##
# Compile vala files to their c equivalents for further processing.
#
# The "vala_precompile" function takes care of calling the valac executable on
# the given source to produce c files which can then be processed further using
# default cmake functions.
#
# The first parameter provided is a variable, which will be filled with a list
# of c files outputted by the vala compiler. This list can than be used in
# conjuction with functions like "add_executable" or others to create the
# neccessary compile rules with CMake.
#
# The following sections may be specified afterwards to provide certain options
# to the vala compiler:
#
# SOURCES
#   A list of .vala files to be compiled. Please take care to add every vala
#   file belonging to the currently compiled project or library as Vala will
#   otherwise not be able to resolve all dependencies.
#
# PACKAGES
#   A list of vala packages/libraries to be used during the compile cycle. The
#   package names are exactly the same, as they would be passed to the valac
#   "--pkg=" option.
#
# OPTIONS
#   A list of optional options to be passed to the valac executable. This can be
#   used to pass "--thread" for example to enable multi-threading support.
#
# CUSTOM_VAPIS
#   A list of custom vapi files to be included for compilation. This can be
#   useful to include freshly created vala libraries without having to install
#   them in the system.
#
# GENERATE_VAPI
#   Pass all the needed flags to the compiler to create an internal vapi for
#   the compiled library. The provided name will be used for this and a
#   <provided_name>.vapi file will be created.
#
# GENERATE_HEADER
#   Let the compiler generate a header file for the compiled code. There will
#   be a header file as well as an internal header file being generated called
#   <provided_name>.h and <provided_name>_internal.h
#
# The following call is a simple example to the vala_precompile macro showing
# an example to every of the optional sections:
#
#   find_package(Vala "0.12" REQUIRED)
#   inlcude(${VALA_USE_FILE})
#
#   vala_precompile(VALA_C
#     SOURCES
#       source1.vala
#       source2.vala
#       source3.vala
#     PACKAGES
#       gtk+-2.0
#       gio-1.0
#       posix
#     DIRECTORY
#       gen
#     OPTIONS
#       --thread
#     CUSTOM_VAPIS
#       some_vapi.vapi
#     GENERATE_VAPI
#       myvapi
#     GENERATE_HEADER
#       myheader
#     )
#
# Most important is the variable VALA_C which will contain all the generated c
# file names after the call.
##

##
# Copyright 2009-2010 Jakob Westhoff. All rights reserved.
# Copyright 2010-2011 Daniel Pfeifer
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#    1. Redistributions of source code must retain the above copyright notice,
#       this list of conditions and the following disclaimer.
#
#    2. Redistributions in binary form must reproduce the above copyright notice,
#       this list of conditions and the following disclaimer in the documentation
#       and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY JAKOB WESTHOFF ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
# EVENT SHALL JAKOB WESTHOFF OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
# OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
# ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# The views and conclusions contained in the software and documentation are those
# of the authors and should not be interpreted as representing official policies,
# either expressed or implied, of Jakob Westhoff
##

include(CMakeParseArguments)

function(vala_precompile output)
    cmake_parse_arguments(ARGS "" "DIRECTORY;GENERATE_HEADER;GENERATE_VAPI"
        "SOURCES;PACKAGES;OPTIONS;CUSTOM_VAPIS" ${ARGN})

    if(ARGS_DIRECTORY)
        set(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/${ARGS_DIRECTORY})
    else(ARGS_DIRECTORY)
        set(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
    endif(ARGS_DIRECTORY)
    include_directories(${DIRECTORY})
    set(vala_pkg_opts "")
    foreach(pkg ${ARGS_PACKAGES})
        list(APPEND vala_pkg_opts "--pkg=${pkg}")
    endforeach(pkg ${ARGS_PACKAGES})
    set(in_files "")
    set(out_files "")
    foreach(src ${ARGS_SOURCES} ${ARGS_UNPARSED_ARGUMENTS})
        list(APPEND in_files "${CMAKE_CURRENT_SOURCE_DIR}/${src}")
        string(REPLACE ".vala" ".c" src ${src})
        string(REPLACE ".gs" ".c" src ${src})
        set(out_file "${DIRECTORY}/${src}")
        list(APPEND out_files "${DIRECTORY}/${src}")
    endforeach(src ${ARGS_SOURCES} ${ARGS_UNPARSED_ARGUMENTS})

    set(custom_vapi_arguments "")
    if(ARGS_CUSTOM_VAPIS)
        foreach(vapi ${ARGS_CUSTOM_VAPIS})
            if(${vapi} MATCHES ${CMAKE_SOURCE_DIR} OR ${vapi} MATCHES ${CMAKE_BINARY_DIR})
                list(APPEND custom_vapi_arguments ${vapi})
            else (${vapi} MATCHES ${CMAKE_SOURCE_DIR} OR ${vapi} MATCHES ${CMAKE_BINARY_DIR})
                list(APPEND custom_vapi_arguments ${CMAKE_CURRENT_SOURCE_DIR}/${vapi})
            endif(${vapi} MATCHES ${CMAKE_SOURCE_DIR} OR ${vapi} MATCHES ${CMAKE_BINARY_DIR})
        endforeach(vapi ${ARGS_CUSTOM_VAPIS})
    endif(ARGS_CUSTOM_VAPIS)

    set(vapi_arguments "")
    if(ARGS_GENERATE_VAPI)
        list(APPEND out_files "${DIRECTORY}/${ARGS_GENERATE_VAPI}.vapi")
        set(vapi_arguments "--internal-vapi=${ARGS_GENERATE_VAPI}.vapi")

        # Header and internal header is needed to generate internal vapi
        if (NOT ARGS_GENERATE_HEADER)
            set(ARGS_GENERATE_HEADER ${ARGS_GENERATE_VAPI})
        endif(NOT ARGS_GENERATE_HEADER)
    endif(ARGS_GENERATE_VAPI)

    set(header_arguments "")
    if(ARGS_GENERATE_HEADER)
        list(APPEND out_files "${DIRECTORY}/${ARGS_GENERATE_HEADER}.h")
        list(APPEND out_files "${DIRECTORY}/${ARGS_GENERATE_HEADER}_internal.h")
        list(APPEND header_arguments "--header=${DIRECTORY}/${ARGS_GENERATE_HEADER}.h")
        list(APPEND header_arguments "--internal-header=${DIRECTORY}/${ARGS_GENERATE_HEADER}_internal.h")
    endif(ARGS_GENERATE_HEADER)

    add_custom_command(OUTPUT ${out_files}
    COMMAND
        ${VALA_EXECUTABLE}
    ARGS
        "-C"
        ${header_arguments}
        ${vapi_arguments}
        "-b" ${CMAKE_CURRENT_SOURCE_DIR}
        "-d" ${DIRECTORY}
        ${vala_pkg_opts}
        ${ARGS_OPTIONS}
        ${in_files}
        ${custom_vapi_arguments}
    DEPENDS
        ${in_files}
        ${ARGS_CUSTOM_VAPIS}
    )
    set(${output} ${out_files} PARENT_SCOPE)
endfunction(vala_precompile)