local tsf = entity.transform
local rig = entity.skeleton
local body = entity.rigidbody

local states = {}

function create_state(name, track, max_intencity)
    states[name] = {
        track = track,
        timer = 0.0,
        fade_time = 0.0,
        fade_timer = 0.0,
        fade_in = false,
        max_intencity = max_intencity,
    }
end

local current_state = nil

function set_state(name, fade_time)
    local state = states[name]
    if state == current_state then
        return
    end
    if current_state then
        current_state.fade_in = false
        current_state.fade_time = fade_time
        current_state.fade_timer = 0.0
    end
    current_state = state
    if state then
        state.timer = 0.0
        state.fade_in = true
        state.fade_time = fade_time
        state.fade_timer = 0.0
    end
end

local function update(delta)
    for key, state in pairs(states) do
        state.timer = state.timer + delta

        local intensity = state.fade_in and 1.0 or 0.0
        if state.fade_timer < state.fade_time then
            state.fade_timer = state.fade_timer + delta
            intensity = math.min(1.0, state.fade_timer / state.fade_time)
            if not state.fade_in then
                intensity = 1.0 - intensity
            end
        end

        if state.track and intensity > 0.0 then
            state.track(rig, state.timer, intensity * state.max_intencity)
        end
    end
end

function on_render()
    update(time.delta())
end