implemented textToUrl and urlToText helpers

2021-09-22 13:06:05 -04:00
parent 258242ccfc
commit 34ee4a57bc
2 changed files with 220 additions and 0 deletions
--- a/src/Helpers.hs
+++ b/src/Helpers.hs
@@ -0,0 +1,120 @@
+{-|
+
+Module     : Helpers
+Copyright  : Jonathan Lamothe
+License    : GPL-3
+Maintainer : jonathan@jlamothe.net
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or (at
+your option) any later version.
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+-}
+
+{-# LANGUAGE LambdaCase, OverloadedStrings #-}
+
+module Helpers (
+  textToUrl,
+  urlToText,
+  ) where
+
+import qualified Data.List as L
+import qualified Data.Text as T
+
+import Types
+
+-- | Convert a text to a 'Url' (if possible)
+textToUrl :: T.Text -> Maybe Url
+textToUrl text = case T.splitOn "#" text of
+  [sub, anchorT] -> do
+    url <- subToUrl sub
+    Just $ url { anchor = Just $ T.unpack anchorT }
+  [sub] -> subToUrl sub
+  _ -> Nothing
+
+-- | Convert a 'Url' to text
+urlToText :: Url -> T.Text
+urlToText url = T.pack $
+  protocol url ++ "://" ++
+  host url ++ "/" ++
+  pathStr ++ paramsStr ++ anchorStr
+  where
+    pathStr = L.intercalate "/" $ path url
+    paramsStr = case params url of
+      [] -> ""
+      ps -> '?' : L.intercalate "&"
+        ( map
+          ( \case
+            (name, Just val) -> name ++ "=" ++ val
+            (name, Nothing)  -> name
+          ) ps
+        )
+    anchorStr = case anchor url of
+      Just str -> "#" ++ str
+      Nothing  -> ""
+
+subToUrl :: T.Text -> Maybe Url
+subToUrl text = case T.splitOn "://" text of
+  [protT, raw] -> do
+    let prot = T.unpack protT
+    url <- getParts raw
+    Just url { protocol = prot }
+  _ -> Nothing
+
+getParts :: T.Text -> Maybe Url
+getParts text = do
+  (host', path', params') <- case T.splitOn "?" text of
+    [pathT, paramsT] -> do
+      (host', path') <- getPath pathT
+      params'       <- getParams paramsT
+      Just (host', path', params')
+    [pathT] -> do
+      (host', path') <- getPath pathT
+      Just (host', path', [])
+    _ -> Nothing
+  Just newUrl
+    { host   = host'
+    , path   = path'
+    , params = params'
+    }
+
+getPath :: T.Text -> Maybe (String, [String])
+getPath text = case T.splitOn "/" (removeTrailing '/' text) of
+  hostT : dirs -> Just
+    ( T.unpack hostT
+    , map T.unpack dirs
+    )
+  _ -> Nothing
+
+getParams :: T.Text -> Maybe [(String, Maybe String)]
+getParams = mapM getParam . T.splitOn "&"
+
+getParam :: T.Text -> Maybe (String, Maybe String)
+getParam text = case T.splitOn "=" text of
+  [name, val] -> Just
+    ( T.unpack name
+    , Just $ T.unpack val
+    )
+  [name] -> Just
+    ( T.unpack name
+    , Nothing
+    )
+  _ -> Nothing
+
+removeTrailing :: Char -> T.Text -> T.Text
+removeTrailing ch text
+  | T.null text = ""
+  | otherwise   = if T.last text == ch
+    then T.init text
+    else text
+
+--jl