{-# LANGUAGE OverloadedStrings #-}

module Web.Hablog.Present where

import           Web.Scotty.Trans
import           Control.Monad.IO.Class (liftIO)
import           Data.Maybe (catMaybes)
import           Data.Either (rights)
import qualified Data.List as L
import qualified Data.Text.Lazy as T
import qualified Data.Text.Lazy.Encoding as T
import qualified Data.ByteString.Lazy as BSL
import qualified Data.ByteString.Lazy.Char8 as BSLC

import qualified Text.Blaze.Html.Renderer.Text as HR
import qualified Text.Blaze.Html5 as H
import qualified Text.Blaze.Html5.Attributes as A
import           Text.Blaze.Html5 ((!))

import qualified System.Directory as DIR (getDirectoryContents)
import           System.IO.Error (catchIOError)
import qualified Text.RSS as RSS

import Web.Hablog.Html
import Web.Hablog.Types
import Web.Hablog.Config
import qualified Web.Hablog.Post as Post
import qualified Web.Hablog.Page  as Page
import Network.URI (URI)

presentMain :: HablogAction ()
presentMain = do
  allPosts <- liftIO getAllPosts
  allPages <- liftIO getAllPages
  tgs <- liftIO getTagList
  auths <- liftIO getAuthorsList
  cfg <- getCfg
  html $ HR.renderHtml $ template cfg False "Posts" $ do
    H.aside ! A.class_ "aside" $ do
      presentPagesList allPages
      H.div ! A.class_ "AllAuthorsList" $ do
        H.h1 "Authors"
        auths
      H.div ! A.class_ "AllTagsList" $ do
        H.h1 "Tags"
        tgs
    postsListHtml allPosts

presentRSS :: URI -> HablogAction ()
presentRSS domain = do
  cfg <- getCfg
  allPosts <- liftIO getAllPosts
  let mime = "application/rss+xml"
  setHeader "content-type" mime
  raw
    . BSLC.pack
    . RSS.showXML
    . RSS.rssToXML
    . RSS.RSS (T.unpack $ blogTitle cfg) domain "" []
    . map (Post.toRSS $ blogDomain cfg)
    $ allPosts

showPostsWhere :: (Post.Post -> Bool) -> HablogAction ()
showPostsWhere test = do
  cfg <- getCfg
  allPosts <- liftIO getAllPosts
  html $ HR.renderHtml $ template cfg False "Posts" $
    postsListHtml $ filter test allPosts

presentPagesList :: [Page.Page] -> H.Html
presentPagesList [] = pure ()
presentPagesList pages =
  H.div ! A.class_ "AllAuthorsList" $ do
    H.h1 "Pages"
    getPageList pages


presentPage :: T.Text -> HablogAction ()
presentPage title =
  showOrNotFound pagePage . filter ((== T.unpack title) . Page.getPageURL) =<< liftIO getAllPages

getAllPages :: IO [Page.Page]
getAllPages = getAllFromDir Page.toPage "_pages"

getAllPosts :: IO [Post.Post]
getAllPosts = getAllFromDir Post.toPost "_posts"

getAllFromDir :: Ord a => (T.Text -> Maybe a) -> FilePath -> IO [a]
getAllFromDir parse dir = do
  posts <- fmap (L.delete ".." . L.delete ".") (DIR.getDirectoryContents dir `catchIOError` (\_ -> pure []))
  contents <- rights <$> mapM ((\x -> (T.decodeUtf8' <$> BSL.readFile x) `catchIOError` const (pure $ Left undefined)) . ((dir++"/")++)) posts
  pure . L.sortBy (flip compare) . catMaybes $ fmap parse (reverse contents)

presentPost :: T.Text -> HablogAction ()
presentPost title = do
  posts <- liftIO getAllPosts
  showOrNotFound postPage $ filter ((== title) . path) posts
  where path p = T.intercalate "/" ([Post.year, Post.month, Post.day, Post.route] <*> [p])

showOrNotFound :: (Config -> a -> H.Html) -> [a] -> HablogAction ()
showOrNotFound showP result = do
  cfg <- getCfg
  case result of
    (p:_) -> html $ HR.renderHtml $ showP cfg p
    []    -> html $ HR.renderHtml $ errorPage cfg "Hablog - 404: not found" "Could not find the page you were looking for."

presentTags :: HablogAction ()
presentTags = do
  cfg <- getCfg
  tags <- liftIO getTagList
  html . HR.renderHtml $ template cfg False "Posts Tags" tags

getTagList :: IO H.Html
getTagList = pure . tagsList . getAllTags =<< getAllPosts

getPageList :: [Page.Page] -> H.Html
getPageList = pagesList


getAuthorsList :: IO H.Html
getAuthorsList = pure . authorsList . getAllAuthors =<< getAllPosts

presentTag :: T.Text -> HablogAction ()
presentTag tag = do
  cfg <- getCfg
  posts <- liftIO getAllPosts
  html . HR.renderHtml . template cfg False tag $ postsListHtml $ filter (hasTag tag) posts

presentAuthors :: HablogAction ()
presentAuthors = do
  cfg <- getCfg
  authors <- liftIO getAuthorsList
  html . HR.renderHtml $ template cfg False "Posts Authors" authors

presentAuthor :: T.Text -> HablogAction ()
presentAuthor auth = do
  cfg <- getCfg
  posts <- liftIO getAllPosts
  html . HR.renderHtml . template cfg False auth . postsListHtml $ filter (hasAuthor auth) posts

getPageFromFile :: T.Text -> IO (Maybe Page.Page)
getPageFromFile title = do
  let path = T.unpack $ mconcat ["_pages/", title]
  getFromFile Page.toPage path

getPostFromFile :: T.Text -> T.Text -> IO (Maybe Post.Post)
getPostFromFile date title = do
  let postPath = T.unpack $ mconcat ["_posts/", date, "-", title, ".md"]
  getFromFile Post.toPost postPath

getFromFile :: (T.Text -> Maybe a) -> String -> IO (Maybe a)
getFromFile constructor path = do
  fileContent <- (T.decodeUtf8' <$> BSL.readFile path) `catchIOError` const (pure $ Left undefined)
  let cont = case fileContent of
              Left _  -> Nothing
              Right x -> Just x
  let content = constructor =<< cont
  pure content

getAllTags :: [Post.Post] -> [T.Text]
getAllTags = getAll Post.tags

hasTag :: T.Text -> Post.Post -> Bool
hasTag tag = ([]/=) . filter (==tag) . Post.tags

getAllAuthors :: [Post.Post] -> [T.Text]
getAllAuthors = getAll Post.authors

getAll :: (Post.Post -> [T.Text]) -> [Post.Post] -> [T.Text]
getAll f  = L.sort . map (T.unwords . T.words . head) . L.group . L.sort . concatMap f

hasAuthor :: T.Text -> Post.Post -> Bool
hasAuthor auth myPost = auth `elem` Post.authors myPost