# SPDX-FileCopyrightText: 2016-2017 Pino Toscano <pino@kde.org>
#
# SPDX-License-Identifier: BSD-3-Clause

#[=======================================================================[.rst:
FindGperf
-----------

Try to find GNU gperf.

If the gperf executable is not in your PATH, you can provide
an alternative name or full path location with the ``Gperf_EXECUTABLE``
variable.

This will define the following variables:

``Gperf_FOUND``
    True if gperf is available.

``Gperf_EXECUTABLE``
    The gperf executable.

``Gperf_VERSION``
    The gperf version. (since 5.85)

If ``Gperf_FOUND`` is TRUE, it will also define the following imported
target:

``GPerf::Gperf``
    The gperf executable.

and the following public function:
::

  ecm_gperf_generate(<GperfInput> <OutputFile> <OutputVariable(|target (since 5.83))>
                     [GENERATION_FLAGS <flags>])

Run ``gperf`` on ``<GperfInput>`` to generate ``<OutputFile>``, adding it to
the ``<OutputVariable>`` variable which contains the source for the target
where ``<OutputFile>`` is going to be built or, since KF 5.83, if the given
argument is a target, to the list of private sources of that target. The
target must not be an alias. The optional ``GENERATION_FLAGS`` argument is
needed to pass extra parameters to ``gperf`` (note you cannot override that
way the output file).

A simple invocation would be:

.. code-block:: cmake

  ecm_gperf_generate(simple.gperf ${CMAKE_CURRENT_BINARY_DIR}/simple.h MySources)

Since 5.35.0.
#]=======================================================================]

cmake_policy(VERSION 3.16)

include(${CMAKE_CURRENT_LIST_DIR}/ECMFindModuleHelpersStub.cmake)

ecm_find_package_version_check(Gperf)

# Find gperf
find_program(Gperf_EXECUTABLE NAMES gperf)

if(Gperf_EXECUTABLE)
    execute_process(COMMAND ${Gperf_EXECUTABLE} -v
        OUTPUT_VARIABLE _version_string
        ERROR_QUIET
        OUTPUT_STRIP_TRAILING_WHITESPACE)
    if(_version_string MATCHES "^GNU gperf ([-0-9\\.]+)")
        set(Gperf_VERSION "${CMAKE_MATCH_1}")
    endif()
    unset(_version_string)
else()
    set(Gperf_VERSION)
endif()

include(FindPackageHandleStandardArgs)
find_package_handle_standard_args(Gperf
    FOUND_VAR
        Gperf_FOUND
    REQUIRED_VARS
        Gperf_EXECUTABLE
    VERSION_VAR
        Gperf_VERSION
)

mark_as_advanced(Gperf_EXECUTABLE)

if (Gperf_FOUND)
    if (NOT TARGET GPerf::Gperf)
        add_executable(GPerf::Gperf IMPORTED)
        set_target_properties(GPerf::Gperf PROPERTIES
            IMPORTED_LOCATION "${Gperf_EXECUTABLE}"
        )
    endif()
endif()

include(FeatureSummary)
set_package_properties(Gperf PROPERTIES
    URL "https://www.gnu.org/software/gperf/"
    DESCRIPTION "Perfect hash function generator"
)

function(ecm_gperf_generate input_file output_file _target_or_sources_var)
    # Parse arguments
    set(oneValueArgs GENERATION_FLAGS)
    cmake_parse_arguments(ARGS "" "${oneValueArgs}" "" ${ARGN})

    if(ARGS_UNPARSED_ARGUMENTS)
        message(FATAL_ERROR "Unknown keywords given to ecm_gperf_generate(): \"${ARGS_UNPARSED_ARGUMENTS}\"")
    endif()
    if (TARGET ${_target_or_sources_var})
        get_target_property(aliased_target ${_target_or_sources_var} ALIASED_TARGET)
        if(aliased_target)
            message(FATAL_ERROR "Target argument passed to ecm_gperf_generate must not be an alias: ${_target_or_sources_var}")
        endif()
    endif()

    get_filename_component(_infile ${input_file} ABSOLUTE)
    set(_extraopts "${ARGS_GENERATION_FLAGS}")
    separate_arguments(_extraopts)
    add_custom_command(OUTPUT ${output_file}
        COMMAND ${Gperf_EXECUTABLE} ${_extraopts} --output-file=${output_file} ${_infile}
        DEPENDS ${_infile}
        WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
        VERBATIM
    )
    set_property(SOURCE ${output_file} PROPERTY SKIP_AUTOMOC ON)

    if (TARGET ${_target_or_sources_var})
        target_sources(${_target_or_sources_var} PRIVATE ${output_file})
    else()
        set(${_target_or_sources_var} ${${_target_or_sources_var}} ${output_file} PARENT_SCOPE)
    endif()
endfunction()
