{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE ScopedTypeVariables #-}

module GHC.Settings.IO
 ( SettingsError (..)
 , initSettings
 ) where

import GHC.Prelude

import GHC.Settings.Utils

import GHC.Settings.Config
import GHC.Utils.CliOption
import GHC.Utils.Fingerprint
import GHC.Platform
import GHC.Utils.Panic
import GHC.ResponseFile
import GHC.Settings
import GHC.SysTools.BaseDir

import Data.Char
import Control.Monad.Trans.Except
import Control.Monad.IO.Class
import qualified Data.Map as Map
import System.FilePath
import System.Directory

data SettingsError
  = SettingsError_MissingData String
  | SettingsError_BadData String

initSettings
  :: forall m
  .  MonadIO m
  => String -- ^ TopDir path
  -> ExceptT SettingsError m Settings
initSettings top_dir = do
  let installed :: FilePath -> FilePath
      installed file = top_dir </> file
      libexec :: FilePath -> FilePath
      libexec file = top_dir </> ".." </> "bin" </> file
      settingsFile = installed "settings"

      readFileSafe :: FilePath -> ExceptT SettingsError m String
      readFileSafe path = liftIO (doesFileExist path) >>= \case
        True -> liftIO $ readFile path
        False -> throwE $ SettingsError_MissingData $ "Missing file: " ++ path

  settingsStr <- readFileSafe settingsFile
  settingsList <- case maybeReadFuzzy settingsStr of
    Just s -> pure s
    Nothing -> throwE $ SettingsError_BadData $
      "Can't parse " ++ show settingsFile
  let mySettings = Map.fromList settingsList
      getBooleanSetting :: String -> ExceptT SettingsError m Bool
      getBooleanSetting key = either pgmError pure $
        getRawBooleanSetting settingsFile mySettings key

  -- On Windows, by mingw is often distributed with GHC,
  -- so we look in TopDir/../mingw/bin,
  -- as well as TopDir/../../mingw/bin for hadrian.
  -- But we might be disabled, in which we we don't do that.
  useInplaceMinGW <- getBooleanSetting "Use inplace MinGW toolchain"

  -- see Note [topdir: How GHC finds its files]
  -- NB: top_dir is assumed to be in standard Unix
  -- format, '/' separated
  mtool_dir <- liftIO $ findToolDir useInplaceMinGW top_dir
        -- see Note [tooldir: How GHC finds mingw on Windows]

  -- See Note [Settings file] for a little more about this file. We're
  -- just partially applying those functions and throwing 'Left's; they're
  -- written in a very portable style to keep ghc-boot light.
  let getSetting key = either pgmError pure $
        -- Escape the 'top_dir', to make sure we don't accidentally introduce an
        -- unescaped space
        getRawFilePathSetting (escapeArg top_dir) settingsFile mySettings key
      getToolSetting :: String -> ExceptT SettingsError m String
        -- Escape the 'mtool_dir', to make sure we don't accidentally introduce
        -- an unescaped space
      getToolSetting key = expandToolDir useInplaceMinGW (fmap escapeArg mtool_dir) <$> getSetting key
  targetPlatformString <- getSetting "target platform string"
  cc_prog <- getToolSetting "C compiler command"
  cxx_prog <- getToolSetting "C++ compiler command"
  cc_args_str <- getToolSetting "C compiler flags"
  cxx_args_str <- getToolSetting "C++ compiler flags"
  gccSupportsNoPie <- getBooleanSetting "C compiler supports -no-pie"
  cmmCppSupportsG0 <- getBooleanSetting "C-- CPP supports -g0"
  cpp_prog <- getToolSetting "CPP command"
  cpp_args_str <- getToolSetting "CPP flags"
  hs_cpp_prog <- getToolSetting "Haskell CPP command"
  hs_cpp_args_str <- getToolSetting "Haskell CPP flags"
  js_cpp_prog <- getToolSetting "JavaScript CPP command"
  js_cpp_args_str <- getToolSetting "JavaScript CPP flags"
  cmmCpp_prog <- getToolSetting "C-- CPP command"
  cmmCpp_args_str <- getToolSetting "C-- CPP flags"

  platform <- either pgmError pure $ getTargetPlatform settingsFile mySettings

  let unreg_cc_args = if platformUnregisterised platform
                      then ["-DNO_REGS", "-DUSE_MINIINTERPRETER"]
                      else []
      cpp_args    = map Option (unescapeArgs cpp_args_str)
      hs_cpp_args = map Option (unescapeArgs hs_cpp_args_str)
      js_cpp_args = map Option (unescapeArgs js_cpp_args_str)
      cmmCpp_args = map Option (unescapeArgs cmmCpp_args_str)
      cc_args  = unescapeArgs cc_args_str ++ unreg_cc_args
      cxx_args = unescapeArgs cxx_args_str

      -- The extra flags we need to pass gcc when we invoke it to compile .hc code.
      --
      -- -fwrapv is needed for gcc to emit well-behaved code in the presence of
      -- integer wrap around (#952).
      extraGccViaCFlags = if platformUnregisterised platform
                            -- configure guarantees cc support these flags
                            then ["-fwrapv", "-fno-builtin"]
                            else []

  ldSupportsCompactUnwind <- getBooleanSetting "ld supports compact unwind"
  ldSupportsFilelist      <- getBooleanSetting "ld supports filelist"
  ldSupportsSingleModule  <- getBooleanSetting "ld supports single module"
  mergeObjsSupportsResponseFiles <- getBooleanSetting "Merge objects supports response files"
  ldIsGnuLd               <- getBooleanSetting "ld is GNU ld"
  arSupportsDashL         <- getBooleanSetting "ar supports -L"


  -- The package database is either a relative path to the location of the settings file
  -- OR an absolute path.
  -- In case the path is absolute then top_dir </> abs_path == abs_path
  --         the path is relative then top_dir </> rel_path == top_dir </> rel_path
  globalpkgdb_path <- installed <$> getSetting "Relative Global Package DB"

  let ghc_usage_msg_path  = installed "ghc-usage.txt"
      ghci_usage_msg_path = installed "ghci-usage.txt"

  -- For all systems, unlit, split, mangle are GHC utilities
  -- architecture-specific stuff is done when building Config.hs
  unlit_path <- getToolSetting "unlit command"

  windres_path <- getToolSetting "windres command"
  ar_path <- getToolSetting "ar command"
  otool_path <- getToolSetting "otool command"
  install_name_tool_path <- getToolSetting "install_name_tool command"
  ranlib_path <- getToolSetting "ranlib command"

  -- HACK, see setPgmP below. We keep 'words' here to remember to fix
  -- Config.hs one day.


  -- Other things being equal, as and ld are simply gcc
  cc_link_args_str <- getToolSetting "C compiler link flags"
  let   as_prog  = cc_prog
        as_args  = map Option cc_args
        ld_prog  = cc_prog
        ld_args  = map Option (cc_args ++ unescapeArgs cc_link_args_str)
  ld_r_prog <- getToolSetting "Merge objects command"
  ld_r_args <- getToolSetting "Merge objects flags"
  let ld_r
        | null ld_r_prog = Nothing
        | otherwise      = Just (ld_r_prog, map Option $ unescapeArgs ld_r_args)

  llvmTarget <- getSetting "LLVM target"

  -- We just assume on command line
  lc_prog <- getSetting "LLVM llc command"
  lo_prog <- getSetting "LLVM opt command"
  las_prog <- getSetting "LLVM llvm-as command"

  let iserv_prog = libexec "ghc-iserv"

  targetRTSLinkerOnlySupportsSharedLibs <- getBooleanSetting "target RTS linker only supports shared libraries"
  ghcWithInterpreter <- getBooleanSetting "Use interpreter"
  useLibFFI <- getBooleanSetting "Use LibFFI"

  return $ Settings
    { sGhcNameVersion = GhcNameVersion
      { ghcNameVersion_programName = "ghc"
      , ghcNameVersion_projectVersion = cProjectVersion
      }

    , sFileSettings = FileSettings
      { fileSettings_ghcUsagePath   = ghc_usage_msg_path
      , fileSettings_ghciUsagePath  = ghci_usage_msg_path
      , fileSettings_toolDir        = mtool_dir
      , fileSettings_topDir         = top_dir
      , fileSettings_globalPackageDatabase = globalpkgdb_path
      }

    , sToolSettings = ToolSettings
      { toolSettings_ldSupportsCompactUnwind = ldSupportsCompactUnwind
      , toolSettings_ldSupportsFilelist      = ldSupportsFilelist
      , toolSettings_ldSupportsSingleModule  = ldSupportsSingleModule
      , toolSettings_mergeObjsSupportsResponseFiles = mergeObjsSupportsResponseFiles
      , toolSettings_ldIsGnuLd               = ldIsGnuLd
      , toolSettings_ccSupportsNoPie         = gccSupportsNoPie
      , toolSettings_useInplaceMinGW         = useInplaceMinGW
      , toolSettings_arSupportsDashL         = arSupportsDashL
      , toolSettings_cmmCppSupportsG0        = cmmCppSupportsG0

      , toolSettings_pgm_L   = unlit_path
      , toolSettings_pgm_P   = (hs_cpp_prog, hs_cpp_args)
      , toolSettings_pgm_JSP = (js_cpp_prog, js_cpp_args)
      , toolSettings_pgm_CmmP = (cmmCpp_prog, cmmCpp_args)
      , toolSettings_pgm_F   = ""
      , toolSettings_pgm_c   = cc_prog
      , toolSettings_pgm_cxx = cxx_prog
      , toolSettings_pgm_cpp = (cpp_prog, cpp_args)
      , toolSettings_pgm_a   = (as_prog, as_args)
      , toolSettings_pgm_l   = (ld_prog, ld_args)
      , toolSettings_pgm_lm  = ld_r
      , toolSettings_pgm_windres = windres_path
      , toolSettings_pgm_ar = ar_path
      , toolSettings_pgm_otool = otool_path
      , toolSettings_pgm_install_name_tool = install_name_tool_path
      , toolSettings_pgm_ranlib = ranlib_path
      , toolSettings_pgm_lo  = (lo_prog,[])
      , toolSettings_pgm_lc  = (lc_prog,[])
      , toolSettings_pgm_las = (las_prog, [])
      , toolSettings_pgm_i   = iserv_prog
      , toolSettings_opt_L       = []
      , toolSettings_opt_P       = []
      , toolSettings_opt_JSP     = []
      , toolSettings_opt_CmmP    = []
      , toolSettings_opt_P_fingerprint   = fingerprint0
      , toolSettings_opt_JSP_fingerprint = fingerprint0
      , toolSettings_opt_CmmP_fingerprint = fingerprint0
      , toolSettings_opt_F       = []
      , toolSettings_opt_c       = cc_args
      , toolSettings_opt_cxx     = cxx_args
      , toolSettings_opt_a       = []
      , toolSettings_opt_l       = []
      , toolSettings_opt_lm      = []
      , toolSettings_opt_windres = []
      , toolSettings_opt_lo      = []
      , toolSettings_opt_lc      = []
      , toolSettings_opt_las     = []
      , toolSettings_opt_i       = []

      , toolSettings_extraGccViaCFlags = extraGccViaCFlags
      }

    , sTargetPlatform = platform
    , sPlatformMisc = PlatformMisc
      { platformMisc_targetPlatformString = targetPlatformString
      , platformMisc_ghcWithInterpreter = ghcWithInterpreter
      , platformMisc_libFFI = useLibFFI
      , platformMisc_llvmTarget = llvmTarget
      , platformMisc_targetRTSLinkerOnlySupportsSharedLibs = targetRTSLinkerOnlySupportsSharedLibs
      }

    , sRawSettings    = settingsList
    }

getTargetPlatform
  :: FilePath     -- ^ Settings filepath (for error messages)
  -> RawSettings  -- ^ Raw settings file contents
  -> Either String Platform
getTargetPlatform settingsFile settings = do
  let
    getBooleanSetting = getRawBooleanSetting settingsFile settings
    readSetting :: (Show a, Read a) => String -> Either String a
    readSetting = readRawSetting settingsFile settings

  targetArchOS <- getTargetArchOS settingsFile settings
  targetWordSize <- readSetting "target word size"
  targetWordBigEndian <- getBooleanSetting "target word big endian"
  targetLeadingUnderscore <- getBooleanSetting "Leading underscore"
  targetUnregisterised <- getBooleanSetting "Unregisterised"
  targetHasGnuNonexecStack <- getBooleanSetting "target has GNU nonexec stack"
  targetHasIdentDirective <- getBooleanSetting "target has .ident directive"
  targetHasSubsectionsViaSymbols <- getBooleanSetting "target has subsections via symbols"
  targetHasLibm <- getBooleanSetting "target has libm"
  crossCompiling <- getBooleanSetting "cross compiling"
  tablesNextToCode <- getBooleanSetting "Tables next to code"

  pure $ Platform
    { platformArchOS    = targetArchOS
    , platformWordSize  = targetWordSize
    , platformByteOrder = if targetWordBigEndian then BigEndian else LittleEndian
    , platformUnregisterised = targetUnregisterised
    , platformHasGnuNonexecStack = targetHasGnuNonexecStack
    , platformHasIdentDirective = targetHasIdentDirective
    , platformHasSubsectionsViaSymbols = targetHasSubsectionsViaSymbols
    , platformIsCrossCompiling = crossCompiling
    , platformLeadingUnderscore = targetLeadingUnderscore
    , platformTablesNextToCode  = tablesNextToCode
    , platformHasLibm = targetHasLibm
    , platform_constants = Nothing -- will be filled later when loading (or building) the RTS unit
    }

-- ----------------------------------------------------------------------------
-- Escape Args helpers
-- ----------------------------------------------------------------------------

-- | Just like 'GHC.ResponseFile.escapeArg', but it is not exposed from base.
escapeArg :: String -> String
escapeArg = reverse . foldl' escape []

escape :: String -> Char -> String
escape cs c
  |    isSpace c
    || '\\' == c
    || '\'' == c
    || '"'  == c = c:'\\':cs -- n.b., our caller must reverse the result
  | otherwise    = c:cs