pezkuwi-subxt-codegen 0.44.0

// Copyright 2019-2025 Parity Technologies (UK) Ltd.
// This file is dual-licensed as Apache-2.0 or GPL-3.0.
// see LICENSE for license details.

use super::CodegenError;
use pezkuwi_subxt_metadata::PalletMetadata;
use proc_macro2::TokenStream as TokenStream2;
use quote::quote;
use scale_typegen::{typegen::ir::ToTokensWithSettings, TypeGenerator};

/// Generate events from the provided pallet metadata.
///
/// The function creates a new module named `events` under the pallet's module.
///
/// ```rust,ignore
/// pub mod PalletName {
///     pub mod events {
///     ...
///     }
/// }
/// ```
///
/// The function generates the events as rust structs that implement the `pezkuwi_subxt::event::StaticEvent`
/// trait to uniquely identify the event's identity when creating the extrinsic.
///
/// ```rust,ignore
/// pub struct EventName {
///      pub event_param: type,
/// }
/// impl ::pezkuwi_subxt::events::StaticEvent for EventName {
/// ...
/// }
/// ```
///
/// # Arguments
///
/// - `type_gen` - [`scale_typegen::TypeGenerator`] that contains settings and all types from the
///   runtime metadata.
/// - `pallet` - Pallet metadata from which the events are generated.
/// - `crate_path` - The crate path under which the `subxt-core` crate is located, e.g.
///   `::pezkuwi_subxt::ext::pezkuwi_subxt_core` when using subxt as a dependency.
pub fn generate_events(
	type_gen: &TypeGenerator,
	pallet: &PalletMetadata,
	crate_path: &syn::Path,
) -> Result<TokenStream2, CodegenError> {
	// Early return if the pallet has no events.
	let Some(event_ty) = pallet.event_ty_id() else {
		return Ok(quote!());
	};

	let variant_names_and_struct_defs =
		super::generate_structs_from_variants(type_gen, event_ty, |name| name.into(), "Event")?;

	let event_structs = variant_names_and_struct_defs.into_iter().map(|var| {
		let pallet_name = pallet.name();
		let event_struct_name = &var.composite.name;
		let event_name = var.variant_name;
		let alias_mod = var.type_alias_mod;
		let struct_def =
			type_gen.upcast_composite(&var.composite).to_token_stream(type_gen.settings());
		quote! {
			#struct_def
			#alias_mod

			impl #crate_path::events::StaticEvent for #event_struct_name {
				const PALLET: &'static str = #pallet_name;
				const EVENT: &'static str = #event_name;
			}
		}
	});

	let event_type = type_gen.resolve_type_path(event_ty)?.to_token_stream(type_gen.settings());
	let event_ty = type_gen.resolve_type(event_ty)?;
	let docs = &event_ty.docs;
	let docs = type_gen
		.settings()
		.should_gen_docs
		.then_some(quote! { #( #[doc = #docs ] )* })
		.unwrap_or_default();
	let types_mod_ident = type_gen.types_mod_ident();

	Ok(quote! {
		#docs
		pub type Event = #event_type;
		pub mod events {
			use super::#types_mod_ident;
			#( #event_structs )*
		}
	})
}