//go:build linux

package cgroups

import (
	"path/filepath"

	"github.com/opencontainers/cgroups"
	"github.com/opencontainers/cgroups/fs"
	"github.com/opencontainers/cgroups/fs2"
)

type linuxCpusetHandler struct {
	CPUSet fs.CpusetGroup
}

func getCpusetHandler() *linuxCpusetHandler {
	return &linuxCpusetHandler{}
}

// Apply set the specified constraints.
func (c *linuxCpusetHandler) Apply(ctr *CgroupControl, res *cgroups.Resources) error {
	if ctr.cgroup2 {
		man, err := fs2.NewManager(ctr.config, filepath.Join(cgroupRoot, ctr.config.Path))
		if err != nil {
			return err
		}
		return man.Set(res)
	}
	path := filepath.Join(cgroupRoot, CPUset, ctr.config.Path)
	return c.CPUSet.Set(path, res)
}

// Create the cgroup.
func (c *linuxCpusetHandler) Create(ctr *CgroupControl) (bool, error) {
	if ctr.cgroup2 {
		path := filepath.Join(cgroupRoot, ctr.config.Path)
		return true, cpusetCopyFromParent(path, true)
	}
	created, err := ctr.createCgroupDirectory(CPUset)
	if !created || err != nil {
		return created, err
	}
	return true, cpusetCopyFromParent(ctr.getCgroupv1Path(CPUset), false)
}

// Destroy the cgroup.
func (c *linuxCpusetHandler) Destroy(ctr *CgroupControl) error {
	return rmDirRecursively(ctr.getCgroupv1Path(CPUset))
}

// Stat fills a metrics structure with usage stats for the controller.
func (c *linuxCpusetHandler) Stat(_ *CgroupControl, _ *cgroups.Stats) error {
	return nil
}