{-# LANGUAGE OverloadedLists #-}
{-# LANGUAGE RecordWildCards #-}

module Main (main) where

import Control.Applicative.Combinators (option, sepBy1)
import Data.Aeson
    ( decodeFileStrict
    , eitherDecodeFileStrict
    )
import Data.Bifunctor                  (bimap)
import Data.Foldable                   (for_)
import Data.Text                       (Text, pack, unpack)
import Data.Void                       (Void)
import Dhall.Core                      (Expr (..))
import Dhall.Format                    (Format (..))
import Numeric.Natural                 (Natural)
import Text.Megaparsec
    ( Parsec
    , eof
    , errorBundlePretty
    , optional
    , parse
    , some
    , (<|>)
    )
import Text.Megaparsec.Char            (alphaNumChar, char)

import Dhall.Kubernetes.Data  (patchCyclicImports)
import Dhall.Kubernetes.Types
    ( DuplicateHandler
    , ModelHierarchy
    , ModelName (..)
    , Prefix
    , Swagger (..)
    )
import System.FilePath        ((</>))

import qualified Data.List                  as List
import qualified Data.Map.Strict            as Data.Map
import qualified Data.Ord                   as Ord
import qualified Data.Text                  as Text
import qualified Data.Text.IO               as Text
import qualified Dhall.Core                 as Dhall
import qualified Dhall.Format
import qualified Dhall.Kubernetes.Convert   as Convert
import qualified Dhall.Kubernetes.Types     as Types
import qualified Dhall.Map
import qualified Dhall.Parser
import qualified Dhall.Util
import qualified GHC.IO.Encoding
import qualified Options.Applicative
import qualified Prettyprinter              as Pretty
import qualified Prettyprinter.Render.Text  as PrettyText
import qualified System.Directory           as Directory
import qualified System.IO
import qualified Text.Megaparsec            as Megaparsec
import qualified Text.Megaparsec.Char.Lexer as Megaparsec.Lexer

-- | Top-level program options
data Options = Options
    { skipDuplicates :: Bool
    , preferNaturalInt :: Bool
    , natIntExceptions :: [(String,String)]
    , prefixMap :: Data.Map.Map Prefix Dhall.Import
    , splits :: Data.Map.Map ModelHierarchy (Maybe ModelName)
    , filename :: String
    , crd :: Bool
    }

-- | Write and format a Dhall expression to a file
writeDhall :: FilePath -> Types.Expr -> IO ()
writeDhall path expr = do
  putStrLn $ "Writing file '" <> path <> "'"
  Text.writeFile path $ pretty expr <> "\n"

  let chosenCharacterSet = Nothing -- Infer from input

  let censor = Dhall.Util.NoCensor

  let outputMode = Dhall.Util.Write

  let inputs = pure (Dhall.Util.InputFile path)

  let transitivity = Dhall.Util.NonTransitive

  let formatOptions = Dhall.Format.Format{..}

  Dhall.Format.format formatOptions

-- | Pretty print things
pretty :: Pretty.Pretty a => a -> Text
pretty = PrettyText.renderStrict
  . Pretty.layoutPretty Pretty.defaultLayoutOptions
  . Pretty.pretty

data Stability = Alpha Natural | Beta Natural | Production deriving (Eq, Ord)

data Version = Version
    { stability :: Stability
    , version :: Natural
    } deriving (Eq, Ord)

parseStability :: Parsec Void Text Stability
parseStability = parseAlpha <|> parseBeta <|> parseProduction
  where
    parseAlpha = do
        _ <- "alpha"
        n <- Megaparsec.Lexer.decimal
        return (Alpha n)

    parseBeta = do
        _ <- "beta"
        n <- Megaparsec.Lexer.decimal
        return (Beta n)

    parseProduction = do
        return Production

parseVersion :: Parsec Void Text Version
parseVersion = Megaparsec.try parseSuffix <|> parsePrefix
  where
    parseComponent = do
        Megaparsec.takeWhile1P (Just "not a period") (/= '.')

    parseSuffix = do
        _ <- "v"
        version <- Megaparsec.Lexer.decimal
        stability <- parseStability
        _ <- "."
        _ <- parseComponent
        Megaparsec.eof
        return Version{..}

    parsePrefix = do
        _ <- parseComponent
        _ <- "."
        parseVersion

getVersion :: ModelName -> Maybe Version
getVersion ModelName{..} =
    case Megaparsec.parse parseVersion "" unModelName of
        Left  _       -> Nothing
        Right version -> Just version

-- https://github.com/dhall-lang/dhall-kubernetes/issues/112
data Autoscaling = AutoscalingV1 | AutoscalingV2beta1 | AutoscalingV2beta2
    deriving (Eq, Ord)

getAutoscaling :: ModelName -> Maybe Autoscaling
getAutoscaling ModelName{..}
    | Text.isPrefixOf "io.k8s.api.autoscaling.v1"      unModelName =
        Just AutoscalingV1
    | Text.isPrefixOf "io.k8s.api.autoscaling.v2beta1" unModelName =
        Just AutoscalingV2beta1
    | Text.isPrefixOf "io.k8s.api.autoscaling.v2beta2" unModelName =
        Just AutoscalingV2beta2
    | otherwise =
        Nothing

isK8sNative :: ModelName -> Bool
isK8sNative ModelName{..} = Text.isPrefixOf "io.k8s." unModelName

preferStableResource :: DuplicateHandler
preferStableResource (_, names) = do
    let issue112 = Ord.comparing getAutoscaling
    let k8sOverCrd = Ord.comparing isK8sNative
    let defaultComparison = Ord.comparing getVersion
    let comparison = issue112 <> k8sOverCrd <> defaultComparison
    return (List.maximumBy comparison names)

skipDuplicatesHandler :: DuplicateHandler
skipDuplicatesHandler = const Nothing

parseImport :: String -> Types.Expr -> Dhall.Parser.Parser Dhall.Import
parseImport _ (Dhall.Note _ (Dhall.Embed l)) = pure l
parseImport prefix e = fail $ "Expected a Dhall import for " <> prefix <> " not:\n" <> show e

parseNatIntExceptions :: Options.Applicative.ReadM [(String, String)]
parseNatIntExceptions =
  Options.Applicative.eitherReader $ \s ->
    bimap errorBundlePretty id $ result (pack s)
  where
    parser = do
      typ <- some alphaNumChar
      char '.'
      fld <- some alphaNumChar
      return (typ, fld)
    result = parse ((Dhall.Parser.unParser parser `sepBy1` char ',') <* eof) "EXCEPTIONS"

parsePrefixMap :: Options.Applicative.ReadM (Data.Map.Map Prefix Dhall.Import)
parsePrefixMap =
  Options.Applicative.eitherReader $ \s ->
    bimap errorBundlePretty Data.Map.fromList $ result (pack s)
  where
    parser = do
      prefix <- some (alphaNumChar <|> char '.')
      char '='
      e <- Dhall.Parser.expr
      imp <- parseImport prefix e
      return (pack prefix, imp)
    result = parse ((Dhall.Parser.unParser parser `sepBy1` char ',') <* eof) "MAPPING"

parseSplits :: Options.Applicative.ReadM (Data.Map.Map ModelHierarchy (Maybe ModelName))
parseSplits =
  Options.Applicative.eitherReader $ \s ->
    bimap errorBundlePretty Data.Map.fromList $ result (pack s)
  where
    parseModelInner = some (alphaNumChar <|> char '-' <|> char '.')
    parseModel = (ModelName . pack) <$> (((char '(') *> parseModelInner <* (char ')')) <|> parseModelInner)
    parser = do
      path <- parseModel `sepBy1` char '.'
      model <- optional $ do
        char '='
        mo <- parseModel
        return mo
      return (path, model)
    result = parse ((Dhall.Parser.unParser parser `sepBy1` char ',') <* eof) "SPLITS"


parseOptions :: Options.Applicative.Parser Options
parseOptions = Options <$> parseSkip <*> parseNaturalInt <*> parseNatIntExceptions' <*> parsePrefixMap' <*> parseSplits' <*> fileArg <*> crdArg
  where
    parseSkip =
      Options.Applicative.switch
        (  Options.Applicative.long "skipDuplicates"
        <> Options.Applicative.help "Skip types with the same name when aggregating types"
        )
    parseNaturalInt =
      Options.Applicative.switch
        (  Options.Applicative.long "preferNaturalInt"
        <> Options.Applicative.help "Render Swagger Integer as Dhall Natural unless negative numbers included in range, and Swagger IntOrString as Dhall NatOrString"
        )
    parseNatIntExceptions' =
      option [] $ Options.Applicative.option parseNatIntExceptions
       (  Options.Applicative.long "natIntExceptions"
        <> Options.Applicative.help "List of Integer and/or IntOrString Type.field that should be treated the opposite way to preferNaturalInt; e.g.: ContainerStateTerminated.exitCode,ContainerStateTerminated.signal"
        <> Options.Applicative.metavar "EXCEPTIONS"
       )
    parsePrefixMap' =
      option Data.Map.empty $ Options.Applicative.option parsePrefixMap
        (  Options.Applicative.long "prefixMap"
        <> Options.Applicative.help "Specify prefix mappings as 'prefix1=importBase1,prefix2=importBase2,...'"
        <> Options.Applicative.metavar "MAPPING"
        )
    parseSplits' =
      option Data.Map.empty $ Options.Applicative.option parseSplits
        (  Options.Applicative.long "splitPaths"
        <> Options.Applicative.help
          "Specifiy path and model name pairs with paths being delimited by '.' and pairs separated by '=' for which \
          \definitions should be artificially split with a ref: \n\
          \'(com.example.v1.Certificate).spec=com.example.v1.CertificateSpec'\n\
          \When the model name is omitted, a guess will be made based on the first word of the definition's \
          \description. Also note that top level model names in a path must use () when the name contains '.'"
        <> Options.Applicative.metavar "SPLITS"
        )
    fileArg = Options.Applicative.strArgument
            (  Options.Applicative.help "The input file to read"
            <> Options.Applicative.metavar "FILE"
            <> Options.Applicative.action "file"
            )
    crdArg = Options.Applicative.switch
      (  Options.Applicative.long "crd"
      <> Options.Applicative.help "The input file is a custom resource definition"
      )

-- | `ParserInfo` for the `Options` type
parserInfoOptions :: Options.Applicative.ParserInfo Options
parserInfoOptions =
    Options.Applicative.info
        (Options.Applicative.helper <*> parseOptions)
        (   Options.Applicative.progDesc "Swagger to Dhall generator"
        <>  Options.Applicative.fullDesc
        )

main :: IO ()
main = do
  GHC.IO.Encoding.setLocaleEncoding System.IO.utf8

  Options{..} <- Options.Applicative.execParser parserInfoOptions

  let duplicateHandler =
        if skipDuplicates
        then skipDuplicatesHandler
        else preferStableResource

  -- Get the Definitions
  defs <-
        if crd then do
          crdFile <- eitherDecodeFileStrict filename
          case crdFile of
            Left e -> do
                fail $ "Unable to decode the CRD file. " <> show e
            Right s -> do
                case Convert.toDefinition s of
                    Left text -> do
                        fail (Text.unpack text)
                    Right result -> do
                        return (Data.Map.fromList [result])
        else do
            swaggerFile <- decodeFileStrict filename
            case swaggerFile of
              Nothing -> fail "Unable to decode the Swagger file"
              Just (Swagger{..})  -> pure definitions

  let fix m = Data.Map.adjust patchCyclicImports (ModelName m)

  let fixedDefs =
        -- TODO: find a better way to deal with this cyclic import
        ( fix "io.k8s.apiextensions-apiserver.pkg.apis.apiextensions.v1beta1.JSONSchemaProps"
        . fix "io.k8s.apiextensions-apiserver.pkg.apis.apiextensions.v1.JSONSchemaProps"
        . fix "io.k8s.apiextensions-apiserver.pkg.apis.apiextensions.v1beta1.JSONSchemaProps.dhall"
        ) defs

  -- Convert to Dhall types in a Map
  let types = Convert.toTypes prefixMap (Convert.pathSplitter splits) preferNaturalInt natIntExceptions fixedDefs

  -- Output to types
  Directory.createDirectoryIfMissing True "types"
  for_ (Data.Map.toList types) $ \(ModelName name, expr) -> do
    let path = "./types" </> unpack name <> ".dhall"
    writeDhall path expr

  -- Convert from Dhall types to defaults
  let defaults = Data.Map.mapMaybeWithKey (Convert.toDefault prefixMap fixedDefs) types

  -- Output to defaults
  Directory.createDirectoryIfMissing True "defaults"
  for_ (Data.Map.toList defaults) $ \(ModelName name, expr) -> do
    let path = "./defaults" </> unpack name <> ".dhall"
    writeDhall path expr

  let mkEmbedField = Dhall.makeRecordField . Dhall.Embed

  let toSchema (ModelName key) _ _ =
        Dhall.RecordLit
          [ ("Type", mkEmbedField (Convert.mkImport prefixMap ["types", ".."] (key <> ".dhall")))
          , ("default", mkEmbedField (Convert.mkImport prefixMap ["defaults", ".."] (key <> ".dhall")))
          ]

  let schemas = Data.Map.intersectionWithKey toSchema types defaults

  let package =
        Combine
          mempty
          Nothing
          (Embed (Convert.mkImport prefixMap [ ] "schemas.dhall"))
          (RecordLit
              [ ( "IntOrString"
                , Dhall.makeRecordField $ Field (Embed (Convert.mkImport prefixMap [ ] "types.dhall")) $ Dhall.makeFieldSelection "IntOrString"
                )
              , ( "NatOrString"
                , Dhall.makeRecordField $ Field (Embed (Convert.mkImport prefixMap [ ] "types.dhall")) $ Dhall.makeFieldSelection "NatOrString"
                )
              , ( "Resource", mkEmbedField (Convert.mkImport prefixMap [ ] "typesUnion.dhall"))
              ]
          )

  -- Output schemas that combine both the types and defaults
  Directory.createDirectoryIfMissing True "schemas"
  for_ (Data.Map.toList schemas) $ \(ModelName name, expr) -> do
    let path = "./schemas" </> unpack name <> ".dhall"
    writeDhall path expr

  -- Output the types record, the defaults record, and the giant union type
  let getImportsMap = Convert.getImportsMap prefixMap duplicateHandler objectNames
      makeRecordMap = Dhall.Map.mapMaybe (Just . Dhall.makeRecordField)
      objectNames = Data.Map.keys types
      typesMap = getImportsMap "types" $ Data.Map.keys types
      defaultsMap = getImportsMap "defaults" $ Data.Map.keys defaults
      schemasMap = getImportsMap "schemas" $ Data.Map.keys schemas

      typesRecordPath = "./types.dhall"
      typesUnionPath = "./typesUnion.dhall"
      defaultsRecordPath = "./defaults.dhall"
      schemasRecordPath = "./schemas.dhall"
      packageRecordPath = "./package.dhall"

  writeDhall typesUnionPath (Dhall.Union $ fmap Just typesMap)
  writeDhall typesRecordPath (Dhall.RecordLit $ makeRecordMap typesMap)
  writeDhall defaultsRecordPath (Dhall.RecordLit $ makeRecordMap defaultsMap)
  writeDhall schemasRecordPath (Dhall.RecordLit $ makeRecordMap schemasMap)
  writeDhall packageRecordPath package