====== Extension Development ======

Guide to developing new extensions for WvdS FPC RAD Studio.

===== Prerequisites =====

  * Development environment set up (see [[.:start|Start]])
  * Basic understanding of Pascal and pas2js
  * Familiarity with VSCode Extension API

===== Creating a New Extension =====

==== 1. Create Directory Structure ====

<code bash>
cd sources/extensions
mkdir -p wvds.vscode.{name}/pas
mkdir -p wvds.vscode.{name}/dist
mkdir -p wvds.vscode.{name}/images
</code>

==== 2. Create package.json ====

<code json>
{
  "name": "wvds-vscode-{name}",
  "displayName": "WvdS VSCode {Name}",
  "description": "{Description}",
  "version": "0.1.0",
  "publisher": "wvds",
  "license": "MIT",
  "icon": "images/icon.png",
  "engines": {
    "vscode": "^1.85.0"
  },
  "categories": ["Other"],
  "main": "./dist/extension_main.js",
  "activationEvents": [
    "onCommand:wvds.{name}.{command}"
  ],
  "contributes": {
    "commands": [
      {
        "command": "wvds.{name}.{command}",
        "title": "{Title}",
        "category": "WvdS"
      }
    ]
  },
  "extensionDependencies": [
    "wvds.wvds-vscode-core"
  ]
}
</code>

==== 3. Create build.cfg ====

<code ini>
[build]
compiler=pas2js
target=vscode-extension
entry=extension_main.pas

[pas2js]
options=-Jc -Jirtl.js -Tbrowser
units=../../common;./pas
output=./dist
</code>

==== 4. Create extension_main.pas ====

<code pascal>
unit extension_main;

{$mode objfpc}{$H+}

interface

uses
  JS,
  VSCode.API,
  VSCode.Commands,
  VSCode.ExtensionExports,
  WvdS.VSCode.Strings;

procedure Activate(AContext: TExtensionContext);
procedure Deactivate;

implementation

procedure Handle{Command}(Args: TJSValueDynArray);
begin
  ShowInfoMessage(rs{Name}CommandExecuted);
end;

procedure DoActivate(AContext: TExtensionContext);
begin
  // Register command
  RegisterCommand('wvds.{name}.{command}', @Handle{Command});

  // Logging
  LogInfo('WvdS {Name} Extension activated');
end;

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

procedure Deactivate;
begin
  LogInfo('WvdS {Name} Extension deactivated');
end;

initialization
  ExportActivateDeactivate(@Activate, @Deactivate);

end.
</code>

==== 5. Compile ====

<code bash>
cd sources/extensions/wvds.vscode.{name}
pas2js -Jc -Jirtl.js -Tbrowser \
  -Fu../../common \
  -Fu./pas \
  -FE./dist \
  pas/extension_main.pas
</code>

==== 6. Test ====

  - F5 in VS Code -> Extension Development Host
  - Command Palette -> ''WvdS: {Command}''

===== Following Layered Architecture =====

==== Model Layer ====

<code pascal>
// {Feature}.Models.pas
unit {Feature}.Models;

{$mode objfpc}{$H+}

interface

type
  // Records for data structures
  TWvdS{Feature}Config = record
    Name: string;
    Value: Integer;
    Enabled: Boolean;
  end;

  // Enums
  TWvdS{Feature}Status = (
    fsIdle,
    fsProcessing,
    fsCompleted,
    fsFailed
  );

  // Arrays
  TWvdS{Feature}ConfigArray = array of TWvdS{Feature}Config;

implementation

end.
</code>

==== Service Layer ====

<code pascal>
// {Feature}.Service.pas
unit {Feature}.Service;

{$mode objfpc}{$H+}

interface

uses
  {Feature}.Models;

// Validation
function ValidateConfig(const AConfig: TWvdS{Feature}Config): Boolean;

// Operations
function ProcessData(const AInput: string): TWvdS{Feature}Config;

// Business logic
procedure ExecuteFeature(const AConfig: TWvdS{Feature}Config);

implementation

uses
  SysUtils, WvdS.VSCode.Strings;

function ValidateConfig(const AConfig: TWvdS{Feature}Config): Boolean;
begin
  Result := (AConfig.Name <> '') and (AConfig.Value >= 0);
end;

function ProcessData(const AInput: string): TWvdS{Feature}Config;
begin
  // Processing...
  Result.Name := AInput;
  Result.Value := Length(AInput);
  Result.Enabled := True;
end;

procedure ExecuteFeature(const AConfig: TWvdS{Feature}Config);
begin
  if not ValidateConfig(AConfig) then
    raise Exception.Create(rs{Feature}InvalidConfig);
  // Execution...
end;

end.
</code>

==== Extension Layer ====

<code pascal>
// extension_main.pas - UI logic only
procedure HandleCommand(Args: TJSValueDynArray);
var
  Config: TWvdS{Feature}Config;
begin
  // 1. Get input from UI
  Config := GetConfigFromDialog;

  // 2. Call service (no logic here!)
  if not ValidateConfig(Config) then
  begin
    ShowWarningMessage(rs{Feature}InvalidInput);
    Exit;
  end;

  // 3. Execution
  try
    ExecuteFeature(Config);
    ShowInfoMessage(rs{Feature}Success);
  except
    on E: Exception do
      ShowErrorMessage(Format(rs{Feature}Failed, [E.Message]));
  end;
end;
</code>

===== Using VSCode API =====

==== Commands ====

<code pascal>
// Register command
RegisterCommand('wvds.{name}.{action}', @Handler);

// Execute command
ExecuteCommand('wvds.other.action');
</code>

==== Configuration ====

<code pascal>
// Read setting
var Value := GetConfiguration('wvds.{name}').Get('setting', DefaultValue);

// Write setting
GetConfiguration('wvds.{name}').Update('setting', NewValue, True);
</code>

==== Output Channel ====

<code pascal>
// Use channel (provided by Core)
LogInfo('Information');
LogWarn('Warning');
LogError('Error: %s', [E.Message]);
LogDebug('Debug: %s', [Data]);  // Only when logLevel=debug
</code>

==== WebView ====

<code pascal>
// Create WebView Panel
var Panel := CreateWebviewPanel(
  'wvds.{name}.view',
  'Title',
  ViewColumn.One,
  WebviewOptions
);

// Set HTML
Panel.Webview.Html := LoadTemplate('template.html');

// Messaging
Panel.Webview.OnDidReceiveMessage(@HandleMessage);
Panel.Webview.PostMessage(JSObject);
</code>

==== StatusBar ====

<code pascal>
var StatusItem := CreateStatusBarItem(StatusBarAlignment.Left, 100);
StatusItem.Text := '$(check) Ready';
StatusItem.Show;
</code>

===== Resourcestrings for i18n =====

**All strings must be defined in WvdS.VSCode.Strings.pas!**

<code pascal>
// WvdS.VSCode.Strings.pas
resourcestring
  // {Feature} Extension
  rs{Feature}CommandExecuted = '{Feature} command executed';
  rs{Feature}InvalidConfig = 'Invalid configuration';
  rs{Feature}Success = 'Operation completed successfully';
  rs{Feature}Failed = 'Operation failed: %s';
</code>

<code pascal>
// WvdS.VSCode.Strings.DE.pas
resourcestring
  rs{Feature}CommandExecuted = '{Feature}-Befehl ausgefuehrt';
  rs{Feature}InvalidConfig = 'Ungueltige Konfiguration';
  rs{Feature}Success = 'Vorgang erfolgreich abgeschlossen';
  rs{Feature}Failed = 'Vorgang fehlgeschlagen: %s';
</code>

===== Error Handling =====

<code pascal>
procedure SafeOperation;
begin
  try
    DoRiskyOperation;
  except
    on E: EFileNotFoundException do
    begin
      LogError(rsFileNotFound, [E.FileName]);
      ShowErrorMessage(Format(rsFileNotFound, [E.FileName]));
    end;
    on E: EAccessDenied do
    begin
      LogError(rsAccessDenied, [E.Path]);
      ShowErrorMessage(Format(rsAccessDenied, [E.Path]));
    end;
    on E: Exception do
    begin
      LogError(rsUnexpectedError, [E.ClassName, E.Message]);
      ShowErrorMessage(Format(rsUnexpectedError, [E.ClassName, E.Message]));
    end;
  end;
end;
</code>

<note warning>**Never use empty except blocks!** Every exception must be handled or logged.</note>

===== Debug Logging =====

<code pascal>
{$IFDEF DEBUG}
procedure LogDebugTrace(const AMessage: string);
begin
  if not DebugEnabled then Exit;
  WriteDebugLog(Format('[%s] %s at %s', [
    FormatDateTime('hh:nn:ss.zzz', Now),
    AMessage,
    GetCallStack
  ]));
end;
{$ENDIF}
</code>

Activation:
  * Compile with ''-dDEBUG''
  * Start extension with ''--debug'' parameter

===== Writing Tests =====

<code pascal>
// Tests/{Feature}.Tests.pas
unit {Feature}.Tests;

{$mode objfpc}{$H+}

interface

uses
  TestFramework, {Feature}.Service, {Feature}.Models;

type
  T{Feature}ServiceTest = class(TTestCase)
  published
    procedure TestValidateConfig_ValidInput_ReturnsTrue;
    procedure TestValidateConfig_EmptyName_ReturnsFalse;
    procedure TestProcessData_ValidInput_ReturnsConfig;
  end;

implementation

procedure T{Feature}ServiceTest.TestValidateConfig_ValidInput_ReturnsTrue;
var
  Config: TWvdS{Feature}Config;
begin
  Config.Name := 'Test';
  Config.Value := 42;
  Config.Enabled := True;

  CheckTrue(ValidateConfig(Config));
end;

procedure T{Feature}ServiceTest.TestValidateConfig_EmptyName_ReturnsFalse;
var
  Config: TWvdS{Feature}Config;
begin
  Config.Name := '';
  Config.Value := 42;

  CheckFalse(ValidateConfig(Config));
end;

end.
</code>

===== Checklist Before Commit =====

<code>
[ ] SoC followed (Model/Service/Extension separated)
[ ] No hardcoded strings (resourcestrings used)
[ ] Translations present (EN, DE, SL, HR)
[ ] Error handling implemented
[ ] Debug logging added
[ ] Security guidelines checked
[ ] Unit tests written
[ ] README updated
[ ] CHANGELOG updated
</code>

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

  * [[.:architektur|Architecture Overview]]
  * [[.:code-konventionen|Code Conventions]]
  * [[.:sicherheit|Security Guidelines]]
  * [[.:testing|Testing]]
  * [[.:vscode-wrapper|VSCode Wrapper API]]