# Checks if a given Haskell package exists (using ghc-pkg)

# and fails if it's missing.

# Loosely based on CheckLibraryExists.cmake from CMake.

#=============================================================================

# Copyright 2002-2009 Kitware, Inc.

#

# Distributed under the OSI-approved BSD License

#

# This software is distributed WITHOUT ANY WARRANTY; without even the

# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

# See the License for more information.

#=============================================================================

macro(CHECK_HASKELL_PACKAGE_EXISTS PACKAGE MODULE FUNCTION PARAMCOUNT REQUIRED)

# NOTE: MODULE, FUNCTION and PARAMCOUNT are curretly ignored.

# TODO: Either implement these or drop?

  set(VARIABLE "HS_PACKAGE_${PACKAGE}")

  if(NOT (${VARIABLE} EQUAL "1"))

    message(STATUS "Looking for Haskell package ${PACKAGE} ...")

    execute_process(COMMAND ${GHC_PKG_EXECUTABLE}

                    "latest"

                    ${PACKAGE}

                    "--simple-output"

                    RESULT_VARIABLE COMMAND_RESULT

                    ERROR_VARIABLE BUILD_ERROR

                    OUTPUT_STRIP_TRAILING_WHITESPACE

                    OUTPUT_QUIET

                    )

    if(${COMMAND_RESULT} EQUAL 0)

      message(STATUS "Looking for Haskell package ${PACKAGE} - found")

      set(${VARIABLE} "1" CACHE INTERNAL "Have package ${PACKAGE}")

      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log

        "Determining if the Haskell package ${PACKAGE} exists has passed\n\n")

    else()

      message(STATUS "Looking for Haskell package ${PACKAGE} - not found")

      set(${VARIABLE} "0" CACHE INTERNAL "Have package ${PACKAGE}")

      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log

        "Determining if the Haskell package ${PACKAGE} "

        "exists failed with the following output:\n"

        "${BUILD_ERROR}\n\n")

      if("${REQUIRED}" STREQUAL "REQUIRED")

        message(FATAL_ERROR "Haskell package '${PACKAGE}' required")

      else()

        message(STATUS "Haskell package '${PACKAGE}' optionally required, but not found")

      endif()

    endif()

  endif()

endmacro()