lsv 0.1.15

use mlua::{
    Lua,
    LuaOptions,
    Result as LuaResult,
    StdLib,
    Table,
};

/// LuaEngine creates a sandboxed Lua runtime for lsv configuration.
/// Safety model:
/// - Load only BASE | STRING | TABLE | MATH stdlibs (no io/os/debug/package).
/// - Provide an `lsv` table with stub functions (`config`, `mapkey`).
/// - A restricted `require()` is installed by the loader.
pub struct LuaEngine
{
    lua: Lua,
}

impl LuaEngine
{
    /// Initialize a new sandboxed Lua state.
    pub fn new() -> LuaResult<Self>
    {
        let lua = Lua::new_with(
            StdLib::STRING | StdLib::TABLE | StdLib::MATH,
            LuaOptions::default(),
        )?;

        // Inject `lsv` namespace with stub APIs that accept calls from user
        // config.
        {
            let globals = lua.globals();
            let lsv: Table = lua.create_table()?;

            // lsv.config(tbl): accept and store later (currently a no-op
            // returning true)
            let config_fn =
                lua.create_function(|_, _tbl: mlua::Value| Ok(true))?;

            // lsv.mapkey(seq, action, description?): accept and store later
            // (no-op returning true)
            let mapkey_fn =
                lua.create_function(
                    |_,
                     (_seq, _action, _desc): (
                        String,
                        String,
                        Option<String>,
                    )| Ok(true),
                )?;

            lsv.set("config", config_fn)?;
            lsv.set("mapkey", mapkey_fn)?;

            globals.set("lsv", lsv)?;
        }

        Ok(Self { lua })
    }

    /// Access to the underlying Lua state (temporary, for future loader work).
    pub fn lua(&self) -> &Lua
    {
        &self.lua
    }
}