# MeTTaLog Language Server

NOTE: very much a work in progress.

An LSP server for the programming language MeTTa. The server itself is written in Prolog and requires MeTTaLog (found at https://github.com/trueagi-io/metta-wam) for some of the tools it has there. It will soon be packaged as part of the MeTTaLog project.

It is based on the `lsp_server` for SWI-Prolog (found at https://github.com/jamesnvc/lsp_server). The README there may still be useful as it describes how to connect to an LSP server from different editors - we have currently only tested VSCode.

Still a work-in-progress - we currently support showing documentation on hover. We are spending time getting a well-designed core, which will make other functionality easier to implement.

Only tested with SWI-Prolog and version requirements are whatever is required for the MeTTalog project (9.3.9 or higher). SWI-Prolog is installed as part of the MeTTalog installation.

There are two components that need to be installed: the Prolog package needs to be installed in SWI-Prolog (and `logicmoo_utils` if you don't have that already), and there are specific installation requirements for each editor. Instructions for VSCode are given below.

## Installing the SWI-Prolog package(s)

NOTE: this will at some point be added to the MeTTalog installation and become unnecessary.

This is a slightly modified version of the directions found at https://www.swi-prolog.org/howto/Pack.html

* Make sure that you are in the `metta-wam/src/packs` directory. From the `metta-wam` directory:

```bash
cd src/packs
```

* Create a `.tgz` (tarred and gzipped) file. Note that the suffix should be `.tgz`, not the more usual `.tar.gz`.

```bash
tar -zcvf lsp_server_metta-0.0.3.tgz --exclude=vscode lsp_server_metta
```

* From SWI-Prolog, install the file directly as a package:

```prolog
?- pack_install('lsp_server_metta-0.0.3.tgz').
```

* You may need to install the `logicmoo_utils` package. If you already have this (you can check with `pack_list('logicmoo_utils').`, where `i` as the first character of the return line means installed, `p` means not installed), it won't hurt to install it again:

```prolog
pack_install('logicmoo_utils').
```

## Installing for VSCode

VSCode requires a `.vsix` file. There are two ways to get that:

### From the Marketplace

![screenshot](images/VSCode_lsp_install.png)

From VSCode, go to the extensions button on the left (four squares with one of them offset, circled in red), at the top of the EXTENSIONS pane, go to the place where it says `Search Extensions in Marketplace`, and type `metta`. Several extensions will appear, you want the `metta-lsp` server written by Roy Ward (the one with a green oval around it). Click the `Install` button and you are done.

### Build the `.vsix` file yourself

* Install `vsce`. If you get permission errors, use `sudo`:

  ```bash
  sudo npm install -g @vscode/vsce
  ```

  If `vsce` installation still throws warnings about deprecated packages, you can ignore these for now.

* Make sure you're in the `vscode` directory:

  ```bash
  cd lsp_server_metta/vscode
  ```

* Install the required dependencies for packaging:

  ```bash
  npm install vscode-languageclient@^9.0.1
  ```

* Package the extension:

  ```bash
  vsce package
  ```

  You may be prompted about a missing license file. Confirm by typing `y` to continue.

* The resulting `.vsix` file will be located in the `vscode` directory (e.g., `metta-lsp-0.0.2.vsix` or something similar).

* Install the resulting `.vsix` file into VSCode (find the `...` at the top right of the EXTENSIONS panel, click on it and select `Install from VSIX...`).

* If you are using the instructions from metta-lsp-0.0.2.vsix, DO NOT `vsce publish` as is suggested there unless you want to fork this and add your own version to the marketplace.