CC netPrint API

local config = '/etc/print.conf'
local labels = {}
local printers = {}
local activePrinter

function version()
    return 'netPrint v1.0.1'
end

--local functions

--Gets the name of the printer.
local function getPrinterName(printer)
    if type(printer) == 'string' then return labels[printer] end
  for n, p in pairs(printers) do
    if p == printer then
      return n
    end
  end
  return nil
end

--Gets the label of the printer
local function getPrinterLabel(p)
  if type(p) == 'string' then
    for l, n in pairs(labels) do
      if n == p then
        return l
      end
    end
    return p
  else
    name = getPrinterName(p)
    return getPrinterLabel(name)
  end
  return nil
end

--Loads the saved labels from the configuration file
local function load()
  if fs.exists(config) then
    local conf = fs.open(config, 'r')
    activePrinter = conf:read()
    labels = textutils.unserialize(conf:readAll())
    conf:close()
  else
    activePrinter = nil
    labels = {}
  end
end

-- Saves the labels to the configuration file
local function save()
  local conf = fs.open(config, 'w')
  conf:write(getPrinterName(activePrinter)..'\n')
  conf:write(textutils.serialize(labels))
  conf.close()
end

--label setting and getting functions

-- Returns the printer with label printLabel
function getPrinter(printLabel)
  if type(printLabel) ~= 'string' then
    return nil, 'Value needs to be a String'
  end
  if not labels[printLabel] then
    if printers[printLabel] then
      return printers[printLabel]
    else
      return nil, 'Printer '..printLabel..' not found'
    end
  else
    return printers[labels[printLabel]]
  end
end

-- Removes the label for printer printerName
function removeLabel(printerName)
  for label, printer in pairs(labels) do
    if printer == printerName then
      labels[label] = nil
    end
  end
  save()
end

-- Sets the label label for printer printerName
function setPrinterLabel(printerName, label)
  if not printers[printerName] then
    return false, 'No such printer: '..printerName
  end
  if labels[label] then
    return false, 'Already a printer with label '..label
  end
  removeLabel(printerName)
  labels[label] = printerName
  save()
  return true
end

--Active printer settings

-- Comparator used for comparing two printers.
comp = function(p1, p2)
    pagep1 = math.min(p1.getPaperLevel(), p1.getInkLevel())
    pagep2 = math.min(p2.getPaperLevel(), p2.getInkLevel())
    if (pagep1 == pagep2) then
        return 0
    elseif (pagep1 > pagep2) then
        return 1
    else
        return -1
    end
end

-- Sets the active printer to printer label
function setActivePrinter(label)
  p, e = getPrinter(label)
  if not p and e then
    return e
  else
    activePrinter = p
  end
end

-- Sets the active printer according to the comp function
function autoSetActivePrinter()
    local bestPrinter = nil
    for name, printer in pairs(printers) do
        if not bestPrinter then
            bestPrinter = name
        elseif(comp(printers[bestPrinter], printer) == -1) then
            bestPrinter = name
        end
    end
    setActivePrinter(bestPrinter)
end

-- Returns the active printer
local function getActivePrinter()
    if not activePrinter then autoSetActivePrinter() end
    return activePrinter
end

--Printer table functions

-- Only update the printer table
local function rawUpdate()
  for _, name in ipairs(peripheral.getNames()) do
    if peripheral.getType(name) == "printer" then
      local printer = peripheral.wrap(name)
      printers[name] = printer
    end
  end
end

-- Save labels and update the printer table
function update()
  printers = {}
  local actName = getPrinterName(activePrinter)
  activePrinter = nil
  rawUpdate()
  if actName then
        setActivePrinter(actName)
  else
        autoSetActivePrinter()
  end
end

-- initialize the system
function init()
    load()
    rawUpdate()
    getActivePrinter()
end

-- reutrns a table with the names for all the printers + ink and paper levels
function getPrinterTable()
  local printTable = {}
  for n, p in pairs(printers) do
    local print = {}
    local name = getPrinterLabel(n) or n
    table.insert(print, name)
    table.insert(print, p.getPaperLevel())
    table.insert(print, p.getInkLevel())
    table.insert(printTable, print)
  end
  return printTable
end

-- Return getPrinterTable as string
function printerTableString()
  local printTable = getPrinterTable()
  local strT = {}
  for _, t in pairs(printTable) do
    local str = t[1]..'\t'..t[2]..'\t'..t[3]
    table.insert(strT, str)
  end
  return table.concat(strT, '\n')
end

--Printer API functions

function getPaperLevel()
    local act = getActivePrinter()
    if act then
        return act.getPaperLevel()
    else
        return nil
    end
end

function newPage()
    local act = getActivePrinter()
    if act then
        return act.newPage()
    else
        return nil
    end
end

function endPage()
    local act = getActivePrinter()
    if act then
        return act.endPage()
    else
        return nil
    end
end

function write(...)
    local mes = table.concat({...}, '')
    local act = getActivePrinter()
    if act then
        return act.write(mes)
    else
        return nil
    end
end

function print(...)
    write(...)
    local x, y = getCursorPos()
    setCursorPos(1, y+1)
end

function setPageTitle(...)
    local act = getActivePrinter()
    if act then
        return act.setPageTitle(...)
    else
        return nil
    end
end

function getInkLevel()
    local act = getActivePrinter()
    if act then
        return act.getInkLevel()
    else
        return nil
    end
end

function getCursorPos()
    local act = getActivePrinter()
    if act then
        return act.getCursorPos()
    else
        return nil
    end
end

function setCursorPos(...)
    local act = getActivePrinter()
    if act then
        return act.setCursorPos(...)
    else
        return nil
    end
end

function getPageSize()
    local act = getActivePrinter()
    if act then
        return act.getPageSize()
    else
        return nil
    end
end

-- Wrap the text while writing
function wrapWrite(...)
    local mes = table.concat(..., '')
    local x, y = getCursorPos()
    local width, height = getPageSize()
    local function newLine()
        setCursorPos(1, y + 1)
    end
    for i = 1, #mes do
        local c = mes:sub(i,i)
        x, y = getCursorPos()
        if c == '\n' then
            newLine()
        elseif (c == ' ' and x == 1) then
            c = nil
        else
            if x > width then
                newLine()
            end
            if y > height then
                endPage()
                newPage()
                x=1
                y=1
                setCursorPos(x,y)
            end
            write(c)
        end
    end
end

--Same as wrapWrite, but set the cursor to the next line after printing
function wrapPrint(...)
    wrapWrite(...)
    local x, y = getCursorPos()
    setCursorPos(1, y+1)
end

init()