Barrel Server (OpenPeripheral)

-- Barrel Tracking
-- ----------------------------------------------------------

-- If connected to a specified barrel, returns its item count.

-- ----------------------------------------------------------

-- Initialise important values:

local barrel, unknownBarrel, tempSlot = {}, {}
do
    local tempTable = peripheral.getNames()
    while #tempTable < 68 do
        print("I'm missing "..(68-#tempTable).." peripherals, will check again soon...")
        sleep(2)
        tempTable = peripheral.getNames()
    end

    local yieldTimer = os.clock() + 5
    for i=1,68 do
        if tempTable[i]:sub(1,6) == "barrel" then
            local tempPeri = peripheral.wrap(tempTable[i])
            local tempSlot = tempPeri.getStackInSlot(1)

            if tempSlot then
                barrel[tempSlot.name.." ("..tempSlot.id..":"..tempSlot.dmg..")"] = tempPeri
            else
                unknownBarrel[#unknownBarrel+1] = tempTable[i]
            end
        end

        if os.clock() > yieldTimer then
            sleep(1)
            yieldTimer = os.clock() + 5
        end
    end
end

rednet.open(peripheral.getType("right")=="modem" and "right" or "left")

term.clear()
term.setCursorPos(1,1)

print("I'm an inventory server.")
print("Other computers talk to me over rednet.")
print("")
print("Go find something else to play with and leave me alone!")
print("")

while true do
    sender, incoming = rednet.receive()

    if incoming == "Hello InvServer" then
        -- A new client wants to know my ID.
        sleep(1) -- Give the client time to switch to receiving mode.
        rednet.send(sender,"Hello, InvServerClient!")
    elseif not barrel[incoming] then for i=1,#unknownBarrel do
        if not unknownBarrel[i] then break end
        tempSlot = peripheral.call(unknownBarrel[i],"getStackInSlot",1)
        if tempSlot then
            barrel[tempSlot.name.." ("..tempSlot.id..":"..tempSlot.dmg..")"] = peripheral.wrap(unknownBarrel[i])
            table.remove(unknownBarrel,i)
        end
    end end

    if barrel[incoming] then
        -- Client is asking about a barrel.
        sleep(1) -- Give the client time to switch to receiving mode.

        if barrel[incoming].getStackInSlot(2) then
            if barrel[incoming].getStackInSlot(1).qty > 0 then
                rednet.send(sender,barrel[incoming].getStackInSlot(2).qty * 63 + barrel[incoming].getStackInSlot(1).qty)
            else
                rednet.send(sender,barrel[incoming].getStackInSlot(2).qty)
            end
        else
            rednet.send(sender,0)
        end
    end
end