-- Dropper Controller: Runs on Computer 1 (next to dropper_0)
-- Listens for rednet "dispense" messages and fires redstone to the back.

local REDSTONE_SIDE = "back"     -- side facing dropper_0
local PULSE_TIME    = 0.3        -- redstone pulse duration in seconds
local PROTOCOL      = "inventory"

-------------------------------------------------
-- Setup
-------------------------------------------------

-- Open any available modem
local function setupModem()
    for _, side in ipairs({"top","bottom","left","right","front","back"}) do
        if peripheral.getType(side) == "modem" then
            rednet.open(side)
            print("[OK] Modem opened on: " .. side)
            return true
        end
    end
    print("[ERR] No modem found!")
    return false
end

-- Send a redstone pulse to trigger the dropper
local function pulseRedstone()
    redstone.setOutput(REDSTONE_SIDE, true)
    sleep(PULSE_TIME)
    redstone.setOutput(REDSTONE_SIDE, false)
end

-------------------------------------------------
-- Main
-------------------------------------------------

print("=================================")
print("  Dropper Controller (ID " .. os.getComputerID() .. ")")
print("=================================")
print("")
print("Dropper side: " .. REDSTONE_SIDE)
print("Listening for dispense commands...")
print("")

if not setupModem() then
    print("Cannot continue without a modem.")
    return
end

while true do
    local senderID, message, protocol = rednet.receive(PROTOCOL)

    if message == "dispense" then
        print(string.format("[RX] Dispense from computer %d", senderID))

        -- Pulse once per item slot in the dropper to eject everything
        -- A dropper has 9 slots; pulse enough times to empty it
        for i = 1, 9 do
            pulseRedstone()
            sleep(0.1)
        end

        print("[OK] Dropper fired (9 pulses)")
    end
end