1 files changed, 30 insertions, 10 deletions

diff --git a/main.nim b/main.nim
index 115808d..07686ed 100644
--- a/main.nim
+++ b/main.nim
@@ -9,6 +9,7 @@ import std/net
 import std/posix
 import std/paths
 import std/strutils
+import std/sequtils
 import std/parseopt
 
 import file
@@ -33,17 +34,24 @@ proc registerTerminationHandlers() =
   for signal in [SIGTERM, SIGHUP, SIGQUIT, SIGINT]:
     discard sigaction(signal, action)
 
+func getArg(
+  args: seq[tuple[kind: CmdLineKind, key, val: string]],
+  index: int,
+  label: string
+): string =
+  try: args[index].key
+  except: raise newException(ValueError, "Missing " & label & " argument")
+
 proc main() =
   var
     scale: Scale = log2
     symbols = UNICODE_SYMBOLS
     timestampHeader = formatTimestampDateTime
     (min, max) = (0, 1000)
-    probe: (timeout: Duration) -> int
 
   for optKind, key, val in getopt():
     if optKind notin {cmdLongOption, cmdShortOption}:
-      raise newException(ValueError, "Invalid argument: " & key)
+      continue
 
     case key:
 
@@ -81,21 +89,33 @@ proc main() =
       if parts.len != 2: raise newException(ValueError, "Invalid range")
       (min, max) = (parseInt(parts[0]), parseInt(parts[1]))
 
+    else:
+      raise newException(ValueError, "Unrecognised option")
+
+  let
+    args = getopt().toSeq.filterIt(it.kind == cmdArgument)
+    monitor = args.getArg(0, "monitor")
+    target = args.getArg(1, "target")
+
+  if args.len > 2:
+    raise newException(ValueError, "Invalid number of arguments")
+
+  let probe = case monitor:
     of "ping":
-      let targetIp = resolve(val)
+      let targetIp = resolve(target)
       let mon = initPingMonitor(targetIp, procIdent())
-      probe = (timeout: Duration) => mon.ping(timeout).inMilliseconds.int
+      (timeout: Duration) => mon.ping(timeout).inMilliseconds.int
 
     of "value":
-      let mon = initFileValueMonitor(Path val)
-      probe = (timeout: Duration) => mon.readValue()
+      let mon = initFileValueMonitor(Path target)
+      (timeout: Duration) => mon.readValue()
 
     of "change":
-      let mon = initFileChangeMonitor(Path val)
-      probe = (timeout: Duration) => mon.readValue()
+      let mon = initFileChangeMonitor(Path target)
+      (timeout: Duration) => mon.readValue()
 
-  if probe == nil:
-    raise newException(ValueError, "Missing monitor argument")
+    else:
+      raise newException(ValueError, "Unrecognised monitor argument")
 
   loop(
     probe,