# Copyright 2021 Memristor Robotics
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import os

from ament_index_python.packages import get_package_share_directory

from launch import LaunchDescription
from launch.actions import (DeclareLaunchArgument, GroupAction, SetEnvironmentVariable)
from launch.conditions import IfCondition
from launch.substitutions import LaunchConfiguration
from launch_ros.actions import Node
from launch_ros.actions import PushRosNamespace
from nav2_common.launch import RewrittenYaml


def generate_launch_description():
    # Get the launch directory
    mep3_navigation_dir = get_package_share_directory('mep3_navigation')

    # Create the launch configuration variables
    namespace = LaunchConfiguration('namespace')
    use_namespace = LaunchConfiguration('use_namespace')
    map_yaml_file = LaunchConfiguration('map')
    use_sim_time = LaunchConfiguration('use_sim_time')
    params_file = LaunchConfiguration('params_file')
    autostart = LaunchConfiguration('autostart')
    nav2_bt_xml_file = LaunchConfiguration('nav2_bt_xml_file')

    lifecycle_nodes = ['controller_server',
                       'planner_server',
                       'recoveries_server',
                       'bt_navigator',
                       'waypoint_follower']

    # Map fully qualified names to relative ones so the node's namespace can be prepended.
    # In case of the transforms (tf), currently, there doesn't seem to be a better alternative
    # https://github.com/ros/geometry2/issues/32
    # https://github.com/ros/robot_state_publisher/pull/30
    # TODO(orduno) Substitute with `PushNodeRemapping`
    #              https://github.com/ros2/launch_ros/issues/56
    remappings = [('/tf', 'tf'),
                  ('/tf_static', 'tf_static')]

    # Create our own temporary YAML files that include substitutions
    param_substitutions = {
        'default_nav_to_pose_bt_xml': nav2_bt_xml_file,
        'use_sim_time': use_sim_time,
        'yaml_filename': map_yaml_file}

    configured_params = RewrittenYaml(
        source_file=params_file,
        root_key=namespace,
        param_rewrites=param_substitutions,
        convert_types=True)

    stdout_linebuf_envvar = SetEnvironmentVariable(
        'RCUTILS_LOGGING_BUFFERED_STREAM', '1')

    nav2_bt_xml_file_cmd = DeclareLaunchArgument(
        'nav2_bt_xml_file',
        default_value=os.path.join(
            mep3_navigation_dir,
            'behavior_trees',
            'navigate_w_recovery_and_replanning_only_if_path_becomes_invalid.xml',
        ),
        description='Full path to the parameter YAML file to use for configuring the behavior tree'
    )

    declare_namespace_cmd = DeclareLaunchArgument(
        'namespace',
        default_value='',
        description='Top-level namespace')

    declare_use_namespace_cmd = DeclareLaunchArgument(
        'use_namespace',
        default_value='false',
        description='Whether to apply a namespace to the navigation stack')

    declare_slam_cmd = DeclareLaunchArgument(
        'slam',
        default_value='False',
        description='Whether run a SLAM')

    declare_map_yaml_cmd = DeclareLaunchArgument(
        'map',
        description='Full path to map yaml file to load')

    declare_use_sim_time_cmd = DeclareLaunchArgument(
        'use_sim_time',
        default_value='false',
        description='Use simulation (Webots) clock if true')

    declare_params_file_cmd = DeclareLaunchArgument(
        'params_file',
        default_value=os.path.join(
            mep3_navigation_dir, 'params', 'nav2_params_big.yaml'),
        description='Full path to the ROS2 parameters file to use for all launched nodes')

    declare_autostart_cmd = DeclareLaunchArgument(
        'autostart', default_value='true',
        description='Automatically startup the nav2 stack')

    # Specify the actions
    bringup_cmd_group = GroupAction([
        PushRosNamespace(
            condition=IfCondition(use_namespace),
            namespace=namespace),
        Node(
            package='nav2_map_server',
            executable='map_server',
            name='map_server',
            output='screen',
            parameters=[configured_params],
            remappings=remappings),
        Node(
            package='nav2_lifecycle_manager',
            executable='lifecycle_manager',
            name='lifecycle_manager_localization',
            output='screen',
            parameters=[{'use_sim_time': use_sim_time},
                        {'autostart': autostart},
                        {'node_names': ['map_server']}]),
        Node(
            package='nav2_controller',
            executable='controller_server',
            output='screen',
            parameters=[configured_params],
            remappings=remappings),

        Node(
            package='nav2_planner',
            executable='planner_server',
            name='planner_server',
            output='screen',
            parameters=[configured_params],
            remappings=remappings),

        Node(
            package='nav2_recoveries',
            executable='recoveries_server',
            name='recoveries_server',
            output='screen',
            parameters=[configured_params],
            remappings=remappings),

        Node(
            package='nav2_bt_navigator',
            executable='bt_navigator',
            name='bt_navigator',
            output='screen',
            parameters=[configured_params],
            remappings=remappings),

        Node(
            package='nav2_waypoint_follower',
            executable='waypoint_follower',
            name='waypoint_follower',
            output='screen',
            parameters=[configured_params],
            remappings=remappings),

        Node(
            package='nav2_lifecycle_manager',
            executable='lifecycle_manager',
            name='lifecycle_manager_navigation',
            output='screen',
            parameters=[{'use_sim_time': use_sim_time},
                        {'autostart': autostart},
                        {'node_names': lifecycle_nodes}]),
    ])

    # Create the launch description and populate
    ld = LaunchDescription()

    # Set environment variables
    ld.add_action(stdout_linebuf_envvar)

    # Declare the launch options
    ld.add_action(declare_namespace_cmd)
    ld.add_action(declare_use_namespace_cmd)
    ld.add_action(declare_slam_cmd)
    ld.add_action(declare_map_yaml_cmd)
    ld.add_action(declare_use_sim_time_cmd)
    ld.add_action(declare_params_file_cmd)
    ld.add_action(declare_autostart_cmd)
    ld.add_action(nav2_bt_xml_file_cmd)

    # Add the actions to launch all of the navigation nodes
    ld.add_action(bringup_cmd_group)

    return ld
