,
+      ],
+      runOptions: utf8Opt);
+}
+
 @Task('Build APKs')
 @Depends(clean, sync, gencode, genlang)
 Future<void> buildapk() async {
@@ -95,7 +110,7 @@ Future<void> checkfmt() async {
       .where((x) =>
           x is File &&
           x.path.endsWith('.dart') &&
-          !x.path.contains(RegExp(r'\.(g|gr|freezed)\.dart$')))
+          !x.path.contains(RegExp(r'\.(freezed|g|gr|pi)\.dart$')))
       .map((x) => x.path);
 
   await runAsync(