{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE ApplicativeDo #-}
{-# LANGUAGE OverloadedStrings #-}

import Protolude hiding (Down, option)

import           Arion.Nix
import           Arion.Aeson
import           Arion.Images (loadImages)
import qualified Arion.DockerCompose as DockerCompose
import           Arion.Services (getDefaultExec)

import Options.Applicative
import Control.Monad.Fail

import qualified Data.Text as T
import qualified Data.Text.IO as T

import Data.List.NonEmpty (NonEmpty(..))

import System.Posix.User (getRealUserID)

data CommonOptions =
  CommonOptions
    { files :: NonEmpty FilePath
    , pkgs :: Text
    , nixArgs :: [Text]
    }
  deriving (Show)

newtype DockerComposeArgs =
  DockerComposeArgs { unDockerComposeArgs :: [Text] }

ensureConfigFile :: [FilePath] -> NonEmpty FilePath
ensureConfigFile []     = "./arion-compose.nix" :| []
ensureConfigFile (x:xs) = x :| xs

parseOptions :: Parser CommonOptions
parseOptions = do
    files <-
      ensureConfigFile <$>
        many (strOption
               (  short 'f'
               <> long "file"
               <> metavar "FILE"
               <> help "Use FILE instead of the default ./arion-compose.nix. \
                        \Can be specified multiple times for a merged configuration" ))
    pkgs <- T.pack <$> strOption
          (  short 'p'
          <> long "pkgs"
          <> metavar "EXPR"
          <> showDefault
          <> value "./arion-pkgs.nix"
          <> help "Use Nix expression EXPR to get the Nixpkgs attrset used for bootstrapping \
                   \and evaluating the configuration." )
    showTrace <- flag False True (long "show-trace"
                    <> help "Causes Nix to print out a stack trace in case of Nix expression evaluation errors.")
    -- TODO --option support (https://github.com/pcapriotti/optparse-applicative/issues/284)
    userNixArgs <- many (T.pack <$> strOption (long "nix-arg" <> metavar "ARG" <> help "Pass an extra argument to nix. Example: --nix-arg --option --nix-arg substitute --nix-arg false"))
    pure $
      let nixArgs = userNixArgs <|> "--show-trace" <$ guard showTrace
      in CommonOptions{..}

textArgument :: Mod ArgumentFields [Char] -> Parser Text
textArgument = fmap T.pack . strArgument

parseCommand :: Parser (CommonOptions -> IO ())
parseCommand =
  hsubparser
    (    command "cat" (info (pure runCat) (progDesc "Spit out the docker compose file as JSON" <> fullDesc))
      <> command "repl" (info (pure runRepl) (progDesc "Start a nix repl for the whole composition" <> fullDesc))
      <> command "exec" (info (parseExecCommand) (progDesc "Execute a command in a running container" <> fullDesc))
    )
  <|>
  hsubparser
    (    commandDC runBuildAndDC "build" "Build or rebuild services"
      <> commandDC runBuildAndDC "bundle" "Generate a Docker bundle from the Compose file"
      <> commandDC runEvalAndDC "config" "Validate and view the Compose file"
      <> commandDC runBuildAndDC "create" "Create services"
      <> commandDC runEvalAndDC "down" "Stop and remove containers, networks, images, and volumes"
      <> commandDC runEvalAndDC "events" "Receive real time events from containers"
      <> commandDC runDC "help" "Get help on a command"
      <> commandDC runEvalAndDC "images" "List images"
      <> commandDC runEvalAndDC "kill" "Kill containers"
      <> commandDC runEvalAndDC "logs" "View output from containers"
      <> commandDC runEvalAndDC "pause" "Pause services"
      <> commandDC runEvalAndDC "port" "Print the public port for a port binding"
      <> commandDC runEvalAndDC "ps" "List containers"
      <> commandDC runBuildAndDC "pull" "Pull service images"
      <> commandDC runBuildAndDC "push" "Push service images"
      <> commandDC runBuildAndDC "restart" "Restart services"
      <> commandDC runEvalAndDC "rm" "Remove stopped containers"
      <> commandDC runBuildAndDC "run" "Run a one-off command"
      <> commandDC runBuildAndDC "scale" "Set number of containers for a service"
      <> commandDC runBuildAndDC "start" "Start services"
      <> commandDC runEvalAndDC "stop" "Stop services"
      <> commandDC runEvalAndDC "top" "Display the running processes"
      <> commandDC runEvalAndDC "unpause" "Unpause services"
      <> commandDC runBuildAndDC "up" "Create and start containers"
      <> commandDC runDC "version" "Show the Docker-Compose version information"

      <> metavar "DOCKER-COMPOSE-COMMAND"
      <> commandGroup "Docker Compose Commands:"
    )

parseAll :: Parser (IO ())
parseAll =
  flip ($) <$> parseOptions <*> parseCommand

parseDockerComposeArgs :: Parser DockerComposeArgs
parseDockerComposeArgs =
  DockerComposeArgs <$>
    many (argument (T.pack <$> str) (metavar "DOCKER-COMPOSE ARGS..."))

commandDC
  :: (Text -> DockerComposeArgs -> CommonOptions -> IO ())
  -> Text
  -> Text
  -> Mod CommandFields (CommonOptions -> IO ())
commandDC run cmdStr helpText =
  command
    (T.unpack cmdStr)
    (info
      (run cmdStr <$> parseDockerComposeArgs)
      (progDesc (T.unpack helpText) <> fullDesc <> forwardOptions))


--------------------------------------------------------------------------------

runDC :: Text -> DockerComposeArgs -> CommonOptions -> IO ()
runDC cmd (DockerComposeArgs args) _opts = do
  DockerCompose.run DockerCompose.Args
    { files = []
    , otherArgs = [cmd] ++ args
    }

runBuildAndDC :: Text -> DockerComposeArgs -> CommonOptions -> IO ()
runBuildAndDC cmd dopts opts = do
  ea <- defaultEvaluationArgs opts
  Arion.Nix.withBuiltComposition ea $ \path -> do
    loadImages path
    DockerCompose.run DockerCompose.Args
      { files = [path]
      , otherArgs = [cmd] ++ unDockerComposeArgs dopts
      }

runEvalAndDC :: Text -> DockerComposeArgs -> CommonOptions -> IO ()
runEvalAndDC cmd dopts opts = do
  ea <- defaultEvaluationArgs opts
  Arion.Nix.withEvaluatedComposition ea $ \path ->
    DockerCompose.run DockerCompose.Args
      { files = [path]
      , otherArgs = [cmd] ++ unDockerComposeArgs dopts
      }

defaultEvaluationArgs :: CommonOptions -> IO EvaluationArgs
defaultEvaluationArgs co = do
  uid <- getRealUserID
  pure EvaluationArgs
    { evalUid = fromIntegral uid
    , evalModules = files co
    , evalPkgs = pkgs co
    , evalWorkDir = Nothing
    , evalMode = ReadWrite
    , evalUserArgs = nixArgs co
    }

runCat :: CommonOptions -> IO ()
runCat co = do
  v <- Arion.Nix.evaluateComposition =<< defaultEvaluationArgs co
  T.hPutStrLn stdout (pretty v)

runRepl :: CommonOptions -> IO ()
runRepl co = do
  putErrText
    "Launching a repl for you. To get started:\n\
    \\n\
    \To see deployment-wide configuration\n\
    \  type config. and use tab completion\n\
    \To bring the top-level Nixpkgs attributes into scope\n\
    \  type :a (config._module.args.pkgs) // { inherit config; }\n\
    \"
  Arion.Nix.replForComposition =<< defaultEvaluationArgs co

detachFlag :: Parser Bool
detachFlag = flag False True (long "detach" <> short 'd' <> help "Detached mode: Run command in the background.")

privilegedFlag :: Parser Bool
privilegedFlag = flag False True (long "privileged" <> help "Give extended privileges to the process.")

userOption :: Parser Text
userOption = strOption (long "user" <> short 'u' <> help "Run the command as this user.")

noTTYFlag :: Parser Bool
noTTYFlag = flag False True (short 'T' <> help "Disable pseudo-tty allocation. By default `exec` allocates a TTY.")

indexOption :: Parser Int
indexOption = option
  (auto >>= \i -> i <$ unless (i >= 1) (fail "container index must be >= 1"))
  (long "index" <> value 1 <> help "Index of the container if there are multiple instances of a service.")

envOption :: Parser (Text, Text)
envOption = option (auto >>= spl) (long "env" <> short 'e' <> help "Set environment variables (can be used multiple times, not supported in Docker API < 1.25)")
  where spl s = case T.break (== '=') s of
          (_, "") -> fail "--env parameter needs to combine key and value with = sign"
          (k, ev) -> pure (k, T.drop 1 ev)

workdirOption :: Parser Text
workdirOption = strOption (long "workdir" <> short 'w' <> metavar "DIR" <> help "Working directory in which to start the command in the container.")

parseExecCommand :: Parser (CommonOptions -> IO ())
parseExecCommand = runExec
  <$> detachFlag
  <*> privilegedFlag
  <*> optional userOption
  <*> noTTYFlag
  <*> indexOption
  <*> many envOption
  <*> optional workdirOption
  <*> textArgument (metavar "SERVICE")
  <*> orEmpty' (
      (:) <$> argument (T.pack <$> str) (metavar "COMMAND")
          <*> many (argument (T.pack <$> str) (metavar "ARG"))
  )

orEmpty' :: (Alternative f, Monoid a) => f a -> f a
orEmpty' m = fromMaybe mempty <$> optional m

runExec :: Bool -> Bool -> Maybe Text -> Bool -> Int -> [(Text, Text)] -> Maybe Text -> Text -> [Text] -> CommonOptions -> IO ()
runExec detach privileged user noTTY index envs workDir service commandAndArgs opts = do
  putErrText $ "Service: " <> service

  ea <- defaultEvaluationArgs opts
  Arion.Nix.withEvaluatedComposition ea $ \path -> do
    commandAndArgs'' <- case commandAndArgs of
      [] -> getDefaultExec path service
      x -> pure x
    let commandAndArgs' = case commandAndArgs'' of
          [] -> ["/bin/sh"]
          x -> x
  
    let args = concat
          [ ["exec"]
          , ("--detach" <$ guard detach :: [Text])
          , "--privileged" <$ guard privileged
          , "-T" <$ guard noTTY
          , (\(k, v) -> ["--env", k <> "=" <> v]) =<< envs
          , join $ toList (user <&> \u -> ["--user", u])
          , ["--index", show index]
          , join $ toList (workDir <&> \w -> ["--workdir", w])
          , [service]
          , commandAndArgs'
          ]
    DockerCompose.run DockerCompose.Args
      { files = [path]
      , otherArgs = args
      }

main :: IO ()
main = 
  (join . arionExecParser) (info (parseAll <**> helper) fullDesc)
  where
    arionExecParser = customExecParser (prefs showHelpOnEmpty)