-----------------------------------------------------------------------------
-- |
-- Module      :  Distribution.Simple.Hpc
-- Copyright   :  Thomas Tuegel 2011
--
-- Maintainer  :  [email protected]
-- Portability :  portable
--
-- This module provides functions for locating various HPC-related paths and
-- a function for adding the necessary options to a PackageDescription to
-- build test suites with HPC enabled.

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module Distribution.Simple.Hpc
    ( hpcDir
    , enableCoverage
    , tixDir
    , tixFilePath
    , doHpcMarkup
    , findTixFiles
    ) where

import Control.Exception ( bracket )
import Control.Monad ( unless, when )
import Distribution.Compiler ( CompilerFlavor(..) )
import Distribution.ModuleName ( main )
import Distribution.PackageDescription
    ( BuildInfo(..)
    , Library(..)
    , PackageDescription(..)
    , TestSuite(..)
    , testModules
    )
import Distribution.Simple.Utils ( die, notice )
import Distribution.Text
import Distribution.Verbosity ( Verbosity() )
import System.Directory ( doesFileExist, getDirectoryContents, removeFile )
import System.Exit ( ExitCode(..) )
import System.FilePath
import System.IO ( hClose, IOMode(..), openFile, openTempFile )
import System.Process ( runProcess, waitForProcess )

-- -------------------------------------------------------------------------
-- Haskell Program Coverage

-- | Conditionally enable Haskell Program Coverage by adding the necessary
-- GHC options to a PackageDescription.
--
-- TODO: do this differently in the build stage by constructing local build
-- info, not by modifying the original PackageDescription.
--
enableCoverage :: Bool                  -- ^ Enable coverage?
               -> String                -- ^ \"dist/\" prefix
               -> PackageDescription
               -> PackageDescription
enableCoverage False _ x = x
enableCoverage True distPref p =
    p { library = fmap enableLibCoverage (library p)
      , testSuites = map enableTestCoverage (testSuites p)
      }
  where
    enableBICoverage name oldBI =
        let oldOptions = options oldBI
            oldGHCOpts = lookup GHC oldOptions
            newGHCOpts = case oldGHCOpts of
                             Just xs -> (GHC, hpcOpts ++ xs)
                             _ -> (GHC, hpcOpts)
            newOptions = (:) newGHCOpts $ filter ((== GHC) . fst) oldOptions
            hpcOpts = ["-fhpc", "-hpcdir", hpcDir distPref name]
        in oldBI { options = newOptions }
    enableLibCoverage l =
        l { libBuildInfo = enableBICoverage (display $ package p)
                                            (libBuildInfo l)
          }
    enableTestCoverage t =
        t { testBuildInfo = enableBICoverage (testName t) (testBuildInfo t) }

hpcDir :: FilePath  -- ^ \"dist/\" prefix
       -> FilePath  -- ^ Component subdirectory name
       -> FilePath  -- ^ Directory containing component's HPC .mix files
hpcDir distPref name = distPref </> "hpc" </> name

tixDir :: FilePath  -- ^ \"dist/\" prefix
       -> TestSuite -- ^ Test suite
       -> FilePath  -- ^ Directory containing test suite's .tix files
tixDir distPref suite = distPref </> "test" </> testName suite

-- | Path to the .tix file containing a test suite's sum statistics.
tixFilePath :: FilePath     -- ^ \"dist/\" prefix
            -> TestSuite    -- ^ Test suite
            -> FilePath     -- Path to test suite's .tix file
tixFilePath distPref suite = tixDir distPref suite </> testName suite <.> "tix"

-- | Returns a list of all the .tix files in a test suite's .tix file
-- directory. Returned paths are the complete relative path to each file.
findTixFiles :: FilePath        -- ^ \"dist/\" prefix
             -> TestSuite       -- ^ Test suite
             -> IO [FilePath]   -- ^ All .tix files belonging to test suite
findTixFiles distPref suite = do
    files <- getDirectoryContents $ tixDir distPref suite
    let tixFiles = flip filter files $ \x -> takeExtension x == ".tix"
    return $ map (tixDir distPref suite </>) tixFiles

-- | Generate the HTML markup for a test suite.
doHpcMarkup :: Verbosity
            -> FilePath     -- ^ \"dist/\" prefix
            -> String       -- ^ Library name
            -> TestSuite
            -> IO ()
doHpcMarkup verbosity distPref libName suite = do
    tixFiles <- findTixFiles distPref suite
    when (not $ null tixFiles) $ do
        let hpcOptions = map (\x -> "--exclude=" ++ display x) excluded
            unionOptions = [ "sum"
                           , "--union"
                           , "--output=" ++ tixFilePath distPref suite
                           ]
                           ++ hpcOptions ++ tixFiles
            markupOptions = [ "markup"
                            , tixFilePath distPref suite
                            , "--hpcdir=" ++ hpcDir distPref libName
                            , "--destdir=" ++ tixDir distPref suite
                            ]
                            ++ hpcOptions
            excluded = testModules suite ++ [ main ]
            --TODO: use standard process utilities from D.S.Utils
            runHpc opts h = runProcess "hpc" opts Nothing Nothing Nothing
                                       (Just h) (Just h)
        bracket (openHpcTemp $ tixDir distPref suite) deleteIfExists
            $ \hpcOut -> do
            hUnion <- openFile hpcOut AppendMode
            procUnion <- runHpc unionOptions hUnion
            exitUnion <- waitForProcess procUnion
            success <- case exitUnion of
                ExitSuccess -> do
                    hMarkup <- openFile hpcOut AppendMode
                    procMarkup <- runHpc markupOptions hMarkup
                    exitMarkup <- waitForProcess procMarkup
                    case exitMarkup of
                        ExitSuccess -> return True
                        _ -> return False
                _ -> return False
            unless success $ do
                errs <- readFile hpcOut
                die $ "HPC failed:\n" ++ errs
            when success $ notice verbosity
                $ "Test coverage report written to "
                  ++ tixDir distPref suite </> "hpc_index"
                  <.> "html"
            return ()
  where openHpcTemp dir = do
            (f, h) <- openTempFile dir $ "cabal-test-hpc-" <.> "log"
            hClose h >> return f
        deleteIfExists path = do
            exists <- doesFileExist path
            when exists $ removeFile path