implemented Handlers.updateLink

src/Helpers.hs

@@ -32,7 +32,8 @@ module Helpers (
   editAnchor,
   incParamBy,
   incAnchorBy,
-  incStrBy
+  incStrBy,
+  updateLink
   ) where
 
 import qualified Data.List as L
@@ -167,6 +168,22 @@ incStrBy n str = case reads str of
   [(m, "")] -> Just $ show $ n + m
   _         -> Nothing
 
+-- | Update an old message board link
+updateLink :: T.Text -> Maybe T.Text
+updateLink text = textToUrl text
+  >>= makeHttps
+  >>= editHost
+    ( \case
+      "www.mormondiscussions.com" -> Just "www.discussmormonism.com"
+      "mormondiscussions.com"     -> Just "discussmormonism.com"
+      _                           -> Nothing
+    )
+  >>= Just . dropParam "f"
+  >>= incParamBy 100000 "t"
+  >>= incParamBy 1500000 "p"
+  >>= incAnchorBy 1500000
+  >>= Just . urlToText
+
 subToUrl :: T.Text -> Maybe Url
 subToUrl text = case T.splitOn "://" text of
   [protT, raw] -> do

test/HelpersSpec.hs

@@ -41,6 +41,7 @@ spec = do
   incParamBySpec
   incAnchorBySpec
   incStrBySpec
+  updateLinkSpec
 
 textToUrlSpec :: Spec
 textToUrlSpec = describe "textToUrl" $ mapM_
@@ -225,6 +226,36 @@ incStrBySpec = describe "incStrBy" $ mapM_
   , ( 2,      "",     Nothing  )
   ]
 
+updateLinkSpec :: Spec
+updateLinkSpec = describe "updateLink" $ mapM_
+  ( \(input, expected) -> context (show input) $
+    it ("should be " ++ show expected) $
+      updateLink input `shouldBe` expected
+  )
+
+  [ ( "http://www.mormondiscussions.com/viewtopic.php?f=1&t=34500"
+    , Just "https://www.discussmormonism.com/viewtopic.php?t=134500"
+    )
+  , ( "http://www.mormondiscussions.com/viewtopic.php?f=1&t=696&p=96969#96969"
+    , Just "https://www.discussmormonism.com/viewtopic.php?t=100696&p=1596969#1596969"
+    )
+  , ( "http://www.mormondiscussions.com/viewtopic.php"
+    , Just "https://www.discussmormonism.com/viewtopic.php"
+    )
+  , ( "http://mormondiscussions.com/viewtopic.php?f=1&t=34500"
+    , Just "https://discussmormonism.com/viewtopic.php?t=134500"
+    )
+  , ( "http://mormondiscussions.com/viewtopic.php?f=1&t=696&p=96969#96969"
+    , Just "https://discussmormonism.com/viewtopic.php?t=100696&p=1596969#1596969"
+    )
+  , ( "http://mormondiscussions.com/viewtopic.php"
+    , Just "https://discussmormonism.com/viewtopic.php"
+    )
+  , ( "http://example.com"
+    , Nothing
+    )
+  ]
+
 simpleTxt :: T.Text
 simpleTxt = "http://example.com/"