local runService = game:GetService("RunService")
local rng = Random.new()

----

local SIZE = 100
local WHITE = BrickColor.White()
local BLACK = BrickColor.Black()

local OFFSETS = {
    {-1, -1},
    {0, -1},
    {1, -1},
    {-1, 1},
    {0, 1},
    {1, 1},
    {-1, 0},
    {1, 0},
}

----

local function getPart(x, y)
    local part = Instance.new("Part")
    part.Anchored = true
    part.CanCollide = false
    part.Size = Vector3.new(1, 1, 1)
    part.CFrame = CFrame.new(x, 0.5, y)
    part.BrickColor = BLACK
    part.Parent = workspace

    return part
end

local tileList = {}
local boardGrid = {}

for x = 1, SIZE, 1 do
    boardGrid[x] = {}

    for y = 1, SIZE, 1 do
        boardGrid[x][y] = {
            State = false,
            Next = false,

            Position = {x, y},
            Part = getPart(x, y),
            Neighbors = {}
        }
    end
end

for originX = 1, SIZE, 1 do
    for originY = 1, SIZE, 1 do
        local tile = boardGrid[originX][originY]

        for offsetIndex = 1, 8, 1 do
            local offset = OFFSETS[offsetIndex]
            local x = originX + offset[1]
            local y = originY + offset[2]

            if x == 0 then
                x = SIZE
            elseif x == SIZE + 1 then
                x = 1
            end

            if y == 0 then
                y = SIZE
            elseif y == SIZE + 1 then
                y = 1
            end

            table.insert(tile.Neighbors, boardGrid[x][y])
        end

        table.insert(tileList, tile)
    end
end

---

--[[ GLIDER GUN
local gliderGun = {
    -- left box
    {2, 6}, {2, 7},
    {3, 6}, {3, 7},

    -- left ship
    {12, 6}, {12, 7}, {12, 8},
    {13, 5}, {13, 9},
    {14, 4}, {14, 10},
    {15, 4}, {15, 10},
    {16, 7},
    {17, 5}, {17, 9},
    {18, 6}, {18, 7}, {18, 8},
    {19, 7},

    -- right ship
    {22, 4}, {22, 5}, {22, 6},
    {23, 4}, {23, 5}, {23, 6},
    {24, 3}, {24, 7},

    {26, 2}, {26, 3}, {26, 7}, {26, 8},

    -- left box
    {36, 4}, {36, 5},
    {37, 4}, {37, 5}
}

for _, coord in next, gliderGun do
    local x, y = unpack(coord)
    local tile = boardGrid[x][y]

    --tile.State = true
    tile.Next = true
end
--]]

-- RNG EVERYTHING
for index, tile in next, tileList do
    tile.Next = rng:NextNumber() > 0.5
end
--]]

--[[ BIG CIRCLE
for index, tile in next, tileList do
    local x, y = unpack(tile.Position)

    x = x - (SIZE * 0.5)
    y = y - (SIZE * 0.5)

    local mag = math.sqrt((x * x) + (y * y))

    if mag < SIZE * 0.25 then
        tile.Next = rng:NextNumber() > 0.5
    end
end
--]]

----

local function setNextTileState(tile)
    local nearLife = 0

    for index = 1, 8, 1 do
        if tile.Neighbors[index].State then
            nearLife = nearLife + 1
        end

        -- no case deals with more life than this
        if nearLife > 3 then
            break
        end
    end

    -- the rules of life
    if tile.State then
        if nearLife < 2 or nearLife > 3 then
            tile.Next = false
        end
    else
        if nearLife == 3 then
            tile.Next = true
        end
    end
end

local function stepBoard()
    -- set next states
    for index = 1, SIZE * SIZE do
        setNextTileState(tileList[index])
    end

    -- comit next states and draw changes
    for index = 1, SIZE * SIZE do
        local tile = tileList[index]

        if tile.Next ~= tile.State then
            if tile.Next then
                tile.Part.BrickColor = WHITE
            else
                tile.Part.BrickColor = BLACK
            end
        end

        tile.State = tile.Next
    end
end

----

while runService.Heartbeat:Wait() do
    stepBoard()
end