{-# LANGUAGE TupleSections #-}
{-# LANGUAGE DataKinds        #-}
{-# LANGUAGE QuasiQuotes      #-}
{-# LANGUAGE RecordWildCards  #-}
{-# LANGUAGE TemplateHaskell  #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE FlexibleContexts #-}

module Handler.Apps where

import           Startlude hiding (Handler)

import           Control.Monad.Logger
import           Data.Aeson
import qualified Data.Attoparsec.Text          as Atto
import qualified Data.ByteString.Lazy          as BS
import           Data.Conduit
import qualified Data.Conduit.Binary           as CB
import qualified Data.Text                     as T
import           Database.Persist
import qualified GHC.Show                       ( Show(..) )
import           Network.HTTP.Types
import           System.Directory
import           System.FilePath                ( (<.>)
                                                , (</>)
                                                )
import           System.Posix.Files             ( fileSize
                                                , getFileStatus
                                                )
import           Yesod.Core
import           Yesod.Persist.Core

import           Foundation
import           Lib.Registry
import           Lib.Types.AppIndex
import           Lib.Types.Emver
import           Lib.Types.FileSystem
import           Lib.Error
import           Lib.External.AppMgr
import           Settings
import           Database.Queries
import           Network.Wai                    ( Request(requestHeaderUserAgent) )
import           Util.Shared

pureLog :: Show a => a -> Handler a
pureLog = liftA2 (*>) ($logInfo . show) pure

logRet :: ToJSON a => Handler a -> Handler a
logRet = (>>= liftA2 (*>) ($logInfo . decodeUtf8 . BS.toStrict . encode) pure)

data FileExtension = FileExtension FilePath (Maybe String)
instance Show FileExtension where
    show (FileExtension f Nothing ) = f
    show (FileExtension f (Just e)) = f <.> e

userAgentOsVersionParser :: Atto.Parser Version
userAgentOsVersionParser = do
    void $ (Atto.string "EmbassyOS" <|> Atto.string "AmbassadorOS" <|> Atto.string "MeshOS") *> Atto.char '/'
    parseVersion

getEmbassyOsVersion :: Handler (Maybe Version)
getEmbassyOsVersion = userAgentOsVersion
    where
        userAgentOsVersion =
            (hush . Atto.parseOnly userAgentOsVersionParser . decodeUtf8 <=< requestHeaderUserAgent) <$> waiRequest

getSysR :: Extension "" -> Handler TypedContent
getSysR e = do
    sysResourceDir <- (</> "sys") . resourcesDir . appSettings <$> getYesod
    -- @TODO update with new response type here
    getApp sysResourceDir e

getAppManifestR :: AppIdentifier -> Handler TypedContent
getAppManifestR appId = do
    (appsDir, appMgrDir) <- getsYesod $ ((</> "apps") . resourcesDir &&& staticBinDir) . appSettings
    av <- getVersionFromQuery appsDir appExt >>= \case
        Nothing -> sendResponseStatus status404 ("Specified App Version Not Found" :: Text)
        Just v  -> pure v
    let appDir = (<> "/") . (</> show av) . (</> toS appId) $ appsDir
    manifest <- handleS9ErrT $ getManifest appMgrDir appDir appExt
    addPackageHeader appMgrDir appDir appExt
    pure $ TypedContent "application/json" (toContent manifest)
    where appExt = Extension (toS appId) :: Extension "s9pk"

getAppConfigR :: AppIdentifier -> Handler TypedContent
getAppConfigR appId = do
    appSettings <- appSettings <$> getYesod
    let appsDir   = (</> "apps") . resourcesDir $ appSettings
    let appMgrDir = staticBinDir appSettings
    av <- getVersionFromQuery appsDir appExt >>= \case
        Nothing -> sendResponseStatus status404 ("Specified App Version Not Found" :: Text)
        Just v  -> pure v
    let appDir = (<> "/") . (</> show av) . (</> toS appId) $ appsDir
    config <- handleS9ErrT $ getConfig appMgrDir appDir appExt
    addPackageHeader appMgrDir appDir appExt
    pure $ TypedContent "application/json" (toContent config)
    where appExt = Extension (toS appId) :: Extension "s9pk"

getAppR :: Extension "s9pk" -> Handler TypedContent
getAppR e = do
    appResourceDir <- (</> "apps") . resourcesDir . appSettings <$> getYesod
    getApp appResourceDir e

getApp :: KnownSymbol a => FilePath -> Extension a -> Handler TypedContent
getApp rootDir ext@(Extension appId) = do
    specString <- T.filter (not . isSpace) . fromMaybe "*" <$> lookupGetParam "spec"
    spec       <- case readMaybe specString of
        Nothing -> sendResponseStatus status400 ("Invalid App Version Specification" :: Text)
        Just t  -> pure t
    appVersions <- liftIO $ getAvailableAppVersions rootDir ext
    putStrLn $ "valid appversion for " <> (show ext :: String) <> ": " <> show appVersions
    let satisfactory = filter ((<|| spec) . fst . unRegisteredAppVersion) appVersions
    let best = fst . getMaxVersion <$> foldMap (Just . MaxVersion . (, fst . unRegisteredAppVersion)) satisfactory
    (appsDir, appMgrDir) <- getsYesod $ ((</> "apps") . resourcesDir &&& staticBinDir) . appSettings
    case best of
        Nothing -> notFound
        Just (RegisteredAppVersion (appVersion, filePath)) -> do
            exists' <- liftIO $ doesFileExist filePath >>= \case
                True  -> pure Existent
                False -> pure NonExistent
            let appDir = (<> "/") . (</> show appVersion) . (</> toS appId) $ appsDir
            let appExt = Extension (toS appId) :: Extension "s9pk"
            addPackageHeader appMgrDir appDir appExt
            determineEvent exists' (extension ext) filePath appVersion
    where
        determineEvent :: FileExistence -> String -> FilePath -> Version -> HandlerFor RegistryCtx TypedContent
        -- for app files
        determineEvent Existent "s9pk" fp av = do
            _ <- recordMetrics appId av
            chunkIt fp
        -- for png, system, etc
        determineEvent Existent    _ fp _ = chunkIt fp
        determineEvent NonExistent _ _  _ = notFound

chunkIt :: FilePath -> HandlerFor RegistryCtx TypedContent
chunkIt fp = do
    sz <- liftIO $ fileSize <$> getFileStatus fp
    addHeader "Content-Length" (show sz)
    respondSource typeOctet $ CB.sourceFile fp .| awaitForever sendChunkBS

recordMetrics :: String -> Version -> HandlerFor RegistryCtx ()
recordMetrics appId appVersion = do
    let appId' = T.pack appId
    sa <- runDB $ fetchApp appId'
    case sa of
        Nothing -> do
            $logError $ appId' <> " not found in database"
            notFound 
        Just a -> do
            let appKey' = entityKey a
            existingVersion <- runDB $ fetchAppVersion appVersion appKey'
            case existingVersion of
                Nothing -> do
                    $logError $ "Version: " <> show appVersion <> " not found in database"
                    notFound
                Just v -> runDB $ createMetric (entityKey a) (entityKey v)