-- |This module implements fetching of individual blog entries from
-- DNS. Yes, you read that correctly.
--
-- Each blog post is stored as a set of records in a designated DNS
-- zone. For the production blog, this zone is `blog.tazj.in.`.
--
-- A top-level record at `_posts` contains a list of all published
-- post IDs.
--
-- For each of these post IDs, there is a record at `_meta.$postID`
-- that contains the title and number of post chunks.
--
-- For each post chunk, there is a record at `_$chunkID.$postID` that
-- contains a base64-encoded post fragment.
--
-- This module implements logic for assembling a post out of these
-- fragments and caching it based on the TTL of its `_meta` record.
module BlogStore(
BlogCache,
EntryId(..),
Entry(..),
withCache,
listEntries,
getEntry,
) where
import Control.Monad.IO.Class (MonadIO)
import Data.Text (Text)
import Data.Time (UTCTime)
import Locales (BlogLang (..))
import Network.DNS.Lookup (lookupTXT)
import qualified Network.DNS.Resolver as R
newtype EntryId = EntryId {unEntryId :: Integer}
deriving (Eq, Ord)
instance Show EntryId where
show = show . unEntryId
data Entry
= Entry
{ entryId :: EntryId,
lang :: BlogLang,
author :: Text,
title :: Text,
btext :: Text,
mtext :: Text,
edate :: UTCTime
}
deriving (Eq, Ord, Show)
-- | Wraps a DNS resolver with caching configured. For the initial
-- version of this, all caching of entries is done by the resolver
-- (i.e. no pre-assembled versions of entries are cached).
data BlogCache
= BlogCache { resolver :: R.Resolver
, zone :: String }
type Offset = Integer
type Count = Integer
withCache :: String -> (BlogCache -> IO a) -> IO a
withCache zone f = do
let conf = R.defaultResolvConf { R.resolvCache = Just R.defaultCacheConf
, R.resolvConcurrent = True }
seed <- R.makeResolvSeed conf
R.withResolver seed $ (\r -> f $ BlogCache r zone)
listEntries :: MonadIO m => BlogCache -> Offset -> Count -> m [Entry]
listEntries (BlogCache r z) offset count = undefined
getEntry :: MonadIO m => BlogCache -> EntryId -> m (Maybe Entry)
getEntry (BlogCache r z) eId = undefined
