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#[macro_use]
extern crate syn;

use proc_macro::TokenStream;
use std::str::FromStr;

/// This attribute macro generates the boilerplate required to call into the
/// contract-specific logic from the entry-points to the Wasm module.
///
/// It should be added to the contract's init, handle, migrate and query implementations
/// like this:
/// ```
/// # use cosmwasm_std::{
/// #     Storage, Api, Querier, DepsMut, Deps, entry_point, Env, StdError, MessageInfo,
/// #     Response, QueryResponse,
/// # };
/// #
/// # type InstantiateMsg = ();
/// # type ExecuteMsg = ();
/// # type QueryMsg = ();
///
/// #[entry_point]
/// pub fn instantiate(
///     deps: DepsMut,
///     env: Env,
///     info: MessageInfo,
///     msg: InstantiateMsg,
/// ) -> Result<Response, StdError> {
/// #   Ok(Default::default())
/// }
///
/// #[entry_point]
/// pub fn handle(
///     deps: DepsMut,
///     env: Env,
///     info: MessageInfo,
///     msg: ExecuteMsg,
/// ) -> Result<Response, StdError> {
/// #   Ok(Default::default())
/// }
///
/// #[entry_point]
/// pub fn query(
///     deps: Deps,
///     env: Env,
///     msg: QueryMsg,
/// ) -> Result<QueryResponse, StdError> {
/// #   Ok(Default::default())
/// }
/// ```
///
/// where `InstantiateMsg`, `ExecuteMsg`, and `QueryMsg` are contract defined
/// types that implement `DeserializeOwned + JsonSchema`.
#[proc_macro_attribute]
pub fn entry_point(_attr: TokenStream, mut item: TokenStream) -> TokenStream {
    let cloned = item.clone();
    let function = parse_macro_input!(cloned as syn::ItemFn);
    let name = function.sig.ident.to_string();
    // The first argument is `deps`, the rest is region pointers
    let args = function.sig.inputs.len() - 1;

    // E.g. "ptr0: u32, ptr1: u32, ptr2: u32, "
    let typed_ptrs = (0..args).fold(String::new(), |acc, i| format!("{}ptr{}: u32, ", acc, i));
    // E.g. "ptr0, ptr1, ptr2, "
    let ptrs = (0..args).fold(String::new(), |acc, i| format!("{}ptr{}, ", acc, i));

    let new_code = format!(
        r##"
        #[cfg(target_arch = "wasm32")]
        mod __wasm_export_{name} {{ // new module to avoid conflict of function name
            #[no_mangle]
            extern "C" fn {name}({typed_ptrs}) -> u32 {{
                cosmwasm_std::do_{name}(&super::{name}, {ptrs})
            }}
        }}
    "##,
        name = name,
        typed_ptrs = typed_ptrs,
        ptrs = ptrs
    );
    let entry = TokenStream::from_str(&new_code).unwrap();
    item.extend(entry);
    item
}