--- So. The main problem with this approach is... it is LOUD
local girders = {}
local clusters = {}
local lastClusterTick = 0
local direction = 1
local SeqLeft = 0
local SeqRight = 0
local CurrPos = 0
-- uses milliseconds but could obviously be once a turn or whatever.
local StepTime = 2000
local PlatWidth = 5
local hogs = {}
local balls = {}

-- This test is just using short horizontal right now
-- it is LOUD so considering adding lua access to tunnel/circle erasure
function removeGirder(g)
    if g.type == 0 then
        for i = -36,36,6 do
            clusters[AddGear(g.x+i,g.y+6,gtCluster,gstCollision,0,0,10)]=1
            clusters[AddGear(g.x+i,g.y-6,gtCluster,gstCollision,0,0,10)]=1
        end
        lastClusterTick = GameTime
    end
end

function onAddGear(g)
    if GetGearType(g) == gtHedgehog then
        hogs[g] = 1
    end
end

function onGameStart()
    PlaceGirder(LeftX+82,TopY+100,4)
    PlaceGirder(RightX-82,TopY+100,4)

    -- Locate a sequence width that is 80, for prettiness.
    local w = div(RightX-LeftX-160,80)*80
    local o = div(RightX-LeftX-160-w,2)
    SeqLeft = LeftX+80+o
    SeqRight = RightX-80-o
    SeqTop = TopY+150
    CurrPos = SeqLeft
    local vg = AddVisualGear(SeqLeft-40, SeqTop, vgtStraightShot, 0, true)
    g1, g2, g3, g4, g5, g6, g7, g8, g9, g10 = GetVisualGearValues(vg)
    g3 = 0
    g4 = 0
    --g5 = 90 -- angle
    g6 = 3 -- frame
    g7 = 999999999 -- frameticks
    g8 = 143 -- sprite
    SetVisualGearValues(vg,g1, g2, g3, g4, g5, g6, g7, g8, g9, g10)
    vg = AddVisualGear(SeqRight+40, SeqTop, vgtStraightShot, 0, true)
    g1, g2, g3, g4, g5, g6, g7, g8, g9, g10 = GetVisualGearValues(vg)
    g3 = 0
    g4 = 0
    --g5 = 270
    g6 = 1 -- frame
    g7 = 999999999 -- frameticks
    g8 = 143
    SetVisualGearValues(vg,g1, g2, g3, g4, g5, g6, g7, g8, g9, g10)
end

-- figured scheduled deletes could be useful for various opening and closing gates and whatnot.

function onGameTick20()
    -- this obv requires a StepTime divisible by 20
    if GameTime % StepTime == 0 then
        if (direction == 1 and CurrPos < SeqRight) or (direction == -1 and CurrPos > SeqLeft) then
            PlaceGirder(CurrPos,SeqTop,0)
            girders[#girders+1] = {x=CurrPos,y=SeqTop,type=0, deleteMe=GameTime+10000}
            CurrPos = CurrPos + 80*direction
        end
    end
   
    -- thought here was to allow more complex animations than this simple "one a time" 
    for c,g in pairs(girders) do
        if GameTime > g.deleteMe then
            -- experiment shoving hogs along out of removegirder danger area
-- didn't seem to shove, and would probably need to find something that sets all gears to active
--           for h,i in pairs(hogs) do
--               dx,dy = GetGearVelocity(h)
--               if dx < 1000 and dy < 1000 and
--                  ((direction == 1 and gearIsInBox(h, g.x, g.y-50,300,50)) or
--                  (direction == -1 and gearIsInBox(h, g.x-160, g.y-50,300,50))) then
--                  AddCaption("Shoving a hog")
--                  SetGearVelocity(h,dx+100000*direction,dy)
--               end
--           end
            removeGirder(g)
            if (direction == -1 and g.x < SeqLeft+80) or (direction == 1 and g.x > SeqRight-80) then
                direction = direction * -1
            end
            girders[c] = nil
        end
    end
    if GameTime > lastClusterTick then
        for c,i in pairs(clusters) do
            DeleteGear(c)
            clusters[c]=nil
        end
    end
end