feat(java): callback API, buffer send

Co-authored-by: alemi <me@alemi.dev>

src/ffi/java/buffer.rs

@@ -1,6 +1,6 @@
 use jni::{objects::{JClass, JObject, JValueGen}, sys::{jlong, jobject, jstring}, JNIEnv};
 
-use crate::api::Controller;
+use crate::{api::Controller, ffi::java::handle_callback};
 
 use super::{JExceptable, RT};
 
@@ -87,3 +87,70 @@ fn recv_jni(env: &mut JNIEnv, change: Option<crate::api::TextChange>) -> jobject
 		}
 	}.as_raw()
 }
+
+#[no_mangle]
+pub extern "system" fn Java_mp_code_BufferController_callback<'local>(
+	mut env: JNIEnv,
+	_class: JClass<'local>,
+	self_ptr: jlong,
+	cb: JObject<'local>,
+) {
+	handle_callback!("mp/code/BufferController", env, self_ptr, cb, crate::buffer::Controller);
+}
+
+/// Receive from Java, converts and sends a [crate::api::TextChange].
+#[no_mangle]
+pub extern "system" fn Java_mp_code_BufferController_send<'local>(
+	mut env: JNIEnv,
+	_class: JClass<'local>,
+	self_ptr: jlong,
+	input: JObject<'local>,
+) {
+	let Ok(start) = env.get_field(&input, "start", "I")
+		.and_then(|sr| sr.i())
+		.jexcept(&mut env)
+		.try_into()
+	else {
+		env.throw_new("java/lang/IllegalArgumentException", "Start index cannot be negative!")
+			.expect("Failed to throw exception!");
+		return;
+	};
+	
+	let Ok(end) = env.get_field(&input, "end", "I")
+		.and_then(|er| er.i())
+		.jexcept(&mut env)
+		.try_into()
+	else {
+		env.throw_new("java/lang/IllegalArgumentException", "End index cannot be negative!")
+			.expect("Failed to throw exception!");
+		return;
+	};
+
+	let content = env.get_field(&input, "content", "Ljava/lang/String;")
+		.and_then(|b| b.l())
+		.map(|b| b.into())
+		.jexcept(&mut env);
+	let content = env.get_string(&content)
+		.map(|b| b.into())
+		.jexcept(&mut env);
+
+	let hash = env.get_field(&input, "hash", "Ljava/util/OptionalLong")
+		.and_then(|hash| hash.l())
+		.and_then(|hash| {
+			if env.call_method(&hash, "isPresent", "()Z", &[]).and_then(|r| r.z()).jexcept(&mut env) {
+				env.call_method(&hash, "getAsLong", "()J", &[])
+					.and_then(|r| r.j())
+					.map(Some)
+			} else {
+				Ok(None)
+			}
+		}).jexcept(&mut env);
+
+	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
+	RT.block_on(controller.send(crate::api::TextChange {
+		start,
+		end,
+		content,
+		hash,
+	})).jexcept(&mut env);
+}

src/ffi/java/cursor.rs

@@ -1,7 +1,7 @@
 use jni::{objects::{JClass, JObject, JString, JValueGen}, sys::{jlong, jobject}, JNIEnv};
 use crate::api::Controller;
 
-use super::{JExceptable, RT};
+use super::{handle_callback, JExceptable, RT};
 
 /// Try to fetch a [crate::api::Cursor], or returns null if there's nothing.
 #[no_mangle]
@@ -56,6 +56,16 @@ fn jni_recv(env: &mut JNIEnv, cursor: Option<crate::api::Cursor>) -> jobject {
 	}.as_raw()
 }
 
+#[no_mangle]
+pub extern "system" fn Java_mp_code_CursorController_callback<'local>(
+	mut env: JNIEnv,
+	_class: JClass<'local>,
+	self_ptr: jlong,
+	cb: JObject<'local>,
+) {
+	handle_callback!("mp/code/CursorController", env, self_ptr, cb, crate::cursor::Controller);
+}
+
 /// Receive from Java, converts and sends a [crate::api::Cursor].
 #[no_mangle]
 pub extern "system" fn Java_mp_code_CursorController_send<'local>(

src/ffi/java/mod.rs

@@ -105,7 +105,7 @@ impl<T> JExceptable<T> for Result<T, uuid::Error> where T: Default {
 /// This is essentially the same as [TryInto], but that can't be emplemented on non-local types.
 pub(crate) trait JObjectify<'local> {
 	/// The error type, likely to be [jni::errors::Error].
-	type Error;
+	type Error: std::fmt::Debug;
 
 	/// Attempt to convert the given object to a [jni::objects::JObject].
 	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, Self::Error>;
@@ -113,7 +113,7 @@ pub(crate) trait JObjectify<'local> {
 
 impl<'local> JObjectify<'local> for uuid::Uuid {
 	type Error = jni::errors::Error;
-	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, jni::errors::Error> {
+	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, Self::Error> {
 		env.find_class("java/util/UUID").and_then(|class| {
 			let (msb, lsb) = self.as_u64_pair();
 			let msb = i64::from_ne_bytes(msb.to_ne_bytes());
@@ -122,3 +122,71 @@ impl<'local> JObjectify<'local> for uuid::Uuid {
 		})
 	}
 }
+
+impl<'local> JObjectify<'local> for crate::cursor::Controller {
+	type Error = jni::errors::Error;
+
+	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, Self::Error> {
+		let class = env.find_class("mp/code/CursorController")?;
+		env.new_object(
+			class,
+			"(J)V",
+			&[
+				jni::objects::JValueGen::Long(Box::into_raw(Box::new(&self)) as jni::sys::jlong)
+			]
+		)
+	}
+}
+
+impl<'local> JObjectify<'local> for crate::buffer::Controller {
+	type Error = jni::errors::Error;
+
+	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, Self::Error> {
+		let class = env.find_class("mp/code/BufferController")?;
+		env.new_object(
+			class,
+			"(J)V",
+			&[
+				jni::objects::JValueGen::Long(Box::into_raw(Box::new(&self)) as jni::sys::jlong)
+			]
+		)
+	}
+}
+
+macro_rules! handle_callback {
+	($jtype:literal, $env:ident, $self_ptr:ident, $cb:ident, $t:ty) => {
+		let controller = unsafe { Box::leak(Box::from_raw($self_ptr as *mut $t)) };
+		
+		let Ok(jvm) = $env.get_java_vm() else {
+			$env.throw_new("mp/code/exceptions/JNIException", "Failed to get JVM reference!")
+				.expect("Failed to throw exception!");
+			return;
+		};
+
+		let Ok(cb_ref) = $env.new_global_ref($cb) else {
+			$env.throw_new("mp/code/exceptions/JNIException", "Failed to pin callback reference!")
+				.expect("Failed to throw exception!");
+			return;
+		};
+		controller.callback(move |controller: $t| {
+			use std::ops::DerefMut;
+			use crate::ffi::java::JObjectify;
+			let mut guard = jvm.attach_current_thread().unwrap();
+			let jcontroller = match controller.jobjectify(guard.deref_mut()) {
+				Err(e) => return tracing::error!("could not convert callback argument: {e:?}"),
+				Ok(x) => x,
+			};
+			let sig = format!("(L{};)V", $jtype);
+			if let Err(e) = guard.call_method(&cb_ref,
+				"invoke",
+				&sig,
+				&[jni::objects::JValueGen::Object(&jcontroller)]
+			) {
+				tracing::error!("error invoking callback: {e:?}");
+			}
+		});
+	};
+}
+
+pub(crate) use handle_callback;
+

src/ffi/java/workspace.rs

@@ -22,9 +22,7 @@ pub extern "system" fn Java_mp_code_Workspace_get_1cursor<'local>(
 	self_ptr: jlong
 ) -> jobject {
 	let workspace = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Workspace)) };
-	env.find_class("mp/code/CursorController").and_then(|class|
-		env.new_object(class, "(J)V", &[JValueGen::Long(Box::into_raw(Box::new(workspace.cursor())) as jlong)])
-	).jexcept(&mut env).as_raw()
+	workspace.cursor().jobjectify(&mut env).jexcept(&mut env).as_raw()
 }
 
 /// Get a buffer controller by name and returns a pointer to it.
@@ -39,12 +37,10 @@ pub extern "system" fn Java_mp_code_Workspace_get_1buffer<'local>(
 	let path = unsafe { env.get_string_unchecked(&input) }
 		.map(|path| path.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	
-	workspace.buffer_by_name(&path).map(|buf| {
-		env.find_class("mp/code/BufferController").and_then(|class|
-			env.new_object(class, "(J)V", &[JValueGen::Long(Box::into_raw(Box::new(buf)) as jlong)])
-		).jexcept(&mut env)
-	}).unwrap_or_default().as_raw()
+	workspace.buffer_by_name(&path)
+		.map(|buf| buf.jobjectify(&mut env).jexcept(&mut env))
+		.unwrap_or_default()
+		.as_raw()
 }
 
 /// Create a new buffer.
@@ -108,12 +104,9 @@ pub extern "system" fn Java_mp_code_Workspace_attach_1to_1buffer<'local>(
 		.map(|path| path.to_string_lossy().to_string())
 		.jexcept(&mut env);
 	RT.block_on(workspace.attach(&path))
-		.map(|buffer| Box::into_raw(Box::new(buffer)) as jlong)
-		.map(|ptr| {
-			env.find_class("mp/code/BufferController")
-				.and_then(|class| env.new_object(class, "(J)V", &[JValueGen::Long(ptr)]))
+		.map(|buffer| buffer.jobjectify(&mut env).jexcept(&mut env))
 		.jexcept(&mut env)
-		}).jexcept(&mut env).as_raw()
+		.as_raw()
 }
 
 /// Detach from a buffer.