local library_base_folders = "extern/"

local function extern_path(local_path)
    if local_path:sub(1,1) == '/' then
        -- TODO : Windows absolute path check
        print(([[[WARN] "%s" is not a local path.]]):format(local_path))
        local_path = local_path:sub(2)
    end

    return library_base_folders .. local_path
end

--- Common function I use to structure projects according to the three-stage
-- configuration pattern I usually see : Debug, optimized Debug and Release.
-- Sometimes I see also a Final version, but it almost is a copy of the Release
-- stage.
local function base_workspace_settings()
    language "C++"
    configurations {"Debug", "DebugOpt", "Release"}
    location "build"
    architecture "x86_64"

    filter "configurations:Debug"
        defines {"DEBUG"}
        symbols "On"
        warnings "Extra"

    filter "configurations:DebugOpt"
        defines {"DEBUG"}
        symbols "On"
        optimize "Debug"
        warnings "Extra"

    filter "configurations:Release"
        defines {"NDEBUG"}
        optimize "On"
        warnings "Extra"

    filter {}
end

local function link_against_modules(modules)
    for _, mod in pairs(modules) do
        links(mod.name)
    end
    for _, mod in pairs(modules) do
        includedirs(mod.public_includes)
    end
end

--- An attempt at making a common ground for multiple libraries I'd use
-- in various projects.
local function library_module(lib_name, folder)
    local mod = {
        name = lib_name,
        folder = folder or lib_name,

        links = {},
        win_links = {},
        linux_links = {},

        files = {},
        win_files = {},
        linux_files = {},

        defines = {},
        win_defines = {},
        linux_defines = {},
        
        -- Separating private/public includes helps
        -- to reuse the public when needed.

        private_includes = {},
        win_private_includes = {},
        linux_private_includes = {},

        public_includes = {},

        module_dependencies = {}

    }

    function mod:_convert_and_store_path(destination, paths)
        local path_prefix = library_base_folders .. self.folder .. "/"
        for k, path in pairs(paths) do
            table.insert(destination, path_prefix .. path)
        end
    end

    function mod:use_private_includes(local_private_paths)
        self:_convert_and_store_path(self.private_includes, local_private_paths)
        return self
    end

    function mod:use_win_private_includes(local_win_private_paths)
        self:_convert_and_store_path(self.win_private_includes, local_win_private_paths)
        return self
    end

    function mod:use_linux_private_includes(local_linux_private_paths)
        self:_convert_and_store_path(self.linux_private_includes, local_linux_private_paths)
        return self
    end

    function mod:use_public_includes(local_public_paths)
        self:_convert_and_store_path(self.public_includes, local_public_paths)
        return self
    end

    function mod:use_files(local_file_paths)
        self:_convert_and_store_path(self.files, local_file_paths)
        return self
    end

    function mod:use_win_files(local_file_paths)
        self:_convert_and_store_path(self.win_files, local_file_paths)
        return self
    end

    function mod:use_linux_files(local_file_paths)
        self:_convert_and_store_path(self.linux_files, local_file_paths)
        return self
    end

    function mod:use_defines(defines)
        self.defines = defines
        return self
    end

    function mod:use_win_defines(defines)
        self.win_defines = defines
        return self
    end

    function mod:use_linux_defines(defines)
        self.linux_defines = defines
        return self
    end

    function mod:require_module(module)
        self.module_dependencies:insert(module)
    end

    function mod:use_links(links)
        self.links = links
        return self
    end

    function mod:use_win_links(links)
        self.win_links = links
        return self
    end

    function mod:use_linux_links(links)
        self.linux_links = links
        return self
    end

    --- Calls premake's code to add the module's project to the current
    -- workspace.
    function mod:use(use_kind)
        -- TODO: handle dependencies
        project(self.name)
            kind(use_kind)
            defines(self.defines)
            files(self.files)
            includedirs(self.public_includes)
            includedirs(self.private_includes)
            links(self.links)

            filter "system:windows"
                defines(self.win_defines)
                files(self.win_files)
                includedirs(self.win_private_includes)
                links(self.win_links)
            
            filter "system:linux"
                defines(self.linux_defines)
                files(self.linux_files)
                includedirs(self.linux_private_includes)
                links(self.linux_links)

            filter {}

    end

    return mod
end

return {
    _VERSION = "0.0.1",
    base_workspace_settings = base_workspace_settings,
    library_module = library_module,
    link_against_modules = link_against_modules
}