{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE NoImplicitPrelude #-}


module Web.Geek.RSS (rss) where

import Air.Data.Record.SimpleLabel hiding (get)
import Air.Env hiding (head, div)
import Air.Extra hiding (date)
import Air.TH (here)

import qualified Web.Geek.Type as Geek
import Data.Text (Text)

import Text.HTML.Moe2 hiding ((/), text)
import Text.HTML.Moe2.Type (MoeUnit)
import Data.ByteString (ByteString)
import qualified Data.Text as T
import Data.Maybe
import Control.Monad (forM_)
import System.Locale (defaultTimeLocale)
import Data.Time (formatTime)

  {-
  
  <?xml version="1.0" encoding="UTF-8"?>
  <rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
    <channel>
      <title>{{ site.name }}</title>
      <description>{{ site.description }}</description>
      <link>{{ site.url }}</link>
      <atom:link href="{{ site.url }}/rss.xml" rel="self" type="application/rss+xml" />
      {% for post in site.posts limit:10 %}
        <item>
          <title>{{ post.title }}</title>
          <description>{{ post.content | xml_escape }}</description>
          <pubDate>{{ post.date | date: "%a, %d %b %Y %H:%M:%S %z" }}</pubDate>
          <link>{{ site.url }}{{ post.url }}</link>
          <guid isPermaLink="true">{{ site.url }}{{ post.url }}</guid>
        </item>
      {% endfor %}
    </channel>
  </rss>
  
  <link rel="alternate" type="application/rss+xml" title="{{ site.name }}" href="{{ site.url }}/rss.xml">
  
  -}

-- xml_header 
xml_header :: MoeUnit
xml_header = no_escape_no_indent_str "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"

text :: T.Text -> MoeUnit
text = T.unpack > str

rss :: Geek.Config -> [Geek.Post] -> Maybe Text -> ByteString
rss _config _posts _maybe_tag = l2s - render_bytestring - do
  let drop_tail_slash xs = xs.reverse.dropWhile (is '/').reverse
  
      site_link = _config.Geek.rss_site_link.T.unpack.drop_tail_slash
      site_link_with_prefix = 
        (
        [
          site_link
        , _config.Geek.rss_site_root_prefix.T.unpack.drop_tail_slash.reverse.drop_tail_slash
        ]
        ).join "/"
        
  xml_header
  
  element "rss" ! [attr "version" "2.0", attr "xmlns:atom" "http://www.w3.org/2005/Atom"] - do
    element "channel" - do
      title - do
        text - _config.Geek.rss_site_title
        
      element "description" - do
        text - _config.Geek.rss_site_description
        
      element "link" - do

              
        str - site_link
      
      element "atom:link" ! [href (site_link + "/rss.xml"), attr "rel" "self", _type "application/rss+xml"] -
        return ()
      
      forM_ _posts - \_post ->
        element "item" - do
          title - do
            text - _post.Geek.title
          
          element "description" - do
            text - _post.Geek.body.Geek.unHTMLText
          
          element "pubDate" - do
            let pub_date_format_string = "%a, %d %b %Y %H:%M:%S %z"
            str - _post.Geek.date.fromMaybe def.formatTime defaultTimeLocale pub_date_format_string
            
          let post_link = site_link_with_prefix + "/" +  _post.Geek.link.Geek.unURIEscapedText.T.unpack
          element "link" - do
            str - post_link
          element "guid" ! [attr "isPermaLink" "true"] - do
            str - post_link