implement --extract

1 files changed, 27 insertions, 1 deletions

diff --git a/src/MdBlocks/Address.hs b/src/MdBlocks/Address.hs
index c3dc5a4..8a32e0f 100644
--- a/src/MdBlocks/Address.hs
+++ b/src/MdBlocks/Address.hs
@@ -1,12 +1,38 @@
 {-# LANGUAGE OverloadedStrings #-}
 
-module MdBlocks.Address where
+module MdBlocks.Address
+  ( Address(..)
+  , parseAddress
+  , addressOf
+  )
+where
 
 import Data.Text (Text)
 import qualified Data.Text as T
 
 import MdBlocks.Types
 
+data Address
+  = GlobalId Text
+  | FileAddress FilePath Text
+  deriving (Show, Eq)
+
+parseAddress :: String -> Either String Address
+parseAddress input =
+  case T.breakOn "#" (T.pack input) of
+    (file, ident)
+      | T.null file ->
+          Left "address must contain a file path"
+
+      | T.null ident ->
+          Left "address must contain a block id after '#'"
+
+      | otherwise ->
+          Right
+            (FileAddress
+              (T.unpack file)
+              (T.drop 1 ident))
+
 addressOf :: Block -> Text
 addressOf b =
   case mdId (blockMeta b) of