package job

import (
	"fmt"
	"sync"

	"github.com/vmware/harbor/dao"
	"github.com/vmware/harbor/job/config"
	"github.com/vmware/harbor/job/imgout"
	"github.com/vmware/harbor/job/utils"
	"github.com/vmware/harbor/models"
	"github.com/vmware/harbor/utils/log"
)

type RepJobParm struct {
	LocalRegURL    string
	TargetURL      string
	TargetUsername string
	TargetPassword string
	Repository     string
	Enabled        int
	Operation      string
}

type JobSM struct {
	JobID         int64
	CurrentState  string
	PreviousState string
	//The states that don't have to exist in transition map, such as "Error", "Canceled"
	ForcedStates map[string]struct{}
	Transitions  map[string]map[string]struct{}
	Handlers     map[string]StateHandler
	desiredState string
	Logger       utils.Logger
	Parms        *RepJobParm
	lock         *sync.Mutex
}

// EnsterState transit the statemachine from the current state to the state in parameter.
// It returns the next state the statemachine should tranit to.
func (sm *JobSM) EnterState(s string) (string, error) {
	log.Debugf("Trying to transit from State: %s, to State: %s", sm.CurrentState, s)
	targets, ok := sm.Transitions[sm.CurrentState]
	_, exist := targets[s]
	_, isForced := sm.ForcedStates[s]
	if !exist && !isForced {
		return "", fmt.Errorf("Transition from %s to %s does not exist!", sm.CurrentState, s)
	}
	exitHandler, ok := sm.Handlers[sm.CurrentState]
	if ok {
		if err := exitHandler.Exit(); err != nil {
			return "", err
		}
	} else {
		log.Debugf("No handler found for state:%s, skip", sm.CurrentState)
	}
	enterHandler, ok := sm.Handlers[s]
	var next string = models.JobContinue
	var err error
	if ok {
		if next, err = enterHandler.Enter(); err != nil {
			return "", err
		}
	} else {
		log.Debugf("No handler found for state:%s, skip", s)
	}
	sm.PreviousState = sm.CurrentState
	sm.CurrentState = s
	log.Debugf("Transition succeeded, current state: %s", s)
	return next, nil
}

// Start kicks off the statemachine to transit from current state to s, and moves on
// It will search the transit map if the next state is "_continue", and
// will enter error state if there's more than one possible path when next state is "_continue"
func (sm *JobSM) Start(s string) {
	n, err := sm.EnterState(s)
	log.Debugf("next state from handler: %s", n)
	for len(n) > 0 && err == nil {
		if d := sm.getDesiredState(); len(d) > 0 {
			log.Debugf("Desired state: %s, will ignore the next state from handler")
			n = d
			sm.setDesiredState("")
			continue
		}
		if n == models.JobContinue && len(sm.Transitions[sm.CurrentState]) == 1 {
			for n = range sm.Transitions[sm.CurrentState] {
				break
			}
			log.Debugf("Continue to state: %s", n)
			continue
		}
		if n == models.JobContinue && len(sm.Transitions[sm.CurrentState]) != 1 {
			log.Errorf("Next state is continue but there are %d possible next states in transition table", len(sm.Transitions[sm.CurrentState]))
			err = fmt.Errorf("Unable to continue")
			break
		}
		n, err = sm.EnterState(n)
		log.Debugf("next state from handler: %s", n)
	}
	if err != nil {
		log.Warningf("The statemachin will enter error state due to error: %v", err)
		sm.EnterState(models.JobError)
	}
}

func (sm *JobSM) AddTransition(from string, to string, h StateHandler) {
	_, ok := sm.Transitions[from]
	if !ok {
		sm.Transitions[from] = make(map[string]struct{})
	}
	sm.Transitions[from][to] = struct{}{}
	sm.Handlers[to] = h
}

func (sm *JobSM) RemoveTransition(from string, to string) {
	_, ok := sm.Transitions[from]
	if !ok {
		return
	}
	delete(sm.Transitions[from], to)
}

func (sm *JobSM) Stop() {
	sm.setDesiredState(models.JobStopped)
}

func (sm *JobSM) getDesiredState() string {
	sm.lock.Lock()
	defer sm.lock.Unlock()
	return sm.desiredState
}

func (sm *JobSM) setDesiredState(s string) {
	sm.lock.Lock()
	defer sm.lock.Unlock()
	sm.desiredState = s
}

func (sm *JobSM) Init() {
	sm.lock = &sync.Mutex{}
	sm.Handlers = make(map[string]StateHandler)
	sm.Transitions = make(map[string]map[string]struct{})
	sm.AddTransition(models.JobPending, models.JobRunning, StatusUpdater{DummyHandler{JobID: sm.JobID}, models.JobRunning})
	sm.Handlers[models.JobError] = StatusUpdater{DummyHandler{JobID: sm.JobID}, models.JobError}
	sm.Handlers[models.JobStopped] = StatusUpdater{DummyHandler{JobID: sm.JobID}, models.JobStopped}
}
func (sm *JobSM) Reset(jid int64) error {
	sm.JobID = jid
	//init parms
	job, err := dao.GetRepJob(sm.JobID)
	if err != nil {
		return fmt.Errorf("Failed to get job, error: %v", err)
	}
	if job == nil {
		return fmt.Errorf("The job doesn't exist in DB, job id: %d", sm.JobID)
	}
	policy, err := dao.GetRepPolicy(job.PolicyID)
	if err != nil {
		return fmt.Errorf("Failed to get policy, error: %v", err)
	}
	if policy == nil {
		return fmt.Errorf("The policy doesn't exist in DB, policy id:%d", job.PolicyID)
	}
	sm.Parms = &RepJobParm{
		LocalRegURL: config.LocalRegURL(),
		Repository:  job.Repository,
		Enabled:     policy.Enabled,
		Operation:   job.Operation,
	}
	if policy.Enabled == 0 {
		//handler will cancel this job
		return nil
	}
	target, err := dao.GetRepTarget(policy.TargetID)
	if err != nil {
		return fmt.Errorf("Failed to get target, error: %v", err)
	}
	if target == nil {
		return fmt.Errorf("The target doesn't exist in DB, target id: %d", policy.TargetID)
	}
	sm.Parms.TargetURL = target.URL
	sm.Parms.TargetUsername = target.Username
	sm.Parms.TargetPassword = target.Password
	//init states handlers
	sm.Logger = utils.Logger{sm.JobID}
	sm.CurrentState = models.JobPending
	if sm.Parms.Operation == models.RepOpTransfer {
		/*
			sm.AddTransition(models.JobRunning, "pull-img", ImgPuller{DummyHandler: DummyHandler{JobID: sm.JobID}, img: sm.Parms.Repository, logger: sm.Logger})
			//only handle on target for now
			sm.AddTransition("pull-img", "push-img", ImgPusher{DummyHandler: DummyHandler{JobID: sm.JobID}, targetURL: sm.Parms.TargetURL, logger: sm.Logger})
			sm.AddTransition("push-img", models.JobFinished, StatusUpdater{DummyHandler{JobID: sm.JobID}, models.JobFinished})
		*/
		if err = addImgOutTransition(sm); err != nil {
			return err
		}
	}
	return nil
}

func addImgOutTransition(sm *JobSM) error {
	base, err := imgout.InitBaseHandler(sm.Parms.Repository, sm.Parms.LocalRegURL, "",
		sm.Parms.TargetURL, sm.Parms.TargetUsername, sm.Parms.TargetPassword,
		nil, &sm.Logger)
	if err != nil {
		return err
	}
	sm.AddTransition(models.JobRunning, imgout.StateCheck, &imgout.Checker{BaseHandler: base})
	sm.AddTransition(imgout.StateCheck, imgout.StatePullManifest, &imgout.ManifestPuller{BaseHandler: base})
	sm.AddTransition(imgout.StatePullManifest, imgout.StateTransferBlob, &imgout.BlobTransfer{BaseHandler: base})
	sm.AddTransition(imgout.StatePullManifest, models.JobFinished, &StatusUpdater{DummyHandler{JobID: sm.JobID}, models.JobFinished})
	sm.AddTransition(imgout.StateTransferBlob, imgout.StatePushManifest, &imgout.ManifestPusher{BaseHandler: base})
	sm.AddTransition(imgout.StatePushManifest, imgout.StatePullManifest, &imgout.ManifestPuller{BaseHandler: base})
	return nil
}