write proper help message

src/twit2blog.nim

@@ -1,4 +1,4 @@
-import twit2blogpkg/twitter
+import twit2blogpkg/twitter, twit2blogpkg/help
 import os, system, parseopt, strutils, tables
 
 when isMainModule:
@@ -12,6 +12,8 @@ when isMainModule:
     case args.kind
       of cmdEnd: break
       of cmdShortOption, cmdLongOption:
+        if (args.key == "help") or (args.key == "h"):
+          writeHelp()
         if args.val == "":
           continue
         else:
@@ -27,7 +29,6 @@ when isMainModule:
     twitterParams["thread"] = twitterParams["t"]
 
   if not (twitterParams.hasKey("user") and twitterParams.hasKey("thread")):
-    stderr.writeLine("Invalid Arguments. Must provide both --user and --thread (or -u and -t). E.g. -u:foo -t:123")
-    quit(1)
+    writeHelp()
 
   echo twitterParams["thread"].renderThread(twitterParams["user"])

src/twit2blogpkg/help.nim

@@ -0,0 +1,18 @@
+import system
+
+const
+  help = """
+Usage: twit2blog [opts]
+
+Options:
+  -u, --user   The screen name of the twitter user. E.g. If your twitter is https://twitter.com/foobar, then `foobar`.
+  -t, --thread The ID of the last tweet in your thread. E.g. 12345.
+
+For more information read the Github readme:
+  https://github.com/weskerfoot/Twit2Blog#readme
+"""
+
+proc writeHelp*(quit=true) =
+  echo(help)
+  if quit:
+    quit(1)