---
-- |
-- Copy from: https://hackage.haskell.org/package/feed-1.0.0.0/docs/src/Text-Atom-Feed-Export.html
-- Custmize export XML
---
{-# LANGUAGE OverloadedStrings #-}

module ScrapBook.Feed.Atom.Internal
    ( xmlFeed
    ) where

import           RIO            hiding (Category)
import qualified RIO.Text       as T

import           Data.XML.Types as XML
import           Text.Atom.Feed

xmlFeed :: Feed -> XML.Element
xmlFeed f = (  atomNode "feed"
            $  map NodeElement
            $  [xmlTitle (feedTitle f)]
            ++ [xmlId (feedId f)]
            ++ [xmlUpdated (feedUpdated f)]
            ++ map xmlLink        (feedLinks f)
            ++ map xmlAuthor      (feedAuthors f)
            ++ map xmlCategory    (feedCategories f)
            ++ map xmlContributor (feedContributors f)
            ++ mb  xmlGenerator   (feedGenerator f)
            ++ mb  xmlIcon        (feedIcon f)
            ++ mb  xmlLogo        (feedLogo f)
            ++ mb  xmlRights      (feedRights f)
            ++ mb  xmlSubtitle    (feedSubtitle f)
            ++ map xmlEntry       (feedEntries f)
            ++ feedOther f
            )
  { elementAttributes = [xmlnsAtom]
  }

---

atomPrefix :: Maybe Text
atomPrefix = Nothing -- Just "atom"

atomThrPrefix :: Maybe Text
atomThrPrefix = Just "thr"

atomNS :: Text
atomNS = "http://www.w3.org/2005/Atom"

atomThreadNS :: Text
atomThreadNS = "http://purl.org/syndication/thread/1.0"

blankElement :: Name -> [Node] -> XML.Element
blankElement name = XML.Element name []

xmlnsAtom :: Attr
xmlnsAtom = (qn, [ContentText atomNS])
 where
  qn = case atomPrefix of
    Nothing -> Name
      { nameLocalName = "xmlns"
      , nameNamespace = Nothing
      , namePrefix    = Nothing
      }
    Just s -> Name
      { nameLocalName = s
      , nameNamespace = Nothing -- XXX: is this ok?
      , namePrefix    = Just "xmlns"
      }

atomName :: Text -> Name
atomName nc =
  Name {nameLocalName = nc, nameNamespace = Nothing, namePrefix = atomPrefix}

atomAttr :: Text -> Text -> Attr
atomAttr x y = (atomName x, [ContentText y])

atomNode :: Text -> [Node] -> XML.Element
atomNode x = blankElement (atomName x)

atomLeaf :: Text -> Text -> XML.Element
atomLeaf tag txt = blankElement (atomName tag) [NodeContent $ ContentText txt]

atomThreadName :: Text -> Name
atomThreadName nc = Name
  { nameLocalName = nc
  , nameNamespace = Just atomThreadNS
  , namePrefix    = atomThrPrefix
  }

atomThreadAttr :: Text -> Text -> Attr
atomThreadAttr x y = (atomThreadName x, [ContentText y])

atomThreadNode :: Text -> [Node] -> XML.Element
atomThreadNode x = blankElement (atomThreadName x)

atomThreadLeaf :: Text -> Text -> XML.Element
atomThreadLeaf tag txt =
  blankElement (atomThreadName tag) [NodeContent $ ContentText txt]

--------------------------------------------------------------------------------

xmlEntry :: Entry -> XML.Element
xmlEntry e = (  atomNode "entry"
             $  map NodeElement
             $  [xmlId (entryId e)]
             ++ [xmlTitle (entryTitle e)]
             ++ [xmlUpdated (entryUpdated e)]
             ++ map xmlAuthor       (entryAuthors e)
             ++ map xmlCategory     (entryCategories e)
             ++ mb  xmlContent      (entryContent e)
             ++ map xmlContributor  (entryContributor e)
             ++ map xmlLink         (entryLinks e)
             ++ mb  xmlPublished    (entryPublished e)
             ++ mb  xmlRights       (entryRights e)
             ++ mb  xmlSource       (entrySource e)
             ++ mb  xmlSummary      (entrySummary e)
             ++ mb  xmlInReplyTo    (entryInReplyTo e)
             ++ mb  xmlInReplyTotal (entryInReplyTotal e)
             ++ entryOther e
             )
  { elementAttributes = entryAttrs e
  }

xmlContent :: EntryContent -> XML.Element
xmlContent cont = case cont of
  TextContent t ->
    (atomLeaf "content" t) { elementAttributes = [atomAttr "type" "text"] }
  HTMLContent t ->
    (atomLeaf "content" t) {elementAttributes = [atomAttr "type" "html"]}
  XHTMLContent x -> (atomNode "content" [NodeElement x])
    { elementAttributes = [atomAttr "type" "xhtml"]
    }
  MixedContent mbTy cs ->
    (atomNode "content" cs) { elementAttributes = mb (atomAttr "type") mbTy }
  ExternalContent mbTy src -> (atomNode "content" [])
    { elementAttributes = atomAttr "src" src : mb (atomAttr "type") mbTy
    }

xmlCategory :: Category -> XML.Element
xmlCategory c = (atomNode "category" (map NodeElement (catOther c)))
  { elementAttributes = [atomAttr "term" (catTerm c)]
    ++ mb (atomAttr "scheme") (catScheme c)
    ++ mb (atomAttr "label")  (catLabel c)
  }

xmlLink :: Link -> XML.Element
xmlLink l = (atomNode "link" (map NodeElement (linkOther l)))
  { elementAttributes = [atomAttr "href" (linkHref l)]
    ++ mb (atomAttr "rel" . either id id) (linkRel l)
    ++ mb (atomAttr "type")               (linkType l)
    ++ mb (atomAttr "hreflang")           (linkHrefLang l)
    ++ mb (atomAttr "title")              (linkTitle l)
    ++ mb (atomAttr "length")             (linkLength l)
    ++ linkAttrs l
  }

xmlSource :: Source -> Element
xmlSource s =
  atomNode "source"
    $  map NodeElement
    $  sourceOther s
    ++ map xmlAuthor    (sourceAuthors s)
    ++ map xmlCategory  (sourceCategories s)
    ++ mb  xmlGenerator (sourceGenerator s)
    ++ mb  xmlIcon      (sourceIcon s)
    ++ mb  xmlId        (sourceId s)
    ++ map xmlLink      (sourceLinks s)
    ++ mb  xmlLogo      (sourceLogo s)
    ++ mb  xmlRights    (sourceRights s)
    ++ mb  xmlSubtitle  (sourceSubtitle s)
    ++ mb  xmlTitle     (sourceTitle s)
    ++ mb  xmlUpdated   (sourceUpdated s)

xmlGenerator :: Generator -> Element
xmlGenerator g = (atomLeaf "generator" (genText g))
  { elementAttributes = mb (atomAttr "uri") (genURI g)
    ++ mb (atomAttr "version") (genVersion g)
  }

xmlAuthor :: Person -> XML.Element
xmlAuthor p = atomNode "author" (xmlPerson p)

xmlContributor :: Person -> XML.Element
xmlContributor c = atomNode "contributor" (xmlPerson c)

xmlPerson :: Person -> [XML.Node]
xmlPerson p =
  map NodeElement
    $  [atomLeaf "name" (personName p)]
    ++ mb (atomLeaf "uri")   (personURI p)
    ++ mb (atomLeaf "email") (personEmail p)
    ++ personOther p

xmlInReplyTo :: InReplyTo -> XML.Element
xmlInReplyTo irt = (atomThreadNode "in-reply-to" (replyToContent irt))
  { elementAttributes = mb (atomThreadAttr "ref") (Just $ replyToRef irt)
    ++ mb (atomThreadAttr "href")   (replyToHRef irt)
    ++ mb (atomThreadAttr "type")   (replyToType irt)
    ++ mb (atomThreadAttr "source") (replyToSource irt)
    ++ replyToOther irt
  }

xmlInReplyTotal :: InReplyTotal -> XML.Element
xmlInReplyTotal irt = (atomThreadLeaf "total" (T.pack $ show $ replyToTotal irt))
  { elementAttributes = replyToTotalOther irt
  }

xmlId :: Text -> XML.Element
xmlId = atomLeaf "id"

xmlIcon :: URI -> XML.Element
xmlIcon = atomLeaf "icon"

xmlLogo :: URI -> XML.Element
xmlLogo = atomLeaf "logo"

xmlUpdated :: Date -> XML.Element
xmlUpdated = atomLeaf "updated"

xmlPublished :: Date -> XML.Element
xmlPublished = atomLeaf "published"

xmlRights :: TextContent -> XML.Element
xmlRights = xmlTextContent "rights"

xmlTitle :: TextContent -> XML.Element
xmlTitle = xmlTextContent "title"

xmlSubtitle :: TextContent -> XML.Element
xmlSubtitle = xmlTextContent "subtitle"

xmlSummary :: TextContent -> XML.Element
xmlSummary = xmlTextContent "summary"

xmlTextContent :: Text -> TextContent -> XML.Element
xmlTextContent tg t = case t of
  TextString s ->
    (atomLeaf tg s) { elementAttributes = [atomAttr "type" "text"] }
  HTMLString s ->
    (atomLeaf tg s) { elementAttributes = [atomAttr "type" "html"] }
  XHTMLString e -> (atomNode tg [XML.NodeElement e])
    { elementAttributes = [atomAttr "type" "xhtml"]
    }

--------------------------------------------------------------------------------
mb :: (a -> b) -> Maybe a -> [b]
mb _ Nothing  = []
mb f (Just x) = [f x]