Computer Craft Energy monitoring V2

--[[
    -- Code made by Tcharim --
    - Energy monitor for Computer Craft
    - This code allows you to show, on all pluged monitor, the quantity available in each pluged energy storage device (in percent).
    - This program can handle advanced monitors and regular ones.
    - The advised size for the monitor is 4 blocks width.
    - You can rename each device in file $(ALIAS_FILE_NAME) by associating "peripheral_name display_name"
    example:
    ae2:controller_0 My applied energestics 2 network controller

    - When writing in $(ALIAS_FILE_NAME) this text you display "My applied energestics 2 network controller" in place of ae2:controller_0
]]

--[[
    - On some devices like powah energy cells, each update can disconnect the reconnect the device.
    - To counter this problem, I used a timer that remove cells that stays more than $(ENERGY_CELL_REMOVE_DELAY)
    seconds in the $(removedCells) list.
    - Each peripheral remove call add that peripheral in this list and associate it the time.
    - Each peripheral add call removes that peripheral from $(removedCells) list.
]]
local ENERGY_CELL_REMOVE_DELAY = 1
local removedCells = {}

-- Declaration of some list to classify the devices
local monitors = {}
local energyCells = {}
local otherPeripheral = {}

-- Declariation of list of aliases
local ALIAS_FILE_NAME = "/hosts"
local aliases = {}

-- Function that write $(text) into $(monitor) with $(textColor) foreground and $(bgColor) background at x=$(posx), y=$(posy)
local function writeText(monitor, text, textColor, bgColor, posx, posy)
    if not monitor then
        return -1
    end

    local oldTextColor = monitor.getTextColor()
    local oldBgColor = monitor.getBackgroundColor()

    if not textColor or not monitor.isColor() then
        textColor = colors.white
    end

    if not bgColor or not monitor.isColor()then
        bgColor = colors.black
    end

    posx = posx or 1
    posy = posy or 1

    monitor.setTextColor(textColor)
    monitor.setBackgroundColor(bgColor)
    monitor.setCursorPos(posx, posy)

    monitor.write(text)

    monitor.setTextColor(oldTextColor)
    monitor.setBackgroundColor(oldBgColor)

    return 0
end

-- Function that list all the energy storage connnected devices and associate it the stored energy, in percent, then show it on $(monitor)
local function showOnMonitor(monitor)
    local RED_LEVEL = 10
    local ORANGE_LEVEL = 50
    local YELLOW_LEVEL = 70

    local stored, capacity
    local row = 1
    local monitor_width, _ = monitor.getSize()
    local text = ""

    monitor.clear()
    text = "Energy Monitor"
    writeText(monitor, text, colors.red, colors.yellow, (monitor_width-string.len(text))/2,1)

    for energyCellName, cell in pairs(energyCells) do
        if cell then
            name = aliases[energyCellName] or energyCellName
            name = string.sub(name, 1, monitor_width - 12)
            if not pcall(function() stored = cell.getEnergy() end) then goto continue end
            if not pcall(function() capacity = cell.getEnergyCapacity() end) then goto continue end
            if not (stored and capacity) then goto continue end

            row = row + 1
            if capacity == 0 then
                writeText(monitor, "Capacity of "..name.." is 0??", red, nil, 1, row)
                goto continue
            end

            writeText(monitor, name, nil, nil, 1, row)
            writeText(monitor, "|", nil, nil, monitor_width - 10, row)
            color = colors.white
            energyLevel = stored/capacity * 100

            if(energyLevel < RED_LEVEL) then
                color = colors.red
            elseif(energyLevel < ORANGE_LEVEL)then
                color = colors.orange
            elseif(energyLevel < YELLOW_LEVEL) then
                color = colors.yellow
            else
                color = colors.green
            end

            text = string.format("%6.2f %%", energyLevel)
            writeText(monitor, text, color, nil, monitor_width - 7, row)

            ::continue::
        end
    end

    if row == 1 then
        text = "There is no energy device connected."
        writeText(monitor, text, colors.red, nil, 1, row+1)
    end
end

-- Function that add the peripheral $(name) into the associated list.
local function addPeripheral(name)
    if peripheral.hasType(name, "monitor") then
        monitors[name] = peripheral.wrap(name)
    elseif peripheral.hasType(name, "energy_storage") then
        cell = peripheral.wrap(name)
        if cell then
            energyCells[name] = peripheral.wrap(name)
            removedCells[name] = nil
        end
    else
        otherPeripheral[name] = peripheral.getType(name)
    end
end

-- Function that remove the peripheral $(name) from the lists.
local function removePeripheral(name)
    if monitors[name] then monitors[name] = nil end
    if otherPeripheral[name] then otherPeripheral[name] = nil end
    if energyCells[name] then
        removedCells[name] = os.clock()
    end
end

-- Function that refreshes all the connected monitors.
local function refresh()
    local REFRESH_DELAY = 2
    local previousTime = 0
    while true do
        sleep(0.05)
        if os.clock()-previousTime > REFRESH_DELAY then
            for monitorName, monitor in pairs(monitors) do
                showOnMonitor(monitor)
            end
            previousTime = os.clock()
        end

        for name, time in pairs(removedCells) do
            if os.clock() - time > ENERGY_CELL_REMOVE_DELAY then
                energyCells[name] = nil
                removedCells[name] = nil
            end
        end
    end
end

-- Function that handle event and manage them.
local function eventManager()
    while true do
        local eventData = {os.pullEventRaw()}

        if eventData[1] == "peripheral" then
            addPeripheral(eventData[2])
        elseif eventData[1] == "peripheral_detach" then
            removePeripheral(eventData[2])
        elseif eventData[1] == "terminate" then
            print("Caught a terminate event")
            break
        end
    end
end

-- Associate device name to alias from file $(ALIAS_FILE_NAME) in $(aliases) list
if fs.exists(ALIAS_FILE_NAME) then

    for line in io.lines(ALIAS_FILE_NAME, "l") do
        local original = ""
        local alias = ""
        local i = 1
        for token in string.gmatch(line, "[^%s]+") do
            if i == 1 then
                original = token
            elseif i == 2 then
                alias = token
            else
                alias = alias.." "..token
            end
            i = i + 1
        end

        aliases[original] = alias
    end
end

-- At program startup this loop allows us to list all plugged devices.
for _,name in ipairs(peripheral.getNames()) do
    addPeripheral(name)
end

-- Run in parallel eventManager function and refredh() function
parallel.waitForAny(eventManager, refresh)