feat(CommandTransferValue): Generalize the API to facilitate multiple languages

The code for the `CommandTransferValue` was deeply entrenched in the
whole Lua execution code, which is obviously not ideal. In trying to
alleviate that, I decided to generalize the API in a way, that makes
adding new languages a lot easier.

language_macros/src/generate/lua_wrapper/rust_wrapper_functions/mod.rs

@@ -126,67 +126,7 @@ fn get_function_body(field: &Field, has_input: bool, output_type: &Option<Type>)
 
     let function_return = if let Some(_) = output_type {
         quote! {
-            let converted_output =  lua
+            return Ok(output.into_lua(lua).expect("This conversion should always work"));
-                .to_value(&output)
-                .expect("This conversion should (indirectely) be checked at compile time");
-            if let mlua::Value::Table(table) = converted_output {
-                let real_output: mlua::Value = match output {
-                    CommandTransferValue::Nil => table
-                        .get("Nil")
-                        .expect("This should exist"),
-                    CommandTransferValue::Boolean(_) => table
-                        .get("Boolean")
-                        .expect("This should exist"),
-                    CommandTransferValue::Integer(_) => table
-                        .get("Integer")
-                        .expect("This should exist"),
-                    CommandTransferValue::Number(_) => table
-                        .get("Number")
-                        .expect("This should exist"),
-                    CommandTransferValue::String(_) => table
-                        .get("String")
-                        .expect("This should exist"),
-                    CommandTransferValue::Table(_) => {
-                        todo!()
-                        // FIXME(@Soispha): This returns a table with the values wrapped the
-                        // same way the values above are wrapped. That is (from the greet_multiple
-                        // function):
-                        // ```json
-                        // {
-                        //   "Table": {
-                        //      "UserName1": {
-                        //          "Integer": 2
-                        //      }
-                        //   }
-                        // }
-                        // ```
-                        // whilst the output should be:
-                        // ```json
-                        // {
-                        //   "UserName1": 2
-                        // }
-                        // ```
-                        // That table would need to be unpacked, but this requires some recursive
-                        // function, which seems not very performance oriented.
-                        //
-                        // My first (quick) attempt:
-                        //let mut output_table = lua.create_table().expect("This should work?");
-                        //let initial_table: mlua::Value = table
-                        //    .get("Table")
-                        //    .expect("This should exist");
-                        //while let mlua::Value::Table(table) = initial_table {
-                        //    for pair in table.pairs() {
-                        //        let (key, value) = pair.expect("This should also work?");
-                        //        output_table.set(key, value);
-                        //    }
-                        //}
-                    },
-                };
-                return Ok(real_output);
-            } else {
-                unreachable!("Lua serializes these things always in a table");
-            }
-
         }
     } else {
         quote! {

src/app/command_interface/command_transfer_value/lua.rs

@@ -0,0 +1,94 @@
+use cli_log::{debug, info};
+use mlua::{IntoLua, LuaSerdeExt, Table, Value};
+
+use super::CommandTransferValue;
+
+impl<'lua> IntoLua<'lua> for CommandTransferValue {
+    fn into_lua(self, lua: &'lua mlua::Lua) -> mlua::Result<mlua::Value<'lua>> {
+        let converted_output = lua.to_value(&self)?;
+        return unwrap(converted_output, lua);
+    }
+}
+fn unwrap<'lua>(
+    value_to_unwrap: Value<'lua>,
+    lua: &'lua mlua::Lua,
+) -> mlua::Result<mlua::Value<'lua>> {
+    fn unwrap_first_level<'lua>(table: Table<'lua>) -> mlua::Result<Value<'lua>> {
+        let (_, value): (Value, Value) = table
+            .pairs()
+            .next()
+            .expect("Exactly one item should extist")?;
+        Ok(value)
+    }
+    // That converted value looks somewhat like this (e.g. a String):
+    // ```
+    // {
+    //   ["String"] = "hi",
+    // }
+    // ```
+    // or like this (e.g. a table):
+    // ```
+    // {
+    //   ["Table"] = {
+    //     ["UserId"] = {
+    //       ["Integer"] = 2,
+    //     },
+    //     ["UserName"] = {
+    //       ["String"] = "James",
+    //     },
+    //   },
+    // }
+    // ```
+    if let Value::Table(table) = value_to_unwrap {
+        let value = unwrap_first_level(table)?;
+        if let Value::Table(wrapped_table) = value {
+            info!("We've got a wtable! wtable: \n{:#?}", wrapped_table);
+            // we now have a wrapped table value for example like this:
+            // ```
+            // {
+            //   ["UserId"] = {
+            //     ["Integer"] = 2,
+            //   },
+            //   ["UserName"] = {
+            //     ["String"] = "James",
+            //   },
+            //   ["Versions"] = {
+            //     ["Table"] = {
+            //       ["api"] = {
+            //         ["Boolean"] = true,
+            //       },
+            //       ["interface"] = {
+            //         ["Integer"] = 3,
+            //       },
+            //     },
+            //   },
+            // }
+            // ```
+            let output_table: Table = lua
+                .load("{}")
+                .eval()
+                .expect("This is static, it should always work");
+
+            // FIXME(@soispha): This still fails for nested tables (i.e. the table above), as it
+            // unpacks too much. While unpacking the while loop should stop, when a key is not from
+            // the CommandTransferValue family (i.e. ["Integer", "Boolean", "String", "Table",
+            // etc.]) <2023-09-09>
+            for pair in wrapped_table.pairs::<Value, Value>() {
+                let (key, mut raw_value) = pair?;
+                while let Value::Table(raw_table) = raw_value {
+                    raw_value = unwrap_first_level(raw_table)?;
+                }
+                output_table.set(key, raw_value)?;
+            }
+
+            return Ok(output_table.into_lua(lua)?);
+        } else {
+            info!("We've got a normal output! output: {:#?}", value);
+            // we had a simple wrapped value, which is already unwrapped, thus it can be
+            // returned directly
+            return Ok(value);
+        }
+    } else {
+        unreachable!("The returned table should always only contain one element");
+    }
+}

src/app/command_interface/command_transfer_value/mod.rs

@@ -0,0 +1,60 @@
+use std::{collections::HashMap, fmt::Display};
+
+use serde::{Deserialize, Serialize};
+
+pub mod type_conversions;
+
+// language support
+pub mod lua;
+
+pub type Table = HashMap<String, CommandTransferValue>;
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub enum CommandTransferValue {
+    /// `nil` or `null` or `undefined`; anything which goes in that group of types.
+    Nil,
+
+    /// `true` or `false`.
+    Boolean(bool),
+
+    // A “light userdata” object, equivalent to a raw pointer.
+    // /* TODO */ LightUserData(LightUserData),
+    /// An integer number.
+    Integer(i64),
+
+    /// A floating point number.
+    Number(f64),
+
+    /// A string
+    String(String),
+
+    /// A table, dictionary or HashMap
+    Table(HashMap<String, CommandTransferValue>),
+    // Reference to a Lua function (or closure).
+    // /* TODO */ Function(Function),
+
+    // Reference to a Lua thread (or coroutine).
+    // /* TODO */ Thread(Thread<'lua>),
+
+    // Reference to an userdata object that holds a custom type which implements `UserData`.
+    // Special builtin userdata types will be represented as other `Value` variants.
+    // /* TODO */ UserData(AnyUserData),
+
+    // `Error` is a special builtin userdata type. When received from Lua it is implicitly cloned.
+    // /* TODO */ Error(Error),
+}
+
+impl Display for CommandTransferValue {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            CommandTransferValue::Nil => f.write_str("Nil"),
+            CommandTransferValue::Boolean(bool) => f.write_str(&format!("{}", bool)),
+            CommandTransferValue::Integer(int) => f.write_str(&format!("{}", int)),
+            CommandTransferValue::Number(num) => f.write_str(&format!("{}", num)),
+            CommandTransferValue::String(str) => f.write_str(&format!("{}", str)),
+            // TODO(@Soispha): The following line should be a real display call, but how do you
+            // format a HashMap?
+            CommandTransferValue::Table(table) => f.write_str(&format!("{:#?}", table)),
+        }
+    }
+}

src/app/command_interface/command_transfer_value/type_conversions.rs

@@ -0,0 +1,34 @@
+use std::collections::HashMap;
+
+use super::CommandTransferValue;
+
+impl From<String> for CommandTransferValue {
+    fn from(s: String) -> Self {
+        Self::String(s.to_owned())
+    }
+}
+impl From<f64> for CommandTransferValue {
+    fn from(s: f64) -> Self {
+        Self::Number(s.to_owned())
+    }
+}
+impl From<i64> for CommandTransferValue {
+    fn from(s: i64) -> Self {
+        Self::Integer(s.to_owned())
+    }
+}
+impl From<HashMap<String, CommandTransferValue>> for CommandTransferValue {
+    fn from(s: HashMap<String, CommandTransferValue>) -> Self {
+        Self::Table(s.to_owned())
+    }
+}
+impl From<bool> for CommandTransferValue {
+    fn from(s: bool) -> Self {
+        Self::Boolean(s.to_owned())
+    }
+}
+impl From<()> for CommandTransferValue {
+    fn from(_: ()) -> Self {
+        Self::Nil
+    }
+}

src/app/command_interface/lua_command_manager/mod.rs

@@ -1,10 +1,9 @@
-use std::{collections::HashMap, fmt::Display, thread};
+use std::thread;
 
 use anyhow::{Context, Result};
-use cli_log::{error, info, debug};
+use cli_log::{debug, error, info};
 use mlua::{Function, Value};
 use once_cell::sync::OnceCell;
-use serde::{Deserialize, Serialize};
 use tokio::{
     runtime::Builder,
     sync::{mpsc, Mutex},
@@ -17,95 +16,13 @@ use crate::app::{
 };
 
 static LUA: OnceCell<Mutex<mlua::Lua>> = OnceCell::new();
-pub type Table = HashMap<String, CommandTransferValue>;
-
-#[derive(Debug, Serialize, Deserialize, Clone)]
-pub enum CommandTransferValue {
-    /// `nil` or `null` or `undefined`; anything which goes in that group of types.
-    Nil,
-
-    /// `true` or `false`.
-    Boolean(bool),
-
-    // A "light userdata" object, equivalent to a raw pointer.
-    // /*TODO*/ LightUserData(LightUserData),
-
-    /// An integer number.
-    Integer(i64),
-
-    /// A floating point number.
-    Number(f64),
-
-    /// A string
-    String(String),
-
-    /// A table, directory or HashMap
-    Table(HashMap<String, CommandTransferValue>),
-
-    // Reference to a Lua function (or closure).
-    // /* TODO */ Function(Function),
-
-    // Reference to a Lua thread (or coroutine).
-    // /* TODO */ Thread(Thread<'lua>),
-
-    // Reference to a userdata object that holds a custom type which implements `UserData`.
-    // Special builtin userdata types will be represented as other `Value` variants.
-    // /* TODO */ UserData(AnyUserData),
-
-    // `Error` is a special builtin userdata type. When received from Lua it is implicitly cloned.
-    // /* TODO */ Error(Error),
-}
-
-impl Display for CommandTransferValue {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            CommandTransferValue::Nil => f.write_str("Nil"),
-            CommandTransferValue::Boolean(bool) => f.write_str(&format!("{}", bool)),
-            CommandTransferValue::Integer(int) => f.write_str(&format!("{}", int)),
-            CommandTransferValue::Number(num) => f.write_str(&format!("{}", num)),
-            CommandTransferValue::String(str) => f.write_str(&format!("{}", str)),
-            // TODO(@Soispha): The following line should be a real display call, but how do you
-            // format a HashMap?
-            CommandTransferValue::Table(table) => f.write_str(&format!("{:#?}", table)),
-        }
-    }
-}
 
+/// This structure contains the necessary state for running an embedded Lua runtime (i.e.
+/// the tread, the Lua memory, etc.).
 pub struct LuaCommandManager {
     lua_command_tx: mpsc::Sender<String>,
 }
 
-impl From<String> for CommandTransferValue {
-    fn from(s: String) -> Self {
-        Self::String(s.to_owned())
-    }
-}
-impl From<f64> for CommandTransferValue {
-    fn from(s: f64) -> Self {
-        Self::Number(s.to_owned())
-    }
-}
-impl From<i64> for CommandTransferValue {
-    fn from(s: i64) -> Self {
-        Self::Integer(s.to_owned())
-    }
-}
-impl From<HashMap<String, CommandTransferValue>> for CommandTransferValue {
-    fn from(s: HashMap<String, CommandTransferValue>) -> Self {
-        Self::Table(s.to_owned())
-    }
-}
-impl From<bool> for CommandTransferValue {
-    fn from(s: bool) -> Self {
-        Self::Boolean(s.to_owned())
-    }
-}
-impl From<()> for CommandTransferValue {
-    fn from(_: ()) -> Self {
-        Self::Nil
-    }
-}
-
 impl LuaCommandManager {
     pub async fn execute_code(&self, code: String) {
         self.lua_command_tx

src/app/command_interface/mod.rs

@@ -1,14 +1,15 @@
 // Use `cargo expand app::command_interface` for an overview of the file contents
 
+pub mod command_transfer_value;
 pub mod lua_command_manager;
 
 use language_macros::ci_command_enum;
 
 // TODO(@Soispha): Should these paths be moved to the proc macro?
 // As they are not static, it could be easier for other people,
-// if they stay here
+// if they stay here.
-use lua_command_manager::CommandTransferValue;
+use crate::app::command_interface::command_transfer_value::CommandTransferValue;
-use mlua::LuaSerdeExt;
+use mlua::IntoLua;
 use crate::app::Event;
 
 #[ci_command_enum]
@@ -25,7 +26,6 @@ struct Commands {
     /// Returns a table of greeted users
     greet_multiple: fn() -> Table,
     // End debug functions
-
     /// Closes the application
     exit: fn(),
 
@@ -46,7 +46,7 @@ struct Commands {
     set_mode_insert: fn(),
 
     /// Send a message to the current room
-    /// The sent message is interpreted literally.
+    /// The send message is interpreted literally.
     room_message_send: fn(String),
 
     /// Open the help pages at the first occurrence of

src/app/events/event_types/event/handlers/command.rs

@@ -4,14 +4,18 @@ use anyhow::{Error, Result};
 use cli_log::{trace, warn};
 use tokio::sync::oneshot;
 
-use crate::{app::{
+use crate::{
-    command_interface::{
+    app::{
-        lua_command_manager::{CommandTransferValue, Table},
+        command_interface::{
-        Command,
+            command_transfer_value::{CommandTransferValue, Table},
+            Command,
+        },
+        events::event_types::EventStatus,
+        status::State,
+        App,
     },
-    events::event_types::EventStatus,
+    ui::central::InputPosition,
-    App, status::State,
+};
-}, ui::central::InputPosition};
 
 pub async fn handle(
     app: &mut App<'_>,
@@ -20,8 +24,8 @@ pub async fn handle(
 ) -> Result<EventStatus> {
     // A command can both return _status output_ (what you would normally print to stderr)
     // and _main output_ (the output which is normally printed to stdout).
-    // We simulate these by returning the main output to the lua function, and printing the
+    // We simulate these by returning the main output to the Lua function, and printing the
-    // status output to a status ui field.
+    // status output to a status UI field.
     //
     // Every function should return some status output to show the user, that something is
     // happening, while only some functions return some value to the main output, as this
@@ -68,7 +72,7 @@ pub async fn handle(
         }
 
         Command::DisplayOutput(output) => {
-            // TODO(@Soispha): This is only used to show the lua command output to the user.
+            // TODO(@Soispha): This is only used to show the Lua command output to the user.
             // Lua commands already receive the output. This should probably be communicated
             // better, should it?
             send_status_output!(output);
@@ -114,7 +118,7 @@ pub async fn handle(
                 room.send(msg.clone()).await?;
                 send_status_output!("Sent message: `{}`", msg);
             } else {
-                // TODO(@Soispha): Should this raise a lua error? It could be very confusing,
+                // TODO(@Soispha): Should this raise a Lua error? It could be very confusing,
                 // when a user doesn't read the log.
                 warn!("Can't send message: `{}`, as there is no open room!", &msg);
             }
@@ -126,13 +130,25 @@ pub async fn handle(
         }
         Command::Print(output) => {
             // FIXME(@Soispha): This only works with strings, which is a clear downside to the
-            // original print function. Find a way to just use the original one
+            // original print function. Find a way to just use the original one.
             send_main_output!("{}", output);
             EventStatus::Ok
         }
         Command::GreetMultiple => {
             let mut table: Table = HashMap::new();
-            table.insert("UserName1".to_owned(), CommandTransferValue::Integer(2));
+            table.insert("UserId".to_owned(), CommandTransferValue::Integer(2));
+            table.insert(
+                "UserName".to_owned(),
+                CommandTransferValue::String("James".to_owned()),
+            );
+
+            let mut second_table: Table = HashMap::new();
+            second_table.insert("interface".to_owned(), CommandTransferValue::Integer(3));
+            second_table.insert("api".to_owned(), CommandTransferValue::Boolean(true));
+            table.insert(
+                "Versions".to_owned(),
+                CommandTransferValue::Table(second_table),
+            );
             send_main_output!(table);
             EventStatus::Ok
         }

src/app/events/event_types/event/mod.rs

@@ -6,7 +6,7 @@ use crossterm::event::Event as CrosstermEvent;
 use tokio::sync::oneshot;
 
 use crate::app::{
-    command_interface::{lua_command_manager::CommandTransferValue, Command},
+    command_interface::{command_transfer_value::CommandTransferValue, Command},
     status::State,
     App,
 };