#!/usr/bin/env lua

--[[
Writing Nagios plugins -
  https://assets.nagios.com/downloads/nagioscore/docs/nagioscore/3/en/pluginapi.html
  https://nagios-plugins.org/doc/guidelines.html
  http://users.telenet.be/mydotcom/howto/nagios/pluginsudo.html
]]

local APT = require 'apt-panopticommon'
local D = APT.D
local I = APT.I
local T = APT.T
local W = APT.W
local E = APT.E
local C = APT.C
--local arg, sendArgs = APT.parseArgs({...})


APT.mirrors = loadfile("results/mirrors.lua")()


-- Nagios result codes
local OK	= 0
local WARNING	= 1
local CRITICAL	= 2
local UNKNOWN	= 3

-- Result variables.
local status		= "UNKNOWN: something went horribly wrong with apt-panopticon-nagios.lua."
local extra		= ""
local returnCode	= UNKNOWN
local perfData		= {}
local perfCount		= 0

-- For collecting debugging text for verbosity level 3.
local debugText = "\nDebugging output -\n"


-- Misc functions.
-------------------------------------------------------------------------------

-- Wrapper coz I'm a C coder.
local function printf(...) io.write(string.format(...)) end


-- Command line argument handling.
-------------------------------------------------------------------------------

-- A bunch of functions for parsing argument values.
local function parseVersion(arguments, token, value)
    arguments[token].value = true
    return false
end

local function parseHelp(arguments, token, value)
    arguments["version"].value = true
    arguments[token].value = 2
    return false
end

local function parseVerbose(arguments, token, value)
    if nil == arguments[token].value then arguments[token].value = 0 end
    arguments[token].value = arguments[token].value + 1
    if arguments[token].value > 3 then arguments[token].value = 3 end
    return false
end

local function parseTimeout(arguments, token, value)
    if nil == value then return true end
    -- The "+ 0" part forces this to be converted to a number.  Coz the comparison wont coerce it automaticaly, which Lua normally does.
    arguments[token].value = value + 0
    if arguments[token].value > 120 then arguments[token].value = 120 end
    return true
end

local function parseString(arguments, token, value)
    if nil == value then return true end
    arguments[token].value = value
    return true
end

local function parseRange(arguments, token, value)
    if nil == value then return true end
-- TODO - actually parse this.
-- Threshhold and ranges, meaning that we can set what is classified as the various thresholds and ranges for the three result codes.
    return true
end


-- Lua doesn't have any sort of C like structure, this is how to fake it.
local function addArgument(short, default, help, parser)
    return { short = short, default = default, help = help, parser = parser }
end
local arguments =
{
    -- Reserved arguments.
    version	= addArgument("V", false,	"Print version string, then exit.",					parseVersion),
    help	= addArgument("h", 0,		"Print version string, verbose help, then exit.",			parseHelp),

    verbose	= addArgument("v", 0,		"Be verbose.  Can be up to three of these to increase the verbosity.",	parseVerbose),
    timeout	= addArgument("t", 50,		"Timeout to wait for the actual results to arrive.",			parseTimeout),

    ok		= addArgument("o", {},		"What range of thresholds counts as OK.",				parseRange),
    warning	= addArgument("w", {},		"What range of thresholds counts as WARNING.",				parseRange),
    critical	= addArgument("c", {},		"What range of thresholds counts as CRITICAL.",				parseRange),

    --Standard, but optional arguments.
--    community	= addArgument("C", "",		"SNMP community.",	parseString),
--    logname	= addArgument("l", "",		"User name.",		parseString),
--    username	= addArgument("u", "",		"User name.",		parseString),
--    authentication	= addArgument("a", "",	"Password.",		parseString),
--    password	= addArgument("p", "",		"Password.",		parseString),
--    passwd	= addArgument("p", "",		"Password.",		parseString),

    -- We can combine hostname, port, and URL.  Avoids duplicate short options.
    hostname	= addArgument("H", "",		"Host name or complete URL, including port number.",	parseString),
    -- url	= addArgument("u", "",		"URL.",							parseString),
    -- port	= addArgument("p", -1,		"Port number.",						parseString),

    -- Our non standard arguments.
}


-- Parse the arguments.
if nil ~= arg[1] then
    local lastArg = nil
    local expectValue = false
    for i, token in ipairs(arg) do
	if 0 < i then
	    if not expectValue then
		if "--" == token:sub(1, 2) then
		    token = token:sub(3)
		    if nil ~= arguments[token] then
			lastArg = token
			expectValue = arguments[token].parser(arguments, lastArg, nil)
		    else
			arguments["version"].value = true
			arguments["help"].value = 1
			lastArg = nil
			expectValue = false
		    end
		elseif "-" == token:sub(1, 1) then
		    token = token:sub(2)
		    -- Scan through the arguments table looking for short token.
		    for k, v in pairs(arguments) do
		        if token == arguments[k].short then
			    lastArg = k
			    expectValue = arguments[k].parser(arguments, lastArg, nil)
			end
		    end
		end
	    elseif nil ~= lastArg then
		arguments[lastArg].parser(arguments, lastArg, token)
		lastArg = nil
		expectValue = false
	    else
		arguments["version"].value = true
		arguments["help"].value = 1
		lastArg = nil
		expectValue = false
	    end
	end
    end
end


-- Fill in default values if needed.
for k, v in pairs(arguments) do
    if nil == arguments[k].value then arguments[k].value = arguments[k].default end
end


-- Deal with the various help and version variations.
-------------------------------------------------------------------------------

if arguments["version"].value then print("apt-panopticon-nagios.lua v0.1") end
if arguments["help"].value >= 1 then
    printf("Usage:\n  apt-panopticon-nagios.lua ")
    for k, v in pairs(arguments) do
	printf("[-%s] ", arguments[k].short, k)
    end
    print("")
end
if arguments["help"].value == 2 then
    print("\nThis Nagios plugin is a generic wrapper around stdio based mini checker scripts that can be written in any language.\n")
    print("Options:")
-- TODO - should sort this somehow, it's coming out in hash order.
    for k, v in pairs(arguments) do
	printf("  -%s, --%s\n", arguments[k].short, k)
	printf("    %s\n", arguments[k].help)
    end
end

-- All the help and version variations don't actually run the checker script, just output stuff and exit.
if arguments["version"].value or arguments["help"].value >= 1 then os.exit(OK) end



local function readFile(name)
  local file = io.open(name, 'r')
  local output = file:read('*a')

  file:close()
  return output
end


-- Actually calculate the results.
-------------------------------------------------------------------------------

if "" == arguments["hostname"].value then
  status = "UNKNOWN: no host specified."
  returnCode = UNKNOWN
else
    local host = arguments["hostname"].value
    if APT.checkFile('results/' .. host .. '.lua') then
	local results = APT.collateAll(APT.mirrors, 'results', host)
	local e = 0
	local w = 0
	local t = 0

	for h, typ in pairs(APT.protocols) do
	    if nil ~= results[typ] then
		e = e + results[typ].errors
		w = w + results[typ].warnings
		t = t + results[typ].timeouts
		for k, v in pairs(results[typ]) do
		    if ("table" == type(v)) and ('redirects' ~= k) then
			if 0 <= v.errors   then e = e + v.errors   end
			if 0 <= v.warnings then w = w + v.warnings end
			if 0 <= v.timeouts then t = t + v.timeouts end
		    end
		end
	    else
		for k, v in pairs(results) do
		    if "table" == type(v) then
			for i, u in pairs(v) do
			    if "table" == type(u) then
				if typ == i then
				    if 0 <= u.errors   then e = e + u.errors   end
				    if 0 <= u.warnings then w = w + u.warnings end
				    if 0 <= u.timeouts then t = t + u.timeouts end
				end
			    end
			end
		    end
		end
	    end
	end

        perfData['errors']   = e
        perfData['warnings'] = w
        perfData['timeouts'] = t
        perfCount = perfCount + 3
	if     0 < e then	returnCode = CRITICAL;	status = 'CRITICAL'
	elseif 0 < w then	returnCode = WARNING;	status = 'WARNING'
--	elseif 0 < t then	returnCode = UNKNOWN;	status = 'UNKNOWN'
        else			returnCode = OK;	status = 'OK'
        end

	 if arguments["verbose"].value == 1 then
            status = status .. ': ' .. APT.plurals(e, w, t)
	else
            extra = '\n' .. APT.plurals(e, w, t)
	end
    else
	status = "UNKNOWN: no records for host " .. host
	returnCode = UNKNOWN
    end
end


-- Send the results to Nagios.
-------------------------------------------------------------------------------

--[[ Verbosity levels mean -
	0 Single line, minimal output. Summary
	1 Single line, additional information (eg list processes that fail)
	2 Multi line, configuration debug output (eg ps command used)
	3 Lots of detail for plugin problem diagnosis
]]

printf(status)
if arguments["verbose"].value > 0 then
  printf(extra)
end

-- Performance data can be a complex format, or a simple format.
if perfCount > 0 then
  printf(" | ")
  for k, v in pairs(perfData) do
    printf("'%s'=%s\n", k, v)
  end
else
  print()
end

if arguments["verbose"].value > 1 then
  print("\nCheckGeneric.lua arguments -")
  for k, v in pairs(arguments) do
    if type(v.value) == "table" then
      APT.dumpTable(v.value, "  --" .. k)
    elseif type(v.value) == "boolean" then
      if (v.value) then
	printf("  --%s: true\n", k)
      else
	printf("  --%s: false\n", k)
      end
    else
      printf("  --%s: %s\n", k, v.value)
    end
  end
end

if arguments["verbose"].value == 3 then
  print(debugText)
end

os.exit(returnCode)