feat(java): general cleanup and overhaul of glue code

dist/java/build.gradle

@@ -23,6 +23,8 @@ sourceSets {
 
 dependencies {
 	implementation 'com.github.adamheinrich:native-utils:master-SNAPSHOT'
+	compileOnly 'org.projectlombok:lombok:1.18.34'
+	annotationProcessor 'org.projectlombok:lombok:1.18.34'
 }
 
 shadowJar {

dist/java/src/mp/code/BufferController.java

@@ -5,6 +5,7 @@ import mp.code.data.Cursor;
 import mp.code.data.TextChange;
 import mp.code.exceptions.ControllerException;
 
+import java.util.Objects;
 import java.util.Optional;
 
 public class BufferController {
@@ -36,12 +37,12 @@ public class BufferController {
 
 	private static native void send(long self, TextChange change) throws ControllerException;
 	public void send(TextChange change) throws ControllerException {
-		send(this.ptr, change);
+		send(this.ptr, Objects.requireNonNull(change));
 	}
 
 	private static native void callback(long self, Callback<BufferController> cb);
 	public void callback(Callback<BufferController> cb) {
-		callback(this.ptr, cb);
+		callback(this.ptr, Objects.requireNonNull(cb));
 	}
 
 	private static native void clear_callback(long self);

dist/java/src/mp/code/Client.java

@@ -1,16 +1,17 @@
 package mp.code;
 
+import mp.code.data.Config;
 import mp.code.data.User;
 import mp.code.exceptions.ConnectionException;
 import mp.code.exceptions.ConnectionRemoteException;
 
+import java.util.Objects;
 import java.util.Optional;
 
 public class Client {
 	private final long ptr;
 
-	public static native Client connect(String username, String password) throws ConnectionException;
-	public static native Client connectToServer(String username, String password, String host, int port, boolean tls) throws ConnectionException;
+	public static native Client connect(Config config) throws ConnectionException;
 
 	Client(long ptr) {
 		this.ptr = ptr;
@@ -23,22 +24,22 @@ public class Client {
 
 	private static native Workspace join_workspace(long self, String id) throws ConnectionException;
 	public Workspace joinWorkspace(String id) throws ConnectionException {
-		return join_workspace(this.ptr, id);
+		return join_workspace(this.ptr, Objects.requireNonNull(id));
 	}
 
 	private static native void create_workspace(long self, String id) throws ConnectionRemoteException;
 	public void createWorkspace(String id) throws ConnectionRemoteException {
-		create_workspace(this.ptr, id);
+		create_workspace(this.ptr, Objects.requireNonNull(id));
 	}
 
 	private static native void delete_workspace(long self, String id) throws ConnectionRemoteException;
 	public void deleteWorkspace(String id) throws ConnectionRemoteException {
-		delete_workspace(this.ptr, id);
+		delete_workspace(this.ptr, Objects.requireNonNull(id));
 	}
 
-	private static native void invite_to_workspace(long self, String ws, String usr) throws ConnectionRemoteException;
-	public void inviteToWorkspace(String ws, String usr) throws ConnectionRemoteException {
-		invite_to_workspace(this.ptr, ws, usr);
+	private static native void invite_to_workspace(long self, String workspaceId, String user) throws ConnectionRemoteException;
+	public void inviteToWorkspace(String workspaceId, String user) throws ConnectionRemoteException {
+		invite_to_workspace(this.ptr, Objects.requireNonNull(workspaceId), Objects.requireNonNull(user));
 	}
 
 	private static native String[] list_workspaces(long self, boolean owned, boolean invited) throws ConnectionRemoteException;
@@ -53,12 +54,12 @@ public class Client {
 
 	private static native boolean leave_workspace(long self, String id);
 	public boolean leaveWorkspace(String id) {
-		return leave_workspace(this.ptr, id);
+		return leave_workspace(this.ptr, Objects.requireNonNull(id));
 	}
 
 	private static native Workspace get_workspace(long self, String workspace);
 	public Optional<Workspace> getWorkspace(String workspace) {
-		return Optional.ofNullable(get_workspace(this.ptr, workspace));
+		return Optional.ofNullable(get_workspace(this.ptr, Objects.requireNonNull(workspace)));
 	}
 
 	private static native void refresh(long self) throws ConnectionRemoteException;

dist/java/src/mp/code/CursorController.java

@@ -4,6 +4,7 @@ import mp.code.data.Callback;
 import mp.code.data.Cursor;
 import mp.code.exceptions.ControllerException;
 
+import java.util.Objects;
 import java.util.Optional;
 
 public class CursorController {
@@ -25,12 +26,12 @@ public class CursorController {
 
 	private static native void send(long self, Cursor cursor) throws ControllerException;
 	public void send(Cursor cursor) throws ControllerException {
-		send(this.ptr, cursor);
+		send(this.ptr, Objects.requireNonNull(cursor));
 	}
 
 	private static native void callback(long self, Callback<CursorController> cb);
 	public void callback(Callback<CursorController> cb) {
-		callback(this.ptr, cb);
+		callback(this.ptr, Objects.requireNonNull(cb));
 	}
 
 	private static native void clear_callback(long self);

dist/java/src/mp/code/Workspace.java

@@ -1,5 +1,6 @@
 package mp.code;
 
+import java.util.Objects;
 import java.util.Optional;
 import java.util.UUID;
 
@@ -27,7 +28,7 @@ public class Workspace {
 
 	private static native BufferController get_buffer(long self, String path);
 	public Optional<BufferController> getBuffer(String path) {
-		return Optional.ofNullable(get_buffer(this.ptr, path));
+		return Optional.ofNullable(get_buffer(this.ptr, Objects.requireNonNull(path)));
 	}
 
 	private static native String[] get_file_tree(long self, String filter, boolean strict);
@@ -42,17 +43,17 @@ public class Workspace {
 
 	private static native void create_buffer(long self, String path) throws ConnectionRemoteException;
 	public void createBuffer(String path) throws ConnectionRemoteException {
-		create_buffer(this.ptr, path);
+		create_buffer(this.ptr, Objects.requireNonNull(path));
 	}
 
 	private static native BufferController attach_to_buffer(long self, String path) throws ConnectionException;
 	public BufferController attachToBuffer(String path) throws ConnectionException {
-		return attach_to_buffer(ptr, path);
+		return attach_to_buffer(ptr, Objects.requireNonNull(path));
 	}
 
 	private static native DetachResult detach_from_buffer(long self, String path);
 	public DetachResult detachFromBuffer(String path) {
-		return detach_from_buffer(this.ptr, path);
+		return detach_from_buffer(this.ptr, Objects.requireNonNull(path));
 	}
 
 	private static native void fetch_buffers(long self) throws ConnectionRemoteException;
@@ -67,12 +68,12 @@ public class Workspace {
 
 	private static native UUID[] list_buffer_users(long self, String path) throws ConnectionRemoteException;
 	public UUID[] listBufferUsers(String path) throws ConnectionRemoteException {
-		return list_buffer_users(this.ptr, path);
+		return list_buffer_users(this.ptr, Objects.requireNonNull(path));
 	}
 
 	private static native void delete_buffer(long self, String path) throws ConnectionRemoteException;
 	public void deleteBuffer(String path) throws ConnectionRemoteException {
-		delete_buffer(this.ptr, path);
+		delete_buffer(this.ptr, Objects.requireNonNull(path));
 	}
 
 	private static native Event event(long self) throws ControllerException;

dist/java/src/mp/code/data/Config.java

@@ -0,0 +1,47 @@
+package mp.code.data;
+
+import lombok.AccessLevel;
+import lombok.EqualsAndHashCode;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+
+import java.util.Optional;
+import java.util.OptionalInt;
+
+@ToString
+@EqualsAndHashCode
+@RequiredArgsConstructor(access = AccessLevel.PRIVATE)
+@SuppressWarnings("OptionalUsedAsFieldOrParameterType")
+public class Config {
+	private final String username;
+	private final String password;
+	private final Optional<String> host;
+	private final OptionalInt port;
+	private final Optional<Boolean> tls;
+
+	public Config(String username, String password) {
+		this(
+			username,
+			password,
+			Optional.empty(),
+			OptionalInt.empty(),
+			Optional.empty()
+		);
+	}
+
+	public Config(String username, String password, String host, int port, boolean tls) {
+		this(
+			username,
+			password,
+			Optional.of(host),
+			OptionalInt.of(checkPort(port)),
+			Optional.of(tls)
+		);
+	}
+
+	private static int checkPort(int port) {
+		if(port < 0 || port > 65535)
+			throw new IllegalArgumentException("Port value must be between 0 and 65535!");
+		return port;
+	}
+}

dist/java/src/mp/code/data/Cursor.java

@@ -1,16 +1,14 @@
 package mp.code.data;
 
+import lombok.EqualsAndHashCode;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+
+@ToString
+@EqualsAndHashCode
+@RequiredArgsConstructor
 public class Cursor {
 	public final int startRow, startCol, endRow, endCol;
 	public final String buffer;
 	public final String user;
-
-	public Cursor(int startRow, int startCol, int endRow, int endCol, String buffer, String user) {
-		this.startRow = startRow;
-		this.startCol = startCol;
-		this.endRow = endRow;
-		this.endCol = endCol;
-		this.buffer = buffer;
-		this.user = user;
-	}
 }

dist/java/src/mp/code/data/TextChange.java

@@ -1,20 +1,21 @@
 package mp.code.data;
 
+import lombok.EqualsAndHashCode;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+
 import java.util.OptionalLong;
 
+@ToString
+@EqualsAndHashCode
+@RequiredArgsConstructor
+@SuppressWarnings("OptionalUsedAsFieldOrParameterType")
 public class TextChange {
-	public final long start;
-	public final long end;
+	public final int start;
+	public final int end;
 	public final String content;
 	public final OptionalLong hash; // xxh3 hash
 
-	public TextChange(long start, long end, String content, OptionalLong hash) {
-		this.start = start;
-		this.end = end;
-		this.content = content;
-		this.hash = hash;
-	}
-
 	public boolean isDelete() {
 		return this.start != this.end;
 	}

dist/java/src/mp/code/data/User.java

@@ -1,13 +1,15 @@
 package mp.code.data;
 
+import lombok.EqualsAndHashCode;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+
 import java.util.UUID;
 
+@ToString
+@EqualsAndHashCode
+@RequiredArgsConstructor
 public class User {
 	public final UUID id;
 	public final String name;
-
-	public User(UUID id, String name) {
-		this.id = id;
-		this.name = name;
-	}
 }

src/ffi/java/buffer.rs

@@ -1,8 +1,8 @@
 use jni::{objects::{JClass, JObject}, sys::{jboolean, jlong, jobject, jstring}, JNIEnv};
 
-use crate::api::Controller;
+use crate::api::{Controller, TextChange};
 
-use super::{JExceptable, JObjectify};
+use super::{handle_error, null_check, tokio, Deobjectify, JExceptable, JObjectify};
 
 /// Gets the name of the buffer. 
 #[no_mangle]
@@ -26,14 +26,14 @@ pub extern "system" fn Java_mp_code_BufferController_get_1content(
 	self_ptr: jlong,
 ) -> jstring {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
-	let content = super::tokio().block_on(controller.content())
+	let content = tokio().block_on(controller.content())
 		.jexcept(&mut env);
 	env.new_string(content)
 		.jexcept(&mut env)
 		.as_raw()
 }
 
-/// Tries to fetch a [crate::api::TextChange], or returns null if there's nothing.
+/// Tries to fetch a [TextChange], or returns null if there's nothing.
 #[no_mangle]
 pub extern "system" fn Java_mp_code_BufferController_try_1recv(
 	mut env: JNIEnv,
@@ -41,13 +41,13 @@ pub extern "system" fn Java_mp_code_BufferController_try_1recv(
 	self_ptr: jlong,
 ) -> jobject {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
-	super::tokio().block_on(controller.try_recv())
+	tokio().block_on(controller.try_recv())
 		.jexcept(&mut env)
 		.map(|change| change.jobjectify(&mut env).jexcept(&mut env).as_raw())
 		.unwrap_or_else(std::ptr::null_mut)
 }
 
-/// Blocks until it receives a [crate::api::TextChange].
+/// Blocks until it receives a [TextChange].
 #[no_mangle]
 pub extern "system" fn Java_mp_code_BufferController_recv(
 	mut env: JNIEnv,
@@ -55,66 +55,29 @@ pub extern "system" fn Java_mp_code_BufferController_recv(
 	self_ptr: jlong,
 ) -> jobject {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
-	super::tokio().block_on(controller.recv())
+	tokio().block_on(controller.recv())
 		.jexcept(&mut env)
 		.jobjectify(&mut env)
 		.jexcept(&mut env)
 		.as_raw()
 }
 
-/// Receive from Java, converts and sends a [crate::api::TextChange].
+/// Receive from Java, converts and sends a [TextChange].
 #[no_mangle]
 pub extern "system" fn Java_mp_code_BufferController_send<'local>(
-	mut env: JNIEnv,
+	mut env: JNIEnv<'local>,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JObject<'local>,
+	change: JObject<'local>,
 ) {
-	let Ok(start) = env.get_field(&input, "start", "J")
-		.and_then(|sr| sr.j())
-		.jexcept(&mut env)
-		.try_into()
-	else {
-		return env.throw_new("java/lang/IllegalArgumentException", "Start index cannot be negative!")
-			.expect("Failed to throw exception!");
-	};
-	
-	let Ok(end) = env.get_field(&input, "end", "J")
-		.and_then(|er| er.j())
-		.jexcept(&mut env)
-		.try_into()
-	else {
-		return env.throw_new("java/lang/IllegalArgumentException", "End index cannot be negative!")
-			.expect("Failed to throw exception!");
-	};
-
-	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);
-
+	null_check!(env, change, {});
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
-	super::tokio().block_on(controller.send(crate::api::TextChange {
-		start,
-		end,
-		content,
-		hash,
-	})).jexcept(&mut env);
+	let change = TextChange::deobjectify(&mut env, change);
+	if let Ok(change) = change {
+		tokio().block_on(controller.send(change)).jexcept(&mut env)
+	} else {
+		handle_error!(&mut env, change, {});
+	}
 }
 
 /// Registers a callback for buffer changes.
@@ -125,8 +88,8 @@ pub extern "system" fn Java_mp_code_BufferController_callback<'local>(
 	self_ptr: jlong,
 	cb: JObject<'local>,
 ) {
+	null_check!(env, cb, {});
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
-	
 	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!");
@@ -176,7 +139,7 @@ pub extern "system" fn Java_mp_code_BufferController_poll(
 	self_ptr: jlong,
 ) {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
-	super::tokio().block_on(controller.poll())
+	tokio().block_on(controller.poll())
 		.jexcept(&mut env);
 }
 

src/ffi/java/client.rs

@@ -1,75 +1,27 @@
-use jni::{objects::{JClass, JObject, JString, JValueGen}, sys::{jboolean, jint, jlong, jobject, jobjectArray}, JNIEnv};
-use crate::{api::Config, client::Client, Workspace};
+use jni::{objects::{JClass, JObject, JString}, sys::{jboolean, jlong, jobject, jobjectArray}, JNIEnv};
+use crate::{api::Config, client::Client, ffi::java::{handle_error, null_check}, Workspace};
 
-use super::{JExceptable, JObjectify};
+use super::{Deobjectify, JExceptable, JObjectify, tokio};
 
 /// Connect using the given credentials to the default server, and return a [Client] to interact with it.
 #[no_mangle]
 pub extern "system" fn Java_mp_code_Client_connect<'local>(
-	mut env: JNIEnv,
+	mut env: JNIEnv<'local>,
 	_class: JClass<'local>,
-	user: JString<'local>,
-	pwd: JString<'local>
+	config: JObject<'local>	
 ) -> jobject {
-	let username: String = env.get_string(&user)
-		.map(|s| s.into())
-		.jexcept(&mut env);
-	let password: String = env.get_string(&pwd)
-		.map(|s| s.into())
-		.jexcept(&mut env);
-	connect_internal(env, Config {
-		username,
-		password,
-		host: None,
-		port: None,
-		tls: None
-	})
-}
-
-/// Connect to a given URL and return a [Client] to interact with that server.
-#[no_mangle]
-#[allow(non_snake_case)]
-pub extern "system" fn Java_mp_code_Client_connectToServer<'local>(
-	mut env: JNIEnv,
-	_class: JClass<'local>,
-	user: JString<'local>,
-	pwd: JString<'local>,
-	host: JString<'local>,
-	port: jint,
-	tls: jboolean
-) -> jobject {
-	let username: String = env.get_string(&user)
-		.map(|s| s.into())
-		.jexcept(&mut env);
-	let password: String = env.get_string(&pwd)
-		.map(|s| s.into())
-		.jexcept(&mut env);
-	let host: String = env.get_string(&host)
-		.map(|s| s.into())
-		.jexcept(&mut env);
-
-	if port < 0 {
-		env.throw_new("mp/code/exceptions/JNIException", "Negative port number!")
-			.jexcept(&mut env);
+	null_check!(env, config, std::ptr::null_mut());
+	let config = Config::deobjectify(&mut env, config);
+	if config.is_err() {
+		handle_error!(&mut env, config, std::ptr::null_mut());
 	}
 
-	connect_internal(env, Config {
-		username,
-		password,
-		host: Some(host),
-		port: Some(port as u16),
-		tls: Some(tls != 0),
-	})
-}
-
-fn connect_internal(mut env: JNIEnv, config: Config) -> jobject {
-	super::tokio().block_on(Client::connect(config))
-		.map(|client| Box::into_raw(Box::new(client)) as jlong)
-		.map(|ptr| {
-			env.find_class("mp/code/Client")
-				.and_then(|class| env.new_object(class, "(J)V", &[JValueGen::Long(ptr)]))
-				.jexcept(&mut env)
-		}).jexcept(&mut env).as_raw()
+	let client = tokio().block_on(Client::connect(config.unwrap()));
+	if let Ok(client) = client {
+		client.jobjectify(&mut env).jexcept(&mut env).as_raw()
+	} else {
+		handle_error!(&mut env, client, std::ptr::null_mut());
+	}
 }
 
 /// Gets the current [crate::api::User].
@@ -92,20 +44,20 @@ pub extern "system" fn Java_mp_code_Client_join_1workspace<'local>(
 	mut env: JNIEnv<'local>,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JString<'local>
+	workspace_id: JString<'local>
 ) -> jobject {
+	null_check!(env, workspace_id, std::ptr::null_mut());
 	let client = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Client)) };
-	let workspace_id = unsafe { env.get_string_unchecked(&input) }
+	let workspace_id = unsafe { env.get_string_unchecked(&workspace_id) }
 		.map(|wid| wid.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	super::tokio().block_on(client.join_workspace(workspace_id))
-		.map(|workspace| spawn_updater(workspace.clone()))
-		.map(|workspace| Box::into_raw(Box::new(workspace)) as jlong)
-		.map(|ptr| {
-			env.find_class("mp/code/Workspace")
-				.and_then(|class| env.new_object(class, "(J)V", &[JValueGen::Long(ptr)]))
-				.jexcept(&mut env)
-		}).jexcept(&mut env).as_raw()
+	let workspace = tokio().block_on(client.join_workspace(workspace_id))
+		.map(|workspace| spawn_updater(workspace.clone()));
+	if let Ok(workspace) = workspace {
+		workspace.jobjectify(&mut env).jexcept(&mut env).as_raw()
+	} else {
+		handle_error!(&mut env, workspace, std::ptr::null_mut())
+	}
 }
 
 /// Create a workspace on server, if allowed to.
@@ -114,13 +66,14 @@ pub extern "system" fn Java_mp_code_Client_create_1workspace<'local>(
 	mut env: JNIEnv<'local>,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JString<'local>
+	workspace_id: JString<'local>
 ) {
+	null_check!(env, workspace_id, {});
 	let client = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Client)) };
-	let workspace_id = unsafe { env.get_string_unchecked(&input) }
+	let workspace_id = unsafe { env.get_string_unchecked(&workspace_id) }
 		.map(|wid| wid.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	super::tokio()
+	tokio()
 		.block_on(client.create_workspace(workspace_id))
 		.jexcept(&mut env);
 }
@@ -131,13 +84,14 @@ pub extern "system" fn Java_mp_code_Client_delete_1workspace<'local>(
 	mut env: JNIEnv<'local>,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JString<'local>
+	workspace_id: JString<'local>
 ) {
+	null_check!(env, workspace_id, {});
 	let client = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Client)) };
-	let workspace_id = unsafe { env.get_string_unchecked(&input) }
+	let workspace_id = unsafe { env.get_string_unchecked(&workspace_id) }
 		.map(|wid| wid.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	super::tokio()
+	tokio()
 		.block_on(client.delete_workspace(workspace_id))
 		.jexcept(&mut env);
 }
@@ -148,17 +102,19 @@ pub extern "system" fn Java_mp_code_Client_invite_1to_1workspace<'local>(
 	mut env: JNIEnv<'local>,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	ws: JString<'local>,
-	usr: JString<'local>
+	workspace_id: JString<'local>,
+	user: JString<'local>
 ) {
+	null_check!(env, workspace_id, {});
+	null_check!(env, user, {});
 	let client = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Client)) };
-	let workspace_id = unsafe { env.get_string_unchecked(&ws) }
+	let workspace_id = unsafe { env.get_string_unchecked(&workspace_id) }
 		.map(|wid| wid.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	let user_name = unsafe { env.get_string_unchecked(&usr) }
+	let user_name = unsafe { env.get_string_unchecked(&user) }
 		.map(|wid| wid.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	super::tokio()
+	tokio()
 		.block_on(client.invite_to_workspace(workspace_id, user_name))
 		.jexcept(&mut env);
 }
@@ -173,7 +129,7 @@ pub extern "system" fn Java_mp_code_Client_list_1workspaces<'local>(
 	invited: jboolean
 ) -> jobjectArray {
 	let client = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Client)) };
-	let list = super::tokio()
+	let list = tokio()
 		.block_on(client.list_workspaces(owned != 0, invited != 0))
 		.jexcept(&mut env);
 	env.find_class("java/lang/String")
@@ -210,7 +166,7 @@ pub extern "system" fn Java_mp_code_Client_active_1workspaces<'local>(
 // TODO: this stays until we get rid of the arc then i'll have to find a better way
 fn spawn_updater(workspace: Workspace) -> Workspace {
 	let w = workspace.clone();
-	super::tokio().spawn(async move {
+	tokio().spawn(async move {
 		loop {
 			tokio::time::sleep(std::time::Duration::from_secs(60)).await;
 			w.fetch_buffers().await.unwrap();
@@ -226,10 +182,11 @@ pub extern "system" fn Java_mp_code_Client_leave_1workspace<'local>(
 	mut env: JNIEnv<'local>,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JString<'local>
+	workspace_id: JString<'local>
 ) -> jboolean {
+	null_check!(env, workspace_id, false as jboolean);
 	let client = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Client)) };
-	unsafe { env.get_string_unchecked(&input) }
+	unsafe { env.get_string_unchecked(&workspace_id) }
 		.map(|wid| wid.to_string_lossy().to_string())
 		.map(|wid| client.leave_workspace(&wid) as jboolean)
 		.jexcept(&mut env)
@@ -241,19 +198,18 @@ pub extern "system" fn Java_mp_code_Client_get_1workspace<'local>(
 	mut env: JNIEnv<'local>,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JString<'local>
+	workspace_id: JString<'local>
 ) -> jobject {
+	null_check!(env, workspace_id, std::ptr::null_mut());
 	let client = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Client)) };
-	let workspace_id = unsafe { env.get_string_unchecked(&input) }
+	let workspace_id = unsafe { env.get_string_unchecked(&workspace_id) }
 		.map(|wid| wid.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	client.get_workspace(&workspace_id)
-		.map(|workspace| Box::into_raw(Box::new(workspace)) as jlong)
-		.map(|ptr| {
-			env.find_class("mp/code/Workspace")
-				.and_then(|class| env.new_object(class, "(J)V", &[JValueGen::Long(ptr)]))
-				.jexcept(&mut env)
-		}).unwrap_or_default().as_raw()
+	if let Some(workspace) = client.get_workspace(&workspace_id) {
+		workspace.jobjectify(&mut env).jexcept(&mut env).as_raw()
+	} else {
+		std::ptr::null_mut()
+	}
 }
 
 /// Refresh the client's session token.
@@ -264,7 +220,7 @@ pub extern "system" fn Java_mp_code_Client_refresh<'local>(
 	self_ptr: jlong,
 ) {
 	let client = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Client)) };
-	super::tokio().block_on(client.refresh())
+	tokio().block_on(client.refresh())
 		.jexcept(&mut env);
 }
 

src/ffi/java/cursor.rs

@@ -1,9 +1,9 @@
-use jni::{objects::{JClass, JObject, JString}, sys::{jboolean, jlong, jobject}, JNIEnv};
-use crate::api::Controller;
+use jni::{objects::{JClass, JObject}, sys::{jboolean, jlong, jobject}, JNIEnv};
+use crate::api::{Controller, Cursor};
 
-use super::{JExceptable, JObjectify};
+use super::{handle_error, null_check, tokio, Deobjectify, JExceptable, JObjectify};
 
-/// Try to fetch a [crate::api::Cursor], or returns null if there's nothing.
+/// Try to fetch a [Cursor], or returns null if there's nothing.
 #[no_mangle]
 pub extern "system" fn Java_mp_code_CursorController_try_1recv(
 	mut env: JNIEnv,
@@ -11,13 +11,13 @@ pub extern "system" fn Java_mp_code_CursorController_try_1recv(
 	self_ptr: jlong,
 ) -> jobject {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::cursor::Controller)) };
-	super::tokio().block_on(controller.try_recv())
+	tokio().block_on(controller.try_recv())
 		.jexcept(&mut env)
 		.map(|change| change.jobjectify(&mut env).jexcept(&mut env).as_raw())
 		.unwrap_or_else(std::ptr::null_mut)
 }
 
-/// Block until it receives a [crate::api::Cursor].
+/// Block until it receives a [Cursor].
 #[no_mangle]
 pub extern "system" fn Java_mp_code_CursorController_recv(
 	mut env: JNIEnv,
@@ -25,62 +25,29 @@ pub extern "system" fn Java_mp_code_CursorController_recv(
 	self_ptr: jlong,
 ) -> jobject {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::cursor::Controller)) };
-	super::tokio().block_on(controller.recv())
+	tokio().block_on(controller.recv())
 		.jexcept(&mut env)
 		.jobjectify(&mut env)
 		.jexcept(&mut env)
 		.as_raw()
 }
 
-/// Receive from Java, converts and sends a [crate::api::Cursor].
+/// Receive from Java, converts and sends a [Cursor].
 #[no_mangle]
 pub extern "system" fn Java_mp_code_CursorController_send<'local>(
-	mut env: JNIEnv,
+	mut env: JNIEnv<'local>,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JObject<'local>,
+	cursor: JObject<'local>,
 ) {
-	let start_row = env.get_field(&input, "startRow", "I")
-		.and_then(|sr| sr.i())
-		.jexcept(&mut env);
-	let start_col = env.get_field(&input, "startCol", "I")
-		.and_then(|sc| sc.i())
-		.jexcept(&mut env);
-	let end_row = env.get_field(&input, "endRow", "I")
-		.and_then(|er| er.i())
-		.jexcept(&mut env);
-	let end_col = env.get_field(&input, "endCol", "I")
-		.and_then(|ec| ec.i())
-		.jexcept(&mut env);
-
-	let buffer = env.get_field(&input, "buffer", "Ljava/lang/String;")
-		.and_then(|b| b.l())
-		.map(|b| b.into())
-		.jexcept(&mut env);
-	let buffer = env.get_string(&buffer)
-		.map(|b| b.into())
-		.jexcept(&mut env);
-
-	let user: JString = env.get_field(&input, "user", "Ljava/lang/String;")
-		.and_then(|u| u.l())
-		.map(|u| u.into())
-		.jexcept(&mut env);
-	let user = if user.is_null() {
-		None
-	} else {
-		Some(env.get_string(&user)
-			.map(|u| u.into())
-			.jexcept(&mut env)
-		)
-	};
-
+	null_check!(env, cursor, {});
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::cursor::Controller)) };
-	super::tokio().block_on(controller.send(crate::api::Cursor {
-		start: (start_row, start_col),
-		end: (end_row, end_col),
-		buffer,
-		user
-	})).jexcept(&mut env);
+	let cursor = Cursor::deobjectify(&mut env, cursor);
+	if let Ok(cursor) = cursor {
+		tokio().block_on(controller.send(cursor)).jexcept(&mut env)
+	} else {
+		handle_error!(&mut env, cursor, {});
+	}
 }
 
 /// Registers a callback for cursor changes.
@@ -91,6 +58,7 @@ pub extern "system" fn Java_mp_code_CursorController_callback<'local>(
 	self_ptr: jlong,
 	cb: JObject<'local>,
 ) {
+	null_check!(env, cb, {});
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::cursor::Controller)) };
 	
 	let Ok(cb_ref) = env.new_global_ref(cb) else {
@@ -142,7 +110,7 @@ pub extern "system" fn Java_mp_code_CursorController_poll(
 	self_ptr: jlong,
 ) {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::cursor::Controller)) };
-	super::tokio().block_on(controller.poll())
+	tokio().block_on(controller.poll())
 		.jexcept(&mut env);
 }
 

src/ffi/java/ext.rs

@@ -1,6 +1,6 @@
 use jni::{objects::{JClass, JString}, sys::{jboolean, jlong}, JNIEnv};
 
-use super::JExceptable;
+use super::{JExceptable, null_check};
 
 /// Calculate the XXH3 hash for a given String.
 #[no_mangle]
@@ -9,6 +9,7 @@ pub extern "system" fn Java_mp_code_Extensions_hash<'local>(
 	_class: JClass<'local>,
 	content: JString<'local>,
 ) -> jlong {
+	null_check!(env, content, 0 as jlong);
 	let content: String = env.get_string(&content)
 		.map(|s| s.into())
 		.jexcept(&mut env);

src/ffi/java/mod.rs

@@ -62,93 +62,94 @@ pub(crate) fn setup_logger(debug: bool, path: Option<String>) {
 	}
 }
 
+/// Utility macro that attempts to handle an error in a [Result].
+/// MUST be called within a $result.is_err() block or similar. Failure to do so is UB.
+/// Will return early with a provided return value, or panic if it fails to throw a Java exception.
+macro_rules! handle_error {
+	($env: expr, $result: ident, $return: expr) => {
+		{
+			let err = unsafe { $result.unwrap_err_unchecked() };
+			tracing::info!("Attempting to throw error {err:#?} as a Java exception...");
+			if let Err(e) = err.jobjectify($env).map(|t| t.into()).and_then(|t: jni::objects::JThrowable| $env.throw(&t)) {
+				panic!("Failed to throw exception: {e}");
+			}
+			return $return;
+		}
+	};
+}
+pub(crate) use handle_error;
+
+/// Performs a null check on the given variable and throws a NullPointerException on the Java side
+/// if it is null. Finally, it returns with the given default value.
+macro_rules! null_check {
+	($env: ident, $var: ident, $return: expr) => {
+		if $var.is_null() {
+			let mut message = stringify!($var).to_string();
+			message.push_str(" cannot be null!");
+			$env.throw_new("java/lang/NullPointerException", message)
+				.expect("Failed to throw exception!");
+			return $return;
+		}
+	};
+}
+pub(crate) use null_check;
+
+
 /// A trait meant for our local result type to make converting it to Java easier.
 /// jni-rs technically has [jni::errors::ToException], but this approach keeps it stream-like.
-pub(crate) trait JExceptable<T> {
+pub(crate) trait JExceptable<'local, T: Default> {
 	/// Unwrap it and throws an appropriate Java exception if it's an error.
 	/// Theoretically it returns the type's default value, but the exception makes the value ignored.
-	fn jexcept(self, env: &mut jni::JNIEnv) -> T;
+	fn jexcept(self, env: &mut jni::JNIEnv<'local>) -> T;
 }
 
-impl<T> JExceptable<T> for crate::errors::ConnectionResult<T> where T: Default {
-	fn jexcept(self, env: &mut jni::JNIEnv) -> T {
-		if let Err(err) = &self {
-			let msg = format!("{err}");
-			match err {
-				crate::errors::ConnectionError::Transport(_) => env.throw_new("mp/code/exceptions/ConnectionTransportException", msg),
-				crate::errors::ConnectionError::Remote(_) => env.throw_new("mp/code/exceptions/ConnectionRemoteException", msg),
-			}.jexcept(env);
+impl<'local, T: Default, E: JObjectify<'local> + std::fmt::Debug> JExceptable<'local, T> for Result<T, E> {
+	fn jexcept(self, env: &mut jni::JNIEnv<'local>) -> T {
+		if let Ok(res) = self {
+			res
+		} else {
+			handle_error!(env, self, Default::default());
 		}
-		self.unwrap_or_default()
-	}
-}
-
-impl<T> JExceptable<T> for crate::errors::RemoteResult<T> where T: Default {
-	fn jexcept(self, env: &mut jni::JNIEnv) -> T {
-		if let Err(err) = &self {
-			let msg = format!("{err}");
-			env.throw_new("mp/code/exceptions/ConnectionRemoteException", msg).jexcept(env);
-		}
-		self.unwrap_or_default()
-	}
-}
-
-impl<T> JExceptable<T> for crate::errors::ControllerResult<T> where T: Default {
-	fn jexcept(self, env: &mut jni::JNIEnv) -> T {
-		if let Err(err) = &self {
-			let msg = format!("{err}");
-			match err {
-				crate::errors::ControllerError::Stopped => env.throw_new("mp/code/exceptions/ControllerStoppedException", msg),
-				crate::errors::ControllerError::Unfulfilled => env.throw_new("mp/code/exceptions/ControllerUnfulfilledException", msg),
-			}.jexcept(env);
-		}
-		self.unwrap_or_default()
-	}
-}
-
-impl<T> JExceptable<T> for Result<T, jni::errors::Error> where T: Default {
-	fn jexcept(self, env: &mut jni::JNIEnv) -> T {
-		if let Err(err) = &self {
-			let msg = format!("{err}");
-			if let Err(err) = env.throw_new("mp/code/exceptions/JNIException", msg) {
-				if let Err(err) = env.exception_describe() {
-					tracing::error!("An exception occurred and we failed to even describe it: {err:#?}.");
-				}
-				panic!("A severe error occurred: we were unable to create a JNIException from {err:#?}. This is an unrecoverable state.");
-			}
-		}
-		self.unwrap_or_default()
-	}
-}
-
-impl<T> JExceptable<T> for Result<T, uuid::Error> where T: Default {
-	fn jexcept(self, env: &mut jni::JNIEnv) -> T {
-		if let Err(err) = &self {
-			let msg = format!("{err}");
-			if let Err(err) = env.throw_new("java/lang/IllegalArgumentException", msg) {
-				if let Err(err) = env.exception_describe() {
-					tracing::error!("An exception occurred and we failed to even describe it: {err:#?}.");
-				}
-				panic!("A severe error occurred: we were unable to create a JNIException from {err:#?}. This is an unrecoverable state.");
-			}
-		}
-		self.unwrap_or_default()
 	}
 }
 
 /// Allows easy conversion for various types into Java objects.
-/// This is essentially the same as [TryInto], but that can't be emplemented on non-local types.
+/// This is similar to [TryInto], but for Java types.
 pub(crate) trait JObjectify<'local> {
-	/// The error type, likely to be [jni::errors::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>;
+	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, jni::errors::Error>;
 }
 
+macro_rules! jobjectify_error {
+	($self: ident, $type: ty, $jclass: expr) => {
+		impl<'local> JObjectify<'local> for $type {
+			fn jobjectify($self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, jni::errors::Error> {
+				let class = env.find_class($jclass)?;
+				let msg = env.new_string(format!("{:#?}", $self))?;
+				env.new_object(class, "(Ljava/lang/String)V", &[jni::objects::JValueGen::Object(&msg)])
+			}
+		}
+	};
+}
+
+jobjectify_error!(self, crate::errors::RemoteError, "mp/code/exceptions/ConnectionRemoteException");
+jobjectify_error!(self, jni::errors::Error, match self {
+	jni::errors::Error::NullPtr(_) => "java/lang/NullPointerException",
+	_ => "mp/code/exceptions/JNIException"
+});
+jobjectify_error!(self, uuid::Error, "java/lang/IllegalArgumentException");
+jobjectify_error!(self, crate::errors::ConnectionError, match self { 
+	crate::errors::ConnectionError::Transport(_) => "mp/code/exceptions/ConnectionTransportException",
+	crate::errors::ConnectionError::Remote(_) => "mp/code/exceptions/ConnectionRemoteException"
+});
+jobjectify_error!(self, crate::errors::ControllerError, match self { 
+	crate::errors::ControllerError::Stopped => "mp/code/exceptions/ControllerStoppedException",
+	crate::errors::ControllerError::Unfulfilled => "mp/code/exceptions/ControllerUnfulfilledException",
+});
+
+
 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>, Self::Error> {
+	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, jni::errors::Error> {
 		let class = env.find_class("java/util/UUID")?;
 		let (msb, lsb) = self.as_u64_pair();
 		let msb = i64::from_ne_bytes(msb.to_ne_bytes());
@@ -157,10 +158,29 @@ impl<'local> JObjectify<'local> for uuid::Uuid {
 	}
 }
 
-impl<'local> JObjectify<'local> for crate::api::User {
-	type Error = jni::errors::Error;
+/// Generates a [JObjectify] implementation for a class that is just a holder for a pointer.
+macro_rules! jobjectify_ptr_class {
+	($type: ty, $jclass: literal) => {
+		impl<'local> JObjectify<'local> for $type {
+			fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, jni::errors::Error> {
+				let class = env.find_class($jclass)?;
+				env.new_object(
+					class,
+					"(J)V",
+					&[jni::objects::JValueGen::Long(Box::into_raw(Box::new(self)) as jni::sys::jlong)]
+				)
+			}
+		}
+	};
+}
 
-	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, Self::Error> {
+jobjectify_ptr_class!(crate::Client, "mp/code/Client");
+jobjectify_ptr_class!(crate::Workspace, "mp/code/Workspace");
+jobjectify_ptr_class!(crate::cursor::Controller, "mp/code/CursorController");
+jobjectify_ptr_class!(crate::buffer::Controller, "mp/code/BufferController");
+
+impl<'local> JObjectify<'local> for crate::api::User {
+	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, jni::errors::Error> {
 		let id_field = self.id.jobjectify(env)?;
 		let name_field = env.new_string(self.name)?;
 		let class = env.find_class("mp/code/data/User")?;
@@ -175,40 +195,56 @@ impl<'local> JObjectify<'local> for crate::api::User {
 	}
 }
 
-impl<'local> JObjectify<'local> for crate::cursor::Controller {
-	type Error = jni::errors::Error;
+impl<'local> JObjectify<'local> for crate::api::Event {
+	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, jni::errors::Error> {
+		let (ordinal, arg) = match self {
+			crate::api::Event::UserJoin(arg) => (0, env.new_string(arg)?),
+			crate::api::Event::UserLeave(arg) => (1, env.new_string(arg)?),
+			crate::api::Event::FileTreeUpdated(arg) => (2, env.new_string(arg)?),
+		};
 
-	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, Self::Error> {
-		let class = env.find_class("mp/code/CursorController")?;
+		let type_class = env.find_class("mp/code/Workspace$Event$Type")?;
+		let variants: jni::objects::JObjectArray = env.call_method(
+			type_class,
+			"getEnumConstants",
+			"()[Ljava/lang/Object;",
+			&[]
+		)?.l()?.into();
+		let event_type = env.get_object_array_element(variants, ordinal)?;
+		
+		let event_class = env.find_class("mp/code/Workspace$Event")?;
 		env.new_object(
-			class,
-			"(J)V",
+			event_class,
+			"(Lmp/code/Workspace$Event$Type;Ljava/lang/String;)V",
 			&[
-				jni::objects::JValueGen::Long(Box::into_raw(Box::new(self)) as jni::sys::jlong)
+				jni::objects::JValueGen::Object(&event_type),
+				jni::objects::JValueGen::Object(&arg)
 			]
 		)
 	}
 }
 
-impl<'local> JObjectify<'local> for crate::buffer::Controller {
-	type Error = jni::errors::Error;
+impl<'local> JObjectify<'local> for crate::workspace::DetachResult {
+	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, jni::errors::Error> {
+		let ordinal = match self {
+			crate::workspace::DetachResult::NotAttached => 0,
+			crate::workspace::DetachResult::Detaching => 1,
+			crate::workspace::DetachResult::AlreadyDetached => 2
+		};
 
-	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(
+		let class = env.find_class("mp/code/data/DetachResult")?;
+		let variants: jni::objects::JObjectArray = env.call_method(
 			class,
-			"(J)V",
-			&[
-				jni::objects::JValueGen::Long(Box::into_raw(Box::new(self)) as jni::sys::jlong)
-			]
-		)
+			"getEnumConstants",
+			"()[Ljava/lang/Object;",
+			&[]
+		)?.l()?.into();
+		env.get_object_array_element(variants, ordinal)
 	}
 }
 
 impl<'local> JObjectify<'local> for crate::api::TextChange {
-	type Error = jni::errors::Error;
-
-	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, Self::Error> {
+	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, jni::errors::Error> {
 		let content = env.new_string(self.content)?;
 
 		let hash = env.find_class("java/util/OptionalLong").and_then(|class| {
@@ -223,8 +259,8 @@ impl<'local> JObjectify<'local> for crate::api::TextChange {
 				class,
 				"(JJLjava/lang/String;Ljava/util/OptionalLong;)V",
 				&[
-					jni::objects::JValueGen::Long(jni::sys::jlong::from(self.start)),
-					jni::objects::JValueGen::Long(jni::sys::jlong::from(self.end)),
+					jni::objects::JValueGen::Long(self.start.into()),
+					jni::objects::JValueGen::Long(self.end.into()),
 					jni::objects::JValueGen::Object(&content),
 					jni::objects::JValueGen::Object(&hash)
 				]
@@ -234,9 +270,7 @@ impl<'local> JObjectify<'local> for crate::api::TextChange {
 }
 
 impl<'local> JObjectify<'local> for crate::api::Cursor {
-	type Error = jni::errors::Error;
-
-	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, Self::Error> {
+	fn jobjectify(self, env: &mut jni::JNIEnv<'local>) -> Result<jni::objects::JObject<'local>, jni::errors::Error> {
 		env.find_class("mp/code/data/Cursor").and_then(|class| {
 			let buffer = env.new_string(&self.buffer)?;
 			let user = if let Some(user) = self.user {
@@ -260,3 +294,114 @@ impl<'local> JObjectify<'local> for crate::api::Cursor {
 		})
 	}
 }
+
+/// Allows easy conversion of Java types into their Rust counterparts.
+pub(crate) trait Deobjectify<'local, T: Sized> {
+	/// Attempt to convert the given [jni::objects::JObject] into its Rust counterpart.
+	fn deobjectify(env: &mut jni::JNIEnv<'local>, jobject: jni::objects::JObject<'local>) -> Result<T, jni::errors::Error>;
+}
+
+impl<'local> Deobjectify<'local, Self> for crate::api::Config {
+	fn deobjectify(env: &mut jni::JNIEnv<'local>, config: jni::objects::JObject<'local>) -> Result<Self, jni::errors::Error> {
+		let username = {
+			let jfield = env.get_field(&config, "username", "Ljava/lang/String;")?.l()?;
+			if jfield.is_null() {
+				return Err(jni::errors::Error::NullPtr("Username can never be null!"));
+			}
+			unsafe { env.get_string_unchecked(&jfield.into()) }?.into()
+		};
+
+		let password = {
+			let jfield = env.get_field(&config, "password", "Ljava/lang/String;")?.l()?;
+			if jfield.is_null() {
+				return Err(jni::errors::Error::NullPtr("Password can never be null!"));
+			}
+			unsafe { env.get_string_unchecked(&jfield.into()) }?.into()
+		};
+
+		let host = {
+			let jfield = env.get_field(&config, "host", "Ljava/util/Optional;")?.l()?;
+			if env.call_method(&jfield, "isPresent", "()Z", &[])?.z()? {
+				let field = env.call_method(&jfield, "get", "()Ljava/lang/Object;", &[])?.l()?;
+				Some(unsafe { env.get_string_unchecked(&field.into()) }?.into())
+			} else {
+				None
+			}
+		};
+
+		let port = {
+			let jfield = env.get_field(&config, "port", "Ljava/util/OptionalInt;")?.l()?;
+			if env.call_method(&jfield, "isPresent", "()Z", &[])?.z()? {
+				let ivalue = env.call_method(&jfield, "get", "()I", &[])?.i()?;
+				Some(ivalue.clamp(0, 65535) as u16)
+			} else {
+				None
+			}
+		};
+
+		let tls = {
+			let jfield = env.get_field(&config, "host", "Ljava/util/Optional;")?.l()?;
+			if env.call_method(&jfield, "isPresent", "()Z", &[])?.z()? {
+				let field = env.call_method(&jfield, "get", "()Ljava/lang/Object;", &[])?.l()?;
+				Some(env.call_method(field, "booleanValue", "()Z", &[])?.z()?)
+			} else {
+				None
+			}
+		};
+
+		Ok(Self { username, password, host, port, tls })
+	}
+}
+
+impl<'local> Deobjectify<'local, Self> for crate::api::Cursor {
+	fn deobjectify(env: &mut jni::JNIEnv<'local>, cursor: jni::objects::JObject<'local>) -> Result<Self, jni::errors::Error> {
+		let start_row = env.get_field(&cursor, "startRow", "I")?.i()?;
+		let start_col = env.get_field(&cursor, "startCol", "I")?.i()?;
+		let end_row = env.get_field(&cursor, "endRow", "I")?.i()?;
+		let end_col = env.get_field(&cursor, "endCol", "I")?.i()?;
+
+		let buffer = {
+			let jfield = env.get_field(&cursor, "buffer", "Ljava/lang/String;")?.l()?;
+			if jfield.is_null() {
+				return Err(jni::errors::Error::NullPtr("Buffer can never be null!"));
+			}
+			unsafe { env.get_string_unchecked(&jfield.into()) }?.into()
+		};
+	
+		let user = {
+			let jfield = env.get_field(&cursor, "user", "Ljava/lang/String;")?.l()?;
+			if jfield.is_null() {
+				None
+			} else {
+				Some(unsafe { env.get_string_unchecked(&jfield.into()) }?.into())
+			}
+		};
+
+		Ok(Self { start: (start_row, start_col), end: (end_row, end_col), buffer, user })
+	}
+}
+
+impl<'local> Deobjectify<'local, Self> for crate::api::TextChange {
+	fn deobjectify(env: &mut jni::JNIEnv<'local>, change: jni::objects::JObject<'local>) -> Result<Self, jni::errors::Error> {
+		let start = env.get_field(&change, "start", "I")?.j()?.max(0) as u32;
+		let end = env.get_field(&change, "end", "I")?.j()?.max(0) as u32;
+
+		let content = {
+			let jfield = env.get_field(&change, "content", "Ljava/lang/String;")?.l()?;
+			if jfield.is_null() {
+				return Err(jni::errors::Error::NullPtr("Content can never be null!"));
+			}
+			unsafe { env.get_string_unchecked(&jfield.into()) }?.into()
+		};
+
+		let hash = {
+			let jfield = env.get_field(&change, "hash", "Ljava/util/OptionalLong;")?.l()?;
+			if env.call_method(&jfield, "isPresent", "()Z", &[])?.z()? {
+				Some(env.call_method(&jfield, "getAsLong", "()J", &[])?.j()?)
+			} else {
+				None
+			}
+		};
+		Ok(Self { start, end, content, hash })
+	}
+}

src/ffi/java/workspace.rs

@@ -1,7 +1,7 @@
-use jni::{objects::{JClass, JObject, JObjectArray, JString, JValueGen}, sys::{jboolean, jlong, jobject, jobjectArray, jstring}, JNIEnv};
+use jni::{objects::{JClass, JObject, JString}, sys::{jboolean, jlong, jobject, jobjectArray, jstring}, JNIEnv};
 use crate::Workspace;
 
-use super::{JExceptable, JObjectify};
+use super::{handle_error, null_check, JExceptable, JObjectify};
 
 /// Get the workspace id.
 #[no_mangle]
@@ -31,14 +31,11 @@ pub extern "system" fn Java_mp_code_Workspace_get_1buffer<'local>(
 	mut env: JNIEnv<'local>,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JString<'local>
+	path: JString<'local>
 ) -> jobject {
-	if input.is_null() {
-		return std::ptr::null_mut();
-	}
-
+	null_check!(env, path, std::ptr::null_mut());
 	let workspace = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Workspace)) };
-	let path = unsafe { env.get_string_unchecked(&input) }
+	let path = unsafe { env.get_string_unchecked(&path) }
 		.map(|path| path.to_string_lossy().to_string())
 		.jexcept(&mut env);
 	workspace.buffer_by_name(&path)
@@ -105,15 +102,11 @@ pub extern "system" fn Java_mp_code_Workspace_create_1buffer<'local>(
 	mut env: JNIEnv,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JString<'local>
+	path: JString<'local>
 ) {
-	if input.is_null() {
-		return env.throw_new("java/lang/NullPointerException", "Buffer name cannot be null!")
-			.expect("Failed to throw exception!");
-	}
-
+	null_check!(env, path, {});
 	let ws = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Workspace)) };
-	let path = unsafe { env.get_string_unchecked(&input) }
+	let path = unsafe { env.get_string_unchecked(&path) }
 		.map(|path| path.to_string_lossy().to_string())
 		.jexcept(&mut env);
 	super::tokio().block_on(ws.create(&path))
@@ -126,10 +119,11 @@ pub extern "system" fn Java_mp_code_Workspace_attach_1to_1buffer<'local>(
 	mut env: JNIEnv,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JString<'local>
+	path: JString<'local>
 ) -> jobject {
+	null_check!(env, path, std::ptr::null_mut());
 	let workspace = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Workspace)) };
-	let path = unsafe { env.get_string_unchecked(&input) }
+	let path = unsafe { env.get_string_unchecked(&path) }
 		.map(|path| path.to_string_lossy().to_string())
 		.jexcept(&mut env);
 	super::tokio().block_on(workspace.attach(&path))
@@ -144,21 +138,15 @@ pub extern "system" fn Java_mp_code_Workspace_detach_1from_1buffer<'local>(
 	mut env: JNIEnv,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JString<'local>
+	path: JString<'local>
 ) -> jobject {
+	null_check!(env, path, std::ptr::null_mut());
 	let workspace = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Workspace)) };
-	let path = unsafe { env.get_string_unchecked(&input) }
+	let path = unsafe { env.get_string_unchecked(&path) }
 		.map(|path| path.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	let name = match workspace.detach(&path) {
-		crate::workspace::DetachResult::NotAttached => "NOT_ATTACHED",
-		crate::workspace::DetachResult::Detaching => "DETACHED",
-		crate::workspace::DetachResult::AlreadyDetached => "ALREADY_DETACHED"
-	};
-
-	env.find_class("mp/code/data/DetachResult")
-		.and_then(|class| env.get_static_field(class, name, "Lmp/code/data/DetachResult;"))
-		.and_then(|res| res.l())
+	workspace.detach(&path)
+		.jobjectify(&mut env)
 		.jexcept(&mut env)
 		.as_raw()
 }
@@ -191,10 +179,11 @@ pub extern "system" fn Java_mp_code_Workspace_list_1buffer_1users<'local>(
 	mut env: JNIEnv,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JString<'local>,
+	path: JString<'local>,
 ) -> jobjectArray {
+	null_check!(env, path, std::ptr::null_mut());
 	let workspace = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Workspace)) };
-	let buffer = unsafe { env.get_string_unchecked(&input) }
+	let buffer = unsafe { env.get_string_unchecked(&path) }
 		.map(|buffer| buffer.to_string_lossy().to_string())
 		.jexcept(&mut env);
 	let users = super::tokio().block_on(workspace.list_buffer_users(&buffer))
@@ -221,10 +210,11 @@ pub extern "system" fn Java_mp_code_Workspace_delete_1buffer<'local>(
 	mut env: JNIEnv,
 	_class: JClass<'local>,
 	self_ptr: jlong,
-	input: JString<'local>,
+	path: JString<'local>,
 ) {
+	null_check!(env, path, {});
 	let workspace = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Workspace)) };
-	let buffer = unsafe { env.get_string_unchecked(&input) }
+	let buffer = unsafe { env.get_string_unchecked(&path) }
 		.map(|buffer| buffer.to_string_lossy().to_string())
 		.jexcept(&mut env);
 	super::tokio().block_on(workspace.delete(&buffer))
@@ -239,30 +229,12 @@ pub extern "system" fn Java_mp_code_Workspace_event(
 	self_ptr: jlong
 ) -> jobject {
 	let workspace = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Workspace)) };
-	super::tokio().block_on(workspace.event())
-		.map(|event| {
-			let (ordinal, arg) = match event {
-				crate::api::Event::UserJoin(arg) => (0, env.new_string(arg).unwrap_or_default()),
-				crate::api::Event::UserLeave(arg) => (1, env.new_string(arg).unwrap_or_default()),
-				crate::api::Event::FileTreeUpdated(arg) => (2, env.new_string(arg).unwrap_or_default()),
-			};
-
-			let event_type = env.find_class("mp/code/Workspace$Event$Type")
-				.and_then(|class| env.call_method(class, "getEnumConstants", "()[Ljava/lang/Object;", &[]))
-				.and_then(|enums| enums.l().map(|e| e.into()))
-				.and_then(|enums: JObjectArray| env.get_object_array_element(enums, ordinal))
-				.jexcept(&mut env);
-			env.find_class("mp/code/Workspace$Event").and_then(|class|
-				env.new_object(
-					class,
-					"(Lmp/code/Workspace$Event$Type;Ljava/lang/String;)V",
-					&[
-						JValueGen::Object(&event_type),
-						JValueGen::Object(&arg)
-					]
-				)
-			).jexcept(&mut env)
-		}).jexcept(&mut env).as_raw()
+	let event = super::tokio().block_on(workspace.event());
+	if let Ok(event) = event {
+		event.jobjectify(&mut env).jexcept(&mut env).as_raw()
+	} else {
+		handle_error!(&mut env, event, std::ptr::null_mut())
+	}
 }
 
 /// Called by the Java GC to drop a [Workspace].