1 files changed, 133 insertions, 0 deletions
diff --git a/src/entity.rs b/src/entity.rs
new file mode 100644
index 0000000..9cf6f17
--- /dev/null
+++ b/src/entity.rs
@@ -0,0 +1,133 @@
+use core::{
+	alloc::Layout,
+	marker::PhantomData,
+	ops::{Deref, DerefMut},
+};
+
+use alloc::{
+	alloc::{alloc, dealloc},
+	borrow::Cow,
+	string::String,
+};
+use serde::{Deserialize, Serialize};
+
+use crate::ScriptContext;
+
+mod tortuise {
+	#[link(wasm_import_module = "tortuise")]
+	unsafe extern "C" {
+		pub unsafe fn entity_size(context: u64, name: *const u8, name_len: usize) -> usize;
+		pub unsafe fn load_entity(context: u64, name: *const u8, name_len: usize, offset: *mut u8);
+		pub unsafe fn save_entity(
+			context: u64,
+			name: *const u8,
+			name_len: usize,
+			offset: *const u8,
+			size: usize,
+		);
+	}
+}
+
+fn load_entity<'de, T: Deserialize<'de>>(context: u64, name: &str) -> Option<T> {
+	unsafe {
+		let size = tortuise::entity_size(context, name.as_ptr(), name.len());
+		let Ok(layout) = Layout::array::<u8>(size) else {
+			log::error!("Failed to create layout for size: {size}");
+			panic!();
+		};
+		let ptr = alloc(layout);
+		tortuise::load_entity(context, name.as_ptr(), name.len(), ptr);
+		let data = core::slice::from_raw_parts(ptr, size);
+		let data = messagepack_serde::from_slice(data).ok()?;
+		dealloc(ptr, layout);
+		Some(data)
+	}
+}
+
+fn save_entity<T: Serialize>(context: u64, name: &str, state: &T) {
+	unsafe {
+		let data = messagepack_serde::to_vec(state).unwrap();
+		tortuise::save_entity(
+			context,
+			name.as_ptr(),
+			name.len(),
+			data.as_ptr(),
+			data.len(),
+		);
+	}
+}
+
+pub struct Entity<T> {
+	name: Cow<'static, str>,
+	default: fn() -> T,
+}
+
+pub struct EntityRef<'entity, T> {
+	entity: PhantomData<&'entity Entity<T>>,
+	data: T,
+}
+
+pub struct EntityMut<'entity, T: Serialize> {
+	context: u64,
+	entity: &'entity Entity<T>,
+	data: T,
+}
+
+impl<'de, T: Serialize + Deserialize<'de>> Entity<T> {
+	pub const fn new(name: &'static str, default: fn() -> T) -> Self {
+		Self {
+			name: Cow::Borrowed(name),
+			default,
+		}
+	}
+
+	pub const fn from_string(name: String, default: fn() -> T) -> Self {
+		Self {
+			name: Cow::Owned(name),
+			default,
+		}
+	}
+
+	pub fn get(&self, context: &ScriptContext) -> EntityRef<'_, T> {
+		EntityRef {
+			entity: PhantomData,
+			data: load_entity(context.0, &self.name).unwrap_or_else(self.default),
+		}
+	}
+
+	pub fn get_mut(&mut self, context: &ScriptContext) -> EntityMut<'_, T> {
+		EntityMut {
+			context: context.0,
+			entity: self,
+			data: load_entity(context.0, &self.name).unwrap_or_else(self.default),
+		}
+	}
+}
+
+impl<T> Deref for EntityRef<'_, T> {
+	type Target = T;
+
+	fn deref(&self) -> &Self::Target {
+		&self.data
+	}
+}
+
+impl<T: Serialize> Deref for EntityMut<'_, T> {
+	type Target = T;
+
+	fn deref(&self) -> &Self::Target {
+		&self.data
+	}
+}
+
+impl<T: Serialize> DerefMut for EntityMut<'_, T> {
+	fn deref_mut(&mut self) -> &mut Self::Target {
+		&mut self.data
+	}
+}
+
+impl<T: Serialize> Drop for EntityMut<'_, T> {
+	fn drop(&mut self) {
+		save_entity(self.context, &self.entity.name, &self.data);
+	}
+}