local gridElements = filteredSystem("gridElements", { gridPosition = T.XyPair, effectsToApply = T.AnyComponent })

local roundRunning = false

filteredSystem("timers", { timerSec = T.number, callback = T.SelfFunction }, function(e, dt, system)
    e.timerSec = e.timerSec - dt
    if e.timerSec < 0 then
        e:callback()
        system.world:removeEntity(e)
    end
end)

local function sign(n)
    return n > 0 and 1 or n < 0 and -1 or 0
end

local roundSystem = filteredSystem("rounds", { round = T.str })

local activeBallEffects = filteredSystem("activeBallEffects", { ballEffects = T.AnyComponent, gridPosition = T.XyPair }, function(e, dt, system)
    local roundActive = false
    for _, state in pairs(roundSystem.entities) do
        if state.round == "start" then
            roundActive = true
        end
    end
    if not roundActive then
        return
    end
    local gridPosition, effects = e.gridPosition, e.ballEffects

    -- Search for new effects from the current tile
    for _, gridElement in pairs(gridElements.entities) do
        if
            gridPosition.x == gridElement.gridPosition.x
            and gridPosition.y == gridElement.gridPosition.y
        then
            -- More direct-mutation-y than I'd like,
            -- but offers a simple way to overwrite existing effects.
            -- We're "setting InRelations" :D
            for key, value in pairs(gridElement.effectsToApply) do
                effects[key] = value
            end
            if gridElement.spriteAfterEffect then
                gridElement.drawAsSprite = gridElement.spriteAfterEffect
                gridElement.spriteAfterEffect = nil
            end
            gridElement.effectsToApply = nil
            system.world:addEntity(gridElement)
        end
    end

    -- Apply any effects currently connected to this ball
    if effects.movement ~= nil then
        gridPosition.x = gridPosition.x + sign(effects.movement.x)
        gridPosition.y = gridPosition.y + sign(effects.movement.y)

        effects.movement.x = effects.movement.x - sign(effects.movement.x)
        effects.movement.y = effects.movement.y - sign(effects.movement.y)

        if effects.movement.x == 0 and effects.movement.y == 0 then
            effects.movement = nil
        end
    end

    -- TODO: Trigger the round end
    -- for _, _ in pairs(effects) do
    --     -- Return if there are any effects left
    --     return
    -- end

    -- system.world:addEntity({ round = "end" })
end)

local stepTimeSec = 0.3
local stepTimer = stepTimeSec

function activeBallEffects:preProcess(dt)
    stepTimer = stepTimer - dt
    if stepTimer <= 0 then
        stepTimer = stepTimeSec
        return
    end
    return tiny.SKIP_PROCESS
end