use proc_macro::TokenStream;

use quote::{format_ident, quote};

/// Allow all fields in the extractor config to be also overrideable by extractor CLI flags

#[proc_macro_attribute]

pub fn extractor_cli_config(_attr: TokenStream, item: TokenStream) -> TokenStream {

let ast = syn::parse_macro_input!(item as syn::ItemStruct);

let name = &ast.ident;

let cli_name = format_ident!("Cli{}", name);

let cli_fields = ast

.fields

.iter()

.map(|f| {

let id = f.ident.as_ref().unwrap();

let ty = &f.ty;

if let syn::Type::Path(p) = ty {

if p.path.is_ident(&format_ident!("bool")) {

return quote! {

#[arg(long)]

#[serde(skip_serializing_if="<&bool>::not")]

#id: bool,

};

}

}

if id == &format_ident!("verbose") {

quote! {

#[arg(long, short, action=clap::ArgAction::Count)]

#[serde(skip_serializing_if="u8::is_zero")]

#id: u8,

}

} else if id == &format_ident!("inputs") {

quote! {

#id: #ty,

}

} else {

quote! {

#[arg(long)]

#id: Option<#ty>,

}

}

})

.collect::<Vec<_>>();

let debug_fields = ast

.fields

.iter()

.map(|f| {

let id = f.ident.as_ref().unwrap();

if id == &format_ident!("inputs") {

quote! {

.field("number of inputs", &self.#id.len())

}

} else {

quote! {

.field(stringify!(#id), &self.#id)

}

}

})

.collect::<Vec<_>>();

let gen = quote! {

#[serde_with::apply(_ => #[serde(default)])]

#[derive(Deserialize, Default)]

#ast

impl Debug for #name {

fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {

f.debug_struct("configuration:")

#(#debug_fields)*

.finish()

}

}

#[serde_with::skip_serializing_none]

#[derive(clap::Parser, Serialize)]

#[command(about, long_about = None)]

struct #cli_name {

#(#cli_fields)*

}

};

gen.into()

}