//! Proc macro ABI
use crate::{ProcMacroClientHandle, ProcMacroKind, ProcMacroSrvSpan, token_stream::TokenStream};
use rustc_proc_macro::bridge;

#[repr(transparent)]
pub(crate) struct ProcMacros([bridge::client::ProcMacro]);

impl From<bridge::PanicMessage> for crate::PanicMessage {
    fn from(p: bridge::PanicMessage) -> Self {
        Self { message: p.into_string() }
    }
}

impl ProcMacros {
    pub(crate) fn expand<S: ProcMacroSrvSpan>(
        &self,
        macro_name: &str,
        macro_body: TokenStream<S>,
        attribute: Option<TokenStream<S>>,
        def_site: S,
        call_site: S,
        mixed_site: S,
        callback: Option<ProcMacroClientHandle<'_>>,
    ) -> Result<TokenStream<S>, crate::PanicMessage> {
        let parsed_attributes = attribute.unwrap_or_default();

        for proc_macro in &self.0 {
            match proc_macro {
                bridge::client::ProcMacro::CustomDerive { trait_name, client, .. }
                    if *trait_name == macro_name =>
                {
                    let res = client.run(
                        &bridge::server::SAME_THREAD,
                        S::make_server(call_site, def_site, mixed_site, callback),
                        macro_body,
                        cfg!(debug_assertions),
                    );
                    return res.map_err(crate::PanicMessage::from);
                }
                bridge::client::ProcMacro::Bang { name, client } if *name == macro_name => {
                    let res = client.run(
                        &bridge::server::SAME_THREAD,
                        S::make_server(call_site, def_site, mixed_site, callback),
                        macro_body,
                        cfg!(debug_assertions),
                    );
                    return res.map_err(crate::PanicMessage::from);
                }
                bridge::client::ProcMacro::Attr { name, client } if *name == macro_name => {
                    let res = client.run(
                        &bridge::server::SAME_THREAD,
                        S::make_server(call_site, def_site, mixed_site, callback),
                        parsed_attributes,
                        macro_body,
                        cfg!(debug_assertions),
                    );
                    return res.map_err(crate::PanicMessage::from);
                }
                _ => continue,
            }
        }

        Err(bridge::PanicMessage::String(format!("proc-macro `{macro_name}` is missing")).into())
    }

    pub(crate) fn list_macros(&self) -> impl Iterator<Item = (&str, ProcMacroKind)> {
        self.0.iter().map(|proc_macro| match *proc_macro {
            bridge::client::ProcMacro::CustomDerive { trait_name, .. } => {
                (trait_name, ProcMacroKind::CustomDerive)
            }
            bridge::client::ProcMacro::Bang { name, .. } => (name, ProcMacroKind::Bang),
            bridge::client::ProcMacro::Attr { name, .. } => (name, ProcMacroKind::Attr),
        })
    }
}
