Add ability to match fixed numbers

src/Lib.hs

@@ -1,9 +1,14 @@
 module Lib
-    ( match
+    ( match,
+      parse,
+      check,
+      createParts
     ) where
 
 import Data.Bool
 import Data.Dates
+import Data.Char (isDigit)
+import Data.Maybe (catMaybes, isNothing)
 
 data Range = Any | Pair Int Int | Sequence [Int]
 
@@ -11,19 +16,81 @@ data Step = All | Value Int
 
 data CronItemPattern = CronItemPattern Range Step
 
-data CronPattern = CronPattern [CronItemPattern]
+data CronPattern = CronPattern {
+    cminute :: CronItemPattern,
+    chour :: CronItemPattern,
+    cday :: CronItemPattern,
+    cmonth :: CronItemPattern,
+    cweek :: CronItemPattern,
+    cyear :: CronItemPattern
+}
 
 match :: String -> DateTime -> Bool
-match s d = matchPattern (parseCronPattern s) d
+match s d =  case parse s of
+    Just p -> check p d
+    Nothing -> error ""
 
-parseCronPattern :: String -> CronPattern
-parseCronPattern s = CronPattern $ map parseCronItemPattern $ words s
+safeMatch :: String -> DateTime -> Maybe Bool
+safeMatch s d = case parse s of
+    Just p -> Just (check p d)
+    Nothing -> Nothing
 
-parseCronItemPattern :: String -> CronItemPattern
-parseCronItemPattern "*" = CronItemPattern Any All
+parse :: String -> Maybe CronPattern
+parse s
+    | isInvalid = Nothing
+    | otherwise = Just (createPattern $ catMaybes parts)
+    where
+        parts = createParts s
+        isInvalid = checkParts parts == False
+        createPattern xs = CronPattern {
+            cminute = xs !! 0,
+            chour = xs !! 1,
+            cday = xs !! 2,
+            cmonth = xs !! 3,
+            cweek = xs !! 4,
+            cyear = xs !! 5
+        }
 
-matchPattern :: CronPattern -> DateTime -> Bool
-matchPattern (CronPattern (x:xs)) d = matchItemPattern x (year d)
+parsers = [parseMinute, parseHour, parseDay, parseMonth, parseWeek, parseYear]
+
+createParts s = map f $ zip parsers (words s)
+    where
+        f (g, s) = g s
+
+checkParts :: [Maybe CronItemPattern] -> Bool
+checkParts xs
+    | length xs /= 6 = False
+    | any isNothing xs = False
+    | otherwise = True
+
+parseCronItemPattern :: (Int, Int) -> String -> Maybe CronItemPattern
+parseCronItemPattern (f, t) s
+    | s == "*" = Just (CronItemPattern Any All)
+    | validNumber == True = Just (CronItemPattern (Pair x x) All)
+    | otherwise = Nothing
+    where 
+        x = read s :: Int
+        validNumber = all isDigit s && x >= f && x <= t
+
+parseMinute = parseCronItemPattern (0, 59)
+parseHour = parseCronItemPattern (0, 59)
+parseDay = parseCronItemPattern (1, 31)
+parseMonth = parseCronItemPattern (1, 12)
+parseWeek = parseCronItemPattern (1, 7)
+parseYear = parseCronItemPattern (0, 9999)
+
+check :: CronPattern -> DateTime -> Bool
+check pattern date = all isRight pairs
+    where 
+        pairs = [ (cminute pattern, minute date),
+                  (chour pattern, hour date),
+                  (cday pattern, day date),
+                  (cmonth pattern, month date),
+                  (cweek pattern, weekdayNumber $ dateWeekDay date),
+                  (cyear pattern, year date)
+                ]
+        isRight (pattern, value) = matchItemPattern pattern value 
 
 matchItemPattern :: CronItemPattern -> Int -> Bool
-matchItemPattern (CronItemPattern Any All) _ = True
+matchItemPattern (CronItemPattern Any All) _ = True
+matchItemPattern (CronItemPattern (Pair f t) All) x = x >= f && x <= t