import launch
import launch_ros
from ament_index_python.packages import get_package_share_directory
import os 
def generate_launch_description():
    #获取urdf路径
    urdf_package_path = get_package_share_directory("fishbot_description")
    default_rviz_config_path = os.path.join(urdf_package_path,"config","display_robot_model.rviz")
    default_urdf_path = os.path.join(urdf_package_path,"urdf","first_robot.urdf")
    #声明一个urdf目录的参数，方便修改
    action_declare_arg_mode_path = launch.actions.DeclareLaunchArgument(
        name="model",default_value=str(default_urdf_path),description="加载模型文件路径"
    )
    #通过文件路径，获取内容，并转化成数值对象，以供传入 robot_state_publisher
    substitutions_command_result = launch.substitutions.Command(["xacro ",launch.substitutions.LaunchConfiguration("model")])
    
    robot_description_value = launch_ros.parameter_descriptions.ParameterValue(substitutions_command_result,value_type=str)

    action_robot_state_publisher = launch_ros.actions.Node(
        package="robot_state_publisher",
        executable="robot_state_publisher",
        parameters=[{f"robot_description":robot_description_value}]
    )
    
    action_joint_state_publisher = launch_ros.actions.Node(
        package="joint_state_publisher",
        executable="joint_state_publisher"
    )

    action_rviz_node = launch_ros.actions.Node(
        package="rviz2",
        executable="rviz2",
        arguments=["-d",default_rviz_config_path]
    )
    
    return launch.LaunchDescription([
        action_declare_arg_mode_path,
        action_robot_state_publisher,
        action_joint_state_publisher,
        action_rviz_node,
    ])