# Import the necessary Verse libraries
using /Fortnite.com/Devices
using /Engine/Engine

# Define our Main Device. This is the "boss" object in our scene graph.
# It will hold the UI widget and the logic.
device HealthBarController <
    # This is a reference to the UI Widget in our level.
    # Think of it as the "container" for our health bar.
    Widget: WidgetDevice = WidgetDevice()
    
    # This is the Material Instance we created.
    # We need to expose it so Verse can talk to it.
    Material: MaterialInstance = MaterialInstance()
    
    # The player we're tracking.
    Player: Player = Player()
>

# This function runs once when the island starts.
OnBegin<override>()<suspends>: void =
    # Wait for the player to spawn
    Player.SpawnedEvent += () ->
        # Every time the player's health changes, update the bar
        Player.HealthChangedEvent += (new_health: float, max_health: float) ->
            UpdateHealthBar(new_health, max_health)

# The core logic: Update the visual appearance
UpdateHealthBar(current_health: float, max_health: float): void =
    # Calculate percentage (0.0 to 1.0)
    # Analogy: If you have 100 HP and take 50 damage, you're at 0.5 (50%)
    health_percent: float = current_health / max_health
    
    # Determine color based on health
    # If health is > 50%, it's green. If < 50%, it's red.
    target_color: vector4 = if (health_percent > 0.5)
        then vector4(0.0, 1.0, 0.0, 1.0) # Green (R, G, B, Alpha)
        else vector4(1.0, 0.0, 0.0, 1.0) # Red
    
    # Update the Material Instance parameters
    # This is where the magic happens! We're changing the "recipe" 
    # for how the texture looks without changing the texture itself.
    Material.SetColorParameter("HealthColor", target_color)
    Material.SetScalarParameter("HealthOpacity", health_percent)
    
    # Optional: Hide the bar if health is 0
    if (current_health <= 0.0)
        Material.SetScalarParameter("HealthOpacity", 0.0)