using AdaptiveDirectorDemo.Director;
using Sandbox;
using Sandbox.UI;

namespace AdaptiveDirectorDemo.UI;

/// <summary>Small world-space health bar that follows its Citizen NPC.</summary>
[Title( "Director NPC Health Bar" )]
[Category( "Adaptive Director Demo" )]
public sealed class NpcHealthBar : PanelComponent
{
	private Panel _fill;
	private DemoNpc _npc;

	protected override void OnStart()
	{
		EnsureVisuals();
	}

	protected override void OnUpdate()
	{
		// Component fields can be reset while the existing panel tree survives a
		// hot load. Rebuild our cached UI references before touching them.
		if ( !EnsureVisuals() )
			return;

		var root = Panel;
		if ( root is null || !root.IsValid )
			return;

		if ( _npc is null || !_npc.IsValid )
			_npc = GameObject.Parent?.Components.Get<DemoNpc>();

		if ( _npc is null || !_npc.IsAlive )
		{
			root.Style.Display = DisplayMode.None;
			return;
		}

		root.Style.Display = DisplayMode.Flex;
		_fill.Style.Width = Length.Percent( _npc.HealthFraction * 100.0f );
	}

	private bool EnsureVisuals()
	{
		var root = Panel;
		if ( root is null || !root.IsValid )
			return false;

		if ( _fill is not null && _fill.IsValid )
			return true;

		root.StyleSheet.Load( "/UI/NpcHealthBar.cs.scss" );
		var track = root.Add.Panel( "npc-health-track" );
		_fill = track.Add.Panel( "npc-health-fill" );
		return true;
	}
}