PkmnLib_rs/src/script_implementations/wasm/export_registry/mod.rs

use anyhow_ext::anyhow;
use anyhow_ext::Result;
use num_traits::{NumCast, PrimInt};
use std::ffi::{c_char, CStr, CString};
use std::mem::{align_of, forget};
use std::ops::{ControlFlow, FromResidual, Try};

use wasmer::{FromToNativeWasmType, FunctionEnv, FunctionEnvMut, Imports, NativeWasmTypeInto, StoreMut};

use crate::script_implementations::wasm::extern_ref::ExternRef;
use crate::script_implementations::wasm::script_resolver::WebAssemblyEnv;
use crate::static_data::EffectParameter;
use crate::StringKey;

/// Dynamic data registration
mod dynamic_data;
/// Static data registration
mod static_data;

/// Register a single function.
macro_rules! register_func_with_env {
    ($imports: ident, $store: ident, $func: ident, $env: expr) => {
        $imports.define(
            "env",
            stringify!($func),
            wasmer::Function::new_typed_with_env($store, $env, $func),
        );
    };
}

/// Utility macro to register a bunch of WASM functions easily.
macro_rules! register {
    (
        $(
            fn $name:ident($($par:ident: $par_type:ty),*$(,)?) $(-> $return:ty)? $block:block
        )*
        $(
            manual $manual_name:ident
        )?
    ) => {

        $(
            fn $name(
                $(
                $par: $par_type,
                )*
            ) $(-> $return)* $block
        )*

        pub(crate) fn register(imports: &mut wasmer::Imports,
            store: &mut wasmer::StoreMut,
            env: &wasmer::FunctionEnv<crate::script_implementations::wasm::script_resolver::WebAssemblyEnv>) {
            $(
                crate::script_implementations::wasm::export_registry::register_func_with_env!(imports, store, $name, env);
            )*
            $( $manual_name(imports, store, env) )*
        }
    };
}

pub(crate) use register;
pub(crate) use register_func_with_env;

/// Register the functions we expose to WASM.
pub(crate) fn register_webassembly_funcs(
    imports: &mut Imports,
    store: &mut StoreMut,
    env: &FunctionEnv<WebAssemblyEnv>,
) {
    register_func_with_env!(imports, store, _print, env);
    register_func_with_env!(imports, store, _error, env);
    register_func_with_env!(imports, store, _vec_extern_ref_get_value, env);

    static_data::register(imports, store, env);
    dynamic_data::register(imports, store, env);

    register_func_with_env!(imports, store, string_key_get_hash, env);
    register_func_with_env!(imports, store, string_key_get_str, env);
    register_func_with_env!(imports, store, effect_parameter_get_type, env);
    register_func_with_env!(imports, store, effect_parameter_as_bool, env);
    register_func_with_env!(imports, store, effect_parameter_as_int, env);
    register_func_with_env!(imports, store, effect_parameter_as_float, env);
    register_func_with_env!(imports, store, effect_parameter_as_string, env);
}

/// Logging function for WASM.
fn _print(env: FunctionEnvMut<WebAssemblyEnv>, p: u32) {
    unsafe {
        let mem: *mut c_char = env.data().data().get_raw_pointer(p);
        let s = CStr::from_ptr(mem);
        println!("{}", s.to_str().unwrap());
    }
}

/// Triggers when WASM panics.
#[track_caller]
fn _error(env: FunctionEnvMut<WebAssemblyEnv>, message: u32, file: u32, line: u32, position: u32) {
    unsafe {
        let mem: *const c_char = env.data().data().get_raw_pointer(message);
        let message_str = CStr::from_ptr(mem);
        let mem: *const c_char = env.data().data().get_raw_pointer(file);
        let file_str = CStr::from_ptr(mem);

        panic!(
            "WASM Error: {} in file {}, line: {}:{}",
            message_str.to_str().unwrap(),
            file_str.to_str().unwrap(),
            line,
            position
        );
    }
}

/// Get a single item from an earlier passed VecExternRef
fn _vec_extern_ref_get_value(env: FunctionEnvMut<WebAssemblyEnv>, reference: u32, index: u32) -> WasmResult<u32> {
    let res = env
        .data()
        .data()
        .get_extern_vec_ref_extern_ref(reference as usize, index as usize)?;
    Ok(res as u32).into()
}

/// Gets the hash value of a StringKey.
fn string_key_get_hash(env: FunctionEnvMut<WebAssemblyEnv>, string_key: ExternRef<StringKey>) -> WasmResult<u32> {
    Ok(string_key.value_func(&env)?.hash()).into()
}

/// Get a null-terminated C string from a StringKey. Note that this involves a copy into WASM
/// memory, so this is relatively heavy.
fn string_key_get_str(env: FunctionEnvMut<WebAssemblyEnv>, string_key: ExternRef<StringKey>) -> WasmResult<u32> {
    let string_key = string_key.value_func(&env)?.str();
    let wasm_string_ptr = env
        .data()
        .data()
        .allocate_mem((string_key.len() + 1) as u32, align_of::<CString>() as u32)?;
    let mut wasm_string: Vec<u8> =
        unsafe { Vec::from_raw_parts(wasm_string_ptr.0, string_key.len() + 1, string_key.len() + 1) };
    wasm_string.resize(string_key.len() + 1, 0);
    string_key.as_bytes().clone_into(&mut wasm_string);
    wasm_string.insert(string_key.len(), 0_u8);
    forget(wasm_string);
    Ok(wasm_string_ptr.1).into()
}

/// Gets the type of an EffectParameter
fn effect_parameter_get_type(
    env: FunctionEnvMut<WebAssemblyEnv>,
    parameter: ExternRef<EffectParameter>,
) -> WasmResult<u8> {
    let v = parameter.value_func(&env)?;
    Ok(match v {
        EffectParameter::Bool(_, _) => 1,
        EffectParameter::Int(_, _) => 2,
        EffectParameter::Float(_, _) => 3,
        EffectParameter::String(_, _) => 4,
    })
    .into()
}

/// Gets the inner bool data of an EffectParameter. Panics if it's not a bool.
fn effect_parameter_as_bool(
    env: FunctionEnvMut<WebAssemblyEnv>,
    parameter: ExternRef<EffectParameter>,
) -> WasmResult<u8> {
    let v = parameter.value_func(&env)?;
    match v {
        EffectParameter::Bool(_, b) => Ok(<u8 as From<bool>>::from(*b)),
        _ => Err(anyhow!("Unexpected parameter type. Expected bool, got {}", v)),
    }
    .into()
}

/// Gets the inner int data of an EffectParameter. Panics if it's not an int.
fn effect_parameter_as_int(
    env: FunctionEnvMut<WebAssemblyEnv>,
    parameter: ExternRef<EffectParameter>,
) -> WasmResult<i64> {
    let v = parameter.value_func(&env)?;
    match v {
        EffectParameter::Int(_, i) => Ok(*i),
        _ => Err(anyhow!("Unexpected parameter type. Expected int, got {}", v)),
    }
    .into()
}

/// Gets the inner float data of an EffectParameter. Panics if it's not a float.
fn effect_parameter_as_float(
    env: FunctionEnvMut<WebAssemblyEnv>,
    parameter: ExternRef<EffectParameter>,
) -> WasmResult<f32> {
    let v = parameter.value_func(&env)?;
    match v {
        EffectParameter::Float(_, f) => Ok(*f),
        _ => Err(anyhow!("Unexpected parameter type. Expected float, got {}", v)),
    }
    .into()
}

/// Gets the inner string data of an EffectParameter. Panics if it's not a string.
fn effect_parameter_as_string(
    env: FunctionEnvMut<WebAssemblyEnv>,
    parameter: ExternRef<EffectParameter>,
) -> WasmResult<ExternRef<StringKey>> {
    let v = parameter.value_func(&env)?;
    match v {
        EffectParameter::String(_, s) => Ok(ExternRef::func_new(&env, s)),
        _ => Err(anyhow!("Unexpected parameter type. Expected string, got {}", v)),
    }
    .into()
}

/// A result type that can be given to, or returned from WASM.
struct WasmResult<T>(Result<T>);

impl<T> WasmResult<T> {
    /// Create a new WasmResult with an OK value.
    pub fn ok(value: T) -> Self {
        Self(Ok(value))
    }

    /// Create a new WasmResult with an Err value.
    pub fn err(value: anyhow_ext::Error) -> Self {
        Self(Err(value))
    }
}

impl<T> From<Result<T>> for WasmResult<T> {
    fn from(value: Result<T>) -> Self {
        Self(value)
    }
}

impl<T> FromResidual for WasmResult<T> {
    fn from_residual(residual: <Self as Try>::Residual) -> Self {
        match residual {
            Ok(_) => {
                unimplemented!()
            }
            Err(e) => WasmResult(Err(e)),
        }
    }
}

impl<T> Try for WasmResult<T> {
    type Output = T;
    type Residual = <Result<T> as Try>::Residual;

    fn from_output(output: Self::Output) -> Self {
        Self(Ok(output))
    }

    fn branch(self) -> ControlFlow<Self::Residual, Self::Output> {
        match self.0 {
            Ok(v) => ControlFlow::Continue(v),
            Err(e) => ControlFlow::Break(Err(e)),
        }
    }
}