use std::collections::BTreeSet;
use heck::ToSnakeCase;
use proc_macro2::TokenStream;
use quote::quote;
use syn::parse::Parse;
use syn::{Attribute, Error, Expr, ItemStruct, Type};
use crate::path::HarmosPath;
pub(crate) fn structure(attribute: TokenStream, mut item: ItemStruct, sdk: &HarmosPath) -> Result<TokenStream, Error> {
if !item.generics.params.is_empty() {
return Err(Error::new_spanned(&item.generics, "an operation implementation struct cannot be generic"));
}
let attribute: Attribute = syn::parse_quote!(#[operation(#attribute)]);
let mut seen = BTreeSet::new();
let mut resources = Vec::<Type>::new();
let mut operations = Vec::<Type>::new();
let mut manual = false;
let mut response = None::<Type>;
let mut input = None::<Type>;
let mut output = None::<Type>;
let mut id = None::<Expr>;
let mut policy = None::<Expr>;
let mut description = None::<Expr>;
let mut visibility = None::<Expr>;
let mut replay = None::<Expr>;
let mut grant = None::<Expr>;
let mut key = None::<Expr>;
let mut grpc = None;
attribute.parse_nested_meta(|meta| {
let Some(name) = meta.path.get_ident() else {
return Err(meta.error("expected an operation metadata field"));
};
let name = name.to_string();
if !seen.insert(name.clone()) {
return Err(meta.error("operation metadata fields cannot repeat"));
}
match name.as_str() {
"resources" | "operations" => {
let content;
let value = meta.value()?;
syn::bracketed!(content in value);
let types = content.parse_terminated(Type::parse, syn::Token![,])?;
let target = if name == "resources" { &mut resources } else { &mut operations };
target.extend(types);
}
"codec" => {
let codec: syn::Ident = meta.value()?.parse()?;
if codec != "manual" {
return Err(meta.error("codec accepts only manual"));
}
manual = true;
}
"response" => response = Some(meta.value()?.parse()?),
"input" => input = Some(meta.value()?.parse()?),
"output" => output = Some(meta.value()?.parse()?),
"id" => id = Some(meta.value()?.parse()?),
"policy" => policy = Some(meta.value()?.parse()?),
"version" => return Err(meta.error("remove `version`: operation identity is a structural fingerprint")),
"description" => description = Some(meta.value()?.parse()?),
"visibility" => visibility = Some(meta.value()?.parse()?),
"replay" => replay = Some(meta.value()?.parse()?),
"grant" => grant = Some(meta.value()?.parse()?),
"key" => key = Some(meta.value()?.parse()?),
"grpc" => grpc = Some(grpc_binding(meta)?),
_ => return Err(meta.error("unknown operation metadata field")),
}
Ok(())
})?;
let missing = |field| Error::new_spanned(&attribute, format!("operation requires `{field}`"));
let response = response.unwrap_or_else(|| syn::parse_quote!(()));
let policy = policy.ok_or_else(|| missing("policy"))?;
let name = item.ident.clone();
let gates = crate::operation::configuration(&item.attrs)?;
let derived = name.to_string().trim_start_matches("r#").to_snake_case();
let id = id.unwrap_or_else(|| syn::parse_quote!(#derived));
let direction =
|item: Option<Type>| item.map_or_else(|| quote!(#sdk::operations::NoStream), |item| quote!(#sdk::operations::Stream<#item>));
let input = direction(input);
let output = direction(output);
let description = description.map(|value| quote!(const DESCRIPTION: &'static str = #value;));
let visibility = visibility.map(|value| {
let value = match &value {
Expr::Path(path) if path.path.is_ident("Shared") || path.path.is_ident("Host") || path.path.is_ident("Private") => {
quote!(#sdk::operations::Visibility::#value)
}
_ => quote!(#value),
};
quote!(const VISIBILITY: #sdk::operations::Visibility = #value;)
});
let replay = replay.map(|value| quote!(const REPLAY: #sdk::operations::ReplaySafety = #value;));
let grpc = grpc.map(|(package, service, method)| {
quote! {
const GRPC: ::core::option::Option<#sdk::operations::Grpc> =
::core::option::Option::Some(#sdk::operations::Grpc::new(#package, #service, #method));
}
});
let grant = grant.map(|value| {
quote! {
fn grant(request: &Self::Request) -> ::core::option::Option<#sdk::plugin::Grant> { (#value)(request) }
}
});
let key = key.map(|value| {
quote! {
fn key(request: &Self::Request) -> ::core::option::Option<#sdk::operations::CacheKey> { (#value)(request) }
}
});
let clone = item.attrs.iter().filter(|attribute| attribute.path().is_ident("derive")).any(|attribute| {
attribute
.parse_args_with(syn::punctuated::Punctuated::<syn::Path, syn::Token![,]>::parse_terminated)
.is_ok_and(|paths| paths.iter().any(|path| path.is_ident("Clone")))
});
if !clone && !manual {
item.attrs.push(syn::parse_quote!(#[derive(Clone)]));
}
let message = if manual { quote!(#item) } else { crate::message::expand(quote!(harmos_path = #sdk), quote!(#item))? };
let execution_gate = sdk.execution_gate();
let requirements = resources.iter().map(|resource| {
quote! {
#(#gates)*
#execution_gate
impl #sdk::operations::Requires<#resource> for #name {}
}
});
let invokes = operations.iter().map(|operation| {
quote! {
#(#gates)*
impl #sdk::operations::Invokes<#operation> for #name {}
}
});
Ok(quote! {
#message
#(#gates)*
const _: () = assert!(
#sdk::__private::operation_identity(#id),
"operation id must contain dotted [a-z][a-z0-9_]* segments"
);
#(#gates)*
impl #sdk::OperationDeclaration for #name {
type Request = Self;
type Response = #response;
type Input = #input;
type Output = #output;
const ID: &'static str = #id;
const OPERATIONS: &'static [#sdk::operations::WireDeclaration] = &[#(#sdk::operations::WireDeclaration::of::<#operations>()),*];
const POLICY: #sdk::OperationPolicy = #policy;
#description #visibility #replay #grpc #grant #key
}
#(#gates)*
#[allow(unexpected_cfgs)]
impl #name {
pub fn definition() -> #sdk::OperationDefinition {
<Self as #sdk::OperationDeclaration>::definition()
}
}
#(#invokes)*
#[allow(unexpected_cfgs)]
const _: () = {
#(#requirements)*
#(#gates)*
#execution_gate
impl #sdk::Dependent for #name {
const RESOURCES: &'static [#sdk::Resource] = &[#(#sdk::Resource::of::<#resources>()),*];
}
};
})
}
fn grpc_binding(meta: syn::meta::ParseNestedMeta<'_>) -> Result<(syn::LitStr, syn::LitStr, syn::LitStr), Error> {
let mut values = std::collections::BTreeMap::new();
meta.parse_nested_meta(|field| {
let name = field.path.get_ident().map(ToString::to_string).ok_or_else(|| field.error("expected package, service or method"))?;
if !matches!(name.as_str(), "package" | "service" | "method") {
return Err(field.error("expected package, service or method"));
}
let value: syn::LitStr = field.value()?.parse()?;
if values.insert(name, value).is_some() {
return Err(field.error("gRPC binding fields cannot repeat"));
}
Ok(())
})?;
let mut take = |name| values.remove(name).ok_or_else(|| meta.error("grpc requires package, service and method"));
let package = take("package")?;
let service = take("service")?;
let method = take("method")?;
for (name, value) in [("package", &package), ("service", &service), ("method", &method)] {
let text = value.value();
let valid = |value: &str| {
let mut bytes = value.bytes();
bytes.next().is_some_and(|byte| byte.is_ascii_alphabetic() || byte == b'_')
&& bytes.all(|byte| byte.is_ascii_alphanumeric() || byte == b'_')
};
if text.len() > 255
|| (name == "package" && text.starts_with("grpc."))
|| !(if name == "package" { text.split('.').all(valid) } else { valid(&text) })
{
return Err(Error::new_spanned(value, "invalid or reserved gRPC binding name"));
}
}
Ok((package, service, method))
}