//! #[clause_param]属性宏实现

use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, Item, AttributeArgs, Meta, NestedMeta, Lit};

/// 实现#[clause_param]属性宏
pub fn clause_param_impl(attr: TokenStream, item: TokenStream) -> TokenStream {
    // 解析属性参数
    let args = parse_macro_input!(attr as AttributeArgs);
    let input = parse_macro_input!(item as Item);

    let mut clause = None;
    let mut description = None;

    for arg in args {
        if let NestedMeta::Meta(Meta::NameValue(nv)) = arg {
            let path_str = nv.path.get_ident().map(|i| i.to_string());
            
            match path_str.as_deref() {
                Some("clause") => {
                    if let Lit::Str(lit) = &nv.lit {
                        clause = Some(lit.value());
                    }
                }
                Some("description") => {
                    if let Lit::Str(lit) = &nv.lit {
                        description = Some(lit.value());
                    }
                }
                _ => {}
            }
        }
    }

    // 生成文档注释
    let doc_comment = if let (Some(clause_id), Some(desc)) = (clause, description) {
        quote! {
            #[doc = concat!("Constitutional parameter from clause: ", #clause_id)]
            #[doc = ""]
            #[doc = #desc]
        }
    } else {
        quote! {}
    };

    // 生成最终代码
    let expanded = quote! {
        #doc_comment
        #input
    };

    TokenStream::from(expanded)
}