41 lines
1.4 KiB
Haskell
41 lines
1.4 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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module Navigation
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( navFinder,
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lndmkScraper
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)
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where
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import Text.HTML.Scalpel (Scraper, attr, (@:), (@=), chroot, chroots, text, match)
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import Types (NavItem(..), EpubType (..), InternalPath(..))
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import Data.Maybe (fromMaybe)
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import Control.Applicative (optional)
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import Control.Monad (guard)
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import qualified Data.Text as T
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-- ------------------------------------------------------------
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-- EPub 3 navigation
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-- ------------------------------------------------------------
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-- The epub-metadata library is good for epub 2.x. As there could be a seperate nav.xhtml file in the epub 3.x spec, we need these functions to support it.
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navFinder :: Scraper String FilePath
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navFinder = attr "href" ("item" @: ["properties" @= "nav"])
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itemScraper :: [EpubType] -> Scraper T.Text NavItem
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itemScraper allowedTypes = do
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label <- text "a"
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path <- attr "href" "a"
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rawTypes <- fromMaybe "" <$> optional (attr "epub:type" "a")
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let foundTypes = map EpubType $ T.words rawTypes
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guard $ any (`elem` allowedTypes) foundTypes
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pure $ NavItem label (InternalPath $ T.unpack path) foundTypes
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lndmkScraper :: [EpubType] -> Scraper T.Text [NavItem]
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lndmkScraper labels =
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chroot ("nav" @: [match navPredicate]) $ chroots "li" (itemScraper labels)
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where
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navPredicate "epub:type" xs = EpubType (T.pack xs) `elem` labels
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navPredicate _ _ = False
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