package services

import (
	"github.com/emvi/logbuch"
	"github.com/muety/artifex/v2"
	"github.com/muety/wakapi/config"
	"github.com/muety/wakapi/utils"
	"go.uber.org/atomic"
	"strconv"
	"sync"
	"time"

	"github.com/muety/wakapi/models"
)

const (
	countUsersEvery = 1 * time.Hour
)

var countLock = sync.Mutex{}

type MiscService struct {
	config          *config.Config
	userService     IUserService
	summaryService  ISummaryService
	keyValueService IKeyValueService
	queueDefault    *artifex.Dispatcher
	queueWorkers    *artifex.Dispatcher
}

func NewMiscService(userService IUserService, summaryService ISummaryService, keyValueService IKeyValueService) *MiscService {
	return &MiscService{
		config:          config.Get(),
		userService:     userService,
		summaryService:  summaryService,
		keyValueService: keyValueService,
		queueDefault:    config.GetDefaultQueue(),
		queueWorkers:    config.GetQueue(config.QueueProcessing),
	}
}

func (srv *MiscService) ScheduleCountTotalTime() {
	logbuch.Info("scheduling total time counting")
	if _, err := srv.queueDefault.DispatchEvery(srv.CountTotalTime, countUsersEvery); err != nil {
		config.Log().Error("failed to schedule user counting jobs, %v", err)
	}
}

func (srv *MiscService) CountTotalTime() {
	logbuch.Info("counting users total time")
	if ok := countLock.TryLock(); !ok {
		config.Log().Warn("couldn't acquire lock for counting users total time, job is still pending")
	}
	defer countLock.Unlock()

	users, err := srv.userService.GetAll()
	if err != nil {
		config.Log().Error("failed to fetch users for time counting, %v", err)
	}

	var totalTime = atomic.NewDuration(0)
	var pendingJobs sync.WaitGroup
	pendingJobs.Add(len(users))

	for _, u := range users {
		user := *u
		if err := srv.queueWorkers.Dispatch(func() {
			defer pendingJobs.Done()
			totalTime.Add(srv.countUserTotalTime(user.ID))
		}); err != nil {
			config.Log().Error("failed to enqueue counting job for user '%s'", user.ID)
			pendingJobs.Done()
		}
	}

	// persist
	go func(wg *sync.WaitGroup) {
		if !utils.WaitTimeout(&pendingJobs, 2*countUsersEvery) {
			if err := srv.keyValueService.PutString(&models.KeyStringValue{
				Key:   config.KeyLatestTotalTime,
				Value: totalTime.Load().String(),
			}); err != nil {
				config.Log().Error("failed to save total time count: %v", err)
			}

			if err := srv.keyValueService.PutString(&models.KeyStringValue{
				Key:   config.KeyLatestTotalUsers,
				Value: strconv.Itoa(len(users)),
			}); err != nil {
				config.Log().Error("failed to save total users count: %v", err)
			}
		} else {
			config.Log().Error("waiting for user counting jobs timed out")
		}
	}(&pendingJobs)
}

func (srv *MiscService) countUserTotalTime(userId string) time.Duration {
	result, err := srv.summaryService.Aliased(time.Time{}, time.Now(), &models.User{ID: userId}, srv.summaryService.Retrieve, nil, false)
	if err != nil {
		config.Log().Error("failed to count total for user %s: %v", userId, err)
		return 0
	}
	return result.TotalTime()
}