#!/usr/bin/env python3

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument, TimerAction
from launch.conditions import IfCondition
from launch.substitutions import LaunchConfiguration, PythonExpression
from launch_ros.actions import Node


def generate_launch_description():
    # Declare launch arguments
    json_file_arg = DeclareLaunchArgument(
        'json_file',
        default_value='',
        description='Path to the JSON layout file'
    )
    
    rviz_config_arg = DeclareLaunchArgument(
        'rviz_config',
        default_value='/home/user/ws/src/db_loader/rviz/layout_view.rviz',
        description='Path to RViz config file (leave empty to skip RViz)'
    )
    
    publisher_delay_arg = DeclareLaunchArgument(
        'publisher_delay',
        default_value='1.5',
        description='Delay in seconds before starting publishers (to let subscribers connect)'
    )
   
    filled_shelves_arg = DeclareLaunchArgument(
        'filled',
        default_value='true',
        description='Display shelves as filled transparent boxes (true/false)'
    )
    
    shelf_alpha_arg = DeclareLaunchArgument(
        'alpha',
        default_value='0.3',
        description='Transparency level for filled shelves (0.0-1.0)'
    )

    # Static transform publisher for map frame
    static_tf_node = Node(
        package='tf2_ros',
        executable='static_transform_publisher',
        name='map_tf_publisher',
        arguments=['0', '0', '0', '0', '0', '0', 'world', 'map'],
        output='screen',
    )
    
    # Layout visualizer node with optional filled shelves arguments
    layout_visualizer_node = Node(
        package='db_loader',
        executable='layout_visualizer',
        name='layout_visualizer',
        output='screen',
        arguments=[
            '--filled',
            '--alpha',
            LaunchConfiguration('alpha')
        ],
        condition=IfCondition(
            PythonExpression([
                '"', LaunchConfiguration('filled'), '" == "true"'
            ])
        ),
    )
    
    # Layout visualizer node WITHOUT filled shelves (default)
    layout_visualizer_wireframe_node = Node(
        package='db_loader',
        executable='layout_visualizer',
        name='layout_visualizer',
        output='screen',
        condition=IfCondition(
            PythonExpression([
                '"', LaunchConfiguration('filled'), '" != "true"'
            ])
        ),
    )

    # RViz2 (only launches if rviz_config is provided)
    rviz_node = Node(
        package='rviz2',
        executable='rviz2',
        name='rviz2',
        output='screen',
        arguments=['-d', LaunchConfiguration('rviz_config')],
        condition=IfCondition(
            PythonExpression([
                '"', LaunchConfiguration('rviz_config'), '" != ""'
            ])
        ),
    )

    # Layout publisher node (DELAYED to ensure subscribers are ready)
    layout_publisher_node = Node(
        package='db_loader',
        executable='layout_publisher',
        name='layout_publisher',
        output='screen',
        arguments=[LaunchConfiguration('json_file')],
        condition=IfCondition(
            PythonExpression([
                '"', LaunchConfiguration('json_file'), '" != ""'
            ])
        ),
    )
      
    # Wrap layout publisher in TimerAction to delay its start
    delayed_layout_publisher = TimerAction(
        period=LaunchConfiguration('publisher_delay'),
        actions=[layout_publisher_node]
    )
    
    return LaunchDescription([
        json_file_arg,
        rviz_config_arg,
        publisher_delay_arg,
        filled_shelves_arg,
        shelf_alpha_arg,
        static_tf_node,
        layout_visualizer_node,
        layout_visualizer_wireframe_node,
        rviz_node,
        delayed_layout_publisher,
    ])