--- /dev/null
+-- import Debug.Trace
+
+import Data.Text (Text)
+import qualified Data.Text as T
+import qualified Data.Text.IO as TIO
+
+import Data.Void (Void)
+
+import Text.Megaparsec hiding (State)
+import Text.Megaparsec.Char
+import qualified Text.Megaparsec.Char.Lexer as L
+import qualified Control.Applicative as CA
+
+import qualified Data.IntMap.Strict as M
+import Data.IntMap.Strict ((!))
+import Data.Functor (void)
+import Prelude hiding (take)
+import Data.Either
+
+
+data Rule = Letter Char
+ | Then [Rule]
+ | Or Rule Rule
+ | See Int
+ deriving (Show, Eq)
+
+type RuleSet = M.IntMap Rule
+
+
+main :: IO ()
+main =
+ do text <- TIO.readFile "data/advent19b.txt"
+ -- print text
+ let (rules, messages) = successfulParse text
+ let messagesT = map T.pack messages
+ -- print rules
+ -- print messages
+ print $ part1 rules messagesT
+ print $ part2 rules messagesT
+ -- print $ part2 text
+
+setup fname =
+ do text <- TIO.readFile fname
+ let (rules, messages) = successfulParse text
+ let messagesT = map T.pack messages
+ let Right newRules = parse rulesP "rules" "8: 42 | 42 8\n11: 42 31 | 42 11 31"
+ let updatedRules = M.union newRules rules
+ let myParser = (makeParser updatedRules (See 0)) -- <* eof
+ return (myParser, updatedRules, messagesT)
+
+
+
+part1 = countMatches
+
+part2 rules messages = countMatches updatedRules messages
+ where Right newRules = parse rulesP "rules" "8: 42 | 42 8\n11: 42 31 | 42 11 31"
+ updatedRules = M.union newRules rules
+
+countMatches rules messages
+ = length
+ $ filter isRight
+ $ map (parse myParser "message") messages
+ where myParser = (makeParser rules (See 0)) -- <* eof
+
+prettyResults rs = map p rs
+ where p (Left e) = errorBundlePretty e
+ p (Right r) = "^" ++ show r
+
+
+-- Generate the rules
+
+makeParser :: RuleSet -> Rule -> Parser ()
+makeParser m (Letter c) = void $ char c
+makeParser m (Then rs) = mapM_ (makeParser m) rs
+makeParser m (Or a b) = (try (makeParser m a)) <|> (makeParser m b)
+makeParser m (See i) = makeParser m (m!i)
+
+
+-- Parse the input
+
+type Parser = Parsec Void Text
+
+sc :: Parser ()
+sc = L.space (skipSome (char ' ')) CA.empty CA.empty
+
+lexeme = L.lexeme sc
+integer = lexeme L.decimal
+symb = L.symbol sc
+colonP = symb ":"
+pipeP = symb "|"
+quoteP = symb "\""
+
+
+rulesP = M.fromList <$> ruleP `sepEndBy` newline
+ruleP = (,) <$> integer <* colonP <*> ruleBodyP
+ruleBodyP = choice [(try letterRuleP), (try orRuleP), (try thenRuleP), (try seeRuleP)]
+
+letterRuleP = Letter <$> between quoteP quoteP letterChar
+orRuleP = Or <$> thenRuleP <* pipeP <*> thenRuleP
+thenRuleP = Then <$> some seeRuleP
+seeRuleP = See <$> integer
+
+
+inputP = (,) <$> rulesP <* (some newline) <*> messagesP
+
+messagesP = messageP `sepBy` newline
+messageP = some letterChar
+
+
+-- successfulParse :: Text -> (Integer, [Maybe Integer])
+successfulParse input =
+ case parse inputP "input" input of
+ Left _err -> (M.empty, []) -- TIO.putStr $ T.pack $ parseErrorPretty err
+ Right expressions -> expressions