{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE UndecidableInstances #-}
{-# LANGUAGE CPP #-}
-- | Widgets combine HTML with JS and CSS dependencies with a unique identifier
-- generator, allowing you to create truly modular HTML components.
module Yesod.Core.Widget
    ( -- * Datatype
      GWidget
    , PageContent (..)
      -- * Special Hamlet quasiquoter/TH for Widgets
    , whamlet
    , whamletFile
    , ihamletToRepHtml
      -- * Convert to Widget
    , ToWidget (..)
    , ToWidgetHead (..)
    , ToWidgetBody (..)
    , ToWidgetMedia (..)
      -- * Creating
      -- ** Head of page
    , setTitle
    , setTitleI
      -- ** CSS
    , addStylesheet
    , addStylesheetAttrs
    , addStylesheetRemote
    , addStylesheetRemoteAttrs
    , addStylesheetEither
    , CssBuilder (..)
      -- ** Javascript
    , addScript
    , addScriptAttrs
    , addScriptRemote
    , addScriptRemoteAttrs
    , addScriptEither
      -- * Internal
    , unGWidget
    , whamletFileWithSettings
    ) where

import Data.Monoid
import qualified Text.Blaze.Html5 as H
import Text.Hamlet
import Text.Cassius
import Text.Julius
import Yesod.Routes.Class
import Yesod.Core.Handler (getMessageRender, getUrlRenderParams)
import Yesod.Core.Class.MonadLift (lift)
import Text.Shakespeare.I18N (RenderMessage)
import Control.Monad (liftM)
import Data.Text (Text)
import qualified Data.Map as Map
import Language.Haskell.TH.Quote (QuasiQuoter)
import Language.Haskell.TH.Syntax (Q, Exp (InfixE, VarE, LamE, AppE), Pat (VarP), newName)

import qualified Text.Hamlet as NP
import Data.Text.Lazy.Builder (fromLazyText)
import Text.Blaze.Html (toHtml, preEscapedToMarkup)
import qualified Data.Text.Lazy as TL

import Yesod.Core.Types

preEscapedLazyText :: TL.Text -> Html
preEscapedLazyText = preEscapedToMarkup

class ToWidget site a where
    toWidget :: a -> GWidget site ()

instance render ~ RY site => ToWidget site (render -> Html) where
    toWidget x = tell $ GWData (Body x) mempty mempty mempty mempty mempty mempty
instance render ~ RY site => ToWidget site (render -> Css) where
    toWidget x = toWidget $ CssBuilder . fromLazyText . renderCss . x
instance render ~ RY site => ToWidget site (render -> CssBuilder) where
    toWidget x = tell $ GWData mempty mempty mempty mempty (Map.singleton Nothing $ unCssBuilder . x) mempty mempty
instance render ~ RY site => ToWidget site (render -> Javascript) where
    toWidget x = tell $ GWData mempty mempty mempty mempty mempty (Just x) mempty
instance (site' ~ site) => ToWidget site' (GWidget site ()) where
    toWidget = id
instance ToWidget site Html where
    toWidget = toWidget . const

-- | Allows adding some CSS to the page with a specific media type.
--
-- Since 1.2
class ToWidgetMedia site a where
    -- | Add the given content to the page, but only for the given media type.
    --
    -- Since 1.2
    toWidgetMedia :: Text -- ^ media value
                  -> a
                  -> GWidget site ()
instance render ~ RY site => ToWidgetMedia site (render -> Css) where
    toWidgetMedia media x = toWidgetMedia media $ CssBuilder . fromLazyText . renderCss . x
instance render ~ RY site => ToWidgetMedia site (render -> CssBuilder) where
    toWidgetMedia media x = tell $ GWData mempty mempty mempty mempty (Map.singleton (Just media) $ unCssBuilder . x) mempty mempty

class ToWidgetBody site a where
    toWidgetBody :: a -> GWidget site ()

instance render ~ RY site => ToWidgetBody site (render -> Html) where
    toWidgetBody = toWidget
instance render ~ RY site => ToWidgetBody site (render -> Javascript) where
    toWidgetBody j = toWidget $ \r -> H.script $ preEscapedLazyText $ renderJavascriptUrl r j
instance ToWidgetBody site Html where
    toWidgetBody = toWidget

class ToWidgetHead site a where
    toWidgetHead :: a -> GWidget site ()

instance render ~ RY site => ToWidgetHead site (render -> Html) where
    toWidgetHead = tell . GWData mempty mempty mempty mempty mempty mempty . Head
instance render ~ RY site => ToWidgetHead site (render -> Css) where
    toWidgetHead = toWidget
instance render ~ RY site => ToWidgetHead site (render -> CssBuilder) where
    toWidgetHead = toWidget
instance render ~ RY site => ToWidgetHead site (render -> Javascript) where
    toWidgetHead j = toWidgetHead $ \r -> H.script $ preEscapedLazyText $ renderJavascriptUrl r j
instance ToWidgetHead site Html where
    toWidgetHead = toWidgetHead . const

-- | Set the page title. Calling 'setTitle' multiple times overrides previously
-- set values.
setTitle :: Html -> GWidget site ()
setTitle x = tell $ GWData mempty (Last $ Just $ Title x) mempty mempty mempty mempty mempty

-- | Set the page title. Calling 'setTitle' multiple times overrides previously
-- set values.
setTitleI :: RenderMessage site msg => msg -> GWidget site ()
setTitleI msg = do
    mr <- lift getMessageRender
    setTitle $ toHtml $ mr msg

-- | Link to the specified local stylesheet.
addStylesheet :: Route site -> GWidget site ()
addStylesheet = flip addStylesheetAttrs []

-- | Link to the specified local stylesheet.
addStylesheetAttrs :: Route site -> [(Text, Text)] -> GWidget site ()
addStylesheetAttrs x y = tell $ GWData mempty mempty mempty (toUnique $ Stylesheet (Local x) y) mempty mempty mempty

-- | Link to the specified remote stylesheet.
addStylesheetRemote :: Text -> GWidget site ()
addStylesheetRemote = flip addStylesheetRemoteAttrs []

-- | Link to the specified remote stylesheet.
addStylesheetRemoteAttrs :: Text -> [(Text, Text)] -> GWidget site ()
addStylesheetRemoteAttrs x y = tell $ GWData mempty mempty mempty (toUnique $ Stylesheet (Remote x) y) mempty mempty mempty

addStylesheetEither :: Either (Route site) Text -> GWidget site ()
addStylesheetEither = either addStylesheet addStylesheetRemote

addScriptEither :: Either (Route site) Text -> GWidget site ()
addScriptEither = either addScript addScriptRemote

-- | Link to the specified local script.
addScript :: Route site -> GWidget site ()
addScript = flip addScriptAttrs []

-- | Link to the specified local script.
addScriptAttrs :: Route site -> [(Text, Text)] -> GWidget site ()
addScriptAttrs x y = tell $ GWData mempty mempty (toUnique $ Script (Local x) y) mempty mempty mempty mempty

-- | Link to the specified remote script.
addScriptRemote :: Text -> GWidget site ()
addScriptRemote = flip addScriptRemoteAttrs []

-- | Link to the specified remote script.
addScriptRemoteAttrs :: Text -> [(Text, Text)] -> GWidget site ()
addScriptRemoteAttrs x y = tell $ GWData mempty mempty (toUnique $ Script (Remote x) y) mempty mempty mempty mempty

whamlet :: QuasiQuoter
whamlet = NP.hamletWithSettings rules NP.defaultHamletSettings

whamletFile :: FilePath -> Q Exp
whamletFile = NP.hamletFileWithSettings rules NP.defaultHamletSettings

whamletFileWithSettings :: NP.HamletSettings -> FilePath -> Q Exp
whamletFileWithSettings = NP.hamletFileWithSettings rules

rules :: Q NP.HamletRules
rules = do
    ah <- [|toWidget|]
    let helper qg f = do
            x <- newName "urender"
            e <- f $ VarE x
            let e' = LamE [VarP x] e
            g <- qg
            bind <- [|(>>=)|]
            return $ InfixE (Just g) bind (Just e')
    let ur f = do
            let env = NP.Env
                    (Just $ helper [|liftW getUrlRenderParams|])
                    (Just $ helper [|liftM (toHtml .) $ liftW getMessageRender|])
            f env
    return $ NP.HamletRules ah ur $ \_ b -> return $ ah `AppE` b

-- | Wraps the 'Content' generated by 'hamletToContent' in a 'RepHtml'.
ihamletToRepHtml :: RenderMessage site message
                 => HtmlUrlI18n message (Route site)
                 -> GHandler site Html
ihamletToRepHtml ih = do
    urender <- getUrlRenderParams
    mrender <- getMessageRender
    return $ ih (toHtml . mrender) urender

tell :: GWData (Route site) -> GWidget site ()
tell w = GWidget $ return ((), w)

-- | Type-restricted version of @lift@. Used internally to create better error
-- messages.
liftW :: GHandler site a -> GWidget site a
liftW = lift

toUnique :: x -> UniqueList x
toUnique = UniqueList . (:)