{-|
Description:    Token processing rules for spans of raw character strings.

Copyright:      (c) 2020-2021 Sam May
License:        MPL-2.0
Maintainer:     ag.eitilt@gmail.com

Stability:      stable
Portability:    portable
-}
module Web.Mangrove.Parse.Tree.InText
    ( treeInText
    , genericRawTextElement
    , genericRCDataElement
    ) where


import qualified Control.Monad.Trans.State as N.S

import qualified Data.Maybe as Y

import Web.Mangrove.Parse.Common.Error
import Web.Mangrove.Parse.Tokenize.Common
import Web.Mangrove.Parse.Tree.Common
import Web.Mangrove.Parse.Tree.Patch
import Web.Willow.Common.Parser
import Web.Willow.Common.Parser.Switch


-- | __HTML:__
--      @[the "text" insertion mode]
--      (https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-incdata)@
-- 
-- The parsing instructions corresponding to the 'InText' section of the state
-- machine.
treeInText :: TreeBuilder TreeOutput
treeInText = next >>= switch
    [ If isCharacter insertCharacter
    , If isEOF $ \t' -> do
        push t'
        N.S.modify $ \state -> state
            { insertionMode = Y.fromMaybe InText $ originalInsertionMode state
            , originalInsertionMode = Nothing
            }
        close <- consTreeError_ EOFInText <$> closeCurrentNode_
        packTree_ close
    , If (isEndTag ["script"]) $ \t' -> do
        resetMode
        close <- closeCurrentNode_
        packTree t' close
    , If isAnyEndTag $ \t' -> do
        resetMode
        closeCurrentNode t'
    ]


-- | __HTML:__
--      @[generic raw text element parsing algorithm]
--      (https://html.spec.whatwg.org/multipage/parsing.html#generic-raw-text-element-parsing-algorithm)@
-- 
-- Insert an element containing unescaped plain text.
genericRawTextElement :: TreeInput -> TreeBuilder TreeOutput
genericRawTextElement = genericParsingAlgorithm RawTextState

-- | __HTML:__
--      @[generic RCDATA element parsing algorithm]
--      (https://html.spec.whatwg.org/multipage/parsing.html#generic-rcdata-element-parsing-algorithm)@
-- 
-- Insert an element containing plain text, potentially with character
-- references.
genericRCDataElement :: TreeInput -> TreeBuilder TreeOutput
genericRCDataElement = genericParsingAlgorithm RCDataState

-- | __HTML:__
--      @[parsing elements that contain only text]
--      (https://html.spec.whatwg.org/multipage/parsing.html#parsing-elements-that-contain-only-text)@
-- 
-- The actual algorithm described for 'genericRawTextElement' and
-- 'genericRCDataElement', with all variables exported.
genericParsingAlgorithm :: CurrentTokenizerState -> TreeInput -> TreeBuilder TreeOutput
genericParsingAlgorithm mode t' = do
    N.S.modify $ \state -> state
        { insertionMode = InText
        , originalInsertionMode = Just $ insertionMode state
        }
    insertElement . mapTokenState t' $ \state -> state
        { currentState = mode
        }