/*
Copyright 2017-2022 CAcert Inc.
SPDX-License-Identifier: Apache-2.0

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 main

import (
	"time"

	log "github.com/sirupsen/logrus"
)

type Job interface {
	Schedule()
	Stop()
	Run()
}

type jobIdentifier int

const (
	JobIDCloseDecisions jobIdentifier = iota
	JobIDRemindVotersJob
	reminderDays = 3
)

var rescheduleChannel = make(chan jobIdentifier, 1)

func JobScheduler(quitChannel chan int) {
	var jobs = map[jobIdentifier]Job{
		JobIDCloseDecisions:  NewCloseDecisionsJob(),
		JobIDRemindVotersJob: NewRemindVotersJob(),
	}

	log.Info("started job scheduler")

	for {
		select {
		case jobID := <-rescheduleChannel:
			job := jobs[jobID]

			log.Infof("reschedule job %s", job)
			job.Schedule()
		case <-quitChannel:
			for _, job := range jobs {
				job.Stop()
			}

			log.Info("stop job scheduler")

			return
		}
	}
}

type CloseDecisionsJob struct {
	timer *time.Timer
}

func NewCloseDecisionsJob() *CloseDecisionsJob {
	job := &CloseDecisionsJob{}
	job.Schedule()

	return job
}

func (j *CloseDecisionsJob) Schedule() {
	var (
		nextDue *time.Time
		err     error
	)

	nextDue, err = GetNextPendingDecisionDue()
	if err != nil {
		log.Error("Could not get next pending due date")

		if j.timer != nil {
			j.timer.Stop()
			j.timer = nil
		}

		return
	}

	if nextDue == nil {
		log.Info("no next planned execution of CloseDecisionsJob")
		j.Stop()
	} else {
		nextDue := nextDue.Add(time.Second)
		log.Infof("scheduling CloseDecisionsJob for %s", nextDue)
		when := time.Until(nextDue)
		if j.timer != nil {
			j.timer.Reset(when)
		} else {
			j.timer = time.AfterFunc(when, j.Run)
		}
	}
}

func (j *CloseDecisionsJob) Stop() {
	if j.timer != nil {
		j.timer.Stop()
		j.timer = nil
	}
}

func (j *CloseDecisionsJob) Run() {
	log.Debug("running CloseDecisionsJob")

	err := CloseDecisions()
	if err != nil {
		log.Errorf("closing decisions %v", err)
	}

	rescheduleChannel <- JobIDCloseDecisions
}

func (j *CloseDecisionsJob) String() string {
	return "CloseDecisionsJob"
}

type RemindVotersJob struct {
	timer *time.Timer
}

func NewRemindVotersJob() *RemindVotersJob {
	job := &RemindVotersJob{}
	job.Schedule()

	return job
}

func (j *RemindVotersJob) Schedule() {
	year, month, day := time.Now().UTC().Date()
	nextExecution := time.Date(year, month, day, 0, 0, 0, 0, time.UTC).AddDate(0, 0, reminderDays)

	log.Infof("scheduling RemindVotersJob for %s", nextExecution)

	when := time.Until(nextExecution)

	if j.timer != nil {
		j.timer.Reset(when)
	} else {
		j.timer = time.AfterFunc(when, j.Run)
	}
}

func (j *RemindVotersJob) Stop() {
	if j.timer != nil {
		j.timer.Stop()
		j.timer = nil
	}
}

func (j *RemindVotersJob) Run() {
	log.Info("running RemindVotersJob")

	defer func() { rescheduleChannel <- JobIDRemindVotersJob }()

	var (
		voters []Voter
		err    error
	)

	voters, err = GetReminderVoters()
	if err != nil {
		log.Errorf("problem getting voters %v", err)

		return
	}

	var decisions []Decision

	for i := range voters {
		decisions, err = FindUnVotedDecisionsForVoter(&voters[i])
		if err != nil {
			log.Errorf("problem getting unvoted decisions: %v", err)

			return
		}

		if len(decisions) > 0 {
			NotifyMailChannel <- &RemindVoterNotification{voter: voters[i], decisions: decisions}
		}
	}
}