{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TemplateHaskell #-}
module Input(fetchDocument, docForText) where

import           Data.Text.Lazy (fromStrict)
import qualified Data.Text as Txt
import           Data.Text.Encoding
import qualified Data.Text.Lazy as LTxt
import qualified Data.ByteString.Lazy as B
import qualified Text.HTML.DOM as HTML
import qualified Text.XML as XML
import           Network.URI
import           Network.URI.Fetch
import           Network.URI.Charset
import qualified Data.Map as M

import System.IO
import System.IO.Temp
import Data.Default.Class
import System.Directory
import Data.FileEmbed

-- For C API
import Types
import Data.HTML2CSS (html2css)
import Data.Maybe (fromMaybe)
import Foreign.StablePtr
import Foreign.C.String

fetchDocument http mime uri = fetchURL' http mime uri >>= parseDocument http
parseDocument sess (uri, "html/x-error\t", resp) = parseDocument sess (uri, "text/html", resp)
parseDocument _ (_, "text/html", Left text) = return $ HTML.parseLT $ fromStrict text
parseDocument _ (_, "text/html", Right bytes) = return $ HTML.parseLBS bytes

parseDocument _ (_, _, Left text)
    | Right doc <- XML.parseText def $ fromStrict text = return doc
    | otherwise = return $ docForText text
parseDocument _ (_, _, Right bytes) | Right doc <- XML.parseLBS def bytes = return doc
parseDocument _ (_, 't':'e':'x':'t':'/':_, Right bytes) =
    -- charset wasn't specified, so assume utf-8.
    return $ docForText $ convertCharset "utf-8" $ B.toStrict bytes
parseDocument sess resp@(_, mime, _) = do
    dir <- getCurrentDirectory -- TODO find Downloads directory.
    ret <- saveDownload nullURI {
        uriScheme = "file:",
        uriAuthority = Just (URIAuth "" "" "")
    } dir resp >>= dispatchByMIME sess mime
    return $ HTML.parseLT $ LTxt.pack $ fromMaybe "Unsupported filetype" ret

docForText txt = XML.Document {
        XML.documentPrologue = XML.Prologue [] Nothing [],
        XML.documentRoot = XML.Element {
            XML.elementName = "pre",
            XML.elementAttributes = M.empty,
            XML.elementNodes = [XML.NodeContent txt]
        },
        XML.documentEpilogue = []
    }

--------
---- C API
--------
foreign export ccall c_newSession :: IO (StablePtr Session)
foreign export ccall c_freeSession :: StablePtr Session -> IO ()

c_newSession = do
    sess <- newSession
    newStablePtr $ sess {aboutPages = map lazify $(embedDir "about")}
  where lazify (a, b) = (a, B.fromStrict b)
c_freeSession = freeStablePtr


foreign export ccall c_fetchURL :: StablePtr Session -> CString -> StablePtr Page -> CString -> IO (StablePtr Page)

c_fetchURL c_session c_mimes c_referer c_uri = do
    session <- deRefStablePtr c_session
    mimes <- peekCString c_mimes
    referer <- deRefStablePtr c_referer
    uri <- peekCString c_uri
    let uri' = nullURI `fromMaybe` parseURIReference uri `relativeTo` url referer
    doc <- fetchDocument session (words mimes) uri'
    newStablePtr $ Page {url = uri', html = doc, css = html2css doc uri'}