    {-# LANGUAGE BangPatterns      #-}
    {-# LANGUAGE CPP               #-}
    {-# LANGUAGE OverloadedStrings #-}
    {-# LANGUAGE TupleSections     #-}

    {-|

    This module defines the core data types used by Heist.  In practice you will
    also want to import one or both of "Heist.Compiled" or "Heist.Interpreted" to
    get functions needed for writing splices.

    The Heist template system allows you to build custom HTML and XML based markup
    languages.  With Heist you can define your own domain-specific tags
    implemented with Haskell and use them in your templates.

    -}

    module Heist
      (
      -- * Primary Heist initialization functions
        loadTemplates
      , reloadTemplates
      , addTemplatePathPrefix
      , initHeist
      , initHeistWithCacheTag
      , defaultInterpretedSplices
      , defaultLoadTimeSplices
      , emptyHeistConfig

      -- * Core Heist data types
      , SpliceConfig
      , HeistConfig
      , TemplateRepo
      , TemplateLocation
      , Template
      , TPath
      , MIMEType
      , DocumentFile(..)
      , AttrSplice
      , RuntimeSplice
      , Chunk
      , HeistState
      , SpliceError(..)
      , CompileException(..)
      , HeistT

      -- * Lenses (can be used with lens or lens-family)
      , scInterpretedSplices
      , scLoadTimeSplices
      , scCompiledSplices
      , scAttributeSplices
      , scTemplateLocations
      , scCompiledTemplateFilter
      , hcSpliceConfig
      , hcNamespace
      , hcErrorNotBound
      , hcInterpretedSplices
      , hcLoadTimeSplices
      , hcCompiledSplices
      , hcAttributeSplices
      , hcTemplateLocations
      , hcCompiledTemplateFilter

      -- * HeistT functions
      , templateNames
      , compiledTemplateNames
      , hasTemplate
      , spliceNames
      , compiledSpliceNames
      , evalHeistT
      , getParamNode
      , getContext
      , getTemplateFilePath
      , localParamNode
      , getsHS
      , getHS
      , putHS
      , modifyHS
      , restoreHS
      , localHS
      , getDoc
      , getXMLDoc
      , tellSpliceError
      , spliceErrorText
      , orError
      , Splices
      ) where

    ------------------------------------------------------------------------------
    import           Control.Exception.Lifted
    import           Control.Monad.State
    import           Data.ByteString               (ByteString)
    import qualified Data.ByteString.Char8         as BC
    import qualified Data.ByteString               as B
    import           Data.Either
    import qualified Data.Foldable                 as F
    import           Data.HashMap.Strict           (HashMap)
    import qualified Data.HashMap.Strict           as Map
    import qualified Data.HeterogeneousEnvironment as HE
    import           Data.Map.Syntax
    #if !MIN_VERSION_base(4,11,0)
    import           Data.Monoid
    #endif
    import           Data.Text                     (Text)
    import qualified Data.Text                     as T
    import           System.Directory.Tree
    import qualified Text.XmlHtml                  as X
    ------------------------------------------------------------------------------
    import           Heist.Common
    import qualified Heist.Compiled.Internal       as C
    import qualified Heist.Interpreted.Internal    as I
    import           Heist.Splices
    import           Heist.Internal.Types
    ------------------------------------------------------------------------------

    ------------------------------------------------------------------------------
    -- | The built-in set of splices that you should use in compiled splice mode.
    -- This list includes everything from 'defaultInterpretedSplices' plus a
    -- splice for the content tag that errors out when it sees any instance of the
    -- old content tag, which has now been moved to two separate tags called
    -- apply-content and bind-content.
    defaultLoadTimeSplices :: MonadIO m => Splices (I.Splice m)
    defaultLoadTimeSplices = do
        -- To be removed in later versions
        defaultInterpretedSplices
        "content" #! deprecatedContentCheck

    ------------------------------------------------------------------------------
    -- | The built-in set of static splices.  All the splices that used to be
    -- enabled by default are included here.  To get the normal Heist behavior you
    -- should include these in the scLoadTimeSplices list in your SpliceConfig.
    -- If you are using interpreted splice mode, then you might also want to bind
    -- the 'deprecatedContentCheck' splice to the content tag as a load time
    -- splice.
    defaultInterpretedSplices :: MonadIO m => Splices (I.Splice m)
    defaultInterpretedSplices = do
        applyTag ## applyImpl
        bindTag ## bindImpl
        ignoreTag ## ignoreImpl
        markdownTag ## markdownSplice

    ------------------------------------------------------------------------------
    -- | An empty HeistConfig that uses the \"h\" namespace with error checking
    -- turned on.
    emptyHeistConfig :: HeistConfig m
    emptyHeistConfig = HeistConfig mempty "h" True

    allErrors :: [Either String (TPath, v)]
              -> Either [String] (HashMap TPath v)
    allErrors tlist =
        case errs of
            [] -> Right $ Map.fromList $ rights tlist
            _  -> Left errs
      where
        errs = lefts tlist

    ------------------------------------------------------------------------------
    -- | Loads templates from disk.  This function returns just a template map so
    -- you can load multiple directories and combine the maps before initializing
    -- your HeistState.
    loadTemplates :: FilePath -> IO (Either [String] TemplateRepo)
    loadTemplates dir = do
        d <- readDirectoryWith (loadTemplate dir) dir
    #if MIN_VERSION_directory_tree(0,11,0)
        return $ allErrors $ F.fold (dirTree d)
    #else
        return $ allErrors $ F.fold (free d)
    #endif

    ------------------------------------------------------------------------------
    -- | Reloads all the templates an an existing TemplateRepo.
    reloadTemplates :: TemplateRepo -> IO (Either [String] TemplateRepo)
    reloadTemplates repo = do
        tlist <- mapM loadOrKeep $ Map.toList repo
        return $ allErrors tlist
      where
        loadOrKeep (p,df) =
          case dfFile df of
            Nothing -> return $ Right (p, df)
            Just fp -> do
              df' <- loadTemplate' fp
              return $ fmap (p,) $ case df' of
                [t] -> t
                _ -> Left "Template repo has non-templates"

    ------------------------------------------------------------------------------
    -- | Adds a path prefix to a templates in a map returned by loadTemplates.  If
    -- you want to add multiple levels of directories, separate them with slashes
    -- as in "foo/bar".  Using an empty string as a path prefix will leave the
    -- map unchanged.
    addTemplatePathPrefix :: ByteString -> TemplateRepo -> TemplateRepo
    addTemplatePathPrefix dir ts
      | B.null dir = ts
      | otherwise  = Map.fromList $
                     map (\(x,y) -> (f x, y)) $
                     Map.toList ts
      where
        f ps = ps++splitTemplatePath dir

    ------------------------------------------------------------------------------
    -- | Creates an empty HeistState.
    emptyHS :: HE.KeyGen -> HeistState m
    emptyHS kg = HeistState Map.empty Map.empty Map.empty Map.empty Map.empty
                            True [] [] 0 [] Nothing kg False Html "" [] False 0

    ------------------------------------------------------------------------------
    -- | This is the main Heist initialization function.  You pass in a map of all
    -- templates and all of your splices and it constructs and returns a
    -- HeistState.
    --
    -- We don't provide functions to add either type of loadtime splices to your
    -- HeistState after initHeist because it doesn't make any sense unless you
    -- re-initialize all templates with the new splices.  If you add any old-style
    -- runtime heist splices after calling this function, they will still work
    -- fine if you use Heist.Interpreted.renderTemplate.  If you add any templates
    -- later, then those templates will be available for interpreted rendering,
    -- but not for compiled rendering.
    --
    -- In the past you could add templates to your HeistState after initialization
    -- using its Monoid instance.  Due to implementation details, this is no
    -- longer possible.  All of your templates must be known when you call this
    -- function.
    initHeist :: Monad n
              => HeistConfig n
              -> IO (Either [String] (HeistState n))
    initHeist hc = do
        keyGen <- HE.newKeyGen
        repos <- sequence $ _scTemplateLocations $ _hcSpliceConfig hc
        case sequence repos of
          Left es -> return $ Left es
          Right rs -> initHeist' keyGen hc (Map.unions rs)

    ------------------------------------------------------------------------------
    mkSplicePrefix :: Text -> Text
    mkSplicePrefix ns
      | T.null ns = ""
      | otherwise = ns `mappend` ":"

    ------------------------------------------------------------------------------
    initHeist' :: Monad n
               => HE.KeyGen
               -> HeistConfig n
               -> TemplateRepo
               -> IO (Either [String] (HeistState n))
    initHeist' keyGen (HeistConfig sc ns enn) repo = do
        let empty = emptyHS keyGen
        let (SpliceConfig i lt c a _ f) = sc
        etmap <- preproc keyGen lt repo ns
        let prefix = mkSplicePrefix ns
        let eis = runHashMap $ mapK (prefix<>) i
            ecs = runHashMap $ mapK (prefix<>) c
            eas = runHashMap $ mapK (prefix<>) a
        let hs1 = do
              tmap <- etmap
              is <- eis
              cs <- ecs
              as <- eas
              return $ empty { _spliceMap = is
                             , _templateMap = tmap
                             , _compiledSpliceMap = cs
                             , _attrSpliceMap = as
                             , _splicePrefix = prefix
                             , _errorNotBound = enn
                             }
        either (return . Left) (C.compileTemplates f) hs1

    ------------------------------------------------------------------------------
    -- | Runs preprocess on a TemplateRepo and returns the modified templates.
    preproc :: HE.KeyGen
            -> Splices (I.Splice IO)
            -> TemplateRepo
            -> Text
            -> IO (Either [String] TemplateRepo)
    preproc keyGen splices templates ns = do
        let esm = runHashMap splices
        case esm of
          Left errs -> return $ Left errs
          Right sm -> do
            let hs = (emptyHS keyGen) { _spliceMap = sm
                                      , _templateMap = templates
                                      , _preprocessingMode = True
                                      , _splicePrefix = mkSplicePrefix ns }
            let eval a = evalHeistT a (X.TextNode "") hs
            tPairs <- mapM (eval . preprocess) $ Map.toList templates
            let bad = lefts tPairs
            return $ if not (null bad)
                       then Left bad
                       else Right $ Map.fromList $ rights tPairs

    ------------------------------------------------------------------------------
    -- | Processes a single template, running load time splices.
    preprocess :: (TPath, DocumentFile)
               -> HeistT IO IO (Either String (TPath, DocumentFile))
    preprocess (tpath, docFile) = do
        let tname = tpathName tpath
            die   = error $ "Preprocess failed because the template `"
                         ++ BC.unpack tname
                         ++ "` was not found in the template repository."
        !emdoc <- try $ I.evalWithDoctypes tname
                  :: HeistT IO IO (Either SomeException (Maybe X.Document))
        let f !doc = (tpath, docFile { dfDoc = doc })
        return $! either (Left . show) (Right . maybe die f) emdoc

    ------------------------------------------------------------------------------
    -- | Wrapper around initHeist that also sets up a cache tag.  It sets up both
    -- compiled and interpreted versions of the cache tag splices.  If you need to
    -- configure the cache tag differently than how this function does it, you
    -- will still probably want to pattern your approach after this function's
    -- implementation.
    initHeistWithCacheTag :: MonadIO n
                          => HeistConfig n
                          -> IO (Either [String] (HeistState n, CacheTagState))
    initHeistWithCacheTag (HeistConfig sc ns enn) = do
        (ss, cts) <- liftIO mkCacheTag
        let tag = "cache"
        keyGen <- HE.newKeyGen

        erepos <- sequence $ _scTemplateLocations sc
        case sequence erepos of
          Left es -> return $ Left es
          Right repos -> do
            -- We have to do one preprocessing pass with the cache setup splice.  This
            -- has to happen for both interpreted and compiled templates, so we do it
            -- here by itself because interpreted templates don't get the same load
            -- time splices as compiled templates.
            eRawWithCache <- preproc keyGen (tag ## ss) (Map.unions repos) ns
            case eRawWithCache of
              Left es -> return $ Left es
              Right rawWithCache -> do
                let sc' = SpliceConfig (tag #! cacheImpl cts) mempty
                                       (tag #! cacheImplCompiled cts)
                                       mempty mempty (const True)
                let hc = HeistConfig (mappend sc sc') ns enn
                hs <- initHeist' keyGen hc rawWithCache
                return $ fmap (,cts) hs