#!/usr/bin/env python3
"""
Detect faces in an image and return their bounding boxes and 128-D encodings.

Usage: python3 faces.py <image_path>

Stdout: JSON array — one object per face:
  [{"box": [top, right, bottom, left], "encoding": [128 floats]}, ...]

Returns "[]" when no faces are found or the image cannot be opened.
Errors are written to stderr; stdout is always valid JSON.
"""
import sys
import json


def main():
    if len(sys.argv) < 2:
        print("[]")
        return

    path = sys.argv[1]
    try:
        import face_recognition
    except ImportError as e:
        print(f"face_recognition not available: {e}", file=sys.stderr)
        print("[]")
        return

    try:
        img = face_recognition.load_image_file(path)
    except Exception as e:
        print(f"Could not load {path}: {e}", file=sys.stderr)
        print("[]")
        return

    try:
        locations = face_recognition.face_locations(img, model="hog")
        encodings = face_recognition.face_encodings(img, locations)
        result = [
            {"box": list(loc), "encoding": enc.tolist()}
            for loc, enc in zip(locations, encodings)
        ]
        print(json.dumps(result))
    except Exception as e:
        print(f"Detection error for {path}: {e}", file=sys.stderr)
        print("[]")


if __name__ == "__main__":
    main()