import System.Environment
import System.IO
import System.Posix.User
import qualified Kiki
import Data.Char
import qualified Data.ByteString.Lazy.Char8 as L8
import qualified Data.ByteString.Lazy.Char8 as L

usage = unlines
    [ "cokiki <command>"
    , ""
    , "COMMANDS"
    , "  ssh-client"
    , "  ssh-server"
    , "  strongswan"
    ]

main = do
    args <- getArgs
    uid <- getEffectiveUserID
    let whenRoot action
            | uid==0    = action
            | otherwise = hPutStrLn stderr "operaiton requires root."
    case args of
        ["ssh-client"] -> sshClient uid id
        ["ssh-server"] -> whenRoot sshServer
        ["strongswan"] -> whenRoot strongswan
        _   -> hPutStr stderr usage

maybeReadFile :: FilePath -> Maybe L.ByteString
maybeReadFile path = do
    doesFileExist path >>= bool (return Nothing) (Just <$> L.readFile path)

sshClient 0 root = do
    -- /etc/ssh/ssh_config    <--  'GlobalKnownHostsFile /var/cache/kiki/ssh_known_hosts'
    sshconfig <- fromMaybe [] parseSshConfig <$> maybeReadFile (root "/etc/ssh/ssh_config")
    let (ps,qs) = sshSplitAtDirective "GlobalKnownHostsFile" sshconfig
    sshconfig' <-
        case qs of
            d:ds -> error "modify GlobalKnownHostsFile"
            []   -> error "append GlobalKnownHostsFile"
    L.writeFile (root "/var/cache/kiki/ssh_known_hosts") $ unparseSshConfig sshconfig'
    -- /root/.gnupg/...       <--  contains known hosts from /etc/ssh/ssh_known_hosts
    Kiki.refresh
    -- /var/cache/kiki/ssh_known_hosts        <--  contains known hosts from /root/.gnupg/...


sshClient uid = return ()

sshServer = do
    -- /etc/ssh/sshd_config <-- 'HostKey /var/cache/kiki/ssh_host_ecdsa_key' etc.
    return ()

strongswan = do
    -- etc/ipsec.conf    <--  'include /var/cache/kiki/ipsec.conf'
    -- /root/.gnupg/...   <--  contains newly-generated ipsec subkey
    Kiki.refresh
    -- /var/cache/kiki/ipsec.conf      <--  contains configurations for each remote ipsec host
    -- /var/cache/kiki/ipsec.conf      <--  contains '%default' configuration for this local host
    -- /var/cache/kiki/ipsec.d/certs   <--  contains relevant certs
    -- /var/cache/kiki/ipsec.d/private <--  contains private key


parseSshConfig bs = map tokenize $ L8.lines bs
 where
    tokenize l = L8.groupBy tokrel l' ++ [comment]
      where (l', comment) = L8.break (=='#') l
    tokrel x y = isSpace x == isSpace y

sshSplitAtDirective d sshconfig = splitAt (sshIsDirective d) sshconfig

sshIsDirective d ls =
    case dropWhile isSpaceTok ls of
        g:_ | g == d -> True
        _            -> False
 where
    isSpaceTok "" = True
    isSpaceTok b  = isSpace $ L8.head b