"""
rplidar.launch.py — RPLIDAR A1M8 driver (standalone)

Launches rplidar_ros with udev symlink (/dev/rplidar) set in 99-saltybot.rules.
Falls back to /dev/ttyUSB0 if the symlink is not present.

RPLIDAR A1M8 specs:
  - 360° omnidirectional scan
  - 8000 samples/s, ~5.5 Hz scan rate at 1440 points/scan
  - 12m range (reliable to ~8m indoors)
  - 115200 baud via CP2102 USB-UART adapter

Published topics:
  /scan    sensor_msgs/LaserScan    ~5.5 Hz

TF frame: laser → matches static_transform_publisher in sensors.launch.py
  frame_id = 'laser'

Verify:
  ros2 topic hz /scan
  ros2 run tf2_ros tf2_echo base_link laser
"""

import os
from launch import LaunchDescription
from launch.actions import IncludeLaunchDescription, DeclareLaunchArgument
from launch.launch_description_sources import PythonLaunchDescriptionSource
from launch.substitutions import LaunchConfiguration
from ament_index_python.packages import get_package_share_directory


def generate_launch_description():
    serial_port_arg = DeclareLaunchArgument(
        'serial_port',
        default_value='/dev/rplidar',
        description='RPLIDAR serial port (udev symlink preferred over /dev/ttyUSB0)',
    )

    rplidar_share = get_package_share_directory('rplidar_ros')

    rplidar_launch = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(rplidar_share, 'launch', 'rplidar_a1_launch.py')
        ),
        launch_arguments={
            'serial_port':      LaunchConfiguration('serial_port'),
            'serial_baudrate':  '115200',
            # 'laser' matches the TF frame in sensors.launch.py and slam config
            'frame_id':         'laser',
            # Compensate for motor rotation angle offset
            'angle_compensate': 'true',
            # A1M8 only supports Standard scan mode
            'scan_mode':        'Standard',
        }.items(),
    )

    return LaunchDescription([
        serial_port_arg,
        rplidar_launch,
    ])