//! # actix-jwt-auth-middleware-macros
//! 
//! This crate provides a derive macro for the `actix_web::FromRequest` trait
//!
//! ## Example
//! 
//! ```rust
//! use actix-jwt-auth-middleware-macros::FromRequest;
//! #[derive(Clone, FromRequest)]
//! struct UserClaims {
//!     id: u32,
//!     role: Role,
//! }
//! ```

use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, DeriveInput, Ident};

#[proc_macro_derive(FromRequest)]
pub fn from_request(tokenstream: TokenStream) -> TokenStream {
    let abstract_syntax_tree = parse_macro_input!(tokenstream as DeriveInput);
    let struct_identifier = abstract_syntax_tree.ident;
    // let struct_generics = abstract_syntax_tree.generics;
    let lower_case_identifier = Ident::new(&struct_identifier.to_string().to_lowercase(), struct_identifier.span());

    let error = format!("could not extract type \"{}\" from HttpRequest extensions", struct_identifier.to_string());

    quote!(
        // stolen from https://stackoverflow.com/questions/63673447/how-can-i-pass-structs-from-an-actix-middleware-to-the-handler

        impl actix_web::FromRequest for #struct_identifier { // works
            type Error = actix_web::Error;
            type Future = std::future::Ready<Result<Self, Self::Error>>;
            fn from_request(req: &actix_web::HttpRequest, _: &mut actix_web::dev::Payload) -> Self::Future {
                std::future::ready(
                    match <actix_web::HttpRequest as actix_web::HttpMessage>::extensions(req).get::<#struct_identifier>() {
                        Some(#lower_case_identifier) => Ok(#lower_case_identifier.clone()),
                        None => Err(actix_web::error::ErrorBadRequest(#error))
                    }
                )
            }
        }
    )
    .into()
}