--- /dev/null
+module Main(main) where
+
+import Text.Parsec
+import Data.List (partition, union, intersect, tails)
+import Data.Char (isAlphaNum)
+
+data Chunk = Include String | Exclude String deriving (Show)
+data ChunkV = Includev Bool | Excludev Bool deriving (Show)
+
+chunkValue :: Chunk -> String
+chunkValue (Include v) = v
+chunkValue (Exclude v) = v
+
+isInclude :: Chunk -> Bool
+isInclude (Include _) = True
+isInclude (Exclude _) = False
+
+chunkValueV :: ChunkV -> Bool
+chunkValueV (Includev v) = v
+chunkValueV (Excludev v) = v
+
+isIncludeV :: ChunkV -> Bool
+isIncludeV (Includev _) = True
+isIncludeV (Excludev _) = False
+
+
+main :: IO ()
+main = do
+ text <- readFile "data/advent07.txt"
+ part1 text
+ part2 text
+
+
+part1 :: String -> IO ()
+part1 text = do
+ print $ length $ filter (allowsAbba) $ successfulParse $ parseI7vf text
+
+
+part2 :: String -> IO ()
+part2 text = do
+ print $ length $ filter (supportsSSL) $ successfulParse $ parseI7f text
+
+allowsAbba :: [ChunkV] -> Bool
+allowsAbba chunks = (any (chunkValueV) includeChunks) && (not (any (chunkValueV) excludeChunks))
+ where (includeChunks, excludeChunks) = partition (isIncludeV) chunks
+
+i7file = i7line `endBy` newline
+i7line = many1 (includeChunk <|> excludeChunk)
+
+chunk = many1 alphaNum
+
+excludeChunk = Exclude <$> (between (char '[') (char ']') $ chunk)
+includeChunk = Include <$> chunk
+
+hasABBA = preambleAbba <* (many alphaNum)
+preambleAbba = (try abba) <|> (alphaNum >> preambleAbba)
+
+-- abba =
+-- do a <- alphaNum
+-- b <- alphaNum
+-- if a == b then
+-- fail "Identical"
+-- else do char b
+-- char a
+-- return [a, b, b, a]
+
+abba =
+ do a <- alphaNum
+ b <- noneOf [a]
+ char b
+ char a
+ return [a, b, b, a]
+
+-- where
+-- firstChar = satisfy (\a -> isLetter a || a == '_')
+-- nonFirstChar = satisfy (\a -> isDigit a || isLetter a || a == '_')
+
+ -- b <- bChar
+-- where bChar = satisfy (\l -> lsLetter l && l /= a)
+
+
+
+i7filev = i7linev `endBy` newline
+i7linev = many1 (includeChunkv <|> excludeChunkv)
+
+excludeChunkv = Excludev <$> (between (char '[') (char ']') $ hasABBAv)
+includeChunkv = Includev <$> hasABBAv
+
+hasABBAv =
+ (try (id True <$ preambleAbba <* (many alphaNum)))
+ <|>
+ (id False <$ (many1 alphaNum))
+
+
+parseI7f :: String -> Either ParseError [[Chunk]]
+parseI7f input = parse i7file "(unknown)" input
+
+parseI7 :: String -> Either ParseError [Chunk]
+parseI7 input = parse i7line "(unknown)" input
+
+parseAbba :: String -> Either ParseError String
+parseAbba input = parse hasABBA "(unknown)" input
+
+parseI7v :: String -> Either ParseError [ChunkV]
+parseI7v input = parse i7linev "(unknown)" input
+
+parseI7vf :: String -> Either ParseError [[ChunkV]]
+parseI7vf input = parse i7filev "(unknown)" input
+
+successfulParse :: Either ParseError [a] -> [a]
+successfulParse (Left _) = []
+successfulParse (Right a) = a
+
+
+allSubstrings :: Int -> [a] -> [[a]]
+-- allSubstrings n es
+-- | length es < n = []
+-- | otherwise = (take n es) : (allSubstrings n $ tail es)
+allSubstrings n e = filter (\s -> length s == n) $ map (take n) $ tails e
+
+
+ieCandidates :: [Chunk] -> ([String], [String])
+ieCandidates chunks = (includeCandidates, excludeCandidates)
+ where (includeChunks, excludeChunks) = partition (isInclude) chunks
+ isABA s = (s!!0 == s!!2) && (s!!0 /= s!!1)
+ candidates = (filter (isABA)) . (foldl (union) []) . (map ((allSubstrings 3) . chunkValue))
+ includeCandidates = candidates includeChunks
+ excludeCandidates = candidates excludeChunks
+
+inverseABA :: String -> String
+inverseABA s = [s!!1, s!!0, s!!1]
+
+supportsSSL :: [Chunk] -> Bool
+supportsSSL chunks = not $ null $ intersect abas eabas
+ where (abas, babs) = ieCandidates chunks
+ eabas = map (inverseABA) babs