"""
  rbs_bt_web
  ROS 2 launch program for Robossembler

  @shalenikol release 0.1
"""
import os
# import json

from launch import LaunchDescription
from launch_ros.actions import Node
from launch.actions import DeclareLaunchArgument, OpaqueFunction, RegisterEventHandler
from launch.substitutions import LaunchConfiguration
from launch.event_handlers import OnExecutionComplete

FILE_BT = "bt.xml"

def launch_setup(context, *args, **kwargs):
    # Initialize Arguments
    bt_path = LaunchConfiguration("bt_path")
    bt_path = bt_path.perform(context)

    rbs_bt = Node(
        package = "behavior_tree",
        executable = "bt_engine",
        parameters = [
            {"bt_file_path": os.path.join(bt_path, FILE_BT)},
            {"plugins": ["rbs_interface"]}
        ]
    )

    bt_param = Node(
        package="rbs_interface",
        executable="bt_param.py",
        parameters = [{"bt_path": bt_path}]
    )
    # nodes_to_start = [rbs_bt]
    # return nodes_to_start
    # return [bt_param]
    return [
            RegisterEventHandler(
                event_handler=OnExecutionComplete(
                    target_action=bt_param,
                    on_completion=[rbs_bt],
                )
            ),
            bt_param
        ] # the order of elements is strictly required

def generate_launch_description():
    declared_arguments = []
    declared_arguments.append(
        DeclareLaunchArgument(
            "bt_path",
            default_value="''",
            description="path to Behavior tree instance"
        )
    )
    return LaunchDescription(declared_arguments + [OpaqueFunction(function=launch_setup)])