use anyhow::Result;
use wasmtime::*;


fn main() -> Result<()> {

    let mut config = wasmtime::Config::new();
    config.debug_info(true);

    let engine = wasmtime::Engine::new(&config)?;

    let module = wasmtime::Module::from_file(&engine, "g:\\dev\\test\\test.wasm")?;

    // All wasm objects operate within the context of a "store". Each
    // `Store` has a type parameter to store host-specific data, which in
    // this case we're using `4` for.
    let mut store = Store::new(&engine, 4);
    let host_fn = Func::wrap(&mut store, |caller: Caller<'_, u32>, param: i32| {
        println!("Got {} from WebAssembly", param);
        println!("my host state is: {}", caller.data());
    });

    // Instantiation of a module requires specifying its imports and then
    // afterwards we can fetch exports by name, as well as asserting the
    // type signature of the function with `get_typed_func`.
    let instance = Instance::new(&mut store, &module, &[host_fn.into()])?;
    let func = instance.get_typed_func::<(), (), _>(&mut store, "mytest")?;

    let result = instance.get_global(&mut store, "my_global");

    match result {
       Some(result) => println!("Found !"),
       None    => println!("Not found."),
    }

    // Call wasm function which should change value of the global.
    func.call(&mut store, ())?;

    Ok(())
}