// GPX XML Header with required namespaces and schema
buffer.writeln('<?xml version="1.0" encoding="UTF-8"?>');
buffer.writeln(
  '<gpx xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" '
  'xsi:schemaLocation="http://www.topografix.com/GPX/1/1 '
  'http://www.topografix.com/GPX/1/1/gpx.xsd" '
  'creator="$creator" version="1.1" xmlns="http://www.topografix.com/GPX/1/1">',
);

// Metadata
final metaTime = metadataTime ?? (points.isNotEmpty ? points.first.time : DateTime.now());
final metaTimeStr = metaTime.toUtc().toIso8601String().replaceFirst(RegExp(r'\.\d+'), '') + 'Z';
buffer.writeln('  <metadata>');
buffer.writeln('    <time>$metaTimeStr</time>');
buffer.writeln('  </metadata>');

// Track
buffer.writeln('  <trk>');
buffer.writeln('    <name>$activityName</name>'); // Use activityName here
buffer.writeln('    <type>$activityType</type>');
buffer.writeln('    <trkseg>');

for (final point in points) {
  // CRITICAL FIX: Include time and elevation (if available) for each track point
  final timeStr = point.time.toUtc().toIso8601String().replaceFirst(RegExp(r'\.\d+'), '') + 'Z';
  buffer.writeln('      <trkpt lat="${point.latitude}" lon="${point.longitude}">');
  if (point.elevation != null) {
    buffer.writeln('        <ele>${point.elevation}</ele>');
  }
  buffer.writeln('        <time>$timeStr</time>');
  buffer.writeln('      </trkpt>');
}

buffer.writeln('    </trkseg>');
buffer.writeln('  </trk>');
buffer.writeln('</gpx>');

// Write to temporary file
final dir = await getTemporaryDirectory();
final file = File('${dir.path}/runflo_${DateTime.now().millisecondsSinceEpoch}.gpx');
await file.writeAsString(buffer.toString());
log("Generated GPX Content:\n${buffer.toString()}"); // Keep this for debugging
return file;