-- hokey.hs: hOpenPGP key tool
-- Copyright © 2013-2022  Clint Adams
--
-- vim: softtabstop=4:shiftwidth=4:expandtab
--
-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU Affero General Public License as
-- published by the Free Software Foundation, either version 3 of the
-- License, or (at your option) any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU Affero General Public License for more details.
--
-- You should have received a copy of the GNU Affero General Public License
-- along with this program.  If not, see <http://www.gnu.org/licenses/>.
{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE TypeApplications #-}

import Codec.Encryption.OpenPGP.Expirations (getKeyExpirationTimesFromSignature)
import Codec.Encryption.OpenPGP.Fingerprint (eightOctetKeyID, fingerprint)
import Codec.Encryption.OpenPGP.KeyInfo (pkalgoAbbrev, pubkeySize)
import Codec.Encryption.OpenPGP.KeySelection (parseFingerprint)
import Codec.Encryption.OpenPGP.Ontology
  ( isCT
  , isCertRevocationSig
  , isKUF
  , isPHA
  , isPKBindingSig
  , isSKBindingSig
  )
import Codec.Encryption.OpenPGP.Serialize ()
import Codec.Encryption.OpenPGP.Types
import Control.Arrow ((***))
import Control.Error.Util (hush)
import Control.Lens ((&), (^.), _1, _2, mapped, over)
import Control.Monad.Trans.Except (runExceptT)
import Control.Monad.Trans.Writer.Lazy (execWriter, tell)
import qualified Crypto.Hash as CH
import qualified Crypto.Hash.Algorithms as CHA
import qualified Data.Aeson as A
import Data.Binary (get, put)
import qualified Data.ByteArray as BA
import qualified Data.ByteString as B
import qualified Data.ByteString.Base16 as Base16
import qualified Data.ByteString.Char8 as BC8
import qualified Data.ByteString.Lazy as BL
import Data.Conduit ((.|), runConduitRes)
import qualified Data.Conduit.Binary as CB
import qualified Data.Conduit.List as CL
import Data.Conduit.OpenPGP.Keyring (conduitToTKsDropping)
import Data.Conduit.Serialization.Binary (conduitGet, conduitPut)
import Data.Foldable (find)
import Data.List (elemIndex, findIndex, intercalate, nub, sort, sortOn)
import qualified Data.Map as Map
import Data.Maybe (fromMaybe, listToMaybe, mapMaybe)
import Data.Ord (Down(..))
import Data.Semigroup (Semigroup, (<>))
import qualified Data.Set as Set
import Data.Text (Text)
import qualified Data.Text as T
import Data.Time.Clock.POSIX (POSIXTime, getPOSIXTime, posixSecondsToUTCTime)
import Data.Time.Format (formatTime)
import qualified Data.Yaml as Y
import GHC.Generics
import HOpenPGP.Tools.Common (banner, versioner, warranty)
import HOpenPGP.Tools.HKP (FetchValidationMethod(..), fetchKeys, rearmorKeys)
import HOpenPGP.Tools.TKUtils (processTK)

import Options.Applicative.Builder
  ( argument
  , auto
  , command
  , eitherReader
  , footerDoc
  , headerDoc
  , help
  , helpDoc
  , info
  , long
  , metavar
  , option
  , prefs
  , progDesc
  , showDefault
  , showHelpOnError
  , str
  , value
  )
import Options.Applicative.Extra (customExecParser, helper, hsubparser)
import Options.Applicative.Types (Parser)

import Data.Time.Locale.Compat (defaultTimeLocale)
import System.IO
  ( BufferMode(..)
  , Handle
  , hFlush
  , hPutStrLn
  , hSetBuffering
  , stderr
  , stdin
  , stdout
  )

import Prettyprinter.Convert.AnsiWlPprint (toAnsiWlPprint)
import Prettyprinter
  ( Doc
  , (<+>)
  , annotate
  , colon
  , flatAlt
  , hardline
  , indent
  , line
  , list
  , pretty
  )
import qualified Prettyprinter.Render.Terminal as PPA

linebreak = flatAlt line mempty

green = annotate (PPA.color PPA.Green)

yellow = annotate (PPA.color PPA.Yellow)

red = annotate (PPA.color PPA.Red)

data KAS =
  KAS
    { pubkeyalgo :: Colored PubKeyAlgorithm
    , pubkeysize :: Colored (Maybe Int)
    , stringrep :: String
    }
  deriving (Generic)

data Color
  = Green
  | Yellow
  | Red
  deriving (Eq, Generic, Ord)

data Colored a =
  Colored
    { color :: Maybe Color
    , explanation :: Maybe String
    , val :: a
    }
  deriving (Functor, Generic)

newtype FakeMap a b =
  FakeMap
    { unFakeMap :: [(a, b)]
    }

data KeyReport =
  KeyReport
    { keyStatus :: String
    , keyFingerprint :: TwentyOctetFingerprint
    , keyVer :: Colored KeyVersion
    , keyCreationTime :: ThirtyTwoBitTimeStamp
    , keyAlgorithmAndSize :: KAS
    , keyUIDsAndUAts :: FakeMap Text (Colored UIDReport)
    , keyBestOf :: Maybe UIDReport
    , keySubkeys :: [SubkeyReport]
    , keyHasEncryptionCapableSubkey :: Colored Bool
    }
  deriving (Generic)

data UIDReport =
  UIDReport
    { uidSelfSigHashAlgorithms :: [Colored HashAlgorithm]
    , uidPreferredHashAlgorithms :: [Colored [HashAlgorithm]]
    , uidKeyExpirationTimes :: [Colored [ThirtyTwoBitDuration]]
    , uidKeyUsageFlags :: [Colored (Set.Set KeyFlag)]
    , uidRevocationStatus :: [RevocationStatus]
    }
  deriving (Generic)

data SubkeyReport =
  SubkeyReport
    { skFingerprint :: Colored TwentyOctetFingerprint
    , skVer :: Colored KeyVersion
    , skCreationTime :: ThirtyTwoBitTimeStamp
    , skAlgorithmAndSize :: KAS
    , skBindingSigHashAlgorithms :: [Colored HashAlgorithm]
    , skUsageFlags :: [Colored (Set.Set KeyFlag)]
    , skCrossCerts :: CrossCertReport
    }
  deriving (Generic)

data CrossCertReport =
  CrossCertReport
    { ccPresent :: Colored Bool
    , ccHashAlgorithms :: [Colored HashAlgorithm]
    }
  deriving (Generic)

data RevocationStatus =
  RevocationStatus
    { isRevoked :: Bool
    , revocationCode :: String
    , revocationReason :: Text
    }
  deriving (Generic)

instance A.ToJSON KAS

instance A.ToJSON Color

instance (A.ToJSON a) => A.ToJSON (Colored a)

instance A.ToJSON KeyReport

instance A.ToJSON UIDReport

instance A.ToJSON SubkeyReport

instance A.ToJSON CrossCertReport

instance A.ToJSON b => A.ToJSON (FakeMap Text b) where
  toJSON = A.toJSON . Map.fromList . unFakeMap

instance A.ToJSON RevocationStatus

instance Semigroup UIDReport where
  (<>) (UIDReport a b c d e) (UIDReport a' b' c' d' e') =
    UIDReport (a <> a') (b <> b') (c <> c') (d <> d') (e <> e')

instance Monoid UIDReport where
  mempty = UIDReport [] [] [] [] []
  mappend = (<>)

checkKey :: Maybe POSIXTime -> TK -> KeyReport
checkKey mpt key =
  (\x ->
     x
       { keyBestOf = populateBestOf x
       , keyHasEncryptionCapableSubkey =
           hasEncryptionCapableSubkey (concatMap skUsageFlags (keySubkeys x))
       })
    KeyReport
      { keyStatus = either id (const "good") processedTK
      , keyFingerprint = key ^. tkKey . _1 & fingerprint
      , keyVer = key ^. tkKey . _1 . keyVersion & colorizeKV
      , keyCreationTime = key ^. tkKey . _1 . timestamp
      , keyAlgorithmAndSize = kasIt (key ^. tkKey . _1)
      , keyUIDsAndUAts =
          FakeMap
            (map (\(x, y) -> (x, uidr (Just x) y)) (processedOrOrig ^. tkUIDs) ++
             map (uatspsToText *** uidr Nothing) (processedOrOrig ^. tkUAts))
      , keyBestOf = Nothing
      , keySubkeys =
          map (checkSK (key ^. tkKey . _1 & fingerprint)) (key ^. tkSubs)
      , keyHasEncryptionCapableSubkey = Colored Nothing Nothing False
      }
  where
    processedOrOrig = either (const key) id processedTK
    processedTK = processTK mpt key
    kasIt :: PKPayload -> KAS
    kasIt pkp = kasIt' (pkp ^. pkalgo) (pkp ^. pubkey & pubkeySize)
    kasIt' :: PubKeyAlgorithm -> Either String Int -> KAS
    kasIt' pka epks =
      KAS
        { pubkeyalgo = colorizePKA pka
        , pubkeysize = colorizePKS pka epks
        , stringrep = (either (const "unknown") show epks) ++ (pkalgoAbbrev pka)
        }
    colorizeKV kv =
      uncurry
        Colored
        (if kv == V4
           then (Just Green, Nothing)
           else (Just Red, Just "not a V4 key"))
        kv
    colorizePKA pka
      | pka `elem` [RSA, EdDSA, ECDH] = Colored (Just Green) Nothing pka
      | otherwise =
        Colored
          (Just Yellow)
          (Just "public key algorithm neither RSA nor EdDSA")
          pka
    colorizePKS pka epks = uncurry Colored (colorizePKS' pka epks) (hush epks)
    colorizePKS' pka (Right pks)
      | pka `elem` [EdDSA, ECDH] && pks >= 256 = (Just Green, Nothing)
      | pka `elem` [EdDSA, ECDH] =
        (Just Yellow, Just "Public key size under 256 bits")
      | pka == RSA && pks >= 3072 = (Just Green, Nothing)
      | pka == RSA && pks >= 2048 =
        (Just Yellow, Just "Public key size between 2048 and 3072 bits")
      | pka == RSA = (Just Red, Just "Public key size under 2048 bits")
      | otherwise = (Nothing, Nothing)
    colorizePKS' _ (Left _) =
      (Just Red, Just "public key algorithm not understood")
    colorizePHAs x =
      uncurry
        Colored
        (if fSHA2Family x < ei DeprecatedMD5 x && fSHA2Family x < ei SHA1 x
           then (Just Green, Nothing)
           else (Just Red, Just "weak hash with higher preference"))
        x
    fSHA2Family = fi (`elem` [SHA512, SHA384, SHA256, SHA224])
    ei x y = fromMaybe maxBound (elemIndex x y)
    fi x y = fromMaybe maxBound (findIndex x y)
    colorizeKETs ct ts kes
      | null kes = Colored (Just Red) (Just "no expiration set") kes
      | any (\ke -> realToFrac ts + realToFrac ke < ct) kes =
        Colored (Just Red) (Just "expiration passed") kes
      | any (\ke -> realToFrac ts + realToFrac ke > ct + (5 * 31557600)) kes =
        Colored (Just Yellow) (Just "expiration too far in future") kes
      | otherwise = Colored (Just Green) Nothing kes
    eoki pkp
      | pkp ^. keyVersion == V4 = hush . eightOctetKeyID $ pkp
      | pkp ^. keyVersion == DeprecatedV3 &&
          elem (pkp ^. pkalgo) [RSA, DeprecatedRSASignOnly] =
        hush . eightOctetKeyID $ pkp
      | otherwise = Nothing
    phas (SigV4 _ _ _ xs _ _ _) =
      colorizePHAs .
      concatMap (\(SigSubPacket _ (PreferredHashAlgorithms x)) -> x) $
      filter isPHA xs
    phas _ = Colored Nothing Nothing []
    has = map (colorizeHA . hashAlgo) . alleged
    colorizeHA ha =
      uncurry
        Colored
        (if ha `elem` [DeprecatedMD5, SHA1]
           then (Just Red, Just "weak hash algorithm")
           else (Nothing, Nothing))
        ha
    sigcts (SigV4 _ _ _ xs _ _ _) =
      map (\(SigSubPacket _ (SigCreationTime x)) -> x) $ filter isCT xs
    alleged =
      filter
        (\x -> ((==) <$> sigissuer x <*> eoki (key ^. tkKey . _1)) == Just True)
    uatspsToText = T.pack . uatspsToString
    uatspsToString us =
      "<uat:[" ++ intercalate "," (map uaspToString us) ++ "]>"
    uaspToString (ImageAttribute hdr d) =
      hdrToString hdr ++ ':' : show (BL.length d) ++ ':' :
      BC8.unpack (Base16.encode (BA.convert (CH.hashlazy @CHA.SHA3_512 d)))
    uaspToString (OtherUASub t d) =
      "other-" ++ show t ++ ':' : show (BL.length d) ++ ':' :
      BC8.unpack (Base16.encode (BA.convert (CH.hashlazy @CHA.SHA3_512 d)))
    hdrToString (ImageHV1 JPEG) = "jpeg"
    hdrToString (ImageHV1 fmt) = "image-" ++ show (fromFVal fmt)
    uidr Nothing sps =
      Colored
        Nothing
        Nothing
        (UIDReport
           (has sps)
           (map phas sps)
           (map
              (colorizeKETs
                 (fromMaybe 0 mpt)
                 (key ^. tkKey . _1 . timestamp & unThirtyTwoBitTimeStamp) .
               getKeyExpirationTimesFromSignature)
              sps -- should that be 0?
            )
           (kufs False sps)
           (findRevocationReason sps))
    uidr (Just u) sps =
      colorizeUID
        u
        (UIDReport
           (has sps)
           (map phas sps)
           (map
              (colorizeKETs
                 (fromMaybe 0 mpt)
                 (key ^. tkKey . _1 . timestamp & unThirtyTwoBitTimeStamp) .
               getKeyExpirationTimesFromSignature)
              sps -- should that be 0?
            )
           (kufs False sps)
           (findRevocationReason sps))
    populateBestOf krep =
      Just
        (UIDReport <$> best . uidSelfSigHashAlgorithms <*> best .
         uidPreferredHashAlgorithms <*>
         best .
         uidKeyExpirationTimes <*>
         best .
         uidKeyUsageFlags <*>
         pure [] $
         mconcat (justTheUIDRs krep))
    justTheUIDRs = map (decolorize . snd) . unFakeMap . keyUIDsAndUAts
    best = take 1 . sortOn color
    decolorize (Colored _ _ x) = x
    colorizeUID u
      | '(' `elem` T.unpack u =
        Colored (Just Yellow) (Just "parenthesis in uid") -- FIXME: be more discerning
      | '<' `notElem` T.unpack u =
        Colored (Just Yellow) (Just "no left angle bracket in uid") -- FIXME: be more discerning
      | otherwise = Colored Nothing Nothing
    findRevocationReason = concatMap grabReasons . filter isCertRevocationSig
    grabReasons (SigV4 CertRevocationSig _ _ has _ _ _) =
      mapMaybe (grabReasons' . _sspPayload) has
    grabReasons _ = []
    grabReasons' (ReasonForRevocation a b) =
      Just (RevocationStatus True (show a) b)
    grabReasons' _ = Nothing
    kufs s =
      map
        (colorizeKUFs s . (\(SigSubPacket _ (KeyFlags x)) -> x) .
         fromMaybe undefined .
         find isKUF .
         hasheds) .
      newestWith (any isKUF . hasheds)
    colorizeKUFs False x =
      uncurry
        Colored
        (if (Set.member EncryptStorageKey x ||
             Set.member EncryptCommunicationsKey x) &&
            (Set.member SignDataKey x || Set.member CertifyKeysKey x)
           then (Just Yellow, Just "both signing & encryption")
           else (Just Green, Nothing))
        x
    colorizeKUFs True x =
      uncurry
        Colored
        (if Set.member CertifyKeysKey x
           then (Just Red, Just "certification-capable subkey")
           else (if (Set.member EncryptStorageKey x ||
                     Set.member EncryptCommunicationsKey x) &&
                    Set.member SignDataKey x
                   then (Just Yellow, Just "both signing & encryption")
                   else (Just Green, Nothing)))
        x
    newestWith p = take 1 . sortOn (Down . take 1 . sigcts) . filter p -- FIXME: this is terrible
    hasheds (SigV4 _ _ _ xs _ _ _) = xs
    hasheds _ = []
    checkSK ::
         TwentyOctetFingerprint -> (Pkt, [SignaturePayload]) -> SubkeyReport
    checkSK pf (PublicSubkeyPkt pkp, sigs) = checkSK' pf pkp sigs
    checkSK pf (SecretSubkeyPkt pkp _, sigs) = checkSK' pf pkp sigs
    checkSK' pf pkp sigs =
      (\x -> x {skCrossCerts = ccr (map decolorize (skUsageFlags x)) sigs})
        SubkeyReport
          { skFingerprint = colorizeF pf (fingerprint pkp)
          , skVer = colorizeKV (pkp ^. keyVersion)
          , skCreationTime = pkp ^. timestamp
          , skAlgorithmAndSize = kasIt pkp
          , skBindingSigHashAlgorithms = has (filter isSKBindingSig sigs)
          , skUsageFlags = kufs True (filter isSKBindingSig sigs)
          , skCrossCerts = CrossCertReport (Colored Nothing Nothing False) []
          }
    hasEncryptionCapableSubkey skrs =
      if any
           ((\x ->
               Set.member EncryptStorageKey x ||
               Set.member EncryptCommunicationsKey x) .
            decolorize)
           skrs
        then Colored (Just Green) Nothing True
        else Colored
               (Just Red)
               (Just "no encryption-capable subkey present")
               False
    embeddedSigs =
      filter isPKBindingSig . concatMap getEmbeds . filter isSKBindingSig
    getEmbeds (SigV4 _ _ _ xs ys _ _) = concatMap getEmbed (xs ++ ys)
    getEmbeds _ = []
    getEmbed (SigSubPacket _ (EmbeddedSignature sp)) = [sp]
    getEmbed _ = []
    ccr kufs sigs =
      CrossCertReport (colorES kufs sigs) (map (colorizeHA . hashAlgo) sigs)
    colorES kufs sigs =
      case ( null (embeddedSigs sigs)
           , any (Set.member SignDataKey) kufs
           , any (Set.member AuthKey) kufs) of
        (True, True, True) ->
          Colored
            (Just Red)
            (Just "signing- and auth-capable subkey without cross-cert")
            False
        (True, True, False) ->
          Colored
            (Just Red)
            (Just "signing-capable subkey without cross-cert")
            False
        (True, False, True) ->
          Colored
            (Just Yellow)
            (Just "auth-capable subkey without cross-cert")
            False
        (False, True, True) -> Colored (Just Green) Nothing True
        (False, True, False) -> Colored (Just Green) Nothing True
        (False, False, True) -> Colored (Just Green) Nothing True
        (False, False, False) -> Colored Nothing Nothing True
        (True, _, _) -> Colored Nothing Nothing False
    colorizeF pf fp =
      uncurry
        Colored
        (if pf == fp
           then (Just Red, Just "subkey has same fingerprint as primary key")
           else (Just Green, Nothing))
        fp

prettyKeyReport :: POSIXTime -> TK -> Doc PPA.AnsiStyle
prettyKeyReport cpt key = do
  let keyReport = checkKey (Just cpt) key
  execWriter $
    tell
      (linebreak <> pretty "Key has potential validity" <> colon <+>
       pretty (keyStatus keyReport) <>
       linebreak <>
       pretty "Key has fingerprint" <>
       colon <+>
       pretty (SpacedFingerprint (keyFingerprint keyReport)) <>
       linebreak <>
       pretty "Checking to see if key is OpenPGPv4" <>
       colon <+>
       coloredToColor (pretty . show) (keyVer keyReport) <>
       linebreak <>
       (\kas ->
          pretty "Checking the strength of your primary asymmetric key" <> colon <+>
          coloredToColor pretty (pubkeyalgo kas) <+>
          coloredToColor (maybe (pretty "unknown") pretty) (pubkeysize kas))
         (keyAlgorithmAndSize keyReport) <>
       linebreak <>
       pretty "Checking user-ID- and user-attribute-related items" <>
       colon <>
       mconcat
         (map
            (uidtrip (keyCreationTime keyReport) . gottabeabetterway)
            (unFakeMap (keyUIDsAndUAts keyReport))) <>
       linebreak <>
       pretty "Checking subkeys" <>
       colon <>
       linebreak <>
       indent
         2
         (pretty "one of the subkeys is encryption-capable" <> colon <+>
          coloredToColor pretty (keyHasEncryptionCapableSubkey keyReport)) <>
       mconcat (map subkeyrep (keySubkeys keyReport)) <>
       linebreak)
  where
    coloredToColor f (Colored (Just Green) _ x) = green (f x)
    coloredToColor f (Colored (Just Yellow) _ x) = yellow (f x)
    coloredToColor f (Colored (Just Red) _ x) = red (f x)
    coloredToColor f (Colored Nothing _ x) = f x
    uidtrip ts (u, ur)
      | null (uidRevocationStatus ur) =
        linebreak <> indent 2 (coloredToColor pretty (fmap T.unpack u)) <> colon <>
        linebreak <>
        indent
          4
          (pretty "Self-sig hash algorithms" <> colon <+>
           (list . map (coloredToColor pretty) . uidSelfSigHashAlgorithms) ur) <>
        linebreak <>
        indent
          4
          (pretty "Preferred hash algorithms" <> colon <+>
           mconcat (map (coloredToColor pretty) (uidPreferredHashAlgorithms ur))) <>
        linebreak <>
        indent
          4
          (pretty "Key expiration times" <> colon <+>
           mconcat
             (map
                (coloredToColor list . fmap (map (pretty . keyExp ts)))
                (uidKeyExpirationTimes ur))) <>
        linebreak <>
        indent
          4
          (pretty "Key usage flags" <> colon <+>
           (list . map (coloredToColor (pretty . Set.toList)))
             (uidKeyUsageFlags ur))
      | otherwise =
        linebreak <> indent 2 (coloredToColor pretty (fmap T.unpack u)) <> colon <+>
        pretty "[revoked]" <>
        linebreak <>
        indent
          4
          (pretty "Revocation code" <> colon <+>
           list (map (pretty . revocationCode) (uidRevocationStatus ur))) <>
        linebreak <>
        indent
          4
          (pretty "Revocation reason" <> colon <+>
           list
             (map
                (pretty . T.unpack . revocationReason)
                (uidRevocationStatus ur)))
    keyExp ts ke =
      (show . pretty) ke ++ " = " ++
      formatTime
        defaultTimeLocale
        "%c"
        (posixSecondsToUTCTime (realToFrac ts + realToFrac ke))
    gottabeabetterway (a, Colored x y z) = (Colored x y a, z)
    subkeyrep skr =
      linebreak <>
      indent
        2
        (pretty "fpr" <> colon <+>
         coloredToColor pretty (fmap SpacedFingerprint (skFingerprint skr))) <>
      linebreak <>
      indent 4 (pretty "version" <> colon <+> coloredToColor pretty (skVer skr)) <>
      linebreak <>
      indent 4 (pretty "timestamp" <> colon <+> pretty (skCreationTime skr)) <>
      linebreak <>
      indent
        4
        ((\kas ->
            pretty "algo/size" <> colon <+>
            coloredToColor pretty (pubkeyalgo kas) <+>
            coloredToColor (maybe (pretty "unknown") pretty) (pubkeysize kas))
           (skAlgorithmAndSize skr)) <>
      linebreak <>
      indent
        4
        (pretty "binding sig hash algorithms" <> colon <+>
         (list . map (coloredToColor pretty) . skBindingSigHashAlgorithms) skr) <>
      linebreak <>
      indent
        4
        (pretty "usage flags" <> colon <+>
         (list . map (coloredToColor (pretty . Set.toList))) (skUsageFlags skr)) <>
      linebreak <>
      indent
        4
        (pretty "embedded cross-cert" <> colon <+>
         (coloredToColor pretty . ccPresent . skCrossCerts) skr) <>
      linebreak <>
      indent
        4
        (pretty "cross-cert hash algorithms" <> colon <+>
         (list . map (coloredToColor pretty) . ccHashAlgorithms . skCrossCerts)
           skr)

jsonReport :: POSIXTime -> TK -> BL.ByteString
jsonReport ps = A.encode . checkKey (Just ps)

yamlReport :: POSIXTime -> TK -> B.ByteString
yamlReport ps = Y.encode . (: []) . checkKey (Just ps)

data LintOutputFormat
  = Pretty
  | JSON
  | YAML
  deriving (Bounded, Enum, Eq, Read, Show)

data LintOptions =
  LintOptions
    { lintOutputFormat :: LintOutputFormat
    }

data FetchOptions =
  FetchOptions
    { keyServer :: String
    , fetchValidation :: FetchValidationMethod
    , fetchQuery :: TwentyOctetFingerprint
    }

data Command
  = CmdLint LintOptions
  | CmdCanonicalize
  | CmdFetch FetchOptions

lintO :: Parser LintOptions
lintO =
  LintOptions <$>
  option
    auto
    (long "output-format" <> metavar "FORMAT" <> value Pretty <> showDefault <>
     ofHelp)
  where
    ofHelp =
      helpDoc . Just . toAnsiWlPprint $ pretty "output format" <> hardline <>
      list (map (pretty . show) ofchoices)
    ofchoices = [minBound .. maxBound] :: [LintOutputFormat]

fetchO :: Parser FetchOptions
fetchO =
  FetchOptions <$>
  option
    str
    (long "keyserver" <> metavar "URL" <>
     value "http://pool.sks-keyservers.net:11371" <>
     showDefault <>
     help "HKP server") <*>
  option
    auto
    (long "validation-method" <> metavar "METHOD" <>
     value MatchPrimaryKeyFingerprint <>
     showDefault <>
     vmHelp) <*>
  argument (eitherReader strToFP) (metavar "FINGERPRINT")
  where
    vmHelp =
      helpDoc . Just . toAnsiWlPprint $ pretty "validation method" <> hardline <>
      list (map (pretty . show) vmchoices)
    vmchoices = [minBound .. maxBound] :: [FetchValidationMethod]
    strToFP = parseFingerprint . T.pack

dispatch :: Command -> IO ()
dispatch (CmdFetch o) = banner' stderr >> hFlush stderr >> doFetch o
dispatch (CmdLint o) = banner' stderr >> hFlush stderr >> doLint o
dispatch CmdCanonicalize = banner' stderr >> hFlush stderr >> doCanonicalize

main :: IO ()
main = do
  hSetBuffering stderr LineBuffering
  customExecParser
    (prefs showHelpOnError)
    (info
       (helper <*> versioner "hokey" <*> cmd)
       (headerDoc (Just (toAnsiWlPprint (banner "hokey"))) <>
        progDesc "hOpenPGP Key utility" <>
        footerDoc (Just (toAnsiWlPprint (warranty "hokey"))))) >>=
    dispatch

cmd :: Parser Command
cmd =
  hsubparser
    (command
       "canonicalize"
       (info
          (pure CmdCanonicalize)
          (progDesc "arrange key components in a canonical ordering")) <>
     command
       "fetch"
       (info (CmdFetch <$> fetchO) (progDesc "fetch key(s) from keyserver")) <>
     command
       "lint"
       (info (CmdLint <$> lintO) (progDesc "check key(s) for 'best practices'")))

doLint :: LintOptions -> IO ()
doLint o = do
  cpt <- getPOSIXTime
  keys <-
    runConduitRes $ CB.sourceHandle stdin .| conduitGet get .|
    conduitToTKsDropping .|
    CL.consume
  output (lintOutputFormat o) cpt keys
  where
    output Pretty cpt = mapM_ (PPA.putDoc . prettyKeyReport cpt)
    output JSON cpt =
      mapM_ (BL.putStr . flip BL.append (BL.singleton 0x0a) . jsonReport cpt)
    output YAML cpt = mapM_ (B.putStr . yamlReport cpt)

doCanonicalize :: IO ()
doCanonicalize =
  runConduitRes $ CB.sourceHandle stdin .| conduitGet get .|
  conduitToTKsDropping .|
  CL.map canonicalize .|
  CL.map put .|
  conduitPut .|
  CB.sinkHandle stdout
  where
    canonicalize (TK k r ui ua s) =
      TK k (sort r) (indepthsort ui) (indepthsort ua) (indepthsort s)
    indepthsort :: (Ord a, Ord b) => [(a, [b])] -> [(a, [b])]
    indepthsort = nub . sort . over (mapped . _2) sort

doFetch :: FetchOptions -> IO ()
doFetch o = do
  ekeys <-
    runExceptT $ fetchKeys (keyServer o) (fetchValidation o) (fetchQuery o)
  case ekeys of
    Left e -> hPutStrLn stderr $ "error fetching keys: " ++ e
    Right ks -> B.putStr $ rearmorKeys ks

banner' :: Handle -> IO ()
banner' h =
  PPA.hPutDoc h (banner "hokey" <> hardline <> warranty "hokey" <> hardline)

sigissuer :: SignaturePayload -> Maybe EightOctetKeyId
getIssuer :: SigSubPacketPayload -> Maybe EightOctetKeyId
hashAlgo :: SignaturePayload -> HashAlgorithm
sigissuer (SigVOther 2 _) = Nothing
sigissuer SigV3 {} = Nothing
sigissuer (SigV4 _ _ _ ys xs _ _) =
  listToMaybe . mapMaybe (getIssuer . _sspPayload) $ (ys ++ xs) -- FIXME: what should this be if there are multiple matches?
sigissuer (SigVOther _ _) = error "We're in the future." -- FIXME

getIssuer (Issuer i) = Just i
getIssuer _ = Nothing

hashAlgo (SigV4 _ _ x _ _ _ _) = x
hashAlgo _ = error "V3 sig not supported here"