# This script makes the boulder trigger a DBNO state on hit

using { /Fortnite.com/Devices }
using { /Fortnite.com/Characters }
using { /Verse.org/Simulation }
using { /UnrealEngine.com/Temporary/Diagnostics }

# A creative_device subclass that holds a reference to the
# down_but_not_out_device placed in the editor and a
# damage_volume_device that surrounds the boulder's collision area.
# Because Verse creative devices cannot directly subscribe to
# physics-body collision events, we use a damage_volume_device
# to detect when the boulder's area overlaps a player, then
# apply the DBNO effect through the down_but_not_out_device.
boulder_manager_device := class(creative_device):

    # This is a 'Constant' - a value that never changes.
    # Think of it like the 'Game Mode' setting in the island settings.
    # Wire this to your Down But Not Out device in the editor.
    @editable
    DownButNotOutDevice : down_but_not_out_device = down_but_not_out_device{}

    # Wire this damage_volume_device so it surrounds the rolling boulder.
    # Set its damage to 100 in the editor so it knocks players to 0 HP,
    # which the DBNO device intercepts before elimination.
    @editable
    BoulderDamageVolume : damage_volume_device = damage_volume_device{}

    # This is the 'Main' function. It runs once when the island starts.
    # Think of it like the 'Start Button' on the battle bus.
    OnBegin<override>()<suspends> : void =
        # We need to listen for when the boulder area overlaps a player.
        # In Verse, we 'subscribe' a function to an event.
        # Event: 'AgentEntersEvent' -> Function: 'HandleBoulderHit'
        BoulderDamageVolume.AgentEntersEvent.Subscribe(HandleBoulderHit)

    # This is a 'Function' - a reusable block of code.
    # Think of it like a 'Trap' that activates when triggered.
    # AgentEntersEvent always delivers an agent, so we know it is a player.
    HandleBoulderHit(HitAgent : agent) : void =
        # Cast the agent to fort_character so we can check game state.
        # 'GetFortCharacter[]' fails if the agent has no living character,
        # which guards us from acting on already-eliminated players.
        if (Character := HitAgent.GetFortCharacter[]):
            # If the character is already in a downed state, do nothing.
            # We don't want to double-down them.
            # IsActive[] fails (returns false) when the character is downed
            # or eliminated, so we only proceed when they are fully active.
            if (Character.IsActive[]):
                # Here is the magic: Trigger the DBNO state.
                # Down() tells the down_but_not_out_device to immediately
                # set this agent into the downed state instead of a full
                # elimination. This is like pressing the 'Revive' button,
                # but backwards.
                DownButNotOutDevice.Down(HitAgent)
                # note: down_but_not_out_device.Down() directly places the
                # agent into the Downed state. Pair this with the damage
                # from BoulderDamageVolume (set to 100 in editor settings)
                # to immediately trigger the transition.