====== Architecture Overview ======

This document describes the overall architecture of the WvdS FPC RAD Studio Suite.

===== Design Decisions =====

==== Why Pascal for VS Code Extensions? ====

**Motivation:**
  * Unified codebase for all targets (GUI, TUI, Web, Extensions)
  * Strong typing reduces runtime errors
  * Leverage developer expertise from existing Pascal projects
  * pas2js enables high-quality JavaScript output

**Alternatives considered:**
^ Alternative ^ Decision ^ Rationale ^
| TypeScript | Rejected | Two languages, more complexity |
| Rust + WASM | Rejected | Complex interop with VSCode API |
| Delphi | Rejected | Commercial, no pas2js alternative |

==== Why PXAML Instead of LFM? ====

**Motivation:**
  * Version control: XML is diff-friendly
  * Multi-target: Same markup for GUI, TUI, Web
  * Tooling: Standard XML parsers available
  * Familiar: WPF/XAML syntax for developers transitioning

===== Layered Architecture =====

<code>
┌─────────────────────────────────────────────────────────────────────┐
│                        Extension Layer                               │
│  (extension_main.pas - Entry Point, Command Handler, UI Integration) │
├─────────────────────────────────────────────────────────────────────┤
│                        Service Layer                                 │
│  (*.Service.pas - Business logic, validation, operations)            │
├─────────────────────────────────────────────────────────────────────┤
│                        Model Layer                                   │
│  (*.Models.pas - Records, types, enums, no logic)                    │
├─────────────────────────────────────────────────────────────────────┤
│                     Infrastructure Layer                             │
│  (WvdS.VSCode.*, WvdS.Node.* - API Wrapper, Platform Abstraction)    │
└─────────────────────────────────────────────────────────────────────┘
</code>

==== Responsibilities ====

^ Layer ^ Content ^ Dependencies ^
| Extension | UI interaction, command registration | Service, Model, Infrastructure |
| Service | Business logic, validation | Model |
| Model | Data structures | None |
| Infrastructure | VSCode/Node APIs | Only external APIs |

==== Rules ====

<code>
ALLOWED:   Extension -> Service -> Model
FORBIDDEN: Service -> Extension (inversion)
FORBIDDEN: Model -> Service (logic in Model)
</code>

===== Dependency Graph =====

<code>
                    wvds.vscode.packaging
                           │
                           ▼
wvds.vscode.ui.preview ─► wvds.vscode.build
         │                      │
         ▼                      │
wvds.vscode.ui.designer         │
         │                      │
         └───────┬──────────────┘
                 ▼
         wvds.vscode.projects
                 │
                 ▼
         wvds.vscode.ui.meta
                 │
                 ▼
         wvds.vscode.core (Base)
</code>

==== Extension Dependencies in Detail ====

^ Extension ^ Dependencies ^ Role ^
| core | - | Base: Toolchain, Logging, Shared Services |
| build | core | Compilation, Uses Formatter |
| projects | core | Project management, templates |
| ui.meta | core | Component registry |
| ui.designer | core | PXAML Editor |
| ui.preview | core, ui.designer | Live preview |
| packaging | core, build | VSIX creation |

===== Monorepo Structure =====

==== sources/ - Single Source of Truth ====

<code>
sources/
├── common/                     # Shared Code
│   ├── core/                   # Base units (no dependencies)
│   │   ├── WvdS.System.pas
│   │   ├── WvdS.Collections.pas
│   │   └── WvdS.Strings.pas
│   │
│   ├── ui/                     # UI Framework
│   │   ├── controls/           # Base controls
│   │   ├── components/         # Composite components
│   │   ├── runtime/            # PXAML Runtime
│   │   └── targets/            # Renderers
│   │       ├── tui/            # Terminal UI
│   │       ├── gui/            # Desktop GUI
│   │       └── web/            # Browser
│   │
│   └── web/                    # Host Bridges
│       ├── nodejs/             # Node.js APIs
│       └── vscode/             # VSCode APIs
│
├── extensions/                 # VSIX packages
│   └── wvds.vscode.{name}/
│       ├── pas/                # Pascal source code
│       ├── dist/               # Compiled JS
│       ├── templates/          # HTML templates
│       ├── images/             # Icons, graphics
│       ├── package.json        # Extension manifest
│       └── build.cfg           # Build configuration
│
├── applications/               # Standalone apps
├── tools/                      # CLI tools
└── packages/                   # IDE Packages
</code>

==== binaries/ - Build Output ====

<code>
binaries/
├── out/{app}/{target}/{mode}/  # Build artifacts
│   ├── gen/                    # Generated code
│   ├── bin/                    # Executables
│   └── assets/                 # Resources
│
├── cache/                      # Compiler cache (.ppu, .o)
├── dist/                       # Release artifacts (.vsix)
└── logs/                       # Build logs
</code>

===== Extension Anatomy =====

==== Directory Structure ====

<code>
wvds.vscode.{name}/
├── pas/
│   ├── extension_main.pas      # Entry Point (REQUIRED)
│   ├── {Feature}.Models.pas    # Data structures
│   ├── {Feature}.Service.pas   # Business logic
│   └── {Feature}.Dialog.pas    # UI components (optional)
│
├── dist/
│   ├── extension_main.js       # Compiled JS
│   └── extension_main.js.map   # Source Map
│
├── templates/
│   └── *.html                  # WebView templates
│
├── images/
│   └── icon.png                # Extension icon
│
├── package.json                # VSCode manifest
├── build.cfg                   # Build configuration
└── README.md                   # Documentation
</code>

==== extension_main.pas Pattern ====

<code pascal>
unit extension_main;

{$mode objfpc}{$H+}

interface

uses
  JS,
  VSCode.API,
  VSCode.Commands,
  VSCode.ExtensionExports,
  {Feature}.Service,
  {Feature}.Models;

procedure Activate(AContext: TExtensionContext);
procedure Deactivate;

implementation

procedure DoActivate(AContext: TExtensionContext);
begin
  // Initialize services
  Initialize{Feature}Service;

  // Register commands
  RegisterCommand('wvds.{feature}.{action}', @Handle{Action});

  // Output Channel
  ShowInfoMessage('WvdS {Name} activated');
end;

procedure Activate(AContext: TExtensionContext);
begin
  try
    DoActivate(AContext);
  except
    on E: Exception do
      ShowErrorMessage(Format(rsActivationFailed, [E.Message]));
  end;
end;

procedure Deactivate;
begin
  // Cleanup
end;

initialization
  ExportActivateDeactivate(@Activate, @Deactivate);

end.
</code>

===== Communication Between Extensions =====

==== Via Shared Services ====

Extensions communicate through the Core extension:

<code pascal>
// In Extension A
CoreService.PublishEvent('build.completed', BuildResult);

// In Extension B
CoreService.SubscribeEvent('build.completed', @OnBuildCompleted);
</code>

==== Via VSCode API ====

For loose coupling:

<code pascal>
// Call commands
ExecuteCommand('wvds.build.run');

// Events
OnDidChangeConfiguration(@HandleConfigChange);
</code>

===== Build Pipeline =====

<code>
┌──────────────────────────────────────────────────────────────┐
│                     BUILD PIPELINE                            │
├──────────────────────────────────────────────────────────────┤
│                                                               │
│  1. Policy Check (wvds-lint)                                  │
│     - No .ts files?                                           │
│     - No duplicates?                                          │
│     - Wrappers only in common?                                │
│                                                               │
│  2. pas2js Compilation                                        │
│     - Unit resolution                                         │
│     - Type checking                                           │
│     - JavaScript generation                                   │
│                                                               │
│  3. Asset Processing                                          │
│     - Copy HTML templates                                     │
│     - Optimize images                                         │
│     - Validate package.json                                   │
│                                                               │
│  4. Output                                                    │
│     - dist/extension_main.js                                  │
│     - dist/extension_main.js.map                              │
│                                                               │
│  5. VSIX Packaging (optional)                                 │
│     - vsce package                                            │
│     - binaries/dist/*.vsix                                    │
│                                                               │
└──────────────────────────────────────────────────────────────┘
</code>

===== See Also =====

  * [[.:pxaml-pipeline|PXAML Pipeline]]
  * [[.:extension-architektur|Extension Architecture in Detail]]
  * [[.:targets|Build Targets]]
  * [[.:extension-entwicklung|Extension Development]]