A small Computercraft reactor control program

MinecraftReactorControl.lua

-- Little reactor control by Decstasy request@decstasy.de
-- Please configure everything for your needs

-- Where the energy store is located relative to the computer
local BatterySide = "back"
-- Where to send the "enable the reactor" redstone signal
local reactorEnableRedstone = "front"
-- Where to abort program when getting a redstone signal
local reactorEmergencyRedstone = "right"
-- Monitor position
local MonitorPosition = "top"
-- Turn reactor on when battery is x% discharged
local reactorThresholdOn = 20
-- Turn reactor off then battery is x% charged
local reactorThresholdOff = 90

--[[
    !!!
    Please don't edit something upon this point unless you know what you're doing
    !!!
--]]

--[[ 
    Vars 
--]]
local state = "init"
-- Interval in seconds to check energy levels etc
local checkInterval = 1
local lastPercentile = 200

--[[ 
    Functions
--]]
function queryEnergy(obj)
    energy = obj.getEnergy()
    -- 2147483647 ~ 2.14 GFE is the maximum readout
    cap = obj.getEnergyCapacity()
end

function queryPercentile(obj)
    queryEnergy(obj)
    percentile = math.ceil(( energy / cap ) * 100)
    return percentile
end

function ts()
    return os.date('%H:%M:%S')
end

function pr(text)
    print(ts() .. " " .. text)
end

-- Newline
function MonitorNL(mon)
    local cX,cY = mon.getCursorPos()
    mon.setCursorPos(1,cY+1)
end

-- https://www.computercraft.info/wiki/Colors_(API)#Colors
function blitWrapper(mon, text, fg, bg)
    local fg = string.rep(fg, string.len(text))
    local bg = string.rep(bg, string.len(text))
    mon.blit(text, bg, fg)
    MonitorNL(mon)
end

function MonitorReactorStatus(mon)
    if state == "full" then
        blitWrapper(mon, "Reactor off", "7", "8")
    else
        blitWrapper(mon, "Reactor  on", "7", "d")
    end
end

function MonitorChargeStatus(mon, charge)
    local chargeText = "Charge: " .. charge .. "%"
    if charge <= reactorThresholdOn then
        blitWrapper(mon, chargeText, "7", "e" )
    elseif charge >= reactorThresholdOff then
        blitWrapper(mon, chargeText, "7", "d" )
    else
        blitWrapper(mon, chargeText, "7", "4" )
    end
end

function showStatus(mon, charge)
    mon.clear()
    mon.setCursorPos(1,1)
    MonitorReactorStatus(mon)
    MonitorChargeStatus(mon, charge)
end

function showEmergency(mon)
    mon.clear()
    mon.setCursorPos(1,1)
    blitWrapper(mon, "EMERGENCY", "f", "e" )
    blitWrapper(mon, "SHUTDOWN", "f", "e" )
    blitWrapper(mon, "EMERGENCY", "f", "e" )
    blitWrapper(mon, "SHUTDOWN", "f", "e" )
end

--[[
    Main Program
--]]

-- Wrap energy storage to object
Battery = peripheral.wrap(BatterySide)

-- Wrap Monitor if present
if peripheral.isPresent(MonitorPosition) then
    if peripheral.getType(MonitorPosition) == "monitor" then
        Monitor = peripheral.wrap(MonitorPosition)
    end
end

-- Startup message
print("Enable/Disable threshold: " .. reactorThresholdOn .. "% / " .. reactorThresholdOff .. "%")
pr("Program started!")

while true do
    -- Check for emergency signal
    if rs.getInput(reactorEmergencyRedstone) then
        -- Disable reactor
        rs.setOutput(reactorEnableRedstone, false)
        -- Inform user
        pr("EMERGENCY INPUT TRIGGERED!")
        if Monitor then
            showEmergency(Monitor)
        end
        -- Terminate program
        break
    end

    -- Turn off reactor when energy level is sufficient
    if queryPercentile(Battery) >= reactorThresholdOff then
        if not (state == "full") then
            pr("Reactor turned off")
            state = "full"
        end
        rs.setOutput(reactorEnableRedstone, false)
    -- Turn on reactor when energy level is below threshold
    elseif queryPercentile(Battery) <= reactorThresholdOn then
        if not (state == "empty") then
            pr("Reactor turned on")
            state = "empty"
        end
        rs.setOutput(reactorEnableRedstone, true)
    -- Condition between threshold
    else
        -- Make sure redstone signal is off while discharging
        if state == "full" then
            rs.setOutput(reactorEnableRedstone, false)
        end
    end

    -- Print actual readings if +- 1% change
    if not (lastPercentile == percentile) then
        lastPercentile = percentile
        pr("Energy: " .. percentile .. "% " .. ( math.floor(energy / 1000^2) ) .. "MFE / " .. ( math.floor(cap / 1000^2) ) .. "MFE")
        if Monitor then
            showStatus(Monitor, percentile)
        end
    end

    -- Interval
    sleep(checkInterval)
end