worldwideportal/src/lua_engine.rs

use self::{frames::*, muds::*};
use anyhow::Error;
use piccolo::{
    Callback, Closure, Context, Executor, ExternError, FromValue, Function, Lua, StashedExecutor,
    Table, Value, Variadic,
};
use yew::UseStateSetter;

use crate::{id_intern::intern_id, GlobalLayoutCell, GlobalMemoCell, TermFrame};
use std::collections::VecDeque;

pub struct LuaState {
    pub interp: Lua,
    pub exec: StashedExecutor,
}

mod frames;
pub mod muds;

impl LuaState {
    pub fn setup() -> Result<LuaState, String> {
        let mut interp = Lua::core();
        let exec: StashedExecutor =
            interp.enter(|ctx| Ok::<StashedExecutor, String>(ctx.stash(Executor::new(ctx))))?;

        Ok(LuaState { interp, exec })
    }

    fn try_set_current_frame(&mut self, frame: &TermFrame) -> Result<(), ExternError> {
        self.interp.try_enter(|ctx| {
            let info_table = Table::from_value(ctx, ctx.get_global("info")?)?;
            info_table.set(
                ctx,
                ctx.intern_static(b"current_frame"),
                intern_id::<TermFrame>(ctx, frame.clone()),
            )?;
            Ok(())
        })
    }

    pub fn set_current_frame(&mut self, frame: &TermFrame) {
        // We silently ignore errors here. Failure can happen if the Lua code does weird things
        // like messes with the info global, so better to just ignore.
        self.try_set_current_frame(frame).unwrap_or(())
    }

    pub fn execute(&mut self, command: &str) -> Result<(), String> {
        self.interp
            .try_enter(|ctx| {
                let closure = Closure::load(ctx, None, format!("return ({})", command).as_bytes())
                    .or_else(|_| Closure::load(ctx, None, command.as_bytes()))?;
                ctx.fetch(&self.exec).restart(ctx, closure.into(), ());
                Ok(())
            })
            .map_err(|err| format!("{}", err))?;
        self.interp
            .execute::<()>(&self.exec)
            .map_err(|err| format!("{}", err))
    }

    pub fn execute_command(
        &mut self,
        command: &str,
        arguments: &VecDeque<&str>,
    ) -> Result<(), String> {
        self.interp
            .try_enter(|ctx| {
                let commands = ctx.get_global::<Table>("commands")?;
                let command_value: Value = commands.get(ctx, ctx.intern(command.as_bytes()))?;
                if command_value.is_nil() {
                    Err(anyhow::Error::msg("Unknown command"))?;
                }
                let command_fn = Function::from_value(ctx, command_value)?;
                ctx.fetch(&self.exec).restart(
                    ctx,
                    command_fn,
                    Variadic(
                        arguments
                            .iter()
                            .map(|s| ctx.intern(s.as_bytes()).into())
                            .collect::<Vec<Value>>(),
                    ),
                );
                Ok(())
            })
            .map_err(|err| format!("{}", err))?;
        self.interp
            .execute::<()>(&self.exec)
            .map_err(|err| format!("{}", err))
    }
}

pub fn install_lua_globals(
    global_memo: &GlobalMemoCell,
    global_layout: UseStateSetter<GlobalLayoutCell>,
) -> Result<(), String> {
    global_memo.lua_engine.borrow_mut().interp.try_enter(|ctx| {
        let cmd_table = Table::new(&ctx);
        macro_rules! register_command {
            ($sym: ident) => {
                cmd_table
                    .set(
                        ctx,
                        ctx.intern_static(stringify!($sym).as_bytes()),
                        $sym(ctx, &global_memo, &global_layout),
                    )
                    .map_err(|_| Error::msg("Can't add command"))?;
            };
        }

        register_command!(echo);
        register_command!(echo_frame);
        register_command!(echo_frame_raw);
        register_command!(connect_mud);
        register_command!(delete_mud);
        register_command!(close_mud);
        register_command!(sendmud_raw);
        register_command!(hsplit);
        register_command!(panel_merge);
        register_command!(vsplit);
        ctx.set_global("commands", cmd_table);
        let info_table = Table::new(&ctx);
        ctx.set_global("info", info_table);
        let muds_table = Table::new(&ctx);
        ctx.set_global("muds", muds_table);

        let handlers_table = Table::new(&ctx);
        ctx.set_global("handlers", handlers_table);
        macro_rules! register_handler {
            ($sym: ident) => {
                handlers_table
                    .set(
                        ctx,
                        ctx.intern_static(stringify!($sym).as_bytes()),
                        $sym(ctx, &global_memo),
                    )
                    .map_err(|_| Error::msg("Can't add handler"))?;
            };
        }
        register_handler!(mudoutput);
        register_handler!(mudoutput_line);
        register_handler!(mudoutput_prompt);
        register_handler!(mudoutput_will);
        register_handler!(mudoutput_wont);
        register_handler!(mudoutput_do);
        register_handler!(mudoutput_dont);
        register_handler!(mudoutput_subnegotiation);

        macro_rules! register_nop_handler {
            ($sym: ident) => {
                handlers_table
                    .set(
                        ctx,
                        ctx.intern_static(stringify!($sym).as_bytes()),
                        lua_nop(ctx),
                    )
                    .map_err(|_| Error::msg("Can't add handler"))?;
            };
        }

        register_nop_handler!(mudoutput_break);
        register_nop_handler!(mudoutput_sync);
        register_nop_handler!(mudoutput_interrupt);
        register_nop_handler!(mudoutput_abort_output);
        register_nop_handler!(mudoutput_areyouthere);

        Ok(())
    });

    Ok(())
}

pub fn lua_nop(ctx: Context<'_>) -> Callback<'_> {
    Callback::from_fn(&ctx, |_ctx, _ex, _stack| {
        Ok(piccolo::CallbackReturn::Return)
    })
}