interface chest control.lua

require "util"

-- Belts lanes have 4 slots: yellow 36 ticks, red 18 ticks, blue 12 ticks
-- Ticks to clear a slot 9, 4.5, 3
-- Splitters/underground 2 slots: need twice the tick rate
-- Red splitter/underground do some magic -- cuase technically they should have a gap
-- Should take 9 ticks for 2 items to clear out of the way, but on splitter/underground they dissapear ahead of schedule.
-- On red splitter/underground belt they alternate sending items on tick 0, 6, 18, 24, 30 = 9 average

local chestThrottle = 6
local railCheckThrottle = chestThrottle * 15
local voidThrottle = chestThrottle * 20
local energy_per_action = 8000
local idleDraw = 500

local beltBalancerThrottle = 12

-- Internal Use
local dataVersion = 14

-- How many a chest can pull from a belt lane 0-8
local inputMultiplier = 8
-- Inventory to Inventory transfer stack size
local maxStackSize = 4

-- Cardinal Directions
local NORTH = defines.direction.north
local EAST = defines.direction.east
local SOUTH = defines.direction.south
local WEST = defines.direction.west

-- Optimal places on a belt to place item
local beltPositions = {0, .182, .463, .744}
local splitterPositions = {0, .28}

-- Adjacent tiles
function areaNorth(position) return {{position.x - 0.5, position.y - 1.5},{position.x + 0.5, position.y - 0.5}} end
function areaSouth(position) return {{position.x - 0.5, position.y + 0.5},{position.x + 0.5, position.y + 1.5}} end
function areaEast(position)  return {{position.x + 0.5, position.y - 0.5},{position.x + 1.5, position.y + 0.5}} end
function areaWest(position)  return {{position.x - 1.5, position.y - 0.5},{position.x - 0.5, position.y + 0.5}} end

-- Area around tile
function getBoundingBox(position, radius)
    return {{x=position.x-radius-.5,y=position.y-radius-.5},{x=position.x+radius+.5,y=position.y+radius+.5}}
end

-- Area around tile
function getBoundingBoxX(position, radius)
    return {{x=position.x-radius-.5,y=position.y-.5},{x=position.x+radius+.5,y=position.y+.5}}
end


-- Area around tile
function getBoundingBoxY(position, radius)
    return {{x=position.x-.5,y=position.y-radius-.5},{x=position.x+.5,y=position.y+radius+.5}}
end


-------------------
function InterfaceChest_Initialize()
    if global.InterfaceChest_MasterList == nil then
        global.InterfaceChest_MasterList = {}
    end

    if global.InterfaceChest_DataVersion == nil then
        global.InterfaceChest_DataVersion = 0
    end

    if global.InterfaceBelt_MasterList == nil then
        global.InterfaceBelt_MasterList = {}
    end

    if global.InterfaceBelt_DataVersion == nil then
        global.InterfaceBelt_DataVersion = 0
    end
end

-------------------
function getKey (entity)
    return "if_x" .. entity.position.x .. "y".. entity.position.y .. entity.surface.index
end

function InterfaceChest_Create(event)
    local entity = event.created_entity
    if isInterfaceChest(entity) then
        local modTick = game.tick % chestThrottle
        local key = getKey(entity)
        if global.InterfaceChest_MasterList[modTick] == nil then
            global.InterfaceChest_MasterList[modTick] = {}
        end
        global.InterfaceChest_MasterList[modTick][key] = updateInterfaceChest(entity)
        --debugPrint("Interface Chest created: " .. key)
    end

    if entity.name == "interface-belt-balancer" then
        local key = getKey(entity)
        local modTick = game.tick % beltBalancerThrottle
        if global.InterfaceBelt_MasterList[modTick] == nil then
            global.InterfaceBelt_MasterList[modTick] = {}
        end
        global.InterfaceBelt_MasterList[modTick][key] = entity
        --debugPrint("Interface Belt count: " .. key)
    end

    if isTransport(entity) or isInventory(entity) or entity.type == "straight-rail" then
        scheduleUpdate(entity, 3)
    end
end

-------------------
function InterfaceChest_Rotated(event)
    local entity = event.entity
    if isTransport(entity) or isInventory(entity) or entity.type == "straight-rail" then
        scheduleUpdate(entity, 3)
    end
end

function InterfaceChest_Mined(event)
    local entity = event.entity
    if isTransport(entity) or isInventory(entity) or entity.type == "straight-rail" then
        scheduleUpdate(entity, 3)
    end
end

-------------------
function scheduleUpdate (entity, range)
    local entities = entity.surface.find_entities(getBoundingBox(entity.position, range))
    for index=1, #entities do
        if isInterfaceChest( entities[index]) then
            local chest = entities[index]
            if chest and chest.valid then
                for modTick=0, chestThrottle-1 do
                    if global.InterfaceChest_MasterList[modTick][getKey(chest)] then
                        global.InterfaceChest_MasterList[modTick][getKey(chest)].dirty = true
                    end
                end
            end
        end
    end
end

-------------------
function InterfaceBelt_RunStep()
    if global.InterfaceBelt_DataVersion ~= dataVersion then
        -- Initialize
        InterfaceChest_Initialize()

        local beltBalancer = game.surfaces[1].find_entities_filtered{area={{-10000, -10000},{10000, 10000}}, name="interface-belt-balancer"}

        local masterList = {}
        for index=0, beltBalancerThrottle-1 do
            masterList[index] = {}
        end

        for index=1, #beltBalancer do
            local entity = beltBalancer[index]
            local modTick = math.random(beltBalancerThrottle) - 1
            masterList[modTick][getKey(entity)] = entity
        end

        global.InterfaceBelt_MasterList = masterList
        global.InterfaceBelt_DataVersion = dataVersion

    else
        local modTick = game.tick % beltBalancerThrottle
        local masterList = global.InterfaceBelt_MasterList[modTick]
        if masterList then
            for index, value in pairs(masterList) do
                local belt = value
                if belt and belt.valid then
                    local left = belt.get_transport_line(1)
                    local right = belt.get_transport_line(2)
                    balanceBelt(right, left)
                    balanceBelt(left, right)
                else
                    global.InterfaceBelt_MasterList[modTick][index] = nil
                end
            end
        end
    end
end

function balanceBelt (source, target)
    local action = false
    for item, size in pairs(source.get_contents()) do
        local diff = size - target.get_item_count(item)
        local itemstack = {name=item, count=1}
        if diff > 2 and size > 2 then
            if target.insert_at(beltPositions[1], itemstack) then
                source.remove_item(itemstack)
                action = true
            end
            if target.insert_at(beltPositions[2], itemstack) then
                source.remove_item(itemstack)
                action = true
            end
        elseif diff > 1 and size > 1 then
            if target.insert_at(beltPositions[1], itemstack) then
                source.remove_item(itemstack)
                action = true
            end
        end
    end
    return action
end

-------------------
function InterfaceChest_RunStep(event)
    if global.InterfaceChest_DataVersion ~= dataVersion then

        -- Initialize
        InterfaceChest_Initialize()

        -- Find all this mod's chests and index them
        trashCan = {}
        for index=1,#game.surfaces do
            local temp = game.surfaces[index].find_entities_filtered{area={{-10000, -10000},{10000, 10000}}, name="interface-chest-trash"}
            for k,v in pairs(temp) do table.insert(trashCan, v) end
        end

        interfaceChests = {}
        for index=1,#game.surfaces do
            local temp = game.surfaces[index].find_entities_filtered{area={{-10000, -10000},{10000, 10000}}, name="interface-chest"}
            for k,v in pairs(temp) do table.insert(interfaceChests, v) end
        end

        local masterList = {}
        for index=0, chestThrottle-1 do
            masterList[index] = {}
        end

        for index=1, #trashCan do
            local modTick = math.random(chestThrottle) - 1
            local chest = trashCan[index]
            masterList[modTick][getKey(chest)] = updateInterfaceChest(chest)
        end

        for index=1, #interfaceChests do
            local modTick = math.random(chestThrottle) - 1
            local chest = interfaceChests[index]
            masterList[modTick][getKey(chest)] = updateInterfaceChest(chest)
        end

        global.InterfaceChest_MasterList = masterList
        global.InterfaceChest_DataVersion = dataVersion
    else
        InterfaceBelt_RunStep()
        local modTick = game.tick % chestThrottle
        local masterList = global.InterfaceChest_MasterList[modTick]

        if masterList then
            for index, value in pairs(masterList) do
                local interfaceChest = value
                if interfaceChest.chest and interfaceChest.chest.valid then
                    if interfaceChest.power == nil or interfaceChest.power.valid == false then
                        interfaceChest = updateInterfaceChest(interfaceChest.chest)
                        global.InterfaceChest_MasterList[modTick][index] = interfaceChest
                        --debugPrint("Create missing power for: " .. index)
                    else
                        if interfaceChest.power and interfaceChest.power.valid and interfaceChest.power.energy >= (idleDraw) then
                            interfaceChest.power.energy = interfaceChest.power.energy - idleDraw
                            if interfaceChest.chest.name == "interface-chest-trash" then
                                voidChest(interfaceChest, modTick, index)
                            else

                                -- No good way to check for nearby train, so if on rail check for train
                                if interfaceChest.onRail and modTick == (game.tick % railCheckThrottle) then
                                    interfaceChest.dirty = true
                                end

                                local chestPosition = getBoundingBox(interfaceChest.chest.position, 0)
                                if interfaceChest.dirty then
                                    interfaceChest = updateInterfaceChest(interfaceChest.chest)
                                    global.InterfaceChest_MasterList[index] = interfaceChest
                                end

                            -- Input items Into Chest
                                for i=1, #interfaceChest.inputBelts do
                                    local belt = interfaceChest.inputBelts[i]
                                    if belt.valid then
                                        if belt.type == "splitter" then
                                            local chestPosition = getBoundingBox(interfaceChest.chest.position, 0)
                                            if (belt.position.x == chestPosition[1].x and belt.position.y < chestPosition[1].y) or (belt.position.x == chestPosition[2].x and belt.position.y > chestPosition[1].y) or (belt.position.y == chestPosition[1].y and belt.position.x > chestPosition[2].x) or (belt.position.y == chestPosition[2].y and belt.position.x < chestPosition[2].x) then
                                                beltToChest(belt, defines.transport_line.left_split_line, interfaceChest.chest, interfaceChest.power)
                                                beltToChest(belt, defines.transport_line.right_split_line, interfaceChest.chest, interfaceChest.power)
                                            else
                                                beltToChest(belt, defines.transport_line.secondary_left_split_line, interfaceChest.chest, interfaceChest.power)
                                                beltToChest(belt, defines.transport_line.secondary_right_split_line, interfaceChest.chest, interfaceChest.power)
                                            end
                                        else
                                            beltToChest(belt, defines.transport_line.left_line, interfaceChest.chest, interfaceChest.power)
                                            beltToChest(belt, defines.transport_line.right_line, interfaceChest.chest, interfaceChest.power)
                                        end
                                    end
                                end

                                -- Pull Items from adjacent Inventories
                                if #interfaceChest.inputBelts == 0 and #interfaceChest.outputBelts > 0 then
                                    for i=1, #interfaceChest.inventories do
                                        local inventory = interfaceChest.inventories[i]
                                        local inventoryIndex = 1
                                        if inventory and inventory.valid then
                                            if inventory.get_output_inventory() and inventory.get_output_inventory().is_empty() == false then
                                                sourceToTargetInventory(inventory, interfaceChest.chest, interfaceChest.power)
                                            end
                                        end
                                    end
                                end

                                -- Output items to adjacent Belts
                                if interfaceChest.chest.get_output_inventory().is_empty() == false then
                                    for i=1, #interfaceChest.outputBelts do
                                        local belt = interfaceChest.outputBelts[i]
                                        if belt.valid then
                                            if belt.type == "splitter" then
                                                local chestPosition = getBoundingBox(interfaceChest.chest.position, 0)
                                                if (belt.position.x == chestPosition[1].x and belt.position.y > chestPosition[1].y) or (belt.position.x == chestPosition[2].x and belt.position.y < chestPosition[1].y) or (belt.position.y == chestPosition[1].y and belt.position.x < chestPosition[2].x) or (belt.position.y == chestPosition[2].y and belt.position.x > chestPosition[2].x) then
                                                    chestToBelt(belt, defines.transport_line.left_line, interfaceChest.chest, interfaceChest.power)
                                                    chestToBelt(belt, defines.transport_line.right_line, interfaceChest.chest, interfaceChest.power)
                                                else
                                                    chestToBelt(belt, defines.transport_line.secondary_left_line, interfaceChest.chest, interfaceChest.power)
                                                    chestToBelt(belt, defines.transport_line.secondary_right_line, interfaceChest.chest, interfaceChest.power)
                                                end
                                            else
                                                chestToBelt(belt, defines.transport_line.left_line, interfaceChest.chest, interfaceChest.power)
                                                chestToBelt(belt, defines.transport_line.right_line, interfaceChest.chest, interfaceChest.power)
                                            end
                                        end
                                    end
                                    -- Output items to adjacent inventories
                                    if #interfaceChest.outputBelts == 0 and #interfaceChest.inputBelts > 0 then
                                        for i=1, #interfaceChest.inventories do
                                            local inventory = interfaceChest.inventories[i]
                                            sourceToTargetInventory(interfaceChest.chest, inventory, interfaceChest.power)
                                        end
                                    end
                                end

                            end
                        end
                    end
                else
                    if interfaceChest ~= nil and interfaceChest.power and interfaceChest.power.valid then
                        if interfaceChest.power.destroy() then
                            --debugPrint("Power removed: " ..   index)
                            global.InterfaceChest_MasterList[modTick][index] = nil
                        end
                    end
                    --debugPrint("Loaded: " ..   index)
                end
            end
        end
    end
end

function updateInterfaceChest(chest)
    local center = getBoundingBox(chest.position, 0)
    local entities = chest.surface.find_entities(getBoundingBox(chest.position, 1))
    local entitiesX = chest.surface.find_entities(getBoundingBoxX(chest.position, 1))
    local entitiesY = chest.surface.find_entities(getBoundingBoxY(chest.position, 1))
    local gridTransport = {}
    local gridInventory = {}
    local isRail = false
    local powerSource = nil

    for index=1, #entities do
        local entity = entities[index]
        if entity.type ~= "decorative" then
            if isRail == false and entity.type == "straight-rail" then
                isRail = true
            elseif powerSource == nil and entity.name == "interface-chest-power" and entity.position.x > center[1].x and entity.position.x < center[2].x and entity.position.y > center[1].y and entity.position.y < center[2].y then
                --debugPrint("Power: " .. entity.position.x .. " > " .. center[1].x .. " and " .. entity.position.x .. " < " ..  center[2].x .. " and " .. entity.position.y .. " > " ..  center[1].y .. " and " .. entity.position.y .. " < " ..  center[2].y)
                powerSource = entity
            end
        end
    end

    for index=1, #entitiesX do
        local entity = entitiesX[index]
        if entity.type ~= "decorative" then
            -- East
            if entity.position.x > center[2].x then
                if isTransport(entity) then gridTransport.east = entity end
                if isInventory(entity, isRail) then gridInventory.east = entity end
            -- West
            elseif entity.position.x < center[1].x then
                if isTransport(entity) then gridTransport.west = entity end
                if isInventory(entity, isRail) then gridInventory.west = entity end
            end
        end
    end

    for index=1, #entitiesY do
        local entity = entitiesY[index]
        if entity.type ~= "decorative" then
            -- North
            if entity.position.y < center[1].y then
                if isTransport(entity) then gridTransport.north = entity end
                if isInventory(entity, isRail) then gridInventory.north = entity end
            -- South
            elseif entity.position.y > center[2].y then
                if isTransport(entity) then gridTransport.south = entity end
                if isInventory(entity, isRail) then gridInventory.south = entity end
            end
        end
    end

    for index=1, #entities do
        local entity = entities[index]
        if entity.type ~= "decorative" then
            -- North West
            if entity.position.x <= center[1].x and entity.position.y <= center[1].y then
                if isTransport(entity) then gridTransport.northWest = entity end
                if isTrain(entity, isRail) then gridInventory.northWest = entity end
            -- North East
            elseif entity.position.x >= center[2].x and entity.position.y <= center[1].y then
                if isTransport(entity) then gridTransport.northEast = entity end
                if isTrain(entity, isRail) then gridInventory.northEast = entity end
            -- South West
            elseif entity.position.x <= center[1].x and entity.position.y >= center[2].y then
                if isTransport(entity) then gridTransport.southWest = entity end
                if isTrain(entity, isRail) then gridInventory.southWest = entity end
            -- South East
            elseif entity.position.x >= center[2].x and entity.position.y >= center[2].y then
                if isTransport(entity) then gridTransport.southEast = entity end
                if isTrain(entity, isRail) then gridInventory.southEast = entity end
            end
        end
    end

    if powerSource == nil then
        --debugPrint("Create power: " .. serpent.block(chest.position))
        powerSource = chest.surface.create_entity{name="interface-chest-power", position=chest.position, force=chest.force}
    end

    return {chest = chest, inputBelts = getInputBelts(gridTransport), outputBelts = getOutputBelts(gridTransport), inventories = getInventories(gridInventory), onRail = isRail, dirty = false, power = powerSource}
end

function voidChest(interfaceChest, modTick, index)
    if interfaceChest.chest and interfaceChest.chest.valid and interfaceChest.power and interfaceChest.power.valid and interfaceChest.power.energy >= energy_per_action then
        if interfaceChest.dirty then
            interfaceChest = updateInterfaceChest(interfaceChest.chest)
            global.InterfaceChest_MasterList[modTick][index] = interfaceChest
        end

        if modTick == (game.tick % voidThrottle) then
            interfaceChest.chest.get_output_inventory().clear()
            interfaceChest.power.energy = interfaceChest.power.energy - energy_per_action
        end

        for i=1, #interfaceChest.inputBelts do
            local belt = interfaceChest.inputBelts[i]
            if belt.valid then
                if belt.type == "splitter" then
                    if (belt.position.x > interfaceChest.chest.position.x and belt.position.y > interfaceChest.chest.position.y) or (belt.position.x < interfaceChest.chest.position.x and belt.position.y < interfaceChest.chest.position.y) then
                        beltToVoid(belt, defines.transport_line.left_split_line, interfaceChest.power)
                        beltToVoid(belt, defines.transport_line.right_split_line, interfaceChest.power)
                    else
                        beltToVoid(belt, defines.transport_line.secondary_left_split_line, interfaceChest.power)
                        beltToVoid(belt, defines.transport_line.secondary_right_split_line, interfaceChest.power)
                    end
                else
                    beltToVoid(belt, defines.transport_line.left_line, interfaceChest.power)
                    beltToVoid(belt, defines.transport_line.right_line, interfaceChest.power)
                end
            end
        end
    end
end


function beltToVoid(belt, laneNumber, power)
    if power and power.valid and power.energy >= energy_per_action then
        if belt.get_transport_line(laneNumber).can_insert_at(0) == false then
            local items = belt.get_transport_line(laneNumber).get_contents()
            local item = next(items)
            local size = items[item]
            if size then
                local itemstack = {name=item, count=size}
                belt.get_transport_line(laneNumber).remove_item(itemstack)
                power.energy = power.energy - energy_per_action
            end
        end
    end
end

function beltToChest(belt, laneNumber, chest, power)
    if chest and chest.valid and power and power.valid and power.energy >= energy_per_action then
        if belt.get_transport_line(laneNumber).can_insert_at(0) == false then
            local lane = belt.get_transport_line(laneNumber)
            local contents = lane.get_contents()
            local item = next(contents)
            local size = contents[item]
            --debugPrint(item .. " " .. size)
            if size then
                local itemstack = {name=item, count=math.min(inputMultiplier,size)}
                if chest and chest.valid and chest.can_insert(itemstack) then
                    itemstack.count = chest.insert(itemstack)
                    lane.remove_item(itemstack)
                    power.energy = power.energy - energy_per_action
                end
            end
        end
    end
end

function chestToBelt(belt, laneNumber, chest, power)
    if chest and chest.valid and power and power.valid and power.energy >= energy_per_action then
        local positions = {}
        if belt.type == "transport-belt" then
            positions = beltPositions
        else
            positions = splitterPositions
        end
        if belt.get_transport_line(laneNumber).can_insert_at(positions[1]) then




            local inventory = chest.get_output_inventory()
            local contents = inventory.get_contents()
            local item = next(contents)
            local size = contents[item]
            local itemstack = {name=item, count=1}



            if size then

            --[[
            --Find Positions 0 to 1
            for i=0, 1000 do
            if belt.get_transport_line(laneNumber).insert_at(i/1000, itemstack) then
                    debugPrint("Inserted: " .. i/1000 .. " tick: " .. game.tick)
                    power.energy = power.energy - energy_per_action
                    inventory.remove({name=item, count=1})
                end
            end

            --Find Positions 1 to 0
            for i=1, 1000 do
            if belt.get_transport_line(laneNumber).insert_at((1001-i)/1000, itemstack) then
                    debugPrint("Inserted: " .. (1001-i)/1000 .. " tick: " .. game.tick)
                    power.energy = power.energy - energy_per_action
                    inventory.remove({name=item, count=1})
                end
            end
            ]]--

                local toTransfer = math.min(#positions, size)
                for i=1, toTransfer do
                    if belt.get_transport_line(laneNumber).insert_at(positions[i], itemstack) then
                        --debugPrint("Inserted: " .. positions[i] .. " tick: " .. game.tick)
                        power.energy = power.energy - energy_per_action
                        inventory.remove({name=item, count=1})
                    end
                end

            end
        end
    end
end

function sourceToTargetInventory(source, target, power)
    if source and source.valid and power and power.valid and power.energy >= energy_per_action then
        local inventory = source.get_output_inventory()
        local contents = inventory.get_contents()
        local item = next(contents)
        local size = contents[item]
        if size then
            local itemstack = {name=item, count=math.min(maxStackSize,size)}
            if target and target.valid and target.can_insert(itemstack) then
                itemstack.count = target.insert(itemstack)
                inventory.remove(itemstack)
                power.energy = power.energy - energy_per_action
            end
        end
    end
end

function getInputBelts(grid)
    local belts = {}
    local belt

    -- North
    belt = checkTransportEntity(grid.north, SOUTH, "output")
    if belt then
        belts[#belts+1] = belt
    end

    -- South
    belt = checkTransportEntity(grid.south, NORTH, "output")
    if belt then
        belts[#belts+1] = belt
    end

    -- East
    belt = checkTransportEntity(grid.east, WEST, "output")
    if belt then
        belts[#belts+1] = belt
    end

    -- West
    belt = checkTransportEntity(grid.west, EAST, "output")
    if belt then
        belts[#belts+1] = belt
    end

    return belts
end

function getOutputBelts(grid)
    local belts = {}
    local belt
    local checkNorth
    local checkEast
    local checkSouth
    local checkWest

    -- North
    belt = checkTransportEntity(grid.north, NORTH, "input")
    if belt then
        if belt.type == "transport-belt" then
            checkWest = checkTransportEntity(grid.northWest, EAST, "output")
            checkEast = checkTransportEntity(grid.northEast, WEST, "output")
            if (checkWest and checkEast) or (checkWest == nil and checkEast == nil) then
                belts[#belts+1] = belt
            end
        else
            belts[#belts+1] = belt
        end
    end

    -- South
    belt = checkTransportEntity(grid.south, SOUTH, "input")
    if belt then
        if belt.type == "transport-belt" then
            checkWest = checkTransportEntity(grid.southWest, EAST, "output")
            checkEast = checkTransportEntity(grid.southEast, WEST, "output")
            if (checkWest and checkEast) or (checkWest == nil and checkEast == nil) then
                belts[#belts+1] = belt
            end
        else
            belts[#belts+1] = belt
        end
    end

    -- East
    belt = checkTransportEntity(grid.east, EAST, "input")
    if belt then
        if belt.type == "transport-belt" then
            checkNorth = checkTransportEntity(grid.northEast, SOUTH, "output")
            checkSouth = checkTransportEntity(grid.southEast, NORTH, "output")
            if (checkNorth and checkSouth) or (checkNorth == nil and checkSouth == nil) then
                belts[#belts+1] = belt
            end
        else
            belts[#belts+1] = belt
        end
    end

    -- West
    belt = checkTransportEntity(grid.west, WEST, "input")
    if belt then
        if belt.type == "transport-belt" then
            checkNorth = checkTransportEntity(grid.northWest, SOUTH, "output")
            checkSouth = checkTransportEntity(grid.southWest, NORTH, "output")
            if (checkNorth and checkSouth) or (checkNorth == nil and checkSouth == nil) then
                belts[#belts+1] = belt
            end
        else
            belts[#belts+1] = belt
        end
    end

    return belts
end

function getInventories(grid)
    local inventories = {}
    local inventory

    -- North
    inventory = grid.north
    if inventory then
        inventories[#inventories+1] = inventory
    end

    -- South
    inventory = grid.south
    if inventory then
        inventories[#inventories+1] = inventory
    end

    -- East
    inventory = grid.east
    if inventory then
        inventories[#inventories+1] = inventory
    end

    --West
    inventory = grid.west
    if inventory then
        inventories[#inventories+1] = inventory
    end

    -- North East
    inventory = grid.northEast
    if inventory then
        inventories[#inventories+1] = inventory
    end

    -- South East
    inventory = grid.southEast
    if inventory then
        inventories[#inventories+1] = inventory
    end

    -- North West
    inventory = grid.northWest
    if inventory then
        inventories[#inventories+1] = inventory
    end

    -- South West
    inventory = grid.southWest
    if inventory then
        inventories[#inventories+1] = inventory
    end

    return inventories
end

function checkTransportEntity(entity, direction, undergroundType)
    if entity and (entity.type ~= "underground-belt" or (entity.type == "underground-belt" and entity.belt_to_ground_type == undergroundType)) and entity.direction == direction then
        return entity
    else
        return nil
    end
end

function isInventory (entity, onTrack)
    if entity and entity.name ~= "interface-chest" and entity.type ~= "beacon" and entity.get_output_inventory() ~= nil and (isMoveable(entity) == false or isTrain(entity, onTrack)) then
        return entity
    else
        return nil
    end
end

function isMoveable (entity)
    if (entity.type == "cargo-wagon" or entity.type == "locomotive" or entity.type == "car" or entity.type == "player") then
        return true
    else
        return false
    end
end

--or (entity.type == "player" and entity.walking_state == false)
function isTrain (entity, onTrack)
    if entity and onTrack and ((entity.type == "cargo-wagon" and entity.train.speed == 0) or (entity.type == "locomotive" and entity.train.speed == 0) or (entity.type == "car" and entity.speed == 0)) then
        return entity
    else
        return nil
    end
end

function isTransport (entity)
    if entity and (entity.type == "transport-belt" or entity.type == "splitter" or entity.type == "underground-belt") then
        return entity
    else
        return nil
    end
end

function isInterfaceChest (entity)
     if entity.name == "interface-chest" or entity.name == "interface-chest-trash"  then
        return true
     else
        return false
     end
end

function debugPrint(thing)
    for _, player in pairs(game.players) do
        player.print(serpent.block(thing))
    end
end

-- Once per save
script.on_init(InterfaceChest_Initialize)

-- Every Tick
script.on_event(defines.events.on_tick, InterfaceChest_RunStep)

-- On create
script.on_event(defines.events.on_built_entity, InterfaceChest_Create)
script.on_event(defines.events.on_robot_built_entity, InterfaceChest_Create)

-- On change
script.on_event(defines.events.on_player_rotated_entity, InterfaceChest_Rotated)

-- On remove
script.on_event(defines.events.on_preplayer_mined_item, InterfaceChest_Mined)
script.on_event(defines.events.on_robot_pre_mined, InterfaceChest_Mined)

script.on_event(defines.events.on_entity_died, function(event)
    local entity = event.entity
    if entity.name == "interface-chest-power" then
        local entities = entity.surface.find_entities(getBoundingBox(entity.position, 0))
        for index=1, #entities do
            if isInterfaceChest( entities[index]) then
                local chest = entities[index]
                if chest and chest.valid then
                    --debugPrint("Chest Destoyed: " .. getKey(chest.location))
                    chest.destroy()
                end
            end
        end
    end
end)