#!/usr/bin/env nix-script
#!>haskell
#! haskell | shell-conduit temporary transformers raw-strings-qq
#! shell   | curl

{-# LANGUAGE QuasiQuotes  #-}

import Control.Monad
import Control.Monad.IO.Class      (liftIO)
import Text.Printf                 (printf)
import Text.RawString.QQ           (r)
import System.IO.Temp              (withSystemTempDirectory)
import System.Directory            (copyFile, createDirectoryIfMissing)
import System.FilePath
import Data.Conduit.Shell          (Segment, run, shell, grep)
import Data.Conduit.Shell.Segments (strings)

type Url = String
type Sed = String


privoxy :: FilePath
privoxy = "/var/lib/privoxy"


urls :: [Url]
urls = 
  [ "https://easylist.to/easylist/easylist.txt"
  , "https://easylist.to/easylist/easyprivacy.txt"
  , "https://easylist.to/easylist/fanboy-annoyance.txt"
  , "https://www.fanboy.co.nz/fanboy-cookiemonster.txt"
  ]


rules :: [Sed]
rules = 
  [ [r|/^!.*/d;1,1 d;/^@@.*/d;/\$.*/d;/#/d;s/\./\\./g;s/\?/\\?/g;s/\*/.*/g;s/(/\\(/g;s/)/\\)/g;s/\[/\\[/g;s/\]/\\]/g;s/\^/[\/\&:\?=_]/g;s/^||/\./g;s/^|/^/g;s/|$/\$/g;/|/d|]
  , [r|/^#/!d;s/^##//g;s/^#\(.*\)\[.*\]\[.*\]*/s|<([a-zA-Z0-9]+)\\s+.*id=.?\1.*>.*<\/\\1>||g/g;s/^#\(.*\)/s|<([a-zA-Z0-9]+)\\s+.*id=.?\1.*>.*<\/\\1>||g/g;s/^\.\(.*\)/s|<([a-zA-Z0-9]+)\\s+.*class=.?\1.*>.*<\/\\1>||g/g;s/^a\[\(.*\)\]/s|<a.*\1.*>.*<\/a>||g/g;s/^\([a-zA-Z0-9]*\)\.\(.*\)\[.*\]\[.*\]*/s|<\1.*class=.?\2.*>.*<\/\1>||g/g;s/^\([a-zA-Z0-9]*\)#\(.*\):.*[\:[^:]]*[^:]*/s|<\1.*id=.?\2.*>.*<\/\1>||g/g;s/^\([a-zA-Z0-9]*\)#\(.*\)/s|<\1.*id=.?\2.*>.*<\/\1>||g/g;s/^\[\([a-zA-Z]*\).=\(.*\)\]/s|\1^=\2>||g/g;s/\^/[\/\&:\?=_]/g;s/\.\([a-zA-Z0-9]\)/\\.\1/g|]
  , [r|/^@@.*/!d;s/^@@//g;/\$.*/d;/#/d;s/\./\\./g;s/\?/\\?/g;s/\*/.*/g;s/(/\\(/g;s/)/\\)/g;s/\[/\\[/g;s/\]/\\]/g;s/\^/[\/\&:\?=_]/g;s/^||/\./g;s/^|/^/g;s/|$/\$/g;/|/d|]
  , [r|/^@@.*/!d;s/^@@//g;/\$.*image.*/!d;s/\$.*image.*//g;/#/d;s/\./\\./g;s/\?/\\?/g;s/\*/.*/g;s/(/\\(/g;s/)/\\)/g;s/\[/\\[/g;s/\]/\\]/g;s/\^/[\/\&:\?=_]/g;s/^||/\./g;s/^|/^/g;s/|$/\$/g;/|/d|]
  ]

main :: IO ()
main = withSystemTempDirectory "privoxy" (forM_ urls . generateConfig)


get :: Segment () -> IO String
get = fmap head . run . strings


notify :: String -> Segment () -> IO ()
notify msg action =
  putStr (printf "  %s..." msg) >> run action >> putStrLn " done"


generateConfig :: FilePath -> Url -> IO ()
generateConfig dir url = do
  let list   = takeBaseName url 
      file   = dir </> list <.> "txt"
      action = dir </> list <.> "action"
      filter = dir </> list <.> "filter"

  putStrLn ("generating config for " ++ list)
  notify "downloading" $ shell (printf "CURL_CA_BUNDLE=/etc/ssl/certs/ca-bundle.crt curl -so %s %s" file url)

  banner <- get (grep "-E" "^.*\\[Adblock.*\\].*$" file)
  when (null banner) (fail "Not a valid adblock list")
  notify "generating actionfile" $ do
    shell (printf "echo -e '{ +block{%s} }' > %s" list action)
    shell (printf "sed '%s' %s >> %s" (rules !! 0) file action)

  notify "generating filterfile" $ do
    shell (printf "echo 'FILTER: %s Tag filter of %s' > %s" list list filter)
    shell (printf "sed '%s' %s >> %s" (rules !! 1) file filter)

  notify "adding filterfile to actionfile" $ do
    shell (printf "echo '{ +filter{%s} }' >> %s" list action)
    shell (printf "echo '*' >> %s" action)

  notify "generating and adding whitelist" $ do
    shell (printf "echo '{ -block }' >> %s" action)
    shell (printf "sed '%s' %s >> %s" (rules !! 2) file action)

  notify "generating and adding image handler" $ do
    shell (printf "echo '{ -block +handle-as-image }' >> %s" action)
    shell (printf "sed '%s' %s >> %s" (rules !! 3) file action)

  notify "copying files to destination" $ liftIO $ do
    createDirectoryIfMissing True privoxy
    copyFile action (replaceDirectory action privoxy)
    copyFile filter (replaceDirectory filter privoxy)