Add FFI JavaScript as a webpack dependency

Resolves #18

1 files changed, 35 insertions, 0 deletions

diff --git a/src/FS.purs b/src/FS.purs
index a56fe26..6955a63 100644
--- a/src/FS.purs
+++ b/src/FS.purs
@@ -1,12 +1,16 @@
 module PursLoader.FS
   ( FS()
   , writeFileUtf8
+  , findFileUtf8
   ) where
 
 import Control.Monad.Aff (Aff(), makeAff)
 import Control.Monad.Eff (Eff())
 import Control.Monad.Eff.Exception (Error())
 
+import Data.Maybe (Maybe(..))
+import Data.String.Regex (Regex())
+
 import Data.Function
 
 foreign import data FS :: !
@@ -30,3 +34,34 @@ function writeFileUtf8Fn(filepath, contents, errback, callback) {
                        (Error -> Eff (fs :: FS | eff) Unit)
                        (Unit -> Eff (fs :: FS | eff) Unit)
                        (Eff (fs :: FS | eff) Unit)
+
+findFileUtf8 :: forall eff. Regex -> [String] -> Aff (fs :: FS | eff) (Maybe String)
+findFileUtf8 regexp filepaths = makeAff $ runFn6 findFileUtf8Fn Nothing Just regexp filepaths
+
+foreign import findFileUtf8Fn """
+function findFileUtf8Fn(nothing, just, regex, filepaths, errback, callback) {
+  return function(){
+    var fs = require('fs');
+
+    var async = require('async');
+
+    function findFile(filepath, callback) {
+      fs.readFile(filepath, {encoding: 'utf-8'}, function(error, result){
+        if (error) callback(false);
+        else callback(regex.test(result));
+      });
+    }
+
+    async.detect(filepaths, findFile, function(result){
+      if (!result) callback(nothing)();
+      else callback(just(result))();
+    });
+  };
+}
+""" :: forall eff. Fn6 (Maybe String)
+                       (String -> Maybe String)
+                       Regex
+                       [String]
+                       (Error -> Eff (fs :: FS | eff) Unit)
+                       (Maybe String -> Eff (fs :: FS | eff) Unit)
+                       (Eff (fs :: FS | eff) Unit)