# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.

#.rst:
# FindLua
# -------
#
#
#
# Locate Lua library This module defines
#
# ::
#
#   LUA_FOUND          - if false, do not try to link to Lua
#   LUA_LIBRARIES      - both lua and lualib
#   LUA_INCLUDE_DIR    - where to find lua.h
#   LUA_VERSION_STRING - the version of Lua found
#   LUA_VERSION_MAJOR  - the major version of Lua
#   LUA_VERSION_MINOR  - the minor version of Lua
#   LUA_VERSION_PATCH  - the patch version of Lua
#
#
#
# Note that the expected include convention is
#
# ::
#
#   #include "lua.h"
#
# and not
#
# ::
#
#   #include <lua/lua.h>
#
# This is because, the lua location is not standardized and may exist in
# locations other than lua/

cmake_policy(PUSH)  # Policies apply to functions at definition-time
cmake_policy(SET CMP0012 NEW)  # For while(TRUE)

unset(_lua_include_subdirs)
unset(_lua_library_names)
unset(_lua_append_versions)

# this is a function only to have all the variables inside go away automatically
function(_lua_get_versions)
    set(LUA_VERSIONS5 5.3 5.2 5.1 5.0)

    if (Lua_FIND_VERSION_EXACT)
        if (Lua_FIND_VERSION_COUNT GREATER 1)
            set(_lua_append_versions ${Lua_FIND_VERSION_MAJOR}.${Lua_FIND_VERSION_MINOR})
        endif ()
    elseif (Lua_FIND_VERSION)
        # once there is a different major version supported this should become a loop
        if (NOT Lua_FIND_VERSION_MAJOR GREATER 5)
            if (Lua_FIND_VERSION_COUNT EQUAL 1)
                set(_lua_append_versions ${LUA_VERSIONS5})
            else ()
                foreach (subver IN LISTS LUA_VERSIONS5)
                    if (NOT subver VERSION_LESS ${Lua_FIND_VERSION})
                        list(APPEND _lua_append_versions ${subver})
                    endif ()
                endforeach ()
                # New version -> Search for it (heuristic only! Defines in include might have changed)
                if (NOT _lua_append_versions)
                    set(_lua_append_versions ${Lua_FIND_VERSION_MAJOR}.${Lua_FIND_VERSION_MINOR})
                endif()
            endif ()
        endif ()
    else ()
        # once there is a different major version supported this should become a loop
        set(_lua_append_versions ${LUA_VERSIONS5})
    endif ()

    if (LUA_Debug)
        message(STATUS "Considering following Lua versions: ${_lua_append_versions}")
    endif()

    set(_lua_append_versions "${_lua_append_versions}" PARENT_SCOPE)
endfunction()

function(_lua_set_version_vars)
   set(_lua_include_subdirs_raw "lua")

    foreach (ver IN LISTS _lua_append_versions)
        string(REGEX MATCH "^([0-9]+)\\.([0-9]+)$" _ver "${ver}")
        list(APPEND _lua_include_subdirs_raw
             lua${CMAKE_MATCH_1}${CMAKE_MATCH_2}
             lua${CMAKE_MATCH_1}.${CMAKE_MATCH_2}
             lua-${CMAKE_MATCH_1}.${CMAKE_MATCH_2}
        )
    endforeach ()

    # Prepend "include/" to each path directly after the path
    set(_lua_include_subdirs "include")
    foreach (dir IN LISTS _lua_include_subdirs_raw)
        list(APPEND _lua_include_subdirs "${dir}" "include/${dir}")
    endforeach ()

    set(_lua_include_subdirs "${_lua_include_subdirs}" PARENT_SCOPE)
endfunction(_lua_set_version_vars)

function(_lua_get_header_version)
    unset(LUA_VERSION_STRING PARENT_SCOPE)
    set(_hdr_file "${LUA_INCLUDE_DIR}/lua.h")

    if (NOT EXISTS "${_hdr_file}")
        return()
    endif ()

    # At least 5.[012] have different ways to express the version
    # so all of them need to be tested. Lua 5.2 defines LUA_VERSION
    # and LUA_RELEASE as joined by the C preprocessor, so avoid those.
    file(STRINGS "${_hdr_file}" lua_version_strings
         REGEX "^#define[ \t]+LUA_(RELEASE[ \t]+\"Lua [0-9]|VERSION([ \t]+\"Lua [0-9]|_[MR])).*")

    string(REGEX REPLACE ".*;#define[ \t]+LUA_VERSION_MAJOR[ \t]+\"([0-9])\"[ \t]*;.*" "\\1" LUA_VERSION_MAJOR ";${lua_version_strings};")
    if (LUA_VERSION_MAJOR MATCHES "^[0-9]+$")
        string(REGEX REPLACE ".*;#define[ \t]+LUA_VERSION_MINOR[ \t]+\"([0-9])\"[ \t]*;.*" "\\1" LUA_VERSION_MINOR ";${lua_version_strings};")
        string(REGEX REPLACE ".*;#define[ \t]+LUA_VERSION_RELEASE[ \t]+\"([0-9])\"[ \t]*;.*" "\\1" LUA_VERSION_PATCH ";${lua_version_strings};")
        set(LUA_VERSION_STRING "${LUA_VERSION_MAJOR}.${LUA_VERSION_MINOR}.${LUA_VERSION_PATCH}")
    else ()
        string(REGEX REPLACE ".*;#define[ \t]+LUA_RELEASE[ \t]+\"Lua ([0-9.]+)\"[ \t]*;.*" "\\1" LUA_VERSION_STRING ";${lua_version_strings};")
        if (NOT LUA_VERSION_STRING MATCHES "^[0-9.]+$")
            string(REGEX REPLACE ".*;#define[ \t]+LUA_VERSION[ \t]+\"Lua ([0-9.]+)\"[ \t]*;.*" "\\1" LUA_VERSION_STRING ";${lua_version_strings};")
        endif ()
        string(REGEX REPLACE "^([0-9]+)\\.[0-9.]*$" "\\1" LUA_VERSION_MAJOR "${LUA_VERSION_STRING}")
        string(REGEX REPLACE "^[0-9]+\\.([0-9]+)[0-9.]*$" "\\1" LUA_VERSION_MINOR "${LUA_VERSION_STRING}")
        string(REGEX REPLACE "^[0-9]+\\.[0-9]+\\.([0-9]).*" "\\1" LUA_VERSION_PATCH "${LUA_VERSION_STRING}")
    endif ()
    foreach (ver IN LISTS _lua_append_versions)
        if (ver STREQUAL "${LUA_VERSION_MAJOR}.${LUA_VERSION_MINOR}")
            set(LUA_VERSION_MAJOR ${LUA_VERSION_MAJOR} PARENT_SCOPE)
            set(LUA_VERSION_MINOR ${LUA_VERSION_MINOR} PARENT_SCOPE)
            set(LUA_VERSION_PATCH ${LUA_VERSION_PATCH} PARENT_SCOPE)
            set(LUA_VERSION_STRING ${LUA_VERSION_STRING} PARENT_SCOPE)
            return()
        endif ()
    endforeach ()
endfunction(_lua_get_header_version)

function(_lua_find_header)
    _lua_set_version_vars()

    # Initialize as local variable
    set(CMAKE_IGNORE_PATH ${CMAKE_IGNORE_PATH})
    while (TRUE)
        # Find the next header to test. Check each possible subdir in order
        # This prefers e.g. higher versions as they are earlier in the list
        # It is also consistent with previous versions of FindLua
        foreach (subdir IN LISTS _lua_include_subdirs)
            find_path(LUA_INCLUDE_DIR lua.h
              HINTS
                ENV LUA_DIR
              PATH_SUFFIXES ${subdir}
            )
            if (LUA_INCLUDE_DIR)
                break()
            endif()
        endforeach()
        # Did not found header -> Fail
        if (NOT LUA_INCLUDE_DIR)
            return()
        endif()
        _lua_get_header_version()
        # Found accepted version -> Ok
        if (LUA_VERSION_STRING)
            if (LUA_Debug)
                message(STATUS "Found suitable version ${LUA_VERSION_STRING} in ${LUA_INCLUDE_DIR}/lua.h")
            endif()
            return()
        endif()
        # Found wrong version -> Ignore this path and retry
        if (LUA_Debug)
            message(STATUS "Ignoring unsuitable version in ${LUA_INCLUDE_DIR}")
        endif()
        list(APPEND CMAKE_IGNORE_PATH "${LUA_INCLUDE_DIR}")
        unset(LUA_INCLUDE_DIR CACHE)
        unset(LUA_INCLUDE_DIR)
        unset(LUA_INCLUDE_DIR PARENT_SCOPE)
    endwhile ()
endfunction()

_lua_get_versions()
_lua_find_header()
_lua_get_header_version()
unset(_lua_append_versions)

if (LUA_VERSION_STRING)
    set(_lua_library_names
        lua${LUA_VERSION_MAJOR}${LUA_VERSION_MINOR}
        lua${LUA_VERSION_MAJOR}.${LUA_VERSION_MINOR}
        lua-${LUA_VERSION_MAJOR}.${LUA_VERSION_MINOR}
        lua.${LUA_VERSION_MAJOR}.${LUA_VERSION_MINOR}
    )
endif ()

find_library(LUA_LIBRARY
  NAMES ${_lua_library_names} lua
  NAMES_PER_DIR
  HINTS
    ENV LUA_DIR
  PATH_SUFFIXES lib
)
unset(_lua_library_names)

if (LUA_LIBRARY)
    # include the math library for Unix
    if (UNIX AND NOT APPLE AND NOT BEOS)
        find_library(LUA_MATH_LIBRARY m)
        set(LUA_LIBRARIES "${LUA_LIBRARY};${LUA_MATH_LIBRARY}")

        # include dl library for statically-linked Lua library
        get_filename_component(LUA_LIB_EXT ${LUA_LIBRARY} EXT)
        if(LUA_LIB_EXT STREQUAL CMAKE_STATIC_LIBRARY_SUFFIX)
          list(APPEND LUA_LIBRARIES ${CMAKE_DL_LIBS})
        endif()

    # For Windows and Mac, don't need to explicitly include the math library
    else ()
        set(LUA_LIBRARIES "${LUA_LIBRARY}")
    endif ()
endif ()

include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
# handle the QUIETLY and REQUIRED arguments and set LUA_FOUND to TRUE if
# all listed variables are TRUE
FIND_PACKAGE_HANDLE_STANDARD_ARGS(Lua
                                  REQUIRED_VARS LUA_LIBRARIES LUA_INCLUDE_DIR
                                  VERSION_VAR LUA_VERSION_STRING)

mark_as_advanced(LUA_INCLUDE_DIR LUA_LIBRARY LUA_MATH_LIBRARY)

cmake_policy(POP)