# tia-lsp - Language Server for Siemens TIA Portal

A Neovim/LazyVim plugin and standalone LSP server providing **Language Server Protocol (LSP)**, **Linting**, **Formatting**, and **Syntax Highlighting** for Siemens TIA Portal languages. Currently supports **SCL** (Structured Control Language), with planned support for **STL/AWL**, **LAD**, and **FBD**.

The project is split into two repos:

- **`tia-lsp`** (this repo) — the standalone LSP server (`src/`) plus the tree-sitter grammar (`grammar.js`, `src/parser.c`). Speaks JSON-RPC over stdio. Editor-agnostic: usable from Neovim, VS Code, or any LSP client.
- **`tia-lsp.nvim`** — the Neovim plugin (`lua/`) that launches the server via `vim.lsp.start()` and adds editor-specific features (auto-prefix, blink.cmp source, workspace UDT scanning, attribute toggle, multiline params).

## Features

### LSP (Language Server Protocol)
| Feature | Description |
|---------|-------------|
| **Hover** | Press `K` to see variable type and struct fields |
| **Completion** | `#` for variables, `.` for struct fields, `(` for functions |
| **Go to Definition** | `gD` jump to function, FB, DB, or UDT definition |
| **Document Symbols** | Shows functions, variables, types |
| **Workspace Symbols** | Search across all `.scl` files with fuzzy matching |
| **Semantic Tokens** | Keywords, variables highlighted |
| **Inlay Hints** | Shows variable types after declaration |
| **External UDT** | Load types from `.plc.json` or `data_types/` folder |

### Linter (Diagnostics)
| Feature | Description |
|---------|-------------|
| **Undefined Variables** | Detects variables used without declaration |
| **Invalid # Prefix** | Detects `#` prefix in VAR sections |
| **Unknown Types** | Warns about unknown data types |
| **Type Validation** | Basic type checking |

### Formatter
| Feature | Description |
|---------|-------------|
| **Document Formatting** | Format entire SCL files with `:SCLFormat` |
| **Multi-line Assignments** | Preserves and formats multi-line expressions with proper alignment |
| **FB Call Formatting** | Formats function block calls in multiline style |
| **Indentation** | Proper block indentation |
| **Keyword Casing** | Maintains SCL keyword casing |

### Syntax Highlighting
- Full SCL syntax support via tree-sitter
- Block definitions: ORGANIZATION_BLOCK, FUNCTION_BLOCK, FUNCTION
- Variable sections: VAR_INPUT, VAR_OUTPUT, VAR_IN_OUT, VAR_TEMP, VAR_CONSTANT
- Control structures: IF/THEN/ELSIF/ELSE/END_IF, CASE/OF/END_CASE, FOR/TO/BY/DO/END_FOR, WHILE/END_WHILE, REPEAT/UNTIL/END_REPEAT
- Built-in data types: BOOL, INT, DINT, REAL, STRING, TIME, etc.
- Function block instances highlighted in calls
- FB parameter names (IN, PT, CU, etc.) highlighted as properties
- `#` prefix for local variables highlighted
- Operators: AND, OR, NOT, XOR, MOD
- Comments: line (`//`), block (`(* *)`), C-style (`/* */`)

### Additional Features
| Feature | Description |
|---------|-------------|
| **Auto-Prefix** | Automatically adds `#` prefix to local variables (like TIA Portal) |
| **Multiline Parameters** | Fill FB/Function call parameters across multiple lines with `<Space>mp` or `:SCLMultilineParams` |
| **Tab Navigation** | Jump between parameters with `<Tab>` in insert mode |
| **Workspace UDT Scanner** | Scans project for user-defined types (.udt files) |
| **Workspace Global DB Scanner** | Scans project for global data blocks (.db files) |
| **blink.cmp Integration** | Smart completion source for blink.cmp |
| **Attribute Block Toggle** | Interactive expand/collapse of `{...}` blocks with `<Leader>xa` |

## Installation

The plugin auto-detects the mason-installed `tia-lsp` executable via `vim.fn.exepath("tia-lsp")` and falls back to `lua <server_path>` for manual installs. See [Mason installation](#mason-installation) below for the recommended path.

### LazyVim
```lua
-- ~/.config/nvim/lua/plugins/tia-lsp.lua
return {
  "lazar/tia-lsp.nvim",
  ft = "scl",
  lazy = true,
  dependencies = {
    "neovim/nvim-lspconfig",
    "nvim-treesitter/nvim-treesitter",
    "saghen/blink.cmp",
  },
  config = function()
    require("tia_lsp").setup({
      -- LSP options
      lsp = {
        on_attach = function(client, bufnr)
          -- custom keymaps
        end,
      },
      cmp = true,              -- Enable blink.cmp integration
      workspace_types = true,  -- Enable workspace UDT scanning
      auto_prefix = true,      -- Enable auto-# prefixing
      debug = false,
    })
  end,
}
```

### Manual Setup
```lua
-- In your init.lua or plugin file
require("tia_lsp").setup({
  server_path = "/path/to/tia-lsp/src/main.lua",  -- only used if tia-lsp is not on PATH
  ts_parser_url = "https://your-gitea/tia-lsp.git", -- tree-sitter parser source
  cmp = true,
  workspace_types = true,
  auto_prefix = true,
})
```

### Mason installation

`tia-lsp` can be installed via [mason.nvim](https://github.com/mason-org/mason.nvim) using a custom registry. The setup below uses a `file:` registry sourced from a Gitea-hosted `tia-mason-registry` repo (cloned by lazy.nvim), and falls back to the official mason registry for any other packages.

1. Clone the registry repo as a lazy.nvim plugin:
   ```lua
   -- ~/.config/nvim/lua/plugins/tia-mason-registry.lua
   return {
     url = "https://your-gitea/tia-mason-registry.git",
     name = "tia-mason-registry",
     lazy = false,  -- must be available before mason setup
   }
   ```
2. Register the registry with mason:
   ```lua
   -- ~/.config/nvim/lua/plugins/mason.lua
   return {
     "mason-org/mason.nvim",
     opts = {
       registries = {
         "file:" .. vim.fn.expand("~/.local/share/nvim/lazy/tia-mason-registry"),
         "github:mason-org/mason-registry",
       },
     },
   }
   ```
3. Install `yq` (one-time prerequisite for mason's `file:` registry):
   ```
   :MasonInstall yq
   ```
4. Install the server:
   ```
   :MasonInstall tia-lsp
   ```
5. Verify: open a `.scl` file and run `:LspInfo` — `tia_lsp` should be attached, and `vim.fn.exepath("tia-lsp")` should resolve to `~/.local/share/nvim/mason/bin/tia-lsp`.

To upgrade: tag a new `vX.Y.Z` release on the `tia-lsp` Gitea repo, bump `source.id` in `tia-mason-registry/packages/tia-lsp/package.yaml`, push the registry repo, then `:MasonInstall tia-lsp` again.

## Configuration Options

| Option | Type | Default | Description |
|--------|------|---------|-------------|
| `server_path` | string | `~/dev/tia-lsp/src/main.lua` | Path to LSP server (only used if `tia-lsp` is not on PATH) |
| `ts_parser_url` | string | `file://~/dev/tia-lsp` | URL passed to nvim-treesitter for the SCL parser source |
| `lsp.on_attach` | function | `nil` | Custom LSP attach callback |
| `lsp.formatting` | boolean | `false` | Enable format command |
| `cmp` | boolean | `true` | Enable blink.cmp integration |
| `workspace_types` | boolean | `true` | Enable workspace UDT scanning |
| `auto_prefix` | boolean | `true` | Enable auto-# prefixing |
| `project_root` | string | `nil` | Custom project root |
| `library_paths` | table | `{}` | Additional library paths |
| `debug` | boolean | `false` | Enable debug logging |

## Commands

| Command | Description |
|---------|-------------|
| `:SCLShowVariables` | Show local variables in current file |
| `:SCLShowWorkspaceTypes` | Show workspace UDTs, FBs, and Global DBs count |
| `:SCLRescanWorkspaceTypes` | Rescan workspace for types and DBs |
| `:SCLPrefixWord` | Manually prefix current word with `#` |
| `:SCLMultilineParams` | Fill multiline parameters for FB/Function call |
| `:SCLFormat` | Format current SCL file |
| `:SCLToggleAttrBlock` | Toggle attribute block under cursor |
| `:SCLExpandAllAttrBlocks` | Expand all `{...}` blocks in buffer |
| `:SCLCollapseAllAttrBlocks` | Collapse all matching attribute blocks |

## Keybindings

| Key | Action |
|-----|--------|
| `K` | Hover (show variable info) |
| `gd` | Go to Definition |
| `<leader>s` | Document Symbols |
| `<leader>w` | Workspace Symbols |
| `<Space>mp` | Fill multiline FB/Function parameters (insert mode) |
| `<Tab>` | Jump to next parameter (insert mode) |
| `<Leader>xa` | Toggle attribute block under cursor |
| `<Leader>xae` | Expand all attribute blocks |
| `<Leader>xac` | Collapse all attribute blocks |
| `<leader>fw` | Workspace Symbols (Telescope) |
| `<leader>ca` | Code Actions |

## Attribute Block Toggle

Interactive expand/collapse of SCL variable attribute blocks:

```scl
-- Before: Verbose attributes
statCounter{EXTERNALACCESSIBLE := 'false'; EXTERNALVISIBLE := 'false'} : Int;

-- After: Collapsed
statCounter{...} : Int;
```

**Usage:**
- Place cursor inside any `{...}` block
- Press `<Leader>xa` to toggle expand/collapse
- Use `<Leader>xae` to expand all blocks in buffer
- Use `<Leader>xac` to collapse all blocks

**Note:** Collapsed blocks are automatically expanded before saving to preserve full content on disk. Use `:SCLFormat` to format, then `:SCLCollapseAllAttrBlocks` to collapse while preserving the ability to expand later.

## External UDT Support

### Option 1: Create `.plc.json`
```json
{
  "dataTypes": [
    {
      "name": "equipmentData",
      "struct": [
        {"name": "id", "dataTypeName": "INT"},
        {"name": "status", "dataTypeName": "BOOL"},
        {"name": "temperature", "dataTypeName": "REAL"}
      ]
    }
  ]
}
```

### Option 2: Auto-scan `data_types/` folder
The LSP automatically scans for SCL files in `data_types/` folder and extracts TYPE definitions.

### Option 3: Generate `.plc.json`
```bash
lua ~/dev/tia-lsp/src/plc_json.lua --generate
```

## Global Data Block Support

The plugin automatically scans for `.db` files in the workspace and provides auto-completion for global data blocks and their members.

### How it works

1. **Workspace Scanning**: When opening a `.scl` file, the plugin scans the project for `.db` files
2. **DB Parsing**: Parses `DATA_BLOCK` definitions and extracts members from `VAR` sections
3. **Auto-completion**: Provides smart completion for DB names and members

### Usage

- Type a space or `#` to trigger completion - global DB names appear alongside local variables
- Type `"` followed by a DB name to get member completions
- Access nested members: `"MyDB".member.submember`

### Example

```scl
// Access global DB members
"HmiData".units
"Parameter".machine.unit100.paramTimeStampApplied

// Inside FB call parameter
#instParameterManager(hmiInterface:="HmiData".units, ...)
```

### Project Structure

```
tia-lsp/
├── README.md                    # This file
├── package.json                 # NPM scripts (tree-sitter)
├── Makefile                     # Build commands
├── grammar.js                   # Tree-sitter grammar (SCL language)
├── tree-sitter.json             # Parser config
├── queries/                     # Tree-sitter queries
│   └── scl/                     # Per-language query dir (SCL)
│       ├── highlights.scm       # Syntax highlighting
│       ├── indents.scm          # Indentation
│       ├── folds.scm            # Code folding
│       ├── locals.scm           # Variable scoping
│       └── tags.scm             # Navigation tags
├── src/                         # LSP server
│   ├── main.lua                 # Main entry point (JSON-RPC over stdio)
│   ├── parser.lua               # SCL parser (will become parser_scl.lua + dispatch)
│   ├── treesitter.lua           # Tree-sitter integration
│   ├── json.lua                 # JSON encoder/decoder
│   ├── plc_json.lua             # External UDT loading (language-agnostic)
│   ├── diagnostics.lua          # Linter diagnostics
│   └── formatter.lua            # Document formatter
└── lua/
    ├── tia_lsp/                 # Neovim plugin
    │   ├── init.lua             # Main plugin setup
    │   └── plugins/
    │       └── scl.lua          # LazyVim plugin spec (SCL filetype)
    └── tia/                     # Language modules (shared across TIA languages)
        ├── auto_prefix.lua
        ├── attr_toggle.lua
        ├── blink_cmp_source.lua
        ├── builtin_instructions.lua
        ├── db_parser.lua
        ├── fb_parser.lua
        ├── multiline_params.lua
        ├── udt_parser.lua
        ├── variables.lua
        └── workspace_types.lua
```

## Building Tree-sitter Parser

```bash
# Generate parser from grammar.js
npm run build
# or: tree-sitter generate

# Run tests
npm test
# or: tree-sitter test
```

## SCL Code Example

```pascal
FUNCTION_BLOCK "Em101Sequence"
VAR
    x : INT;
    myVar : equipmentData;  // User-defined type
END_VAR

IF x > 5 THEN
    myVar.id := 10;
END_IF

myVar.status := TRUE;
myVar.temperature := 25.5;

END_FUNCTION_BLOCK
```

## Architecture

The plugin uses a standalone LSP server (`src/main.lua`) that communicates via JSON-RPC over stdio. The server handles:
- Text document synchronization
- Diagnostics (linting)
- Formatting
- Completion, hover, go-to-definition
- Semantic tokens

The Neovim plugin (`lua/tia_lsp/init.lua`) manages:
- LSP client lifecycle via `vim.lsp.start()`
- FileType autocmd for lazy loading
- blink.cmp integration
- Workspace scanning for UDTs/DBs

## Requirements

- **Neovim 0.11+** (uses `vim.lsp.start()`)
- **nvim-treesitter** - Syntax highlighting
- **blink.cmp** - Optional, for completion
- **Lua 5.1+** - LSP server runtime