// Copyright 2019 Yunion
//
// 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.

package stats

import (
	"fmt"
	"path"
	"sort"
	"strings"

	cadvisorapiv2 "github.com/google/cadvisor/info/v2"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/klog/v2"

	"yunion.io/x/log"

	"yunion.io/x/onecloud/pkg/util/pod/cadvisor"
)

// containerID is the identity of a container in a pod.
type containerID struct {
	podRef        PodReference
	containerName string
}

// buildPodRef returns a PodReference that identifies the Pod managing cinfo
func buildPodRef(containerLabels map[string]string) PodReference {
	podName := GetPodName(containerLabels)
	podNamespace := GetPodNamespace(containerLabels)
	podUID := GetPodUID(containerLabels)
	return PodReference{Name: podName, Namespace: podNamespace, UID: podUID}
}

func getCadvisorContainerInfo(ca cadvisor.Interface) (map[string]cadvisorapiv2.ContainerInfo, error) {
	infos, err := ca.ContainerInfoV2("/", cadvisorapiv2.RequestOptions{
		IdType:    cadvisorapiv2.TypeName,
		Count:     2, // 2 samples are needed to compute "instantaneous" CPU
		Recursive: true,
	})
	if err != nil {
		if _, ok := infos["/"]; ok {
			// If the failure is partial, log it and return a best-effort
			// response.
			log.Errorf("Partial failure issuing cadvisor.ContainerInfoV2: %v", err)
		} else {
			return nil, fmt.Errorf("failed to get root cgroup stats: %v", err)
		}
	}
	return infos, nil
}

// libcontainerCgroupManagerType defines how to interface with libcontainer
type libcontainerCgroupManagerType string

const (
	// libcontainerCgroupfs means use libcontainer with cgroupfs
	libcontainerCgroupfs libcontainerCgroupManagerType = "cgroupfs"
	// libcontainerSystemd means use libcontainer with systemd
	libcontainerSystemd libcontainerCgroupManagerType = "systemd"
	// systemdSuffix is the cgroup name suffix for systemd
	systemdSuffix string = ".slice"
)

func IsSystemdStyleName(name string) bool {
	return strings.HasSuffix(name, systemdSuffix)
}

// CgroupName is the abstract name of a cgroup prior to any driver specific conversion.
// It is specified as a list of strings from its individual components, such as:
// {"kubepods", "burstable", "pod1234-abcd-5678-efgh"}
type CgroupName []string

func ParseCgroupfsToCgroupName(name string) CgroupName {
	components := strings.Split(strings.TrimPrefix(name, "/"), "/")
	if len(components) == 1 && components[0] == "" {
		components = []string{}
	}
	return CgroupName(components)
}

func unescapeSystemdCgroupName(part string) string {
	return strings.Replace(part, "_", "-", -1)
}

func ParseSystemdToCgroupName(name string) CgroupName {
	driverName := path.Base(name)
	driverName = strings.TrimSuffix(driverName, systemdSuffix)
	parts := strings.Split(driverName, "-")
	result := []string{}
	for _, part := range parts {
		result = append(result, unescapeSystemdCgroupName(part))
	}
	return CgroupName(result)
}

const (
	podCgroupNamePrefix = "pod"
)

// GetPodCgroupNameSuffix returns the last element of the pod CgroupName identifier
func GetPodCgroupNameSuffix(podUID types.UID) string {
	return podCgroupNamePrefix + string(podUID)
}

func getContainerInfoById(id string, infos map[string]cadvisorapiv2.ContainerInfo) *cadvisorapiv2.ContainerInfo {
	for key, info := range infos {
		if IsSystemdStyleName(key) {
			// Convert to internal cgroup name and take the last component only.
			internalCgroupName := ParseSystemdToCgroupName(key)
			key = internalCgroupName[len(internalCgroupName)-1]
		} else {
			// Take last component only.
			key = path.Base(key)
		}
		//if GetPodCgroupNameSuffix(podUID) == key {
		if id == key {
			return &info
		}
	}
	return nil
}

func getLatestContainerStatsById(id string, infos map[string]cadvisorapiv2.ContainerInfo) *cadvisorapiv2.ContainerStats {
	info := getContainerInfoById(id, infos)
	if info == nil {
		return nil
	}
	cstat, found := latestContainerStats(info)
	if !found {
		return nil
	}
	return cstat
}

// getCadvisorPodInfoFromPodUID returns a pod cgroup information by matching the podUID with its CgroupName identifier base name
func getCadvisorPodInfoFromPodUID(podUID types.UID, infos map[string]cadvisorapiv2.ContainerInfo) *cadvisorapiv2.ContainerInfo {
	return getContainerInfoById(string(podUID), infos)
}

// containerInfoWithCgroup contains the ContainerInfo and its cgroup name.
type containerInfoWithCgroup struct {
	cinfo  cadvisorapiv2.ContainerInfo
	cgroup string
}

// removeTerminatedContainerInfo returns the specified containerInfo but with
// the stats of the terminated containers removed.
//
// A ContainerInfo is considered to be of a terminated container if it has an
// older CreationTime and zero CPU instantaneous and memory RSS usage.
func removeTerminatedContainerInfo(containerInfo map[string]cadvisorapiv2.ContainerInfo) map[string]cadvisorapiv2.ContainerInfo {
	cinfoMap := make(map[containerID][]containerInfoWithCgroup)
	for key, cinfo := range containerInfo {
		if !isPodManagedContainer(&cinfo) {
			continue
		}
		cinfoID := containerID{
			podRef:        buildPodRef(cinfo.Spec.Labels),
			containerName: GetContainerName(cinfo.Spec.Labels),
		}
		cinfoMap[cinfoID] = append(cinfoMap[cinfoID], containerInfoWithCgroup{
			cinfo:  cinfo,
			cgroup: key,
		})
	}
	result := make(map[string]cadvisorapiv2.ContainerInfo)
	for _, refs := range cinfoMap {
		if len(refs) == 1 {
			result[refs[0].cgroup] = refs[0].cinfo
			continue
		}
		sort.Sort(ByCreationTime(refs))
		for i := len(refs) - 1; i >= 0; i-- {
			if hasMemoryAndCPUInstUsage(&refs[i].cinfo) {
				result[refs[i].cgroup] = refs[i].cinfo
				break
			}
		}
	}
	return result
}

// hasMemoryAndCPUInstUsage returns true if the specified container info has
// both non-zero CPU instantaneous usage and non-zero memory RSS usage, and
// false otherwise.
func hasMemoryAndCPUInstUsage(info *cadvisorapiv2.ContainerInfo) bool {
	if !info.Spec.HasCpu || !info.Spec.HasMemory {
		return false
	}
	cstat, found := latestContainerStats(info)
	if !found {
		return false
	}
	if cstat.CpuInst == nil {
		return false
	}
	return cstat.CpuInst.Usage.Total != 0 && cstat.Memory.RSS != 0
}

// ByCreationTime implements sort.Interface for []containerInfoWithCgroup based
// on the cinfo.Spec.CreationTime field.
type ByCreationTime []containerInfoWithCgroup

func (a ByCreationTime) Len() int      { return len(a) }
func (a ByCreationTime) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
func (a ByCreationTime) Less(i, j int) bool {
	if a[i].cinfo.Spec.CreationTime.Equal(a[j].cinfo.Spec.CreationTime) {
		// There shouldn't be two containers with the same name and/or the same
		// creation time. However, to make the logic here robust, we break the
		// tie by moving the one without CPU instantaneous or memory RSS usage
		// to the beginning.
		return hasMemoryAndCPUInstUsage(&a[j].cinfo)
	}
	return a[i].cinfo.Spec.CreationTime.Before(a[j].cinfo.Spec.CreationTime)
}

// isPodManagedContainer returns true if the cinfo container is managed by a Pod
func isPodManagedContainer(cinfo *cadvisorapiv2.ContainerInfo) bool {
	podName := GetPodName(cinfo.Spec.Labels)
	podNamespace := GetPodNamespace(cinfo.Spec.Labels)
	managed := podName != "" && podNamespace != ""
	if !managed && podName != podNamespace {
		klog.Warningf(
			"Expect container to have either both podName (%s) and podNamespace (%s) labels, or neither.",
			podName, podNamespace)
	}
	return managed
}