import csv
import math
from pathlib import Path

input_path = Path('triangulation_observations_with_centers.csv')
output_path = Path('triangulation_observations_with_angles.csv')

if not input_path.exists():
    raise FileNotFoundError(f'Not find input: {input_path.resolve()}')

image_width = 1280.0
image_height = 720.0
cx = image_width / 2.0
cy = image_height / 2.0

horizontal_fov_deg = 90.0
vertical_fov_deg = 60.0

fx = (image_width / 2.0) / math.tan(math.radians(horizontal_fov_deg / 2.0))
fy = (image_height / 2.0) / math.tan(math.radians(vertical_fov_deg / 2.0))

with open(input_path, 'r', encoding='utf-8-sig') as f:
    reader = csv.DictReader(f)
    rows = list(reader)
    fieldnames = reader.fieldnames[:] if reader.fieldnames else []

new_fields = ['camera_cx', 'camera_cy', 'fx_px', 'fy_px', 'azimuth_deg', 'elevation_deg']
for col in new_fields:
    if col not in fieldnames:
        fieldnames.append(col)

computed = 0
missing = 0

for row in rows:
    row['camera_cx'] = cx
    row['camera_cy'] = cy
    row['fx_px'] = round(fx, 6)
    row['fy_px'] = round(fy, 6)
    row['azimuth_deg'] = ''
    row['elevation_deg'] = ''

    x_str = (row.get('bbox_center_x_px') or '').strip()
    y_str = (row.get('bbox_center_y_px') or '').strip()

    if not x_str or not y_str:
        missing += 1
        continue

    x = float(x_str)
    y = float(y_str)

    dx = x - cx
    dy = y - cy

    azimuth_deg = math.degrees(math.atan(dx / fx))
    elevation_deg = -math.degrees(math.atan(dy / fy))

    row['azimuth_deg'] = round(azimuth_deg, 6)
    row['elevation_deg'] = round(elevation_deg, 6)
    computed += 1

with open(output_path, 'w', newline='', encoding='utf-8-sig') as f:
    writer = csv.DictWriter(f, fieldnames=fieldnames)
    writer.writeheader()
    writer.writerows(rows)

print(f'Đã tạo: {output_path}')
print(f'Tổng số dòng: {len(rows)}')
print(f'Số dòng tính được góc: {computed}')
print(f'Số dòng thiếu center pixel: {missing}')
print(f'Giả định camera: HFOV={horizontal_fov_deg}°, VFOV={vertical_fov_deg}°')
print(f'fx={fx:.3f}px, fy={fy:.3f}px, cx={cx:.1f}, cy={cy:.1f}')