Applies dark theme to Slack

Apply-SlackDarkTheme.ps1

# Find ssb-interop.js file thata needs to be patched
# Test-Path Machine-Wide 64-bit install
If (Test-Path "C:\Program Files\Slack\resources\app.asar.unpacked\src\static\ssb-interop.js") {
  $ssbinteropPath = "C:\Program Files\Slack\resources\app.asar.unpacked\src\static\ssb-interop.js"
  $exePath = "C:\Program Files\Slack\Slack.exe"
}
# Test-Path Machine-Wide 32-bit install
ElseIf (Test-Path "C:\Program Files (x86)\Slack\resources\app.asar.unpacked\src\static\ssb-interop.js") {
  $ssbinteropPath = "C:\Program Files (x86)\Slack\resources\app.asar.unpacked\src\static\ssb-interop.js"
  $exePath = "C:\Program Files (x86)\Slack\Slack.exe"
}
# Test-Path standard per-user install
ElseIf (Test-Path "$env:localappdata\slack") {
  $rootPath = Get-Childitem -Path "$env:localappdata\slack" -Filter "app*" -directory | Sort-Object -Descending | Select-Object -First 1
  $ssbinteropPath = "$($rootPath.FullName)\resources\app.asar.unpacked\src\static\ssb-interop.js"
  $exePath = "$($rootPath.FullName)\slack.exe"
}
Else {
  Write-Error "Slack doesn't seem to be installed"
  Exit 1
}

$newCode = @'

// This was dynamically added by "Apply-SlackDarkTheme.ps1"
// See here for more info: https://github.com/Nockiro/slack-black-theme
// First make sure the wrapper app is loaded
document.addEventListener("DOMContentLoaded", function() {
  // Then get its webviews
  let webviews = document.querySelectorAll(".TeamView webview");

  // Fetch our CSS in parallel ahead of time
  const cssPath = "https://raw.githubusercontent.com/Nockiro/slack-black-theme/master/custom.css";
  let cssPromise = fetch(cssPath).then(response => response.text());

  let customCustomCSS = `
  :root {
     /* Modify these to change your theme colors: */
     --primary: #09F;
     --text: #CCC;
     --background: #080808;
     --background-elevated: #222;
  } 

  a[aria-label^="NAME_OF_CHANNEL_OR_DIRECT_CONVO_TO_STYLE"]
  {
       --background: #4d0000  !important;
       --text-transform: uppercase  !important;
       --letter-spacing: 2px !important;
       --text-shadow: 1px 1px white;

   }   `;

  // Insert a style tag into the wrapper view
  cssPromise.then(css => {
    let s = document.createElement("style");
    s.type = "text/css";
    s.innerHTML = css + customCustomCSS;
    document.head.appendChild(s);
  });

  // Wait for each webview to load
  webviews.forEach(webview => {
    webview.addEventListener("ipc-message", message => {
      if (message.channel == "didFinishLoading")
        // Finally add the CSS into the webview
        cssPromise.then(css => {
          let script = `
                    let s = document.createElement('style');
                    s.type = 'text/css';
                    s.id = 'slack-custom-css';
                    s.innerHTML = \`${css + customCustomCSS}\`;
                    document.head.appendChild(s);
                    `;
          webview.executeJavaScript(script);
        });
    });
  });
});
'@;

$alreadyBlackssbInterop = Get-Content $ssbinteropPath | Where-Object { $_.Contains("This was dynamically added") }

if ($alreadyBlackssbInterop) {
  Write-Output "$ssbinteropPath already has dark theme"
}
else {
  Add-Content -Path $ssbinteropPath -Value $newCode
  Get-Process -Name "Slack*" | Stop-Process
  Start-Process -FilePath $exePath -RedirectStandardOutput Out-Null
}