1 files changed, 84 insertions, 0 deletions
diff --git a/src/storage.rs b/src/storage.rs
new file mode 100644
index 0000000..48fdcb4
--- /dev/null
+++ b/src/storage.rs
@@ -0,0 +1,84 @@
+use core::{
+	alloc::Layout,
+	ops::{Deref, DerefMut},
+};
+
+use alloc::alloc::{alloc, dealloc};
+use serde::{Deserialize, Serialize};
+
+use crate::ScriptContext;
+
+mod tortuise {
+	#[link(wasm_import_module = "tortuise")]
+	unsafe extern "C" {
+		pub safe fn storage_size(context: u64) -> usize;
+		pub unsafe fn load_storage(context: u64, ptr: *mut u8);
+		pub unsafe fn save_storage(context: u64, ptr: *const u8, size: usize);
+	}
+}
+
+fn load_storage<'de, T: Deserialize<'de>>(context: u64) -> Option<T> {
+	unsafe {
+		let size = tortuise::storage_size(context);
+		let layout = Layout::array::<u8>(size).unwrap();
+		let ptr = alloc(layout);
+		tortuise::load_storage(context, 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_storage<T: Serialize>(context: u64, state: &T) {
+	unsafe {
+		let data = messagepack_serde::to_vec(state).unwrap();
+		tortuise::save_storage(context, data.as_ptr(), data.len());
+	}
+}
+
+pub struct Storage<T> {
+	initial_state: fn() -> T,
+}
+
+pub struct StorageMut<T: Serialize> {
+	context: u64,
+	data: T,
+}
+
+impl<'de, T: Serialize + Deserialize<'de>> Storage<T> {
+	pub const fn new(initial_state: fn() -> T) -> Self {
+		Self { initial_state }
+	}
+
+	pub fn load(&self, context: &ScriptContext) -> T {
+		load_storage(context.0).unwrap_or_else(self.initial_state)
+	}
+
+	pub fn load_mut(&self, context: &ScriptContext) -> StorageMut<T> {
+		StorageMut {
+			context: context.0,
+			data: load_storage(context.0).unwrap_or_else(self.initial_state),
+		}
+	}
+}
+
+impl<T: Serialize> Deref for StorageMut<T> {
+	type Target = T;
+
+	fn deref(&self) -> &Self::Target {
+		&self.data
+	}
+}
+
+impl<T: Serialize> DerefMut for StorageMut<T> {
+	fn deref_mut(&mut self) -> &mut Self::Target {
+		&mut self.data
+	}
+}
+
+impl<T: Serialize> Drop for StorageMut<T> {
+	fn drop(&mut self) {
+		save_storage(self.context, &self.data);
+	}
+}