====== Debugging ======

Guide to debugging WvdS FPC RAD Studio extensions and applications.

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

==== Two-Stage Activation ====

Debug logging requires **two conditions**:

  - **Compile-time:** Compile with ''-dDEBUG''
  - **Runtime:** Start extension with ''--debug'' parameter

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

==== Log File ====

  * Format: ''debug-yymmddhhnnss.log''
  * Location: ''~/binaries/logs/''
  * **Never** commit to ''~/sources/''

==== MS Exception Trace Format ====

For detailed debugging with call stack:

<code pascal>
procedure LogDebugTrace(const AMessage: string; const AArgs: array of const);
var
  CallStack: string;
begin
  {$IFDEF DEBUG}
  if not DebugEnabled then Exit;

  (* Call Stack with get_caller_frame / get_frame *)
  CallStack := GetCallStackTrace;

  WriteToDebugLog(Format(
    '[%s] %s'#13#10 +
    '   at %s'#13#10 +
    '   Parameters: %s',
    [
      FormatDateTime('yyyy-MM-dd hh:nn:ss.zzz', Now),
      Format(AMessage, AArgs),
      CallStack,
      FormatParams(AArgs)
    ]
  ));
  {$ENDIF}
end;
</code>

==== Call Stack Helper ====

<code pascal>
function GetCallStackTrace: string;
var
  Frame: Pointer;
  Addr: Pointer;
  Info: string;
begin
  Result := '';
  {$IFDEF DEBUG}
  Frame := get_frame;
  while Frame <> nil do
  begin
    Addr := get_caller_addr(Frame);
    Info := BackTraceStrFunc(Addr);  (* Unit:Line Format *)
    if Info <> '' then
      Result := Result + '   at ' + Info + #13#10;
    Frame := get_caller_frame(Frame);
  end;
  {$ENDIF}
end;
</code>

==== Log File Example ====

<code>
================================================================================
DEBUG LOG: debug-260112143022.log
Started: 2026-01-12 14:30:22.001
================================================================================

[2026-01-12 14:30:22.001] Application started with --debug
   at TWvdSApplication.Initialize(Application.Main.pas:42)
   at program.main(extension_main.pas:398)
   Parameters: (CommandLine='--debug')

[2026-01-12 14:30:22.015] Loading configuration
   at TWvdSToolchainConfigService.LoadFromSettings(Toolchain.ConfigService.pas:156)
   at TWvdSToolchainConfigService.AutoDetectAll(Toolchain.ConfigService.pas:89)
   at DoActivate(extension_main.pas:368)
   Parameters: (ConfigPath='~/.vscode/settings.json')

[2026-01-12 14:30:22.042] Service initialized
   at TWvdSBuildService.Initialize(Build.Service.pas:45)
   at DoActivate(extension_main.pas:370)
   Parameters: (ServiceName='BuildService', Mode=debug)

================================================================================
ERROR TRACE (if any):
================================================================================

[2026-01-12 14:30:24.500] ERROR: File not found
   at ValidateBuildPath(Build.Service.pas:144)
   at GenerateCleanCommand(Build.Service.pas:174)
   at OnBuildClean(extension_main.pas:112)
   Parameters: (Path='~/invalid/path', ValidationResult=False)
   Exception: EFileNotFound
   Message: The specified path does not exist
   Stack Trace:
      Build.Service.ValidateBuildPath(144)
      Build.Service.GenerateCleanCommand(179)
      extension_main.OnBuildClean(112)
      VSCode.Commands.ExecuteCommand(89)
</code>

<note>**Important:** Never log sensitive data (tokens, passwords) in Parameters!</note>

==== What to Log? ====

^ Allowed ^ Forbidden ^
| Action names | Tokens, API keys |
| Filenames/paths | Passwords |
| Error messages | Session IDs |
| Configuration keys | Sensitive values |

===== VS Code Extension Debugging =====

==== Extension Development Host ====

  - Open the extension project in VS Code
  - Press ''F5'' or ''Run > Start Debugging''
  - A new VS Code window opens
  - The extension is loaded there

==== launch.json ====

<code json>
{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Run Extension",
      "type": "extensionHost",
      "request": "launch",
      "args": [
        "--extensionDevelopmentPath=${workspaceFolder}"
      ],
      "outFiles": [
        "${workspaceFolder}/dist/**/*.js"
      ]
    }
  ]
}
</code>

==== Breakpoints ====

Since the code is transpiled (Pascal -> JavaScript), breakpoints only work with source maps:

  - Compile with ''-Jm'' (generate source map)
  - Set breakpoints in the .pas file
  - VS Code maps to the JavaScript position

===== Output Channel =====

The WvdS Output Channel shows runtime messages:

  - ''View'' -> ''Output''
  - Select "WvdS" in the dropdown

<code pascal>
// In code
LogInfo('Information message');
LogWarn('Warning message');
LogError('Error: %s', [E.Message]);
</code>

===== Developer Console =====

For low-level debugging:

  - ''Help'' -> ''Toggle Developer Tools''
  - Open Console tab
  - JavaScript errors and console.log visible

===== Common Problems =====

==== Extension Does Not Start ====

**Diagnosis:**
<code bash>
# Check extension logs
code --verbose --log trace
</code>

**Common causes:**
  * Syntax error in generated JavaScript
  * Missing dependencies in package.json
  * Wrong path in "main"

==== Command Does Not Work ====

**Diagnosis:**
  - Open Developer Console
  - Execute command
  - Check for errors

**Common causes:**
  * Command not in contributes.commands
  * Handler not registered
  * Exception in handler

==== WebView Shows Nothing ====

**Diagnosis:**
  - Right-click in WebView -> "Inspect"
  - Browser DevTools open

**Common causes:**
  * Wrong HTML
  * CSP blocks resources
  * JavaScript error

===== Profiling =====

==== Performance Measurement ====

<code pascal>
{$IFDEF DEBUG}
var
  StartTime: TDateTime;

procedure StartTiming(const AOperation: string);
begin
  StartTime := Now;
  LogDebug('Starting: %s', [AOperation]);
end;

procedure EndTiming(const AOperation: string);
begin
  LogDebug('Completed: %s in %d ms', [
    AOperation,
    MilliSecondsBetween(Now, StartTime)
  ]);
end;
{$ENDIF}
</code>

==== Memory Leaks ====

pas2js/JavaScript has garbage collection, but watch out for:
  * Circular references with closures
  * Event handlers not removed
  * Large arrays/objects in memory

===== Debugging Unit Tests =====

<code pascal>
// Test with debug output
procedure TMyTest.TestFeature;
begin
  {$IFDEF DEBUG}
  LogDebug('Testing with input: %s', [TestInput]);
  {$ENDIF}

  Result := ProcessInput(TestInput);

  {$IFDEF DEBUG}
  LogDebug('Result: %s', [Result]);
  {$ENDIF}

  CheckEquals(Expected, Result);
end;
</code>

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

  * [[.:sicherheit|Security Guidelines]]
  * [[.:testing|Testing]]
  * [[.:extension-entwicklung|Extension Development]]