control.lua for dirt path mod

DIRT_THRESHOLD = 10

if MODULE_LIST then
    module_list_add("Dirt Path")
end

--This is all subjective.
DIRT= {
    ["grass-1"]="grass-3",
    ["grass-2"]="grass-3",
    ["grass-3"]="grass-4",
    ["grass-4"]="dirt-4",
    ["dirt-4"]="dirt-6",
    ["dirt-6"]="dirt-7",
    ["dirt-7"]="dirt-5",
    ["dirt-5"]="dirt-3",
    ["dirt-3"]="dirt-2",
    ["dirt-2"]="dirt-1",
    ["dirt-1"]="red-desert-3",
    ["red-desert-3"]="sand-3",

    ["red-desert-0"]="red-desert-1",
    ["red-desert-1"]="red-desert-2",
    ["red-desert-2"]="red-desert-3"
}

global.dirt = {}

function dirtDirt(event)
    --for __, p in pairs(game.connected_players) do
        local p = game.players[event.player_index]

        -- Trains aren't cars!  This breaks it.  Dunno why they're handled differently.
        --if p.walking_state.walking or (p.driving and p.vehicle.speed ~= 0) then
        -- Special conditional check for Factorissimo
        if p.walking_state.walking or (p.vehicle and p.vehicle.type == "car" and p.vehicle.speed ~= 0) then
            local tile = p.surface.get_tile(p.position)
            if p.surface == game.surfaces[1] then
                if not (tile.hidden_tile or string.find(tile.name, "concrete")) then

                --game.print("Dirt value now at: ".. global.dirt[tile.position.x][tile.position.y])
                --if global.dirt[tile.position.x][tile.position.y] >= DIRT_THRESHOLD then
                    --game.print("Converting patch to dirt.")

                    -- No longer necessary for 0.16
                    -- Check for waterfix, else prevent exploit
                    -- local waterfix = false
                    -- if game.active_mods["water-fix"] then
                    --  waterfix = true
                    -- end
                    -- -- for module, version in pairs(game.active_mods) do
                    --  -- if module == "water-fix" then
                    --      -- waterfix = true
                    --  -- end
                    -- -- end
                    -- if not waterfix then
                    -- -- Check for water to prevent landfill exploit
                    --  for xx = -1, 2 do
                    --      for yy = -1, 2 do
                    --          local waterCheck = p.surface.get_tile(tile.position.x + xx, tile.position.y + yy)
                    --          if not waterCheck or not waterCheck.valid or waterCheck.collides_with("water-tile") then
                    --              return
                    --          end
                    --      end
                    --  end
                    -- end

                    dirtAdd(tile.position.x, tile.position.y) --Wear the center tile out one additional step.
                    local dirt = {}
                    for xx = -1, 1 do
                        for yy = -1, 1 do
                            if not (math.abs(xx) == math.abs(yy)) or xx == 0 then
                                -- Check twice at xx == 0, yy == 0
                                if dirtAdd(tile.position.x + xx, tile.position.y + yy) then

                                    local validTile = p.surface.get_tile(tile.position.x + xx, tile.position.y + yy)
                                    if not validTile.collides_with("water-tile") and not validTile.hidden_tile and not string.find(validTile.name, "sand") then
                                        local newtile = DIRT[validTile.name] or "dirt-6"
                                        table.insert(dirt, {name=newtile, position={tile.position.x+xx, tile.position.y+yy}})
                                    end
                                end
                            end
                        end
                    end
                    if #dirt > 0 then
                        p.surface.set_tiles(dirt)
                    end
                end
            end
        end
    --end
end

function dirtAdd(x, y)
    local key = x .. "," .. y
    if global.dirt[key] then
        global.dirt[key] = global.dirt[key] + 1
    else
        global.dirt[key] = 1
    end
    if global.dirt[key] >= DIRT_THRESHOLD then
        global.dirt[key] = 0
        return true
    end
end

function cleanDirt()
    if not global.dirt then
        log("Dirt Path not initialized!")
        return
    end
    for k, v in pairs(global.dirt) do
        global.dirt[k] = global.dirt[k] - 1
        if global.dirt[k] <= 0 then
            global.dirt[k] = nil
        end
    end
end

function dirt_handler(event)
    -- if event.tick % 30 == 0 then
    --  dirtDirt()
    -- end
    --if (event.tick) % (60 * 2) == 0 then -- debug
    if (event.tick+500) % (60 * 60 * 30) == 0 then
        cleanDirt()
    end
end

--Since the migration failed:
--Migration from 1.1.1
script.on_configuration_changed(function()
    if not global.flattening then
        global.flattening = true
        global.dirt = {}
    end
end)

script.on_nth_tick(108000, cleanDirt) --30 minutes
--script.on_nth_tick(300, function() game.write_file("dirtdump", serpent.block(global.dirt)) end)
script.on_event(defines.events.on_player_changed_position, function(event) dirtDirt(event) end)