# Copyright (c) 2020 Samsung Research Russia
#
# 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, IncludeLaunchDescription, GroupAction
from launch.launch_description_sources import PythonLaunchDescriptionSource
from launch.substitutions import LaunchConfiguration
from launch_ros.actions import Node, SetRemap
from launch_ros.descriptions import ParameterFile
from nav2_common.launch import RewrittenYaml


def generate_launch_description():
    # Input parameters declaration
    namespace = LaunchConfiguration("namespace")
    params_file = LaunchConfiguration("params_file")
    use_sim_time = LaunchConfiguration("use_sim_time")
    autostart = LaunchConfiguration("autostart")
    use_respawn = LaunchConfiguration("use_respawn")
    log_level = LaunchConfiguration("log_level")

    # Variables
    lifecycle_nodes = ["map_saver"]

    # Getting directories and launch-files
    slam_toolbox_dir = get_package_share_directory("slam_toolbox")
    slam_launch_file = os.path.join(slam_toolbox_dir, "launch", "online_sync_launch.py")

    # Create our own temporary YAML files that include substitutions
    param_substitutions = {"use_sim_time": use_sim_time}

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

    # Declare the launch arguments
    declare_namespace_cmd = DeclareLaunchArgument(
        "namespace", default_value="robot", description="Top-level namespace"
    )

    declare_params_file_cmd = DeclareLaunchArgument(
        "params_file",
        default_value="/params.yaml",
        description="Full path to the ROS2 parameters file to use for all launched nodes",
    )

    declare_use_sim_time_cmd = DeclareLaunchArgument(
        "use_sim_time", default_value="True", description="Use simulation (Gazebo) clock if true"
    )

    declare_autostart_cmd = DeclareLaunchArgument(
        "autostart", default_value="True", description="Automatically startup the nav2 stack"
    )

    declare_use_respawn_cmd = DeclareLaunchArgument(
        "use_respawn",
        default_value="False",
        description="Whether to respawn if a node crashes. Applied when composition is disabled.",
    )

    declare_log_level_cmd = DeclareLaunchArgument(
        "log_level", default_value="info", description="log level"
    )

    # Nodes launching commands

    start_map_saver_server_cmd = Node(
        package="nav2_map_server",
        executable="map_saver_server",
        output="screen",
        respawn=use_respawn,
        respawn_delay=2.0,
        arguments=["--ros-args", "--log-level", log_level],
        parameters=[configured_params],
    )

    start_lifecycle_manager_cmd = Node(
        package="nav2_lifecycle_manager",
        executable="lifecycle_manager",
        name="lifecycle_manager_slam",
        output="screen",
        arguments=["--ros-args", "--log-level", log_level],
        parameters=[
            {"use_sim_time": use_sim_time},
            {"autostart": autostart},
            {"node_names": lifecycle_nodes},
        ],
    )

    start_slam_toolbox_cmd_with_params = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(slam_launch_file),
        launch_arguments={"use_sim_time": use_sim_time, "slam_params_file": params_file}.items(),
    )

    group_actions = []

    # Remapping
    group_actions.append(SetRemap("/map", "map"))
    group_actions.append(SetRemap("/map_metadata", "map_metadata"))
    group_actions.append(SetRemap("/scan", "scan"))

    # Running Map Saver Server
    group_actions.append(start_map_saver_server_cmd)
    group_actions.append(start_lifecycle_manager_cmd)

    # Running SLAM Toolbox (Only one of them will be run)
    group_actions.append(start_slam_toolbox_cmd_with_params)

    slam_ns = GroupAction(actions=group_actions)

    ld = LaunchDescription()

    # Declare the launch options
    ld.add_action(declare_namespace_cmd)
    ld.add_action(declare_params_file_cmd)
    ld.add_action(declare_use_sim_time_cmd)
    ld.add_action(declare_autostart_cmd)
    ld.add_action(declare_use_respawn_cmd)
    ld.add_action(declare_log_level_cmd)

    # Running SLAM
    ld.add_action(slam_ns)

    return ld