Parse and serialize rules.json
TL;DR: - Write FromJSON instances to decode rules.json file - Prefer Text to String and use the OverloadedStrings language extension - Read /etc/hosts and append the serialized rules.json to the end Notes: - I can remove some of the FromJSON instances and use GHC Generics to define them for me. TODO: - Define the systemd timer unit for this to run - Ensure script can run with root privileges
This commit is contained in:
William Carroll
parent
059af12bea
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5 changed files with 216 additions and 110 deletions
165
tools/website-blocker/Main.hs
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165
tools/website-blocker/Main.hs
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE NamedFieldPuns #-}
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{-# LANGUAGE DeriveGeneric #-}
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module Main
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( main
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, getRules
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, URL(..)
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, Rule(..)
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) where
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--------------------------------------------------------------------------------
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-- Dependencies
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--------------------------------------------------------------------------------
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import qualified Data.Maybe as Maybe
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import qualified Data.Time.Clock as Clock
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import qualified Data.Time.Calendar as Calendar
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import qualified Data.Time.LocalTime as LocalTime
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import qualified Data.ByteString.Lazy as LazyByteString
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import qualified Data.Aeson as Aeson
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import qualified Data.Either.Combinators as Either
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import qualified Data.HashMap.Strict as HashMap
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import qualified Data.Text as Text
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import qualified Data.Text.IO as TextIO
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import qualified Data.Text.Read as TextRead
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import qualified Data.List as List
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import GHC.Generics
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import Data.Aeson ((.:))
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import Data.Text (Text)
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--------------------------------------------------------------------------------
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-- Types
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--------------------------------------------------------------------------------
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newtype URL = URL { getURL :: Text } deriving (Show, Eq, Generic)
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newtype IPAddress = IPAddress { getIPAddress :: Text } deriving (Show)
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newtype Domain = Domain { getDomain :: Text } deriving (Show)
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newtype Hour = Hour { getHour :: Int } deriving (Show, Eq, Generic)
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newtype Minute = Minute { getMinute :: Int } deriving (Show, Eq, Generic)
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data EtcHostEntry = EtcHostEntry { ip :: IPAddress
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, domains :: [Domain]
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} deriving (Show)
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-- | Write these in terms of your system's local time (i.e. `date`).
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data TimeSlot = TimeSlot { beg :: (Hour, Minute)
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, end :: (Hour, Minute)
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} deriving (Show, Eq, Generic)
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data Allowance = Allowance { day :: Calendar.DayOfWeek
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, timeslots :: [TimeSlot]
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} deriving (Show, Eq, Generic)
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data Rule = Rule { urls :: [URL]
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, allowed :: [Allowance]
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} deriving (Show, Eq, Generic)
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--------------------------------------------------------------------------------
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-- Instances
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--------------------------------------------------------------------------------
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instance Aeson.FromJSON TimeSlot where
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parseJSON = Aeson.withText "timeslot" $ \x -> do
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let [a, b] = Text.splitOn "-" x
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[ah, am] = Text.splitOn ":" a
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[bh, bm] = Text.splitOn ":" b
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case extractTimeSlot ah am bh bm of
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Left s -> fail s
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Right x -> pure x
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where
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extractTimeSlot :: Text -> Text -> Text -> Text -> Either String TimeSlot
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extractTimeSlot ah am bh bm = do
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(begh, _) <- TextRead.decimal ah
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(begm, _) <- TextRead.decimal am
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(endh, _) <- TextRead.decimal bh
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(endm, _) <- TextRead.decimal bm
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pure $ TimeSlot{ beg = (Hour begh, Minute begm)
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, end = (Hour endh, Minute endm)
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}
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instance Aeson.FromJSON Allowance where
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parseJSON = Aeson.withObject "allowance" $ \x -> do
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day <- x .: "day"
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timeslots <- x .: "timeslots"
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pure $ Allowance{day, timeslots}
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instance Aeson.FromJSON URL where
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parseJSON = Aeson.withText "URL" $ \x -> do
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pure $ URL { getURL = x }
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instance Aeson.FromJSON Rule where
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parseJSON = Aeson.withObject "rule" $ \x -> do
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urls <- x .: "urls"
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allowed <- x .: "allowed"
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pure Rule{urls, allowed}
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--------------------------------------------------------------------------------
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-- Functions
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--------------------------------------------------------------------------------
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isWithinTimeSlot :: LocalTime.LocalTime -> [TimeSlot] -> Bool
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isWithinTimeSlot date timeslots =
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List.any withinTimeSlot timeslots
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where
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withinTimeSlot :: TimeSlot -> Bool
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withinTimeSlot TimeSlot{ beg = (Hour ah, Minute am)
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, end = (Hour bh, Minute bm)
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} =
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let LocalTime.TimeOfDay{LocalTime.todHour, LocalTime.todMin} =
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LocalTime.localTimeOfDay date
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in (todHour > ah) && (todMin > am) && (todHour < bh) && (todMin < bm)
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isToday :: LocalTime.LocalTime -> Calendar.DayOfWeek -> Bool
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isToday date day = Calendar.dayOfWeek (LocalTime.localDay date) == day
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isAllowed :: LocalTime.LocalTime -> [Allowance] -> Bool
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isAllowed _ [] = False
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isAllowed date allowances = do
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case filter (isToday date . day) allowances of
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[Allowance{timeslots}] ->
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isWithinTimeSlot date timeslots
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[] -> False
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-- Error when more than one rule per day
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_ -> False
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serializeEntry :: EtcHostEntry -> Text
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serializeEntry EtcHostEntry{ip, domains} =
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(getIPAddress ip) <> "\t" <> (Text.unwords $ fmap getDomain domains)
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toEtcHostEntry :: LocalTime.LocalTime -> Rule -> Maybe EtcHostEntry
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toEtcHostEntry date Rule{urls, allowed} =
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if isAllowed date allowed then
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Nothing
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else
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Just $ EtcHostEntry { ip = IPAddress "127.0.0.1"
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, domains = fmap (Domain . getURL) urls
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}
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getRules :: IO [Rule]
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getRules = do
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contents <- LazyByteString.readFile "rules.json"
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let payload = Aeson.eitherDecode contents
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pure $ Either.fromRight [] payload
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header :: Text
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header =
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Text.unlines [ "################################################################################"
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, "# Added by url-blocker"
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, "################################################################################"
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]
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main :: IO ()
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main = do
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rules <- getRules
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tz <- LocalTime.getCurrentTimeZone
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ct <- Clock.getCurrentTime
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let date = LocalTime.utcToLocalTime tz ct
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etcHosts = Text.unlines . fmap serializeEntry . Maybe.catMaybes $ fmap (toEtcHostEntry date) rules
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existingEtcHosts <- TextIO.readFile "/etc/hosts"
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TextIO.putStrLn $ existingEtcHosts <> "\n" <> header <> "\n" <> etcHosts
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38
tools/website-blocker/Spec.hs
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38
tools/website-blocker/Spec.hs
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@ -0,0 +1,38 @@
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module Spec (main) where
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--------------------------------------------------------------------------------
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-- Dependencies
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--------------------------------------------------------------------------------
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import qualified Main as Main
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import Test.Hspec
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--------------------------------------------------------------------------------
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-- Tests
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--------------------------------------------------------------------------------
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main :: IO ()
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main = hspec $ do
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describe "getRules" $ do
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it "returns the parsed rules from rules.json" $ do
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rules <- Main.getRules
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rules `shouldBe` [ Main.Rule { Main.urls = [ Main.URL "facebook.com"
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, Main.URL "www.facebook.com"
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, Main.URL "twitter.com"
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, Main.URL "www.twitter.com"
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, Main.URL "youtube.com"
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, Main.URL "www.youtube.com"
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, Main.URL "instagram.com"
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, Main.URL "www.instagram.com"
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]
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, Main.allowed = []
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}
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, Main.Rule { Main.urls = [ Main.URL "chat.googleplex.com" ]
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, Main.allowed = []
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}
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]
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describe "Prelude.head" $ do
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it "returns the first element of a list" $ do
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head [23 ..] `shouldBe` (23 :: Int)
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@ -1,103 +0,0 @@
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{-# LANGUAGE NamedFieldPuns #-}
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module Main (main) where
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--------------------------------------------------------------------------------
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-- Dependencies
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--------------------------------------------------------------------------------
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import qualified Data.Maybe as Maybe
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import qualified Data.Time.Clock as Clock
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import qualified Data.Time.Calendar as Calendar
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--------------------------------------------------------------------------------
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-- Types
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--------------------------------------------------------------------------------
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newtype URL = URL { getURL :: String } deriving (Show)
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newtype IPAddress = IPAddress { getIPAddress :: String } deriving (Show)
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newtype Domain = Domain { getDomain :: String } deriving (Show)
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newtype Hour = Hour { getHour :: Integer }
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newtype Minute = Minute { getMinute :: Integer }
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data EtcHostEntry = EtcHostEntry { ip :: IPAddress
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, domains :: [Domain]
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} deriving (Show)
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data TimeRange = TimeRange { beg :: (Hour, Minute)
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, end :: (Hour, Minute)
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}
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data Allowance = Allowance { day :: Calendar.DayOfWeek
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, timeslots :: [TimeRange]
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}
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data Rule = Rule { urls :: [URL]
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, allowed :: [Allowance]
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}
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--------------------------------------------------------------------------------
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-- Functions
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--------------------------------------------------------------------------------
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isToday :: Clock.UTCTime -> Calendar.DayOfWeek -> Bool
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isToday date day = Calendar.dayOfWeek (Clock.utctDay date) == day
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isAllowed :: Clock.UTCTime -> [Allowance] -> Bool
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isAllowed _ [] = False
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isAllowed date xs = do
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let rules = filter (isToday date . day) xs
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case rules of
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[day] -> True
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[] -> False
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-- Error when more than one rule per day
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_ -> False
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serializeEntry :: EtcHostEntry -> String
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serializeEntry EtcHostEntry{ip, domains} =
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(getIPAddress ip) ++ "\t" ++ (unwords $ fmap getDomain domains)
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toEtcHostEntry :: Clock.UTCTime -> Rule -> Maybe EtcHostEntry
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toEtcHostEntry date Rule{urls, allowed} =
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if isAllowed date allowed then
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Nothing
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else
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Just $ EtcHostEntry { ip = IPAddress "127.0.0.1"
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, domains = fmap (Domain . getURL) urls
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}
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-- | Location of the rules.json file.
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rulesFile :: FilePath
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rulesFile =
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"~/.config/website-blocker/rules.json"
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-- | Reads and parses JSON from `rulesFile` and returns the result.
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getRules :: IO [Rule]
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getRules = pure $
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[ Rule { urls = [ URL "facebook.com"
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, URL "twitter.com"
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, URL "youtube.com"
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, URL "instagram.com"
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]
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, allowed = []
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}
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, Rule { urls = [ URL "chat.googleplex.com" ]
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, allowed = [ Allowance { day = Calendar.Saturday
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, timeslots = [ TimeRange { beg = (Hour 0, Minute 0)
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, end = (Hour 0, Minute 0)
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}
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]
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}
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]
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}
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]
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main :: IO ()
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main = do
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rules <- getRules
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date <- Clock.getCurrentTime
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let etcHosts = unlines . fmap serializeEntry . Maybe.catMaybes $ fmap (toEtcHostEntry date) rules
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putStrLn etcHosts
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"www.facebook.com",
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"twitter.com",
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"www.twitter.com",
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"youtube.com"
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"www.youtube.com"
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"instagram.com"
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"youtube.com",
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"www.youtube.com",
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"instagram.com",
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"www.instagram.com"
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],
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"allowed": []
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@ -18,8 +18,10 @@
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],
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"allowed": [
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{
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"day": "Tuesday",
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"timeslots": []
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"day": "Sunday",
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"timeslots": [
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"18:35-18:39"
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]
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}
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]
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}
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@ -2,7 +2,11 @@ let
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pkgs = import <unstable> {};
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in pkgs.mkShell {
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buildInputs = with pkgs; [
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ghc
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haskellPackages.time
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(haskellPackages.ghcWithPackages (hpkgs: with hpkgs; [
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time
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aeson
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either
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hspec
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]))
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];
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}
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