//! Client-side Proc-Macro crate
//!
//! We separate proc-macro expanding logic to an extern program to allow
//! different implementations (e.g. wasm or dylib loading). And this crate
//! is used to provide basic infrastructure for communication between two
//! processes: Client (RA itself), Server (the external program)

mod rpc;
mod process;
pub mod msg;

use std::{
    ffi::OsStr,
    io,
    path::{Path, PathBuf},
    sync::Arc,
};

use base_db::ProcMacro;
use tt::{SmolStr, Subtree};

use crate::process::{ProcMacroProcessSrv, ProcMacroProcessThread};

pub use rpc::{ExpansionResult, ExpansionTask, ListMacrosResult, ListMacrosTask, ProcMacroKind};

#[derive(Debug, Clone)]
struct ProcMacroProcessExpander {
    process: Arc<ProcMacroProcessSrv>,
    dylib_path: PathBuf,
    name: SmolStr,
}

impl Eq for ProcMacroProcessExpander {}
impl PartialEq for ProcMacroProcessExpander {
    fn eq(&self, other: &Self) -> bool {
        self.name == other.name
            && self.dylib_path == other.dylib_path
            && Arc::ptr_eq(&self.process, &other.process)
    }
}

impl tt::TokenExpander for ProcMacroProcessExpander {
    fn expand(
        &self,
        subtree: &Subtree,
        attr: Option<&Subtree>,
    ) -> Result<Subtree, tt::ExpansionError> {
        let task = ExpansionTask {
            macro_body: subtree.clone(),
            macro_name: self.name.to_string(),
            attributes: attr.cloned(),
            lib: self.dylib_path.to_path_buf(),
        };

        let result: ExpansionResult = self.process.send_task(msg::Request::ExpansionMacro(task))?;
        Ok(result.expansion)
    }
}

#[derive(Debug)]
enum ProcMacroClientKind {
    Process { process: Arc<ProcMacroProcessSrv>, thread: ProcMacroProcessThread },
    Dummy,
}

#[derive(Debug)]
pub struct ProcMacroClient {
    kind: ProcMacroClientKind,
}

impl ProcMacroClient {
    pub fn extern_process(
        process_path: PathBuf,
        args: impl IntoIterator<Item = impl AsRef<OsStr>>,
    ) -> io::Result<ProcMacroClient> {
        let (thread, process) = ProcMacroProcessSrv::run(process_path, args)?;
        Ok(ProcMacroClient {
            kind: ProcMacroClientKind::Process { process: Arc::new(process), thread },
        })
    }

    pub fn dummy() -> ProcMacroClient {
        ProcMacroClient { kind: ProcMacroClientKind::Dummy }
    }

    pub fn by_dylib_path(&self, dylib_path: &Path) -> Vec<ProcMacro> {
        match &self.kind {
            ProcMacroClientKind::Dummy => vec![],
            ProcMacroClientKind::Process { process, .. } => {
                let macros = match process.find_proc_macros(dylib_path) {
                    Err(err) => {
                        eprintln!("Failed to find proc macros. Error: {:#?}", err);
                        return vec![];
                    }
                    Ok(macros) => macros,
                };

                macros
                    .into_iter()
                    .map(|(name, kind)| {
                        let name = SmolStr::new(&name);
                        let kind = match kind {
                            ProcMacroKind::CustomDerive => base_db::ProcMacroKind::CustomDerive,
                            ProcMacroKind::FuncLike => base_db::ProcMacroKind::FuncLike,
                            ProcMacroKind::Attr => base_db::ProcMacroKind::Attr,
                        };
                        let expander: Arc<dyn tt::TokenExpander> =
                            Arc::new(ProcMacroProcessExpander {
                                process: process.clone(),
                                name: name.clone(),
                                dylib_path: dylib_path.into(),
                            });

                        ProcMacro { name, kind, expander }
                    })
                    .collect()
            }
        }
    }
}