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use super::super::store::wasm_store_t;
use super::super::types::wasm_globaltype_t;
use super::super::value::wasm_val_t;
use crate::error::update_last_error;
use std::convert::TryInto;
use wasmer::{Global, Val};

#[allow(non_camel_case_types)]
pub struct wasm_global_t {
    // maybe needs to hold onto instance
    pub(crate) inner: Global,
}

#[no_mangle]
pub unsafe extern "C" fn wasm_global_new(
    store: Option<&wasm_store_t>,
    global_type: Option<&wasm_globaltype_t>,
    val: Option<&wasm_val_t>,
) -> Option<Box<wasm_global_t>> {
    let store = store?;
    let global_type = global_type?;
    let val = val?;

    let global_type = &global_type.inner().global_type;
    let wasm_val = val.try_into().ok()?;
    let store = &store.inner;
    let global = if global_type.mutability.is_mutable() {
        Global::new_mut(store, wasm_val)
    } else {
        Global::new(store, wasm_val)
    };

    Some(Box::new(wasm_global_t { inner: global }))
}

#[no_mangle]
pub unsafe extern "C" fn wasm_global_delete(_global: Option<Box<wasm_global_t>>) {}

// TODO: figure out if these should be deep or shallow copies
#[no_mangle]
pub unsafe extern "C" fn wasm_global_copy(global: &wasm_global_t) -> Box<wasm_global_t> {
    // do shallow copy
    Box::new(wasm_global_t {
        inner: global.inner.clone(),
    })
}

#[no_mangle]
pub unsafe extern "C" fn wasm_global_get(
    global: &wasm_global_t,
    // own
    out: &mut wasm_val_t,
) {
    let value = global.inner.get();
    *out = value.try_into().unwrap();
}

/// Note: This function returns nothing by design but it can raise an
/// error if setting a new value fails.
#[no_mangle]
pub unsafe extern "C" fn wasm_global_set(global: &mut wasm_global_t, val: &wasm_val_t) {
    let value: Val = val.try_into().unwrap();

    if let Err(e) = global.inner.set(value) {
        update_last_error(e);
    }
}

#[no_mangle]
pub unsafe extern "C" fn wasm_global_same(
    wasm_global1: &wasm_global_t,
    wasm_global2: &wasm_global_t,
) -> bool {
    wasm_global1.inner.same(&wasm_global2.inner)
}

#[no_mangle]
pub extern "C" fn wasm_global_type(global: &wasm_global_t) -> Box<wasm_globaltype_t> {
    Box::new(wasm_globaltype_t::new(global.inner.ty().clone()))
}

#[cfg(test)]
mod tests {
    use inline_c::assert_c;

    #[test]
    fn test_set_host_global_immutable() {
        (assert_c! {
            #include "tests/wasmer_wasm.h"

            int main() {
                wasm_engine_t* engine = wasm_engine_new();
                wasm_store_t* store = wasm_store_new(engine);

                wasm_val_t forty_two = WASM_F32_VAL(42);
                wasm_val_t forty_three = WASM_F32_VAL(43);

                wasm_valtype_t* valtype = wasm_valtype_new_i32();
                wasm_globaltype_t* global_type = wasm_globaltype_new(valtype, WASM_CONST);
                wasm_global_t* global = wasm_global_new(store, global_type, &forty_two);

                wasm_globaltype_delete(global_type);

                wasm_global_set(global, &forty_three);

                assert(wasmer_last_error_length() > 0);

                wasm_global_delete(global);
                wasm_store_delete(store);
                wasm_engine_delete(engine);

                return 0;
            }
        })
        .success();
    }

    #[test]
    fn test_set_guest_global_immutable() {
        (assert_c! {
            #include "tests/wasmer_wasm.h"

            int main() {
                wasm_engine_t* engine = wasm_engine_new();
                wasm_store_t* store = wasm_store_new(engine);

                wasm_byte_vec_t wat;
                wasmer_byte_vec_new_from_string(&wat, "(module (global $global (export \"global\") f32 (f32.const 1)))");
                wasm_byte_vec_t wasm_bytes;
                wat2wasm(&wat, &wasm_bytes);
                wasm_module_t* module = wasm_module_new(store, &wasm_bytes);
                wasm_extern_vec_t import_object = WASM_EMPTY_VEC;
                wasm_instance_t* instance = wasm_instance_new(store, module, &import_object, NULL);

                wasm_extern_vec_t exports;
                wasm_instance_exports(instance, &exports);
                wasm_global_t* global = wasm_extern_as_global(exports.data[0]);

                wasm_val_t forty_two = WASM_F32_VAL(42);
                wasm_global_set(global, &forty_two);

                printf("%d", wasmer_last_error_length());
                assert(wasmer_last_error_length() > 0);

                wasm_instance_delete(instance);
                wasm_byte_vec_delete(&wasm_bytes);
                wasm_byte_vec_delete(&wat);
                wasm_store_delete(store);
                wasm_engine_delete(engine);

                return 0;
            }
        })
        .success();
    }
}