AIActivityHandler

local ACTIVITY_HANDLER = script.parent

local LOBBY_DURATION = 7
local MIN_PLAYERS_TO_START = 1
local SCORE_TO_WIN = 5
local GAME_OVER_DURATION = 5

local isLobby = false
local isRound = false
local isGameOver = false

local Lobby = {}
local Round = {}
local GameOver = {}

-- Lobby

-- Called every frame for all activities, usually used to set the priority
function Lobby.tick(activity, deltaTime)
    if isLobby
    and activity.elapsedTime >= LOBBY_DURATION
    and #Game.GetPlayers() >= MIN_PLAYERS_TO_START then
        activity.priority = 0

    elseif not isRound then
        activity.priority = 200
    end
end
-- Called when this activity first becomes the highest priority
function Lobby.start(activity)
    print("Lobby start")

    isLobby = true
end
-- called when this was the highest priority, and a different activity has just taken over
function Lobby.stop(activity)
    print("Lobby stop")

    isLobby = false
end

-- Round

-- Called every frame for all activities, usually used to set the priority
function Round.tick(activity, deltaTime)
    activity.priority = 100
end
-- called when this activity first becomes the highest priority
function Round.start(activity)
    print("Round start")

    Game.StartRound()
    isRound = true
end
-- called when this was the highest priority, and a different activity has just taken over
function Round.stop(activity)
    print("Round stop")

    Game.EndRound()
    isRound = false
end

-- Game Over

-- Called every frame for all activities, usually used to set the priority
function GameOver.tick(activity, deltaTime)
    local team1Win = Game.GetTeamScore(1) >= SCORE_TO_WIN
    local team2Win = Game.GetTeamScore(2) >= SCORE_TO_WIN
    if team1Win or team2Win then
        activity.priority = 300
    else
        activity.priority = 0
    end
end
-- called after all activities have tick'd, but only for the activity with the highest priority
function GameOver.tickHighestPriority(activity, deltaTime)
    if activity.elapsedTime >= GAME_OVER_DURATION then
        -- Reset scores
        Game.SetTeamScore(1, 0)
        Game.SetTeamScore(2, 0)
    end
end
-- called when this activity first becomes the highest priority
function GameOver.start(activity)
    print("GameOver start")

    isGameOver = true
end
-- called when this was the highest priority, and a different activity has just taken over
function GameOver.stop(activity)
    print("GameOver stop")

    isGameOver = false
end

ACTIVITY_HANDLER:AddActivity("Lobby", Lobby)
ACTIVITY_HANDLER:AddActivity("Round", Round)
ACTIVITY_HANDLER:AddActivity("GameOver", GameOver)

-- For testing: Click left mouse button to score 1 point
-- The Shoot action in the Binding Set will need to be networked for it to be detected on the server.
function OnActionPressed(player, action)
    if action == "Shoot" then
        print("Goal!")
        Game.IncreaseTeamScore(player.team, 1)
    end
end

Input.actionPressedEvent:Connect(OnActionPressed)

local ACTIVITY_HANDLER = script.parent
local VEHICLE = script:FindAncestorByType("Vehicle")

local averageSpeed = 100
local centerHit
local leftHit
local rightHit

local reverseTimeRemaining = 0

local throttle = 0
local steering = 0

local drivingActivityTable = {}
local reverseActivityTable = {}

-- Driving forward activity
function drivingActivityTable.tick(activity, deltaTime)
    activity.priority = 100
end

function drivingActivityTable.tickHighestPriority(activity, deltaTime)
    UpdateKnowledge()

    if centerHit and activity.elapsedTime > 0.5 then
        throttle = 0 -- Let go of gas
    else
        throttle = 1 -- Press the gas
    end

    if rightHit then
        steering = -1 -- Left

    elseif leftHit then
        steering = 1 -- Right
    else
        steering = 0 -- Don't steer
    end

    if averageSpeed < 30 and activity.elapsedTime > 1 then
        -- Go in reverse under these conditions
        ACTIVITY_HANDLER:AddActivity("Reverse", reverseActivityTable)
    end
end

-- Reverse activity
function reverseActivityTable.tick(activity, deltaTime)
    activity.priority = 200
end

function reverseActivityTable.tickHighestPriority(activity, deltaTime)
    UpdateKnowledge()

    throttle = -1 -- Go in reverse
    steering = 1 -- and steer to the right

    reverseTimeRemaining = reverseTimeRemaining - deltaTime
    if reverseTimeRemaining <= 0 then
        -- Stop going in reverse
        ACTIVITY_HANDLER:RemoveActivity("Reverse")
    end
end

function reverseActivityTable.start(activity)
    reverseTimeRemaining = 1 + math.random()
end

ACTIVITY_HANDLER:AddActivity("Driving", drivingActivityTable)

-- Gather information about the vehicle's speed and obstacles ahead
function UpdateKnowledge()
    local pos = script:GetWorldPosition()
    local qRotation = Quaternion.New(script:GetWorldRotation())
    local forwardV = qRotation:GetForwardVector()
    local rightV = qRotation:GetRightVector() * 120
    local speed = VEHICLE:GetVelocity().size
    averageSpeed = CoreMath.Lerp(averageSpeed, speed, 0.1)
    speed = math.max(speed * 1.2, 120)
    local velocity = forwardV * speed
    -- Cast 3 rays forward to see if they hit something. The decisions to
    -- steer and accelerate are based on the results of these:
    centerHit = World.Raycast(pos, pos + velocity)
    leftHit = World.Raycast(pos - rightV, pos - rightV + velocity)
    rightHit = World.Raycast(pos + rightV, pos + rightV + velocity)
end

-- Apply driving decisions to vehicle
function OnMovementHook(vehicle, params)
    -- Disable the handbrake
    params.isHandbrakeEngaged = false
    -- Copy throttle and steering
    params.throttleInput = throttle
    params.steeringInput = steering
end

VEHICLE.serverMovementHook:Connect(OnMovementHook)