--!A cross-platform build utility based on Lua
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
--     http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--
-- Copyright (C) 2015-present, TBOOX Open Source Group.
--
-- @author      ruki
-- @file        xmake.lua
--

-- define rule: device-link
rule("cuda.build.devlink")

    -- add rule: cuda environment
    add_deps("cuda.env")

    -- @see https://devblogs.nvidia.com/separate-compilation-linking-cuda-device-code/
    before_link(function (target, opt)

        -- imports
        import("core.base.option")
        import("core.theme.theme")
        import("core.project.config")
        import("core.project.depend")
        import("core.tool.linker")
        import("core.platform.platform")
        import("utils.progress")

        -- disable devlink?
        --
        -- @note cuda.build.devlink value will be deprecated
        --
        local devlink = target:policy("build.cuda.devlink") or target:values("cuda.build.devlink")
        if devlink == false then
            return
        end

        -- only for binary/shared by default
        -- https://github.com/xmake-io/xmake/issues/1976
        if not (devlink == true or target:is_binary() or target:is_shared()) then
            return
        end

        -- load linker instance
        local linkinst = linker.load("gpucode", "cu", {target = target})

        -- init culdflags
        local culdflags = {"-dlink"}

        -- add shared flag
        if target:is_shared() then
            table.insert(culdflags, "-shared")
        end

        -- get link flags
        local linkflags = linkinst:linkflags({target = target, configs = {force = {culdflags = culdflags}}})

        -- get target file
        local targetfile = target:objectfile(path.join("rules", "cuda", "devlink", target:basename() .. "_gpucode.cu"))

        -- get object files
        local objectfiles = nil
        for _, sourcebatch in pairs(target:sourcebatches()) do
            if sourcebatch.sourcekind == "cu" then
                objectfiles = sourcebatch.objectfiles
            end
        end
        if not objectfiles then
            return
        end

        -- insert gpucode.o to the object files
        table.insert(target:objectfiles(), targetfile)

        -- load dependent info
        local dependfile = target:dependfile(targetfile)
        local dependinfo = option.get("rebuild") and {} or (depend.load(dependfile) or {})

        -- need build this target?
        local depfiles = objectfiles
        local depvalues = {linkinst:program(), linkflags}
        if not depend.is_changed(dependinfo, {lastmtime = os.mtime(target:targetfile()), values = depvalues, files = depfiles}) then
            return
        end

        -- is verbose?
        local verbose = option.get("verbose")

        -- trace progress info
        progress.show(opt.progress, "${color.build.target}devlinking.$(mode) %s", path.filename(targetfile))

        -- trace verbose info
        if verbose then
            print(linkinst:linkcmd(objectfiles, targetfile, {linkflags = linkflags}))
        end

        -- flush io buffer to update progress info
        io.flush()

        -- link it
        assert(linkinst:link(objectfiles, targetfile, {linkflags = linkflags}))

        -- update files and values to the dependent file
        dependinfo.files  = depfiles
        dependinfo.values = depvalues
        depend.save(dependinfo, dependfile)
    end)

