rs-luau 0.0.3

#[cfg(feature = "compiler")]
pub mod compile;

pub mod ffi;
mod libs;
mod memory;
mod threads;
mod userdata;

use std::{
    any::Any,
    cell::Cell,
    ffi::{c_int, c_uint, c_void, CStr, CString},
    ptr::{null, null_mut},
    rc::Rc,
    slice,
};

use ffi::{
    luauconf::{LUAI_MAXCSTACK, LUA_MEMORY_CATEGORIES},
    prelude::*,
};
use memory::{luau_alloc_cb, DefaultLuauAllocator};
use userdata::{
    drop_userdata, dtor_rs_luau_userdata_callback, Userdata, UserdataBorrowError, UserdataRef,
    UserdataRefMut, UD_TAG,
};

pub use ffi::prelude::LuauStatus;
pub use libs::LuauLibs;
pub use memory::LuauAllocator;
pub use threads::LuauThread;

macro_rules! luau_stack_precondition {
    ($cond:expr) => {
        assert!(
            $cond,
            "Stack indicies should not exceed the top of the stack or extend below."
        )
    };
}

struct AssociatedData {
    main_thread_rc: Rc<Cell<bool>>,
    allocator: Box<dyn LuauAllocator>,
    app_data: Option<Box<dyn Any>>,
}

#[cfg(feature = "codegen")]
/// Returns true if codegen is supported for the given platform
pub fn codegen_supported() -> bool {
    unsafe { luau_codegen_supported() == 1 }
}

/// Main struct implementing luau functionality
pub struct Luau {
    owned: bool,
    state: *mut _LuaState,
}

impl Luau {
    unsafe fn new_state(allocator: impl LuauAllocator + 'static) -> *mut _LuaState {
        let associated_data = Box::new(AssociatedData {
            main_thread_rc: Rc::new(Cell::new(true)),
            app_data: None,
            allocator: Box::new(allocator),
        });

        let state = lua_newstate(luau_alloc_cb, Box::into_raw(associated_data) as _);

        lua_setuserdatadtor(state, UD_TAG, Some(dtor_rs_luau_userdata_callback));

        (*lua_callbacks(state)).panic = Some(fatal_error_handler);

        state
    }

    pub fn new(allocator: impl LuauAllocator + 'static) -> Self {
        let state = unsafe { Self::new_state(allocator) };

        if state.is_null() {
            panic!("Initialization of Luau failed");
        }

        Self { owned: true, state }
    }

    #[cfg(feature = "codegen")]
    /// Enables codegen for the given state
    pub fn enable_codegen(&self) {
        unsafe {
            luau_codegen_create(self.state);
        }
    }

    /// Creates a Luau struct from a raw state pointer
    ///
    /// # Safety
    /// The pointer must be a valid Luau state created by `Luau::new`
    pub unsafe fn from_ptr(state: *mut _LuaState) -> Self {
        Self {
            owned: false,
            state,
        }
    }

    /// Creates a Luau struct from a raw state pointer
    ///
    /// # Safety
    /// The pointer must be a valid Luau state and must not alias a Luau struct
    pub unsafe fn from_ptr_owned(state: *mut _LuaState) -> Self {
        Self { owned: true, state }
    }

    const ASSOCIATED_DATA_ERROR: &str = "Expected associated data structure";

    pub(crate) fn get_associated(&self) -> &AssociatedData {
        unsafe {
            let mut ptr: *const AssociatedData = null();
            lua_getallocf(self.state, &raw mut ptr as _);

            ptr.as_ref().expect(Self::ASSOCIATED_DATA_ERROR)
        }
    }

    pub(crate) fn get_associated_mut(&self) -> *mut AssociatedData {
        unsafe {
            let mut ptr: *mut AssociatedData = null_mut();
            lua_getallocf(self.state, &raw mut ptr as _);

            assert!(!ptr.is_null(), "{}", Self::ASSOCIATED_DATA_ERROR);

            ptr
        }
    }

    pub fn get_app_data<T: Any>(&self) -> Option<&T> {
        self.get_associated()
            .app_data
            .as_ref()
            .and_then(|v| v.downcast_ref())
    }

    /// Sets the associated app data for the Luau state returning the previous value
    pub fn set_app_data<T: Any>(&self, ud: Option<T>) -> Option<Box<dyn Any>> {
        let associated = unsafe { &mut *self.get_associated_mut() };

        if let Some(v) = ud {
            let boxed_data = Box::new(v);

            associated.app_data.replace(boxed_data)
        } else {
            associated.app_data.take()
        }
    }

    pub fn load_libs(&self, lib: LuauLibs) {
        macro_rules! load_lib {
            ($func:ident) => {
                unsafe {
                    self.push_raw_function(
                        $func,
                        Some(&CString::new(stringify!($func)).unwrap()),
                        0,
                        None,
                    );
                    self.push_string("");
                    self.call(1, 0);
                };
            };

            ($idnt:expr, $func:ident) => {
                unsafe {
                    self.push_raw_function(
                        $func,
                        Some(&CString::new(stringify!($func)).unwrap()),
                        0,
                        None,
                    );
                    self.push_string($idnt);
                    self.call(1, 0);
                };
            };
        }

        if lib.has(LuauLibs::ALL_LIBS) {
            unsafe { luaL_openlibs(self.state) };

            return;
        }

        if lib.has(LuauLibs::LIB_BASE) {
            load_lib!(luaopen_base);
        }

        if lib.has(LuauLibs::LIB_COROUTINE) {
            load_lib!(LUA_COLIBNAME, luaopen_coroutine);
        }

        if lib.has(LuauLibs::LIB_TABLE) {
            load_lib!(LUA_TABLIBNAME, luaopen_table);
        }

        if lib.has(LuauLibs::LIB_OS) {
            load_lib!(LUA_OSLIBNAME, luaopen_os);
        }

        if lib.has(LuauLibs::LIB_STRING) {
            load_lib!(LUA_STRLIBNAME, luaopen_string);
        }

        if lib.has(LuauLibs::LIB_MATH) {
            load_lib!(LUA_MATHLIBNAME, luaopen_math);
        }

        if lib.has(LuauLibs::LIB_DEBUG) {
            load_lib!(LUA_DBLIBNAME, luaopen_debug);
        }

        if lib.has(LuauLibs::LIB_UTF8) {
            load_lib!(LUA_UTF8LIBNAME, luaopen_utf8);
        }

        if lib.has(LuauLibs::LIB_BIT32) {
            load_lib!(LUA_BITLIBNAME, luaopen_bit32);
        }

        if lib.has(LuauLibs::LIB_BUFFER) {
            load_lib!(LUA_BUFFERLIBNAME, luaopen_buffer);
        }
    }

    #[inline]
    pub fn to_ptr(&self) -> *mut _LuaState {
        self.state
    }

    #[inline]
    pub fn top(&self) -> c_int {
        unsafe { lua_gettop(self.state) }
    }

    /// Returns the status of the Luau state
    pub fn status(&self) -> LuauStatus {
        unsafe { lua_status(self.state) }
    }

    /// Yields the luau state with the number of results
    ///
    /// Should be used as the end expression or a return from a function as this returns `-1`
    pub fn yield_luau(&self, nresults: c_int) -> c_int {
        assert!(
            self.top() >= nresults,
            "The number of yield returns must not exceed the stack size"
        );

        unsafe { lua_yield(self.state, nresults) }
    }

    /// Breaks the luau state for the purposes of a debug interrupt
    ///
    /// Should be used as the end expression or a return from a function as this returns `-1`
    pub fn break_luau(&self) -> c_int {
        unsafe { lua_break(self.state) }
    }

    /// Produces an error with the value on the top of the stack
    pub fn error(&self) -> c_int {
        luau_stack_precondition!(self.check_index(-1));

        // SAFETY: a value on the top of the stack exists as verified by the precondition
        unsafe { lua_error(self.state) }
    }

    /// Returns the type of a luau value at `idx`
    pub fn type_of(&self, idx: c_int) -> LuauType {
        luau_stack_precondition!(self.check_index(idx));

        unsafe { lua_type(self.state, idx) }
    }

    /// Pops `n` values from the stack
    pub fn pop(&self, n: c_int) {
        // assert that the set position is not greater than the top
        luau_stack_precondition!(self.check_index(-n));

        // SAFETY: -n is validated by the precondition
        unsafe { lua_settop(self.state, -(n + 1)) }
    }

    /// Returns an upvalue index for the specified upvalue index
    pub fn upvalue(&self, uv_idx: c_int) -> c_int {
        lua_upvalueindex(uv_idx)
    }

    /// Sets the memory category for all allocations taking place after its set
    pub fn set_memory_category(&self, cat: c_int) {
        assert!(
            cat < LUA_MEMORY_CATEGORIES,
            "Memory category index must not exceed {LUA_MEMORY_CATEGORIES}"
        );

        unsafe {
            lua_setmemcat(self.state, cat);
        }
    }

    pub fn check_index(&self, idx: c_int) -> bool {
        if idx <= LUA_REGISTRYINDEX {
            return true;
        }

        if idx == 0 {
            return false;
        }

        let top = self.top();

        let idx = if idx < 0 {
            // "subtract" the top (idx is negative)
            top.wrapping_add(idx)
        } else {
            idx
        };

        if idx < LUA_GLOBALSINDEX {
            // upvalue idx
            return true;
        }

        // zero is acceptable here

        idx >= 0 && // greater or equal to zero and
        idx <= top && // lesser than or equal to the top and
        idx < LUAI_MAXCSTACK // smaller than the maximum c stack
    }

    pub fn check_stack(&self, sz: c_int) -> bool {
        unsafe { lua_checkstack(self.state, sz) == 1 }
    }

    #[inline]
    pub fn registry(&self) -> c_int {
        LUA_REGISTRYINDEX
    }

    #[inline]
    pub fn globals(&self) -> c_int {
        LUA_GLOBALSINDEX
    }

    pub fn check_args(&self, count: c_int, extra_message: Option<&CStr>) {
        if self.top() >= count {
            return;
        }

        unsafe {
            luaL_argerrorL(
                self.state,
                count - self.top(),
                extra_message.map(CStr::as_ptr).unwrap_or(null()),
            );
        }
    }

    /// Returns true if the value at `idx` is nil
    pub fn is_nil(&self, idx: c_int) -> bool {
        self.type_of(idx) == LuauType::LUA_TNIL
    }

    /// Pushes a nil value to the stack
    pub fn push_nil(&self) {
        luau_stack_precondition!(self.check_stack(1));

        // SAFETY: stack size is validated by precondition
        unsafe {
            lua_pushnil(self.state);
        }
    }

    /// Returns true if the value at `idx` is a bool, false otherwise
    pub fn is_boolean(&self, idx: c_int) -> bool {
        self.type_of(idx) == LuauType::LUA_TBOOLEAN
    }

    /// Returns true if the value at `idx` is not nil or false, otherwise returns false
    pub fn to_boolean(&self, idx: c_int) -> bool {
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: idx is validated by the precondition
        unsafe { lua_toboolean(self.state, idx) == 1 }
    }

    /// Pushes a boolean value to the Luau stack
    pub fn push_boolean(&self, value: bool) {
        luau_stack_precondition!(self.check_stack(1));

        // SAFETY: stack size is validated by the precondition
        unsafe {
            lua_pushboolean(self.state, value as i32);
        }
    }

    /// Returns true if the value at idx is a number, false otherwise
    pub fn is_number(&self, idx: c_int) -> bool {
        self.type_of(idx) == LuauType::LUA_TNUMBER
    }

    /// Pushes an integer onto the Luau stack
    pub fn push_integer(&self, n: c_int) {
        luau_stack_precondition!(self.check_stack(1));

        // SAFETY: we have adequate stack space as checked by the precondition
        unsafe {
            lua_pushinteger(self.state, n);
        }
    }

    /// Pushes an unsigned integer onto the Luau stack
    pub fn push_unsigned_integer(&self, n: c_uint) {
        luau_stack_precondition!(self.check_stack(1));

        // SAFETY: we have adequate stack space as checked by the precondition
        unsafe {
            lua_pushunsigned(self.state, n);
        }
    }

    /// Push a double into the Luau stack
    pub fn push_number(&self, n: f64) {
        // validate if the pushed index will not exceed the max C stack length
        luau_stack_precondition!(self.check_stack(1));

        // SAFETY: stack is appropriately sized, as checked by the precondition above
        unsafe {
            lua_pushnumber(self.state, n);
        }
    }

    /// Gets/converts a Lua value at `idx` to a number.
    ///
    /// Will convert a compatible string to a number
    pub fn to_number(&self, idx: c_int) -> Option<f64> {
        luau_stack_precondition!(self.check_index(idx));

        let mut is_number = 0;
        // SAFETY: idx is validated by the precondition and is therefore safe to access
        let number = unsafe { lua_tonumberx(self.state, idx, &raw mut is_number) };

        if is_number == 1 {
            Some(number)
        } else {
            None
        }
    }

    /// Returns true if the value at `idx` is a number, false otherwise
    pub fn is_string(&self, idx: c_int) -> bool {
        self.type_of(idx) == LuauType::LUA_TSTRING
    }

    /// Pushes a string to the top of the Luau stack
    pub fn push_string(&self, str: impl AsRef<[u8]>) {
        luau_stack_precondition!(self.check_stack(1));

        let slice = str.as_ref();

        // SAFETY: the stack size is checked by the precondition
        unsafe {
            lua_pushlstring(self.state, slice.as_ptr() as _, slice.len());
        }
    }

    /// Gets or tries to coerce a Luau value at `idx` into a slice of u8s
    pub fn to_str_slice(&self, idx: c_int) -> Option<&[u8]> {
        luau_stack_precondition!(self.check_index(idx));

        // needs to have a lifetime to bind the result on a lifetime to prevent use after frees
        let mut len = 0;
        // SAFETY: idx is validated by the precondition
        let data = unsafe { lua_tolstring(self.state, idx, &mut len) };

        if !data.is_null() {
            // SAFETY: Luau can be trusted to return the correct len
            unsafe { Some(std::slice::from_raw_parts(data as _, len)) }
        } else {
            None
        }
    }

    /// Gets or tries to coerce a Luau value at `idx` into a str reference
    pub fn to_str(&self, idx: c_int) -> Option<Result<&str, std::str::Utf8Error>> {
        // preconditions are checked by to_string_slice
        self.to_str_slice(idx).map(|v| std::str::from_utf8(v))
    }

    /// Gets or converts a Luau value at `idx` into a string with a reasonable format, will invoke __tostring metamethods.
    pub fn convert_to_str_slice(&self, idx: c_int) -> &[u8] {
        luau_stack_precondition!(self.check_index(idx));

        unsafe {
            let mut len = 0;
            let data = luaL_tolstring(self.state, idx, &raw mut len);

            if data.is_null() {
                unreachable!("Luau string conversion returned NULL ptr");
            } else {
                std::slice::from_raw_parts(data as _, len)
            }
        }
    }

    /// Returns true if the userdata at `idx` is a userdata and is of type T
    pub fn is_userdata<T: Any>(&self, idx: c_int) -> bool {
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: idx is validated by the precondition and the behavior of userdata is checked
        unsafe {
            let userdata_ptr: *mut Userdata<()> =
                lua_touserdatatagged(self.state, idx, UD_TAG) as _;

            !userdata_ptr.is_null() && (*userdata_ptr).is::<T>()
        }
    }

    /// Returns true if the userdata at `idx` is any type of userdata
    pub fn is_any_userdata<T: Any>(&self, idx: c_int) -> bool {
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: idx is validated by the precondition
        unsafe { lua_isuserdata(self.state, idx) == 1 }
    }

    /// Pushes a value T as a userdata to Luau
    pub fn push_userdata<T: Any>(&self, object: T) {
        luau_stack_precondition!(self.check_stack(1));

        // SAFETY: We allocate a DST as a userdata on a stack with the known proper size with our own tag.
        // if the userdat allo
        // if our type T has drop glue then we will set the dtor field which will be invoked
        // we then construct a struct which has ownership of T
        // we need the dtor field because the struct is opaque elsewhere
        unsafe {
            let userdata_ptr: *mut Userdata<T> =
                lua_newuserdatatagged(self.state, size_of::<Userdata<T>>(), UD_TAG).cast();

            let dtor = if std::mem::needs_drop::<T>() {
                let fn_item: unsafe fn(*mut Userdata<T>) = drop_userdata::<T>;

                Some(fn_item)
            } else {
                None
            };

            userdata_ptr.write(Userdata {
                id: object.type_id(),
                count_cell: Cell::new(0),
                dtor,
                inner: object,
            });
        }
    }

    fn get_userdata_ptr<T: Any>(&self, idx: c_int) -> Option<*mut Userdata<T>> {
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: We validate that the userdata at the checked idx is of the proper type T or null
        unsafe {
            let userdata_ptr: *mut Userdata<()> =
                lua_touserdatatagged(self.state, idx, UD_TAG) as _;

            if !userdata_ptr.is_null() && (*userdata_ptr).is::<T>() {
                Some(userdata_ptr as _)
            } else {
                None
            }
        }
    }

    /// Returns a result with a ref to a userdata value of type T or an error if the userdata is already mutably borrowed.
    ///
    /// Returns `None` if the value isn't a userdata or the userdata is not of type T.
    pub fn try_borrow_userdata<T: Any>(
        &self,
        idx: c_int,
    ) -> Option<Result<UserdataRef<T>, UserdataBorrowError>> {
        // SAFETY: We validate that the userdata at the checked idx is a userdata and a valid T through `get_userdata_ptr`
        unsafe {
            let userdata_ptr = self.get_userdata_ptr(idx)?;

            Some(UserdataRef::try_from_ptr(userdata_ptr))
        }
    }

    /// Gets a reference to a userdata value of type T, returning None if the value isn't a userdata or the userdata is not of type T.
    ///
    /// Will panic if the userdata is already mutably borrowed
    pub fn borrow_userdata<T: Any>(&self, idx: c_int) -> Option<UserdataRef<T>> {
        self.try_borrow_userdata(idx).map(Result::unwrap)
    }

    /// Tries to get a mutable reference to a userdata value of type T. Returns a result with the ref or an error.
    ///
    /// Returns `None` if the value is not of the correct type or if the value is already at idx.
    pub fn try_borrow_userdata_mut<T: Any>(
        &self,
        idx: c_int,
    ) -> Option<Result<UserdataRefMut<T>, UserdataBorrowError>> {
        // SAFETY: We validate that the userdata at the checked idx is a userdata and a valid T through `get_userdata_ptr`
        unsafe {
            let userdata_ptr = self.get_userdata_ptr(idx)?;

            Some(UserdataRefMut::try_from_ptr(userdata_ptr))
        }
    }

    /// Retrives a userdata of type T without performing a type check to determine if the inner type is really T
    ///
    /// Will return None if the value at idx is not a userdata
    ///
    /// # Safety
    /// You need to know beforehand that the userdata here is of the correct type or has such a layout that the type requested is valid
    pub unsafe fn get_userdata_unchecked<T: 'static>(&self, idx: c_int) -> Option<&mut T> {
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: we don't do any checking other than validating idx
        unsafe { Some(&mut (*self.get_userdata_ptr(idx)?).inner) }
    }

    /// Returns true if the value at `idx` is a light userdata, it returns false otherwise.
    pub fn is_lightuserdata(&self, idx: c_int) -> bool {
        self.type_of(idx) == LuauType::LUA_TLIGHTUSERDATA
    }

    /// Returns an option of a raw pointer. Will be Some if the value at `idx` is a lightuserdata, None otherwise.
    pub fn to_lightuserdata<T>(&self, idx: c_int) -> Option<*mut T> {
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: idx is checked by precondition
        unsafe {
            let ptr: *mut T = lua_tolightuserdata(self.state, idx).cast();

            if ptr.is_null() {
                None
            } else {
                Some(ptr)
            }
        }
    }

    /// Returns true if the Luau value at `idx` is a buffer, false otherwise
    pub fn is_buffer(&self, idx: c_int) -> bool {
        self.type_of(idx) == LuauType::LUA_TBUFFER
    }

    /// Creates a luau buffer of a provided size and pushes it on the stack
    ///
    /// This will issue an error if the allocation cannot be performed
    pub fn push_buffer(&mut self, size: usize) -> &mut [u8] {
        luau_stack_precondition!(self.check_stack(1));

        unsafe {
            let ptr: *mut u8 = lua_newbuffer(self.state, size) as _;

            std::slice::from_raw_parts_mut(ptr, size)
        }
    }

    /// Pushes a slice to the Luau stack as a buffer
    pub fn push_buffer_from_slice(&mut self, slice: impl AsRef<[u8]>) -> &mut [u8] {
        // precondition is validated by push_buffer

        let slice = slice.as_ref();

        let buffer = self.push_buffer(slice.len());
        buffer.copy_from_slice(slice);

        buffer
    }

    /// Gets a Luau value at `idx` as a mutable slice of bytes
    pub fn to_buffer(&mut self, idx: c_int) -> Option<&mut [u8]> {
        luau_stack_precondition!(self.check_index(idx));

        let mut len = 0;
        // SAFETY: idx is validated by the precondition
        let data: *mut u8 = unsafe { lua_tobuffer(self.state, idx, &mut len) as _ };

        // will be null if the value is not a buffer
        if !data.is_null() {
            // SAFETY: Luau will report the right length
            unsafe { Some(slice::from_raw_parts_mut(data, len)) }
        } else {
            None
        }
    }

    /// Gets the pointer of a buffer value returning NULL if the value at `idx` is not a buffer
    pub fn to_buffer_ptr(&self, idx: c_int, len: &mut usize) -> *mut c_void {
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: idx is validated by precondition
        unsafe { lua_tobuffer(self.state, idx, len) }
    }

    /// Pushes an empty table to the Luau stack
    pub fn create_table(&self) {
        unsafe {
            lua_createtable(self.state, 0, 0);
        }
    }

    /// Pushes an empty table to the Luau stack with a preallocated array portion of `narr` and an associative portion of `nrec`
    pub fn create_table_with_capacity(&self, narr: c_int, nrec: c_int) {
        unsafe {
            lua_createtable(self.state, narr, nrec);
        }
    }

    pub fn shift(&self, to: c_int) {
        luau_stack_precondition!(self.check_index(to));

        unsafe {
            lua_insert(self.state, to);
        }
    }

    /// Makes a reference to the value at `idx` which can be retrieved from `get_reference`
    pub fn reference(&self, idx: c_int) -> RefIndex {
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: idx is checked
        unsafe { lua_ref(self.state, idx) }
    }

    /// Retrieves a reference from a RefIndex and pushes it to the top of the stack while returning the type's value
    pub fn get_reference(&self, ref_index: RefIndex) -> LuauType {
        luau_stack_precondition!(self.check_stack(1));

        // SAFETY: stack size is checked
        unsafe { lua_getref(self.state, ref_index) }
    }

    /// Removes a reference
    pub fn unreference(&self, ref_index: RefIndex) {
        unsafe {
            lua_unref(self.state, ref_index);
        }
    }

    /// Returns true if the value at `idx` is a table, false otherwise
    pub fn is_table(&self, idx: c_int) -> bool {
        self.type_of(idx) == LuauType::LUA_TTABLE
    }

    /// Sets t\[k\] = v where k is the field string, t is the table at idx and k is the value on the top of the stack
    ///
    /// May invoke a __newindex metamethod
    pub fn set_field(&self, idx: c_int, field: impl AsRef<[u8]>) {
        luau_stack_precondition!(self.check_stack(1));

        // bad hack
        let idx = if idx < 0 && !lua_ispseudo(idx) && !(idx == -1 && self.top() == 1) {
            idx - 1
        } else {
            idx
        };

        self.push_string(field);
        self.shift(-2);

        self.set_table(idx);
    }

    /// Sets t\[k\] = v where k is the field string, t is the table at idx and k is the value on the top of the stack
    ///
    /// Will not invoke a __newindex metamethod
    pub fn raw_set_field(&self, idx: c_int, field: &str) {
        luau_stack_precondition!(self.check_stack(1));

        let idx = if idx < 0 && !lua_ispseudo(idx) && !(idx == -1 && self.top() == 1) {
            idx - 1
        } else {
            idx
        };

        self.push_string(field);
        self.shift(-2);

        self.raw_set_table(idx);
    }

    /// Sets the value of t\[k\] with the value at the top of the stack where t is at the index and k is the value beneath the top of the stack.
    ///
    /// May invoke a __newindex metamethod
    pub fn set_table(&self, idx: c_int) {
        assert!(
            self.top() >= 2,
            "There must be a key and value on the stack to set table"
        );
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: idx is validated by the precondition
        unsafe {
            lua_settable(self.state, idx);
        }
    }

    /// Sets the value of t\[k\] with the value at the top of the stack where t is at the index and k is the value beneath the top of the stack.
    ///
    /// Will not invoke a __newindex metamethod
    pub fn raw_set_table(&self, idx: c_int) {
        assert!(
            self.top() >= 2,
            "There must be a key and value on the stack to set table"
        );
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: idx is validated by the precondition
        unsafe {
            lua_rawset(self.state, idx);
        }
    }

    /// Gets t\[k\] where k is the field string where t is the table at idx.
    ///
    /// May invoke a __index metamethod
    pub fn get_field(&self, idx: c_int, field: impl AsRef<[u8]>) {
        luau_stack_precondition!(self.check_index(idx));
        luau_stack_precondition!(self.check_stack(1));

        let idx = if idx < 0 && !lua_ispseudo(idx) {
            idx - 1
        } else {
            idx
        };

        self.push_string(field);
        self.get_table(idx);
    }

    /// Gets t\[k\] where k is the field string where t is the table at idx.
    ///
    /// Will not invoke a __index metamethod
    pub fn raw_get_field(&self, idx: c_int, field: impl AsRef<[u8]>) {
        luau_stack_precondition!(self.check_index(idx));
        luau_stack_precondition!(self.check_stack(1));

        let idx = if idx < 0 && !lua_ispseudo(idx) {
            idx - 1
        } else {
            idx
        };

        self.push_string(field);
        self.raw_get_table(idx);
    }

    /// Gets the value of t\[k\] where t is the value at the index and k is the value on the top of the stack.
    ///
    /// May invoke a __index metamethod
    pub fn get_table(&self, idx: c_int) {
        assert!(
            self.top() >= 1,
            "There must be a key on the stack to index the table"
        );
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: idx is validated by the precondition
        unsafe {
            lua_gettable(self.state, idx);
        }
    }

    /// Gets the value of t\[k\] where t is the value at the index and k is the value on the top of the stack.
    ///
    /// Will not invoke a __index metamethod
    pub fn raw_get_table(&self, idx: c_int) {
        assert!(
            self.top() >= 1,
            "There must be a key on the stack to index the table"
        );
        luau_stack_precondition!(self.check_index(idx));

        // SAFETY: idx is validated by the precondition
        unsafe {
            lua_rawget(self.state, idx);
        }
    }

    /// Changes the readonly mode of a table at `idx` to the supplied boolean
    pub fn set_readonly(&self, idx: c_int, enabled: bool) {
        assert!(self.is_table(idx));

        // SAFETY: is_table has a precondition to validate idx
        unsafe {
            lua_setreadonly(self.state, idx, enabled as c_int);
        }
    }

    /// Sets the metatable for the value idx to the table located on the top of the stack.
    ///
    /// Sets the metatable for individual tables and userdata or sets the metatable for an entire type.
    pub fn set_metatable(&self, idx: c_int) {
        luau_stack_precondition!(self.check_index(idx));

        unsafe {
            lua_setmetatable(self.state, idx);
        }
    }

    /// Returns true if the value at idx is a vector, false otherwise
    pub fn is_vector(&self, idx: c_int) -> bool {
        self.type_of(idx) == LuauType::LUA_TVECTOR
    }

    /// Pushes a vector to the Luau stack
    pub fn push_vector(&self, x: f32, y: f32, z: f32, #[cfg(feature = "luau_vector4")] w: f32) {
        luau_stack_precondition!(self.check_stack(1));

        // SAFETY: stack size is validated by precondition
        unsafe {
            #[cfg(not(feature = "luau_vector4"))]
            lua_pushvector(self.state, x, y, z);
            #[cfg(feature = "luau_vector4")]
            lua_pushvector(self.state, x, y, z, w);
        }
    }

    #[cfg(not(feature = "luau_vector4"))]
    /// Returns the value of a vector if the value at idx is a vector or will return None
    pub fn to_vector(&self, idx: c_int) -> Option<(f32, f32, f32)> {
        luau_stack_precondition!(self.check_index(idx));
        unsafe {
            Option::from(lua_tovector(self.state, idx)).map(|ptr| (*ptr, *ptr.add(1), *ptr.add(2)))
        }
    }

    #[cfg(feature = "luau_vector4")]
    /// Returns the value of a vector if the value at idx is a vector or will return None
    pub fn to_vector(&self, idx: c_int) -> Option<(f32, f32, f32, f32)> {
        luau_stack_precondition!(self.check_index(idx));
        unsafe {
            Option::from(lua_tovector(self.state, idx))
                .map(|ptr| (*ptr, *ptr.add(1), *ptr.add(2), *ptr.add(3)))
        }
    }

    /// Returns true if the value at `idx` is a thread, false otherwise
    pub fn is_thread(&self, idx: c_int) -> bool {
        self.type_of(idx) == LuauType::LUA_TTHREAD
    }

    pub fn new_thread(&self) -> LuauThread {
        unsafe {
            let thread_ptr = lua_newthread(self.state);
            LuauThread::from_ptr(thread_ptr, self.get_associated().main_thread_rc.clone())
        }
    }

    pub fn get_thread(&self, idx: c_int) -> Option<LuauThread> {
        let ptr = unsafe { lua_tothread(self.state, idx) };

        if !ptr.is_null() {
            unsafe {
                Some(LuauThread::from_ptr(
                    ptr,
                    self.get_associated().main_thread_rc.clone(),
                ))
            }
        } else {
            None
        }
    }

    /// Returns the thread local userdata
    pub fn get_thread_data<T: Any>(&self) -> Option<&T> {
        let boxed = unsafe { (lua_getthreaddata(self.state) as *const Box<dyn Any>).as_ref()? };

        boxed.downcast_ref()
    }

    /// Sets the thread local userdata
    pub fn set_thread_data<T: Any>(&self, userdata: T) {
        let b: Box<dyn Any> = Box::new(userdata);

        unsafe {
            lua_setthreaddata(self.state, Box::into_raw(b) as _);
        }
    }

    /// Resumes the given Luau thread with the number of arguments.
    ///
    /// Will resume the function on the top of the given Luau thread's execution stack
    pub fn resume(&self, luau_thread: &LuauThread, nargs: c_int) -> LuauStatus {
        unsafe { lua_resume(luau_thread.get_state().state, self.state, nargs) }
    }

    /// Returns true if the value at `idx` is a function, false otherwise
    pub fn is_function(&self, idx: c_int) -> bool {
        self.type_of(idx) == LuauType::LUA_TFUNCTION
    }

    /// Pushes a raw rust function to the stack which receives a pointer to the luau state and returns the number of result values
    ///
    /// Can receive a number of upvalues specified by the `num_upvalues` argument which are accessed through ffi's upvalueindex
    ///
    /// # Safety
    /// You will need to uphold all safety invariants with respect to the Luau VM in the user supplied `func`
    pub unsafe fn push_raw_function(
        &self,
        func: CFunction,
        debug_name: Option<&CStr>,
        num_upvals: c_int,
        continuation: Option<LuaContinuation>,
    ) {
        luau_stack_precondition!(self.check_stack(1));

        assert!(
            self.top() >= num_upvals,
            "The number of upvalues for a raw function must not exceed the stack length"
        );

        // SAFETY: upvalue count and stack size are validated as a precondition and assert
        unsafe {
            lua_pushcclosurek(
                self.state,
                func,
                if let Some(name) = debug_name {
                    name.as_ptr()
                } else {
                    null()
                },
                num_upvals,
                continuation,
            );
        }
    }

    /// Pushes a Rust function into Luau with an associated continuation
    ///
    /// This function wraps a Rust function to allow closures to capture values, to avoid this minor overhead you can use `push_function_raw`
    pub fn push_function_continuation<
        F: FnMut(&Luau) -> c_int,
        Cont: FnMut(&Luau, LuauStatus) -> c_int,
    >(
        &self,
        func: F,
        debug_name: Option<&CStr>,
        num_upvals: c_int,
        cont: Cont,
    ) {
        assert!(
            self.top() >= num_upvals,
            "The number of upvalues for a raw function must not exceed the stack length"
        );

        luau_stack_precondition!(self.check_stack(2));

        struct CallState<F, Cont> {
            func: F,
            cont: Cont,
        }

        let call_state = Box::new(CallState { func, cont });

        unsafe extern "C-unwind" fn invoke_fn<
            F: FnMut(&Luau) -> c_int,
            Cont: FnMut(&Luau, LuauStatus) -> c_int,
        >(
            state: *mut _LuaState,
        ) -> c_int {
            let call_state =
                lua_tolightuserdata(state, lua_upvalueindex(1)).cast::<CallState<F, Cont>>();

            let luau = Luau::from_ptr(state);

            ((*call_state).func)(&luau)
        }

        unsafe extern "C-unwind" fn invoke_continuation<
            F: FnMut(&Luau) -> c_int,
            Cont: FnMut(&Luau, LuauStatus) -> c_int,
        >(
            state: *mut _LuaState,
            status: c_int,
        ) -> c_int {
            let call_state =
                lua_tolightuserdata(state, lua_upvalueindex(1)).cast::<CallState<F, Cont>>();

            let luau = Luau::from_ptr(state);
            ((*call_state).cont)(&luau, std::mem::transmute::<c_int, LuauStatus>(status))
        }

        unsafe {
            lua_pushlightuserdata(self.state, Box::into_raw(call_state) as _);

            self.push_raw_function(
                invoke_fn::<F, Cont>,
                debug_name,
                1 + num_upvals,
                Some(invoke_continuation::<F, Cont>),
            );
        }
    }

    /// Pushes a Rust function into Luau
    ///
    /// This function wraps a Rust function to allow closures to capture values, to avoid this minor overhead you can use `push_function_raw`
    pub fn push_function<F: FnMut(&Luau) -> i32>(
        &self,
        func: F,
        debug_name: Option<&CStr>,
        num_upvals: c_int,
    ) {
        assert!(
            self.top() >= num_upvals,
            "The number of upvalues for a raw function must not exceed the stack length"
        );

        luau_stack_precondition!(self.check_stack(2));

        let func_box = Box::new(func);

        unsafe extern "C-unwind" fn invoke_fn<T: FnMut(&Luau) -> i32>(
            state: *mut _LuaState,
        ) -> c_int {
            let func = lua_tolightuserdata(state, lua_upvalueindex(1)).cast::<T>();

            let state = Luau::from_ptr(state);
            (*func)(&state)
        }

        unsafe {
            lua_pushlightuserdata(self.state, Box::into_raw(func_box) as _);

            self.push_raw_function(invoke_fn::<F>, debug_name, 1 + num_upvals, None);
        }
    }

    /// Calls the Luau function at the top of the stack returning the status of the Luau state when it returns
    pub fn call(&self, nargs: c_int, nresults: c_int) -> LuauStatus {
        assert!(
            self.is_function(-1),
            "The value at top of stack must be a function"
        );

        assert!(
            self.top() >= nargs,
            "Argument count may not exceed the total stack size"
        );

        luau_stack_precondition!(self.check_stack(nresults));

        unsafe { lua_pcall(self.state, nargs, nresults, 0) }
    }

    /// Loads bytecode into the VM and pushes a function to the stack
    pub fn load(&self, chunk_name: Option<&CStr>, bytecode: &[u8], env: c_int) -> Result<(), &str> {
        // specifically allow env 0
        luau_stack_precondition!(env == 0 || self.check_index(env));
        luau_stack_precondition!(self.check_stack(2));

        let success = unsafe {
            luau_load(
                self.state,
                chunk_name.unwrap_or(c"").as_ptr(),
                bytecode.as_ptr() as _,
                bytecode.len(),
                env,
            )
        };

        if success == 0 {
            Ok(())
        } else {
            dbg!(self.top());
            // we have an error and know its ascii
            Err(self.to_str(-1).unwrap().unwrap())
        }
    }

    #[cfg(feature = "codegen")]
    /// Compiles a function with native code generation.
    ///
    /// This will fail silently if the codegen is not supported and initialized
    pub fn codegen(&self, idx: c_int) {
        luau_stack_precondition!(self.check_index(idx));
        assert!(
            self.is_function(idx),
            "The value at idx must be a function to be compiled with codegen"
        );

        unsafe {
            luau_codegen_compile(self.state, idx);
        }
    }
}

// TODO: do this
unsafe extern "C-unwind" fn fatal_runtime_error_handler(state: *mut _LuaState) -> c_int {
    let luau = unsafe { Luau::from_ptr(state) };

    panic!(
        "Uncaught runtime error - \"{}\"",
        String::from_utf8_lossy(luau.convert_to_str_slice(-1))
    );
}

/// Final resting place for Luau code, we don't return from this.
unsafe extern "C-unwind" fn fatal_error_handler(state: *mut _LuaState, status: LuauStatus) {
    match status {
        // Unhandled runtime error
        LuauStatus::LUA_ERRRUN => fatal_runtime_error_handler(state),
        // memory allocation error, just die
        LuauStatus::LUA_ERRMEM => std::process::abort(),
        // some error handling mechanism errored
        LuauStatus::LUA_ERRERR => panic!("Error originating from error handling mechanism"),
        // shouldnt be reachable
        _ => unreachable!(),
    };

    panic!("Fatal error in Luau execution");
}

impl Default for Luau {
    fn default() -> Self {
        Self::new(DefaultLuauAllocator {})
    }
}

impl Drop for Luau {
    fn drop(&mut self) {
        if !self.owned {
            return;
        }

        unsafe {
            let mut associated: *mut AssociatedData = null_mut();
            lua_getallocf(self.state, &raw mut associated as _);

            let associated_owned = Box::from_raw(associated);

            // mark main thread dead
            associated_owned.main_thread_rc.set(false);

            lua_close(self.state);

            _ = associated_owned
        }
    }
}

#[macro_export]
macro_rules! try_luau {
    ($state:ident, $block:block) => {{
        $state.push_function(|$state| $block, Some(c"_try_lua"), 0);
        $state.call(0, 0)
    }};
}

#[cfg(test)]
#[allow(non_snake_case)]
mod tests {
    use std::{
        ffi::{c_int, c_void},
        hint::black_box,
        rc::Rc,
    };

    use crate::{
        Luau, LuauAllocator, _LuaState,
        compile::Compiler,
        lua_error, lua_tonumber, lua_upvalueindex,
        userdata::{UserdataBorrowError, UserdataRef},
        LuauLibs, LuauStatus, LuauType,
    };

    #[test]
    fn try_test() {
        let luau = Luau::default();

        let status = try_luau!(luau, {
            luau.push_boolean(true);
            luau.error()
        });

        assert!(
            matches!(status, LuauStatus::LUA_ERRRUN),
            "Expected a runtime error"
        );
        assert!(luau.to_boolean(-1), "Expected the boolean to be true");
    }

    #[test]
    #[should_panic]
    fn stack_checking_no_value() {
        let luau = Luau::default();

        luau.is_number(1);
    }

    #[test]
    #[should_panic]
    fn stack_checking_neg_no_value() {
        let luau = Luau::default();

        luau.is_number(-1);
    }

    #[test]
    fn stack_checking_has_value() {
        let luau = Luau::default();

        luau.push_number(0.0);

        luau.is_number(-1);
        luau.is_number(1);
    }

    #[cfg(all(feature = "codegen", feature = "compiler"))]
    #[test]
    fn codegen() {
        use crate::compile::Compiler;

        let compiler = Compiler::new();
        let luau = Luau::default();

        let result = compiler.compile("(function() return 123 end)()");

        assert!(result.is_ok(), "Compiler result is expected to be OK");

        let load_result = luau.load(None, result.bytecode().unwrap(), 0);

        assert!(load_result.is_ok(), "Load result should be Ok");

        let load_result = luau.load(Some(c"test"), result.bytecode().unwrap(), 0);

        assert!(load_result.is_ok(), "Load result should be Ok");

        luau.codegen(-1);

        luau.call(0, 0);
    }

    #[test]
    fn load_error() {
        let luau = Luau::default();

        let load_result = luau.load(None, b"\0Error!", 0);

        // might change depending on luau updates
        assert!(
            load_result.is_err_and(|v| v == r#"[string ""]Error!"#),
            "Expected load result to be an error and be the correct error message."
        );
    }

    #[test]
    fn load_libs() {
        let luau = Luau::default();

        luau.load_libs(LuauLibs::ALL_LIBS);

        luau.get_field(luau.globals(), "table");

        assert_eq!(luau.type_of(-1), LuauType::LUA_TTABLE);

        luau.get_field(luau.globals(), "print");

        assert_eq!(luau.type_of(-1), LuauType::LUA_TFUNCTION);
    }

    #[test]
    fn tables() {
        let luau = Luau::default();

        luau.create_table();

        luau.push_number(123.0);

        luau.set_field(-2, "abc");

        luau.get_field(-1, "abc");

        assert_eq!(luau.to_number(-1), Some(123.0));

        luau.pop(1);

        // should be valid
        luau.set_field(-1, "a");
    }

    #[test]
    fn metatables() {
        let luau = Luau::default();

        luau.create_table();
        luau.create_table();

        let mut called: Option<String> = None;
        luau.push_function(
            |luau| {
                called = luau.to_str(-1).map(Result::unwrap).map(str::to_string);
                0
            },
            None,
            0,
        );
        luau.set_field(-2, "__index");
        luau.set_metatable(-2);

        let index = "Hello!".to_string();
        luau.get_field(-1, &index);

        assert_eq!(called, Some(index));
    }

    #[test]
    #[should_panic]
    fn unhandled_error() {
        let luau = Luau::default();

        luau.push_string("hello error!");

        unsafe {
            lua_error(luau.to_ptr());
        }
    }

    #[test]
    fn pop() {
        let luau = Luau::default();

        luau.push_number(0.0);

        assert_eq!(luau.top(), 1);

        luau.pop(1);

        assert_eq!(luau.top(), 0);

        luau.push_number(0.0);
        luau.push_number(0.0);

        assert_eq!(luau.top(), 2);

        luau.pop(2);

        assert_eq!(luau.top(), 0);
    }

    #[test]
    fn threads() {
        let luau = Luau::default();

        let thread = luau.new_thread();
        let thread_state = thread.get_state();

        let mut was_called = false;

        thread_state.push_function(
            |_| {
                was_called = true;
                0
            },
            None,
            0,
        );

        luau.resume(&thread, 0);

        assert!(was_called, "Expected thread function to be called");
    }

    #[test]
    fn app_data() {
        let luau = Luau::default();

        luau.set_app_data(Some(true));

        assert_eq!(luau.get_app_data::<bool>().copied(), Some(true))
    }

    #[test]
    fn function_upvalue_test() {
        let luau = Luau::default();

        luau.push_number(1.0);
        luau.push_number(2.0);
        luau.push_number(3.0);

        luau.push_function(
            |luau| {
                assert_eq!(luau.to_number(luau.upvalue(1)), Some(1.0));
                assert_eq!(luau.to_number(luau.upvalue(2)), Some(2.0));
                assert_eq!(luau.to_number(luau.upvalue(3)), Some(3.0));

                0
            },
            Some(c"test"),
            3,
        );

        luau.call(0, 0);
    }

    #[test]
    fn raw_function_upvalue_test() {
        let luau = Luau::default();

        luau.push_number(1.0);
        luau.push_number(2.0);
        luau.push_number(3.0);

        unsafe extern "C-unwind" fn test_extern_fn(state: *mut _LuaState) -> c_int {
            assert_eq!(lua_tonumber(state, lua_upvalueindex(1)), 1.0);
            assert_eq!(lua_tonumber(state, lua_upvalueindex(2)), 2.0);
            assert_eq!(lua_tonumber(state, lua_upvalueindex(3)), 3.0);

            0
        }

        unsafe {
            luau.push_raw_function(test_extern_fn, Some(c"test"), 3, None);
        }

        luau.call(0, 0);
    }

    #[test]
    fn continuations() {
        let luau = Luau::default();
        let compiler = Compiler::new();

        let bc = compiler.compile("(...)()");

        let thread = luau.new_thread();
        let thread_state = thread.get_state();

        let mut cont = false;

        thread_state.push_function_continuation(
            |l| l.yield_luau(0),
            None,
            0,
            |_, _| {
                cont = true;
                0
            },
        );
        thread_state.load(None, bc.bytecode().unwrap(), 0).unwrap();

        luau.resume(&thread, 1);
        luau.resume(&thread, 0);

        assert!(cont, "Expected that the continuation would be called.")
    }

    #[test]
    #[should_panic]
    fn luau_panic_unwind() {
        struct PanicAllocator;

        impl LuauAllocator for PanicAllocator {
            fn allocate(&self, _: usize) -> *mut std::ffi::c_void {
                panic!()
            }

            fn reallocate(&self, _: *mut c_void, _: usize, _: usize) -> *mut std::ffi::c_void {
                panic!()
            }

            fn deallocate(&self, _: *mut c_void, _: usize) {
                panic!()
            }
        }

        {
            black_box(Luau::new(PanicAllocator {}));
        };
    }

    #[test]
    fn function_check() {
        let luau = Luau::default();

        luau.push_function(
            |l| {
                l.check_args(1, None);

                0
            },
            None,
            0,
        );

        let status = luau.call(0, 0);

        assert!(
            matches!(status, LuauStatus::LUA_ERRRUN),
            "Expected there to be a runtime error."
        );

        luau.push_function(
            |l| {
                l.check_args(1, None);

                0
            },
            Some(c"test"),
            0,
        );

        let status = luau.call(0, 0);

        assert!(
            matches!(status, LuauStatus::LUA_ERRRUN),
            "Expected there to be a runtime error."
        );

    }

    #[test]
    fn userdata_borrow() {
        let luau = Luau::default();

        luau.push_userdata(());

        {
            let borrow = luau.try_borrow_userdata_mut::<()>(-1);

            assert!(
                borrow.as_ref().is_some_and(Result::is_ok),
                "Expected mutable borrow for userdata to be valid"
            );

            assert!(
                matches!(
                    luau.try_borrow_userdata::<()>(-1),
                    Some(Err(UserdataBorrowError::AlreadyMutable))
                ),
                "Expected immutable borrow for userdata to be invalid"
            );

            assert!(
                matches!(
                    luau.try_borrow_userdata_mut::<()>(-1),
                    Some(Err(UserdataBorrowError::AlreadyMutable))
                ),
                "Expected mutable borrow for userdata to be invalid"
            );

            drop(borrow);

            assert!(
                matches!(luau.try_borrow_userdata_mut::<()>(-1), Some(Ok(_))),
                "Expected mutable borrow for userdata to be valid"
            );
        }

        {
            let borrow = luau.try_borrow_userdata::<()>(-1);

            assert!(
                matches!(borrow, Some(Ok(_))),
                "Expected to be a valid borrow"
            );

            assert!(
                matches!(
                    luau.try_borrow_userdata_mut::<()>(-1),
                    Some(Err(UserdataBorrowError::AlreadyImmutable))
                ),
                "Expected borrow to be an AlreadyImmutable error"
            );
        }
    }

    #[test]
    fn userdata_values() {
        let luau = Luau::default();

        luau.push_userdata(());

        let mut vec = Vec::with_capacity(128);
        for i in 0..128 {
            vec.push(i);
        }

        luau.push_userdata(vec);

        #[repr(transparent)]
        struct DropCheck(Rc<bool>);

        let drop_rc = Rc::new(true);
        let yes_drop = DropCheck(drop_rc.clone());

        luau.push_userdata(yes_drop);

        assert!(luau.borrow_userdata(-3).is_some_and(
            #[allow(clippy::unit_cmp)]
            |v: UserdataRef<()>| *v == ()
        ));

        assert!(luau
            .borrow_userdata::<Vec<i32>>(-2)
            .is_some_and(|v| v.is_sorted())); // is larger data preserved correctly

        assert!(luau.borrow_userdata::<DropCheck>(-1).is_some());

        drop(luau);

        // assert!(, "Expected userdata to be dropped with luau state");
    }

    #[test]
    fn string_values() {
        let luau = Luau::default();

        const TEST_CONST: &[u8] = &[0xCA, 0xFE, 0xBA, 0xBE];
        const INVALID_SEQUENCE: &[u8] = &[0xC3, 0x28];

        luau.push_string("Hello, world!");
        luau.push_string(TEST_CONST);
        luau.push_number(12345.0f64);
        luau.push_string(INVALID_SEQUENCE);

        assert_eq!(luau.to_str_slice(-4), Some(b"Hello, world!" as _));
        assert_eq!(luau.to_str(-4), Some(Ok("Hello, world!")));
        assert_eq!(luau.to_str_slice(1), Some(b"Hello, world!" as _));
        assert_eq!(luau.to_str(1), Some(Ok("Hello, world!")));

        assert_eq!(luau.to_str_slice(-3), Some(TEST_CONST));
        assert_eq!(luau.to_str_slice(2), Some(TEST_CONST));

        assert_eq!(luau.to_str_slice(-2), Some(b"12345" as _));
        assert_eq!(luau.to_str(-2), Some(Ok("12345")));
        assert_eq!(luau.to_str_slice(3), Some(b"12345" as _));
        assert_eq!(luau.to_str(3), Some(Ok("12345")));

        assert_eq!(luau.to_str_slice(-1), Some(INVALID_SEQUENCE));
        assert!(luau.to_str(-1).is_some_and(|r| r.is_err()));
        assert_eq!(luau.to_str_slice(4), Some(INVALID_SEQUENCE));
        assert!(luau.to_str(4).is_some_and(|r| r.is_err()));
    }

    #[test]
    fn numeric_values() {
        let luau = Luau::default();

        luau.push_number(f64::NAN);
        luau.push_number(f64::INFINITY);
        luau.push_number(f64::EPSILON);
        luau.push_string("12345");

        // nan is not equal to itself, because that makes sense
        assert_eq!(
            luau.to_number(-4).map(f64::to_bits),
            Some(f64::NAN.to_bits())
        );
        assert_eq!(
            luau.to_number(1).map(f64::to_bits),
            Some(f64::NAN.to_bits())
        );

        assert_eq!(luau.to_number(-3), Some(f64::INFINITY));
        assert_eq!(luau.to_number(2), Some(f64::INFINITY));

        assert_eq!(luau.to_number(-2), Some(f64::EPSILON));
        assert_eq!(luau.to_number(3), Some(f64::EPSILON));

        assert_eq!(luau.to_number(-1), Some(12345.0f64));
        assert_eq!(luau.to_number(4), Some(12345.0f64));
    }
}