injectScript static method

String injectScript(String body, int port)

Generates the single unified JS script to inject into the index.html. We pass the port dynamically so it always connects correctly.

Implementation

static String injectScript(String body, int port) {
  final script = '''
<script>
// FlutSim Unified Client
(function() {
const ws = new WebSocket('ws://' + window.location.hostname + ':$port');

ws.onopen = function() {
  console.log('⚡ FlutSim Unified Client connected.');
};

ws.onmessage = function(event) {
  try {
    const data = JSON.parse(event.data);

    if (data.type === 'hot_reload') {
      if (window.flutter_inappwebview) {
        window.flutter_inappwebview.callHandler('hotReload');
      } else {
        // Standard web fallback if inappwebview isn't available
        console.log('🔥 Hot reload triggered natively');
      }
    }
    else if (data.type === 'auto_reload') {
      window.location.reload();
    }
    else if (data.type === 'error') {
      showErrorOverlay(data.message);
    }
    else if (data.type === 'clear_error') {
      clearErrorOverlay();
    }
    else if (data.type === 'instant_update') {
      applyUIChanges(data.changes);
    }
  } catch (e) {
    console.error('FlutSim message error:', e);
  }
};

ws.onclose = function() {
  console.log('🔌 FlutSim disconnected. Attempting reconnect...');
  setTimeout(() => window.location.reload(), 2000);
};

// --- Error Overlay Logic ---
function showErrorOverlay(message) {
  clearErrorOverlay(); // Remove existing if any

  const overlay = document.createElement('div');
  overlay.id = 'flutsim-error-overlay';
  overlay.style.position = 'fixed';
  overlay.style.top = '0';
  overlay.style.left = '0';
  overlay.style.width = '100vw';
  overlay.style.height = '100vh';
  overlay.style.backgroundColor = 'rgba(255, 0, 0, 0.9)';
  overlay.style.color = '#fff';
  overlay.style.zIndex = '999999';
  overlay.style.display = 'flex';
  overlay.style.flexDirection = 'column';
  overlay.style.padding = '2rem';
  overlay.style.boxSizing = 'border-box';
  overlay.style.fontFamily = 'monospace';
  overlay.style.overflowY = 'auto';

  const title = document.createElement('h1');
  title.innerText = 'Flutter Compilation Error';
  title.style.margin = '0 0 1rem 0';

  const pre = document.createElement('pre');
  pre.innerText = message;
  pre.style.whiteSpace = 'pre-wrap';
  pre.style.wordBreak = 'break-word';
  pre.style.backgroundColor = 'rgba(0,0,0,0.3)';
  pre.style.padding = '1rem';
  pre.style.borderRadius = '8px';

  overlay.appendChild(title);
  overlay.appendChild(pre);
  document.body.appendChild(overlay);
}

function clearErrorOverlay() {
  const overlay = document.getElementById('flutsim-error-overlay');
  if (overlay) {
    overlay.remove();
  }
}

// --- Instant UI Logic ---
function applyUIChanges(changes) {
  if (!changes || !Array.isArray(changes)) return;
  changes.forEach(change => {
    try {
      if (change.action === 'update_text') {
         const el = document.querySelector(change.selector);
         if (el) el.textContent = change.text;
      }
    } catch (e) {}
  });
}
})();
</script>
''';

  if (body.contains('</body>')) {
    return body.replaceFirst('</body>', '$script</body>');
  }
  return body + script;
}