module Wiki where

--------------------------------------------------------------------------------

-- List of imported modules and functions

import Data.Maybe (fromJust)
import Text.Html
import Network.Shed.Httpd
import Network.URI

--------------------------------------------------------------------------------

-- | String formatting alternatives for inline text.

data Inline
  = Bold String
  | Unformatted String
  deriving (Eq, Show)

-- | A list of (un)formatted strings.

type Text
  = [Inline]

-- | Text formatting alternatives for blocks of text (between newlines).

data Block
  = Bullet Text
  | Paragraph Text
  deriving (Eq, Show)

-- | A list of (un)formatted blocks.

type Page
  = [Block]

--------------------------------------------------------------------------------

-- | Split a string into its lexical components to simplify manipulation.

inlinify :: String -> [String]
inlinify [] = []
inlinify str =
  case split [] str of
    (ln, wd, next) -> appCons reverse ln . appCons id wd $ inlinify next
  where
    split ln ('*':'*':cs) = (ln, "**", cs)
    split ln (c:cs)       = split (c : ln) cs
    split ln ""           = (ln, "", "")

-- | Apply a function to a list and cons the result to another list.

appCons :: ([a] -> b) -> [a] -> [b] -> [b]
appCons _ [] = id
appCons f xs = (f xs :)

-- | Split lines into their lexical components to simplify manipulation.

blockify :: [String] -> [String]
blockify [] = []
blockify lns =
  case split [] lns of
    (paras, ln, next) -> appCons (unwords . reverse) paras . appCons id ln $ blockify next
  where
    split paras (l@('*':' ':_):ls)     = (paras, l, ls)
    split paras ("":ls)                = (paras, [], ls)
    split paras (l:ls)                 = split (l : paras) ls
    split paras []                     = (paras, [], [])

-- | Merge two |Maybe| values with priority on the first one.

mplus :: Maybe a -> Maybe a -> Maybe a
mplus Nothing y = y
mplus x       _ = x

--------------------------------------------------------------------------------

-- Ex. 3
-- Ex. 4

readInline :: [String] -> Maybe (Inline, [String])
readInline inp =
  readBold inp `mplus`
  readUnformattedInline inp

readUnformattedInline :: [String] -> Maybe (Inline, [String])
readUnformattedInline []      = Nothing
readUnformattedInline (c:cs)  = Just (Unformatted c, cs)

readBold :: [String] -> Maybe (Inline, [String])
readBold inp =
  case inp of
    "**":txt:"**":rest  -> Just (Bold txt, rest)
    _                   -> Nothing

--------------------------------------------------------------------------------

-- Ex. 5

readText :: String -> Text
readText = undefined

--------------------------------------------------------------------------------

-- Ex. 6

readBlock :: String -> Block
readBlock inp = fromJust $
  readBullet inp `mplus`
  readUnformattedBlock inp

readUnformattedBlock :: String -> Maybe Block
readUnformattedBlock = Just . Paragraph . readText

readBullet :: String -> Maybe Block
readBullet inp =
  case inp of
    '*':' ':txt  -> Just . Bullet $ readText txt
    _            -> Nothing

--------------------------------------------------------------------------------

-- Ex. 7

readPage :: String -> Page
readPage = undefined

--------------------------------------------------------------------------------

-- Ex. 9

-- | Example use of Text.HTML: make a paragraph with |"Hello, World!"| in bold.

exampleHtml :: Html
exampleHtml = thehtml << body << p << bold << "Hello, World!"

inlineToHtml :: Inline -> Html
inlineToHtml = undefined

textToHtml :: Text -> Html
textToHtml = undefined

--------------------------------------------------------------------------------

-- Ex. 10

-- | Example unordered list with list items in HTML.

exampleList :: Html
exampleList = ulist << [li << "item 1", li << "item 2"]

blockToHtml :: Block -> Html
blockToHtml = undefined

pageToHtml :: Page -> Html
pageToHtml = undefined

-- | Convert a wiki-formatted string to a renderable HTML string.

wikify :: String -> String
wikify = renderHtml . (body <<) . pageToHtml . readPage

--------------------------------------------------------------------------------

simpleServer :: Request -> IO Response	
simpleServer = return . Response responseOK [contentText] . show

initMyServer :: (Request -> IO Response) -> IO Server
initMyServer = initServer myPort

myPort :: Int
myPort = 7734

contentText, contentHtml :: (String, String)
contentText = contentType "text/plain"
contentHtml = contentType "text/html"

responseOK, responseNotFound :: Int
responseOK       = 200
responseNotFound = 404

methodGET, methodPOST :: String
methodGET  = "GET"
methodPOST = "POST"

--------------------------------------------------------------------------------

-- Ex. 12

fileServer :: Request -> IO Response	
fileServer = undefined

--------------------------------------------------------------------------------

-- Ex. 13

-- | Example form with a single text field.

exampleForm :: Html
exampleForm =
  form ! [action $ "http://localhost:" ++ show myPort ++ "/post", method methodPOST]
    << [ input ! [thetype "text"]
       , input ! [thetype "submit", value "Submit"]
       ]

wikiFormServer :: Request -> IO Response	
wikiFormServer = undefined