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{-# LANGUAGE OverloadedStrings #-}
import           Data.Monoid (mappend)
import           Hakyll
import           Data.List (sortBy, sortOn)
import           Data.Time (formatTime, defaultTimeLocale)


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main :: IO ()
main = hakyll $ do
    match "images/*" $ do
        route   idRoute
        compile copyFileCompiler

    match "resources/*" $ do
        route   idRoute
        compile copyFileCompiler

    match "css/*" $ do
        route   idRoute
        compile compressCssCompiler

    match "js/*" $ do
        route   idRoute
        compile compressCssCompiler

    match (fromList ["about.markdown", "contact.markdown"]) $ do
        route   $ setExtension "html"
        compile $ pandocCompiler
            >>= loadAndApplyTemplate "templates/default.html" defaultContext
            >>= relativizeUrls

    match "posts/guides/*" $ do
      route $ setExtension "html"
      compile $ pandocCompiler
        >>= loadAndApplyTemplate "templates/post.html"    postCtx
        >>= loadAndApplyTemplate "templates/default.html" postCtx
        >>= relativizeUrls

    match "posts/brainstorming/*" $ do
      route $ setExtension "html"
      compile $ pandocCompiler
        >>= loadAndApplyTemplate "templates/post.html"    postCtx
        >>= loadAndApplyTemplate "templates/default.html" postCtx
        >>= relativizeUrls

    create ["guides.html"] $ do
        route idRoute
        compile $ do
            posts <- modFirst =<< loadAll "posts/guides/*"
            let archiveCtx =
                    listField "posts" postCtx (return posts) `mappend`
                    constField "title" "Guides"            `mappend`
                    defaultContext

            makeItem ""
                >>= loadAndApplyTemplate "templates/guides.html" archiveCtx
                >>= loadAndApplyTemplate "templates/default.html" archiveCtx
                >>= relativizeUrls

    match "index.html" $ do
        route idRoute
        compile $ do
            let indexCtx =
                    constField "title" "Home"                `mappend`
                    defaultContext

            getResourceBody
                >>= applyAsTemplate indexCtx
                >>= loadAndApplyTemplate "templates/default.html" indexCtx
                >>= relativizeUrls

    match "templates/*" $ compile templateBodyCompiler

modFirst :: [Item a] -> Compiler [Item a]
modFirst = fmap reverse . modified
  where
    modified = sortByM (getItemModificationTime . itemIdentifier)
    sortByM f xs = map fst . sortOn snd <$> mapM (\x -> (,) x <$> f x) xs

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postCtx :: Context String
postCtx =
    dateField "date" "%B %e, %Y" `mappend`
    modifiedField "modified" "%B %e, %Y" `mappend`
    defaultContext
  where
    modifiedField key format = field key $ \i -> do
      time <- getItemModificationTime $ itemIdentifier i
      return $ formatTime defaultTimeLocale format time