{-|
Functions to read, write, and handle manifest files.
-}

{-# LANGUAGE CPP #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE NamedFieldPuns #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE OverloadedStrings #-}

module Clash.Driver.Manifest where

import           Control.Exception (tryJust)
import           Control.Monad (guard, forM)
import           Control.Monad.State (evalState)
import qualified Crypto.Hash.SHA256 as Sha256
import qualified Data.Aeson as Aeson
import qualified Data.Aeson.Encode.Pretty as Aeson
import           Data.Aeson
  (ToJSON(toJSON), FromJSON(parseJSON), KeyValue ((.=)), (.:), (.:?))
import           Data.Aeson.Types (Parser)
import qualified Data.ByteString.Base16 as Base16
import qualified Data.ByteString.Lazy as ByteStringLazy
import           Data.ByteString (ByteString)
import           Data.Hashable (hash)
import           Data.HashMap.Strict (HashMap)
import qualified Data.HashMap.Strict as HashMap
import           Data.Maybe (catMaybes)
import qualified Data.Text as Text
import qualified Data.Text.Encoding as Text
import qualified Data.Text.Lazy as LText
import qualified Data.Text.Lazy.Encoding as LText
import           Data.Text (Text)
import           Data.Text.Prettyprint.Doc.Extra (renderOneLine)
import           Data.Time (UTCTime)
import qualified Data.Set as Set
import           Data.Semigroup.Monad (getMon)
import           Data.String (IsString)
import           System.IO.Error (isDoesNotExistError)
import           System.FilePath (takeDirectory, (</>))
import           System.Directory (listDirectory, doesFileExist)
import           Text.Read (readMaybe)

import           Clash.Annotations.TopEntity.Extra ()
import           Clash.Backend (Backend (hdlType), Usage (External))
import           Clash.Core.Name (nameOcc)
import           Clash.Driver.Types
import           Clash.Primitives.Types
import           Clash.Core.Var (Id, varName)
import           Clash.Netlist.Types
  (TopEntityT, Component(..), HWType (Clock), hwTypeDomain)
import qualified Clash.Netlist.Types as Netlist
import qualified Clash.Netlist.Id as Id
import           Clash.Netlist.Util (typeSize)
import           Clash.Primitives.Util (hashCompiledPrimMap)
import           Clash.Signal (VDomainConfiguration(..))
import           Clash.Util.Graph (callGraphBindings)

#if MIN_VERSION_ghc(9,0,0)
import GHC.Utils.Misc (OverridingBool(..))
#else
import Util (OverridingBool(..))
#endif

data ManifestPort = ManifestPort
  { mpName :: Text
  -- ^ Port name (as rendered in HDL)
  , mpTypeName :: Text
  -- ^ Type name (as rendered in HDL)
  , mpWidth :: Int
  -- ^ Port width in bits
  , mpIsClock :: Bool
  -- ^ Is this port a clock?
  , mpDomain :: Maybe Text
  -- ^ Domain this port belongs to. This is currently only included for clock,
  -- reset, and enable ports. TODO: add to all ports originally defined as a
  -- @Signal@ too.
  } deriving (Show,Read,Eq)

instance ToJSON ManifestPort where
  toJSON (ManifestPort{..}) =
    Aeson.object $
      [ "name" .= mpName
      , "type_name" .= mpTypeName
      , "width" .= mpWidth
      , "is_clock" .= mpIsClock
      ] <>
      (case mpDomain of
        Just dom -> ["domain" .= dom]
        Nothing -> [] )

instance FromJSON ManifestPort where
  parseJSON = Aeson.withObject "ManifestPort" $ \v ->
    ManifestPort
      <$> v .: "name"
      <*> v .: "type_name"
      <*> v .: "width"
      <*> v .: "is_clock"
      <*> v .:? "domain"

-- | Information about the generated HDL between (sub)runs of the compiler
data Manifest
  = Manifest
  { manifestHash :: Int
    -- ^ Hash of the TopEntity and all its dependencies.
    --
    -- TODO: This is currently calculated using 'hash', but this function wasn't
    --       really designed to give any performance (in the collision / crypto
    --       sense) guarantees. We should switch to a proper hashing algo like
    --       SHA256.
  , successFlags  :: (Int,Int,Bool)
    -- ^ Compiler flags used to achieve successful compilation:
    --
    --   * opt_inlineLimit
    --   * opt_specLimit
    --   * opt_floatSupport
  , inPorts :: [ManifestPort]
  , outPorts :: [ManifestPort]
  , componentNames :: [Text]
    -- ^ Names of all the generated components for the @TopEntity@ (does not
    -- include the names of the components of the @TestBench@ accompanying
    -- the @TopEntity@).
    --
    -- This list is reverse topologically sorted. I.e., a component might depend
    -- on any component listed before it, but not after it.
  , topComponent :: Text
    -- ^ Design entry point. This is usually the component annotated with a
    -- @TopEntity@ annotation.
  , fileNames :: [(FilePath, ByteString)]
    -- ^ Names and hashes of all the generated files for the @TopEntity@. Hashes
    -- are SHA256.
  , domains :: HashMap Text VDomainConfiguration
    -- ^ Domains encountered in design
  , transitiveDependencies :: [Text]
    -- ^ Dependencies of this design (fully qualified binder names). Is a
    -- transitive closure of all dependencies.
  } deriving (Show,Read,Eq)

instance ToJSON Manifest where
  toJSON (Manifest{..}) =
    Aeson.object
      [ "version" .= ("unstable" :: Text)
      , "hash" .= manifestHash
      , "flags" .= successFlags
        -- TODO: add nested ports (i.e., how Clash split/filtered arguments)
      , "components" .= componentNames
      , "top_component" .= Aeson.object
        [ "name" .= topComponent
        , "ports_flat" .= Aeson.object
          [ "in" .= inPorts
          , "out" .= outPorts ]
        ]
      , "files" .=
        [ Aeson.object
          [ "name" .= fName
          , "sha256" .= Text.decodeUtf8 (Base16.encode fHash)
            -- TODO: Add Edam like fields
          ]
        | (fName, fHash) <- fileNames]
      , "domains" .= HashMap.fromList
        [ ( domNm
          , Aeson.object
            [ "period" .= vPeriod
            , "active_edge" .= show vActiveEdge
            , "reset_kind" .= show vResetKind
            , "init_behavior" .= show vInitBehavior
            , "reset_polarity" .= show vResetPolarity
            ]
          )
        | (domNm, VDomainConfiguration{..}) <- HashMap.toList domains ]
      , "dependencies" .= Aeson.object
        [ "transitive" .= transitiveDependencies ]
      ]

instance FromJSON Manifest where
  parseJSON = Aeson.withObject "Manifest" $ \v ->
    let
      topComponent = v .: "top_component"
      portsFlat = topComponent >>= (.: "ports_flat")
    in
      Manifest
        <$> v .: "hash"
        <*> v .: "flags"
        <*> (portsFlat >>= (.: "in"))
        <*> (portsFlat >>= (.: "out"))
        <*> v .: "components"
        <*> (topComponent >>= (.: "name"))
        <*> do
              files <- v .: "files"
              forM files $ \obj -> do
                fName <- obj .: "name"
                sha256 <- obj .: "sha256"
                -- Note that we don't particularly care about hash decode
                -- failures. Realistically it shouldn't happen, and if it does
                -- there's almost no chance it would result in accidental caching.
#if MIN_VERSION_base16_bytestring(1,0,0)
                pure (fName, Base16.decodeLenient (Text.encodeUtf8 sha256))
#else
                pure (fName, fst (Base16.decode (Text.encodeUtf8 sha256)))
#endif
        <*> (v .: "domains" >>= HashMap.traverseWithKey parseDomain)
        <*> (v .: "dependencies" >>= (.: "transitive"))
   where
    parseDomain :: Text -> Aeson.Object -> Parser VDomainConfiguration
    parseDomain nm v =
      VDomainConfiguration
        <$> pure (Text.unpack nm)
        <*> (v .: "period")
        <*> parseWithRead "active_edge" v
        <*> parseWithRead "reset_kind" v
        <*> parseWithRead "init_behavior" v
        <*> parseWithRead "reset_polarity" v

    parseWithRead field obj = do
      v <- obj .:? field
      case readMaybe =<< v of
        Just a -> pure a
        Nothing -> fail $ "Could not read field: " <> show field

data UnexpectedModification
  -- | Clash generated file was modified
  = Modified FilePath
  -- | Non-clash generated file was added
  | Added FilePath
  -- | Clash generated file was removed
  | Removed FilePath
  deriving (Show)

mkManifestPort ::
  Backend backend =>
  -- | Backend used to lookup port type names
  backend ->
  -- | Port name
  Id.Identifier ->
  -- | Port type
  HWType ->
  ManifestPort
mkManifestPort backend portId portType = ManifestPort{..}
 where
  mpName = Id.toText portId
  mpWidth = typeSize portType
  mpIsClock = case portType of {Clock _ -> True; _ -> False}
  mpDomain = hwTypeDomain portType
  mpTypeName = flip evalState backend $ getMon $ do
     LText.toStrict . renderOneLine <$> hdlType (External mpName) portType

-- | Filename manifest file should be written to and read from
manifestFilename :: IsString a => a
manifestFilename = "clash-manifest.json"

mkManifest ::
  Backend backend =>
  -- | Backend used to lookup port type names
  backend ->
  -- | Domains encountered in design
  HashMap Text VDomainConfiguration ->
  -- | Options Clash was run with
  ClashOpts ->
  -- | Component of top entity
  Component ->
  -- | All other entities
  [Component] ->
  -- | Names of dependencies (transitive closure)
  [Id] ->
  -- | Files and  their hashes
  [(FilePath, ByteString)] ->
  -- | Hash returned by 'readFreshManifest'
  Int ->
  -- | New manifest
  Manifest
mkManifest backend domains ClashOpts{..} Component{..} components deps files topHash = Manifest
  { manifestHash = topHash
  , inPorts = [mkManifestPort backend pName pType | (pName, pType) <- inputs]
  , outPorts = [mkManifestPort backend pName pType | (_, (pName, pType), _) <- outputs]
  , componentNames = map Id.toText compNames
  , topComponent = Id.toText componentName
  , fileNames = files
  , successFlags = (opt_inlineLimit, opt_specLimit, opt_floatSupport)
  , domains = domains
  , transitiveDependencies = map (nameOcc . varName) deps
  }
 where
  compNames = map Netlist.componentName components

-- | Pretty print an unexpected modification as a list item.
pprintUnexpectedModification :: UnexpectedModification -> String
pprintUnexpectedModification = \case
  Modified p -> "Unexpected modification in " <> p
  Added p -> "Unexpected extra file " <> p
  Removed p -> "Unexpected removed file " <> p

-- | Pretty print a list of unexpected modifications. Print a maximum of /n/
-- modifications.
pprintUnexpectedModifications :: Int -> [UnexpectedModification] -> String
pprintUnexpectedModifications 0 us = pprintUnexpectedModifications maxBound us
pprintUnexpectedModifications _ [] = []
pprintUnexpectedModifications _ [u] = "* " <> pprintUnexpectedModification u
pprintUnexpectedModifications 1 (u:us) =
  "* and " <> show (length (u:us)) <> " more unexpected changes"
pprintUnexpectedModifications n (u:us) =
  "* " <> pprintUnexpectedModification u
        <> "\n" <> pprintUnexpectedModifications (n-1) us

-- | Reads a manifest file. Does not return manifest file if:
--
--  * Caching is disabled through @-fclash-no-cache@.
--  * Manifest could not be found.
--  * Cache is stale. This could be triggered by any of the given arguments.
--
-- Raises an exception if the manifest file or any of the files it is referring
-- to was inaccessible.
--
readFreshManifest ::
  -- | "This" top entity plus all that depend on it.
  [TopEntityT] ->
  -- | Core expressions and entry point. Any changes in the call graph will
  -- trigger a recompile.
  (BindingMap, Id) ->
  -- | Any changes in any primitive will trigger a recompile.
  CompiledPrimMap ->
  -- | Certain options will trigger recompiles if changed
  ClashOpts ->
  -- | Clash modification date
  UTCTime ->
  -- | Path to manifest file.
  FilePath ->
  -- | ( Nothing if no manifest file was found
  --   , Nothing on stale cache, disabled cache, or not manifest file found )
  IO (Maybe [UnexpectedModification], Maybe Manifest, Int)
readFreshManifest tops (bindingsMap, topId) primMap opts@(ClashOpts{..}) clashModDate path = do
  manifestM <- readManifest path
  modificationsM <- traverse (isUserModified path) manifestM

  pure
    ( modificationsM
    , checkManifest =<< if opt_cachehdl then manifestM else Nothing
    , topHash
    )

 where
  optsHash = hash opts {
      -- Ignore the following settings, they don't affect the generated HDL:

      -- 1. Debug
      opt_dbgLevel = DebugNone
    , opt_dbgTransformations = Set.empty
    , opt_dbgRewriteHistoryFile = Nothing

      -- 2. Caching
    , opt_cachehdl = True

      -- 3. Warnings
    , opt_primWarn = True
    , opt_color = Auto
    , opt_errorExtra = False
    , opt_checkIDir = True

      -- 4. Optional output
    , opt_edalize = False

      -- Ignore the following settings, they don't affect the generated HDL. However,
      -- they do influence whether HDL can be generated at all.
      --
      -- We therefore check whether the new flags changed in such a way that
      -- they could affect successful compilation, and use that information
      -- to decide whether to use caching or not (see: XXXX).
      --
      -- 1. termination measures
    , opt_inlineLimit = 20
    , opt_specLimit = 20

      -- 2. Float support
    , opt_floatSupport = False

      -- Finally, also ignore the HDL dir setting, because when a user moves the
      -- entire dir with generated HDL, they probably still want to use that as
      -- a cache
    , opt_hdlDir = Nothing
    }

  topHash = hash
    ( tops
    , hashCompiledPrimMap primMap
    , show clashModDate
    , callGraphBindings bindingsMap topId
    , optsHash
    )

  checkManifest manifest@Manifest{manifestHash,successFlags}
    | (cachedInline, cachedSpec, cachedFloat) <- successFlags

    -- Higher limits shouldn't affect HDL
    , cachedInline <= opt_inlineLimit
    , cachedSpec <= opt_specLimit

    -- /Enabling/ float support should compile more designs. Of course, keeping
    -- the same value for float support shouldn't invalidate caches either.
    , ((cachedFloat && not opt_floatSupport) || (cachedFloat == opt_floatSupport))

    -- Callgraph hashes should correspond
    , manifestHash == topHash
    = Just manifest

    -- One or more checks failed
    | otherwise = Nothing

-- | Determines whether the HDL directory the given 'LocatedManifest' was found
-- in contains any user made modifications. This is used by Clash to protect the
-- user against lost work.
isUserModified :: FilePath -> Manifest -> IO [UnexpectedModification]
isUserModified (takeDirectory -> topDir) Manifest{fileNames} = do
  let
    manifestFiles = Set.fromList (map fst fileNames)

  currentFiles <- (Set.delete manifestFilename . Set.fromList) <$> listDirectory topDir

  let
    removedFiles = Set.toList (manifestFiles `Set.difference` currentFiles)
    addedFiles = Set.toList (currentFiles `Set.difference` manifestFiles)

  changedFiles <- catMaybes <$> mapM detectModification fileNames

  pure
    (  map Removed removedFiles
    <> map Added addedFiles
    <> map Modified changedFiles )
 where
  detectModification :: (FilePath, ByteString) -> IO (Maybe FilePath)
  detectModification (filename, manifestDigest) = do
    let fullPath = topDir </> filename
    fileExists <- doesFileExist fullPath
    if fileExists then do
      contents <- ByteStringLazy.readFile fullPath
      if manifestDigest == Sha256.hashlazy contents
      then pure Nothing
      else pure (Just filename)
    else
      -- Will be caught by @removedFiles@
      pure Nothing

-- | Read a manifest file from disk. Returns 'Nothing' if file does not exist.
-- Any other IO exception is re-raised.
readManifest :: FilePath -> IO (Maybe Manifest)
readManifest path = do
  contentsE <- tryJust (guard . isDoesNotExistError) (Aeson.decodeFileStrict path)
  pure (either (const Nothing) id contentsE)

-- | Write manifest file to disk
writeManifest :: FilePath -> Manifest -> IO ()
writeManifest path = ByteStringLazy.writeFile path . Aeson.encodePretty

-- | Serialize a manifest.
--
-- TODO: This should really yield a 'ByteString'.
serializeManifest :: Manifest -> Text
serializeManifest = LText.toStrict . LText.decodeUtf8 . Aeson.encodePretty