{-# LANGUAGE CPP, GADTs, RankNTypes, FlexibleContexts #-}
module Clash.Clashilator.Setup
    ( clashToVerilog
    , buildVerilator
    , clashilate

    , clashilatorMain
    , clashilatorBuildHook
    ) where

import qualified Clash.Main as Clash
import qualified Clash.Clashilator as Clashilator
import Clash.Clashilator.Cabal
import Clash.Driver.Manifest (Manifest, readManifest)

import Distribution.Simple
import Distribution.Simple.LocalBuildInfo
import Distribution.Simple.Setup
import Distribution.Simple.Program
import Distribution.Simple.Utils (infoNoWrap)
import Distribution.Verbosity
import Distribution.ModuleName
import Distribution.Types.UnqualComponentName

import Distribution.Types.Lens
import Control.Lens hiding ((<.>))
import Data.List (intercalate, sort, nub)
import Data.Maybe (fromMaybe)
import System.FilePath
import GHC (Ghc)
#if MIN_VERSION_ghc(8,10,0)
import GHC (getSession, setSession)
import HscTypes (HscEnv (..))
import Linker
#endif

lookupX :: String -> BuildInfo -> Maybe String
lookupX key buildInfo = lookup ("x-clashilator-" <> key) (view customFieldsBI buildInfo)

clashilatorBuildHook :: BuildHook
clashilatorBuildHook = withComponentHook clashilate $ buildHook simpleUserHooks

clashToVerilog :: Ghc () -> LocalBuildInfo -> BuildFlags -> [FilePath] -> BuildInfo -> ModuleName -> String -> FilePath -> IO (FilePath, Manifest)
clashToVerilog startAction lbi flags srcDirs buildInfo mod entity outDir = do
    pkgdbs <- packageDBs lbi flags
    let dbpaths = nub . sort $ [ path | SpecificPackageDB path <- pkgdbs ]
        dbflags = concat [ ["-package-db", path] | path <- dbpaths ]
        iflags = [ "-i" <> dir | dir <- srcDirs ]
        clashflags = maybe [] words $ lookupX "clash-flags" buildInfo

    let args = concat
            [ [ "--verilog"
              , "-outputdir", outDir
              , "-main-is", entity
              , intercalate "." (components mod)
              ]
            , iflags
            , dbflags
            , clashflags
            ]
    infoNoWrap verbosity $ unwords $ "Clash.defaultMain" : args
    Clash.defaultMainWithAction startAction args

    let modDir = intercalate "." (components mod)
        verilogDir = outDir </> modDir <.> entity
    Just manifest <- readManifest (verilogDir </> "clash-manifest.json")

    return (verilogDir, manifest)
  where
    verbosity = fromFlagOrDefault normal (buildVerbosity flags)

buildVerilator :: Ghc () -> LocalBuildInfo -> BuildFlags -> Maybe UnqualComponentName -> BuildInfo -> IO BuildInfo
buildVerilator startAction lbi flags compName buildInfo = case top of
    Nothing -> return buildInfo
    Just mod -> buildVerilator' startAction lbi flags compName buildInfo (fromString mod) entity
  where
    top = lookupX "top-is" buildInfo
    entity = fromMaybe "topEntity" $ lookupX "entity" buildInfo

buildVerilator' :: Ghc () -> LocalBuildInfo -> BuildFlags -> Maybe UnqualComponentName -> BuildInfo -> ModuleName -> String -> IO BuildInfo
buildVerilator' startAction lbi flags compName buildInfo mod entity = do
    cflags <- do
        mpkgConfig <- needProgram verbosity pkgConfigProgram (withPrograms lbi)
        case mpkgConfig of
            Nothing -> error "Cannot find pkg-config program"
            Just (pkgConfig, _) -> getProgramOutput verbosity pkgConfig ["--cflags", "verilator"]

    -- TODO: dependency tracking
    (verilogDir, manifest) <- clashToVerilog startAction lbi flags srcDirs buildInfo mod entity synDir
    Clashilator.generateFiles (Just cflags) verilogDir verilatorDir (fromString <$> clk) manifest

    -- TODO: get `make` location from configuration
    _ <- getProgramInvocationOutput verbosity $
         simpleProgramInvocation "make" ["-f", verilatorDir </> "Makefile"]

    let incDir = verilatorDir </> "src"
        libDir = verilatorDir </> "obj"
        lib = "VerilatorFFI"

    let fixupOptions f (PerCompilerFlavor x y) = PerCompilerFlavor (f x) (f y)

        compileFlags =
            [ "-fPIC"
            , "-pgml c++"
            ]

        ldFlags =
            [ "-Wl,--whole-archive"
            , "-Wl,-Bstatic"
            , "-Wl,-l" <> lib
            , "-Wl,-Bdynamic"
            , "-Wl,--no-whole-archive"
            ]

    return $ buildInfo
      & includeDirs %~ (incDir:)
      & extraLibDirs %~ (libDir:)
      & extraLibs %~ ("stdc++":)
      & options %~ fixupOptions (compileFlags++)
      & ldOptions %~ (ldFlags++)
      & hsSourceDirs %~ (incDir:)
      & otherModules %~ (fromComponents ["Clash", "Clashilator", "FFI"]:)
  where
    verbosity = fromFlagOrDefault normal (buildVerbosity flags)

    clk = lookup "x-clashilator-clock" $ view customFieldsBI buildInfo

    -- TODO: Maybe we could add extra source dirs from "x-clashilator-source-dirs"?
    srcDirs = view hsSourceDirs buildInfo
    outDir = case compName of
        Nothing -> buildDir lbi
        Just name -> buildDir lbi </> unUnqualComponentName name
    verilatorDir = outDir </> "_clashilator" </> "verilator"
    synDir = outDir </> "_clashilator" </> "clash-syn"

clashilate :: LocalBuildInfo -> BuildFlags -> Component -> IO BuildInfo
clashilate lbi flags c = do
#if MIN_VERSION_ghc(8,10,0)
    linker <- uninitializedLinker
    let startAction = do
            env <- getSession
            setSession (env {hsc_dynLinker = linker})
#else
    let startAction = return ()
#endif
    buildVerilator startAction lbi flags (componentNameString $ componentName c) (c ^. buildInfo)

clashilatorMain :: IO ()
clashilatorMain = defaultMainWithHooks simpleUserHooks
    { buildHook = clashilatorBuildHook
    }