"""Convert recorded intrinsics and optional exported ARKit poses to per-frame geometry."""
import argparse
import csv
import json
from pathlib import Path

import numpy as np
from scipy.spatial.transform import Rotation


def read_csv(path):
    with path.open(encoding='utf-8-sig', newline='') as stream:
        return list(csv.DictReader(line for line in stream if not line.startswith('#')))


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--intrinsics', type=Path, required=True)
    parser.add_argument('--poses', type=Path)
    parser.add_argument('--alignment', type=Path)
    parser.add_argument('--parameters', type=Path)
    parser.add_argument('--out', type=Path, required=True)
    args = parser.parse_args()
    intrinsics = read_csv(args.intrinsics)
    poses = alignment = None
    if args.poses:
        if not args.parameters or not args.alignment:
            parser.error('--poses requires --parameters and --alignment')
        parameters = json.loads(args.parameters.read_text(encoding='utf-8-sig'))
        pose_info = parameters['pose']
        if (pose_info['world_alignment'] != 'gravity' or
                pose_info['convention'] != 'T_world_camera (parent_from_child)' or
                pose_info['camera_coordinates'] != 'OpenCV/Rerun RDF (x right, y down, z forward)'):
            raise ValueError('Expected gravity-aligned T_world_camera already exported in camera RDF coordinates')
        poses, alignment = read_csv(args.poses), read_csv(args.alignment)
        if len(alignment) != len(intrinsics):
            raise ValueError('Intrinsics and alignment must have the same frame count')
    rows = []
    for index, params in enumerate(intrinsics):
        if int(params['frame_idx']) != index:
            raise ValueError('Intrinsics frame_idx must start at zero and be in order')
        row = dict(frame_idx=index, width=params['native_width_px'], height=params['native_height_px'],
                   fx=params['native_fx_px'], fy=params['native_fy_px'],
                   cx=params['native_cx_px'], cy=params['native_cy_px'])
        if poses is not None:
            match = alignment[index]
            pose = poses[int(match['arkit_row_index'])]
            if int(match['frame_idx']) != index or abs(float(pose['sensor_sec'])-float(params['sensor_sec'])) > 1e-5:
                raise ValueError(f'Pose/intrinsics alignment mismatch at frame {index}')
            if pose['tracking_state'] != 'normal':
                raise ValueError(f'ARKit tracking is not normal at frame {index}')
            q = np.array([float(pose[key]) for key in ['qx','qy','qz','qw']])
            q /= np.linalg.norm(q)
            up = Rotation.from_quat(q).as_matrix().T @ np.array([0.,1.,0.])
            row.update(stamp=match['stamp'], up_x=up[0], up_y=up[1], up_z=up[2])
        rows.append(row)
    with args.out.open('w', encoding='utf-8', newline='') as stream:
        writer = csv.DictWriter(stream, fieldnames=list(rows[0]))
        writer.writeheader()
        writer.writerows(rows)
    print(f'Saved {len(rows)} frames; gravity aligned: {poses is not None}')


if __name__ == '__main__':
    main()