/*
Copyright 2019 The Volcano Authors.

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 helpers

import (
	"fmt"
	"math/rand"
	"strconv"
	"strings"
	"time"

	v1 "k8s.io/api/core/v1"

	batch "volcano.sh/apis/pkg/apis/batch/v1alpha1"
	"volcano.sh/volcano/pkg/controllers/apis"
	"volcano.sh/volcano/pkg/scheduler/api"
)

const (
	// PodNameFmt pod name format
	PodNameFmt = "%s-%s-%d"
	// persistentVolumeClaimFmt represents persistent volume claim name format
	persistentVolumeClaimFmt = "%s-pvc-%s"
	// OutOfSyncKey is the pod annotation indicates that the pod should be restarted.
	// And vcjob events (e.g. PodFailed, PodEvicted) of the pod with the annotation will be ignored.
	OutOfSyncKey = "volcano.sh/controller-out-of-sync"
)

// GetPodIndexUnderTask returns task Index.
func GetPodIndexUnderTask(pod *v1.Pod) string {
	num := strings.Split(pod.Name, "-")
	if len(num) >= 3 {
		return num[len(num)-1]
	}

	return ""
}

// CompareTask by pod index
func CompareTask(lv, rv *api.TaskInfo) bool {
	lStr := GetPodIndexUnderTask(lv.Pod)
	rStr := GetPodIndexUnderTask(rv.Pod)
	lIndex, lErr := strconv.Atoi(lStr)
	rIndex, rErr := strconv.Atoi(rStr)
	if lErr != nil || rErr != nil || lIndex == rIndex {
		if lv.Pod.CreationTimestamp.Equal(&rv.Pod.CreationTimestamp) {
			return lv.UID < rv.UID
		}
		return lv.Pod.CreationTimestamp.Before(&rv.Pod.CreationTimestamp)
	}
	if lIndex > rIndex {
		return false
	}
	return true
}

// GetTaskKey returns task key/name
func GetTaskKey(pod *v1.Pod) string {
	if pod.Annotations == nil || pod.Annotations[batch.TaskSpecKey] == "" {
		return batch.DefaultTaskSpec
	}
	return pod.Annotations[batch.TaskSpecKey]
}

// GetTaskSpec returns task spec
func GetTaskSpec(job *batch.Job, taskName string) (batch.TaskSpec, bool) {
	for _, ts := range job.Spec.Tasks {
		if ts.Name == taskName {
			return ts, true
		}
	}
	return batch.TaskSpec{}, false
}

// MakeDomainName creates task domain name
func MakeDomainName(ts batch.TaskSpec, job *batch.Job, index int) string {
	hostName := ts.Template.Spec.Hostname
	subdomain := ts.Template.Spec.Subdomain
	if len(hostName) == 0 {
		hostName = MakePodName(job.Name, ts.Name, index)
	}
	if len(subdomain) == 0 {
		subdomain = job.Name
	}
	return hostName + "." + subdomain
}

// MakePodName creates pod name.
func MakePodName(jobName string, taskName string, index int) string {
	return fmt.Sprintf(PodNameFmt, jobName, taskName, index)
}

// GenRandomStr generate random str with specified length l.
func GenRandomStr(l int) string {
	str := "0123456789abcdefghijklmnopqrstuvwxyz"
	bytes := []byte(str)
	var result []byte
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	for i := 0; i < l; i++ {
		result = append(result, bytes[r.Intn(len(bytes))])
	}
	return string(result)
}

// GenPVCName generates pvc name with job name.
func GenPVCName(jobName string) string {
	return fmt.Sprintf(persistentVolumeClaimFmt, jobName, GenRandomStr(12))
}

// GetJobKeyByReq gets the key for the job request.
func GetJobKeyByReq(req *apis.Request) string {
	return fmt.Sprintf("%s/%s", req.Namespace, req.JobName)
}

// GetTaskIndexUnderJob return index of the task in the job.
func GetTaskIndexUnderJob(taskName string, job *batch.Job) int {
	for index, task := range job.Spec.Tasks {
		if task.Name == taskName {
			return index
		}
	}
	return -1
}

// GetPodsNameUnderTask return names of all pods in the task.
func GetPodsNameUnderTask(taskName string, job *batch.Job) []string {
	var res []string
	for _, task := range job.Spec.Tasks {
		if task.Name == taskName {
			for index := 0; index < int(task.Replicas); index++ {
				res = append(res, MakePodName(job.Name, taskName, index))
			}
			break
		}
	}
	return res
}

// GetTaskIndexOfPod reads the task index from pod.Labels[batch.TaskIndex].
// This function is used by plugins to determine the task index of a pod within a job.
func GetTaskIndexOfPod(pod *v1.Pod) (int, error) {
	// Read task index from pod.Labels[batch.TaskIndex]
	taskIndexStr, exists := pod.Labels[batch.TaskIndex]
	if !exists {
		return -1, fmt.Errorf("pod %v doesn't have %v label", pod.Name, batch.TaskIndex)
	}
	taskIndex, err := strconv.Atoi(taskIndexStr)
	if err != nil {
		return -1, fmt.Errorf("failed to parse task index for pod %v: %v", pod.Name, err)
	}
	return taskIndex, nil
}

// GetTaskReplicasUnderJob return replicas of the task in the job.
func GetTaskReplicasUnderJob(taskName string, job *batch.Job) int32 {
	for _, task := range job.Spec.Tasks {
		if task.Name == taskName {
			return task.Replicas
		}
	}
	return 0
}

// IsOutOfSyncPod checks whether the pod is marked as out-of-sync.
func IsOutOfSyncPod(pod *v1.Pod) bool {
	if pod.Annotations == nil {
		return false
	}
	_, exists := pod.Annotations[OutOfSyncKey]
	return exists
}

// OutOfSyncJSONPatch generates a JSON patch to mark the pod as out-of-sync with the given reason.
func OutOfSyncJSONPatch() []byte {
	return []byte(fmt.Sprintf(`[{"op":"add","path":"/metadata/annotations/%s","value":"true"}]`,
		escapeJSONPointer(OutOfSyncKey)))
}

// escapeJSONPointer escapes a string for use in a JSON Pointer.
// See RFC 6901 for details: https://datatracker.ietf.org/doc/html/rfc6901
func escapeJSONPointer(s string) string {
	s = strings.ReplaceAll(s, "~", "~0")
	s = strings.ReplaceAll(s, "/", "~1")
	return s
}
