feat: finalize AI analyzer, sync endpoints, and stabilize builds

walkguide-mobile/walkguide_app/lib/core/ai/obstacle_analyzer.dart

@@ -1,5 +1,23 @@
 enum ObstacleDirection { left, center, right }
 
+class BoundingBox {
+  final double left;
+  final double top;
+  final double right;
+  final double bottom;
+
+  const BoundingBox({
+    required this.left,
+    required this.top,
+    required this.right,
+    required this.bottom,
+  });
+
+  double get width => right - left;
+  double get height => bottom - top;
+  double get centerX => left + width / 2;
+}
+
 class DetectionResult {
   final String label;
   final double confidence;
@@ -26,12 +44,73 @@ class DetectionResult {
 }
 
 class ObstacleAnalyzer {
-  DetectionResult analyzeFallback({String label = 'person', double confidence = 0.86}) {
+  static const double frameWidth = 640.0;
+  static const double frameHeight = 480.0;
+
+  ObstacleDirection analyzeDirection(BoundingBox box) {
+    final cx = box.centerX;
+    if (cx < frameWidth * 0.33) return ObstacleDirection.left;
+    if (cx > frameWidth * 0.67) return ObstacleDirection.right;
+    return ObstacleDirection.center;
+  }
+
+  String estimateDistance(BoundingBox box) {
+    final ratio = box.height / frameHeight;
+    if (ratio > 0.60) return 'Very Close (< 1m)';
+    if (ratio > 0.35) return 'Close (1-2m)';
+    if (ratio > 0.15) return 'Medium (2-4m)';
+    return 'Far (> 4m)';
+  }
+
+  String buildTtsMessage(DetectionResult result) {
+    final directionLabel = switch (result.direction) {
+      ObstacleDirection.left => 'kiri',
+      ObstacleDirection.center => 'depan',
+      ObstacleDirection.right => 'kanan',
+    };
+    return 'Hati-hati, ${result.label} di $directionLabel. '
+        'Jarak ${result.estimatedDistance}.';
+  }
+
+  DetectionResult? prioritize(List<DetectionResult> detections) {
+    if (detections.isEmpty) return null;
+    const order = [
+      'Very Close (< 1m)',
+      'Very Close',
+      'Close (1-2m)',
+      'Close',
+      'Medium (2-4m)',
+      'Medium',
+      'Far (> 4m)',
+      'Far',
+    ];
+    final sorted = List<DetectionResult>.of(detections);
+    sorted.sort((a, b) {
+      final ai = order.indexOf(a.estimatedDistance);
+      final bi = order.indexOf(b.estimatedDistance);
+      final aRank = ai == -1 ? order.length : ai;
+      final bRank = bi == -1 ? order.length : bi;
+      return aRank.compareTo(bRank);
+    });
+    return sorted.first;
+  }
+
+  List<DetectionResult> filterByConfidence(
+    List<DetectionResult> detections,
+    double threshold,
+  ) {
+    return detections.where((d) => d.confidence >= threshold).toList();
+  }
+
+  DetectionResult analyzeFallback({
+    String label = 'person',
+    double confidence = 0.86,
+  }) {
     return DetectionResult(
       label: label,
       confidence: confidence,
       direction: ObstacleDirection.center,
-      estimatedDistance: 'Close',
+      estimatedDistance: 'Close (1-2m)',
     );
   }
 }