// © 2013 the CatBase Authors under the WTFPL. See AUTHORS for the list of authors.

package reminder

import (
	"github.com/olebedev/when"
	"github.com/olebedev/when/rules/common"
	"github.com/olebedev/when/rules/en"
	bh "github.com/timshannon/bolthold"
	"github.com/velour/catbase/bot"
	"github.com/velour/catbase/bot/msg"
	"github.com/velour/catbase/config"
	"sync"
	"time"
)

import (
	"fmt"
	"github.com/rs/zerolog/log"
	"strconv"
	"strings"

	"github.com/velour/catbase/plugins/sms"
)

const (
	TIMESTAMP = "2006-01-02 15:04:05"
)

type ReminderPlugin struct {
	bot    bot.Bot
	store  *bh.Store
	mutex  *sync.Mutex
	timer  *time.Timer
	config *config.Config
	when   *when.Parser
}

type Reminder struct {
	ID      uint64 `boltholdKey:"ID"`
	From    string
	Who     string
	What    string
	When    time.Time
	Channel string
}

func New(b bot.Bot) *ReminderPlugin {
	dur, _ := time.ParseDuration("1h")
	timer := time.NewTimer(dur)
	timer.Stop()

	w := when.New(nil)
	w.Add(en.All...)
	w.Add(common.All...)

	plugin := &ReminderPlugin{
		bot:    b,
		store:  b.Store(),
		mutex:  &sync.Mutex{},
		timer:  timer,
		config: b.Config(),
		when:   w,
	}

	plugin.queueUpNextReminder()

	go reminderer(b.DefaultConnector(), plugin)

	b.Register(plugin, bot.Message, plugin.message)
	b.Register(plugin, bot.Help, plugin.help)

	return plugin
}

func (p *ReminderPlugin) message(c bot.Connector, kind bot.Kind, message msg.Message, args ...interface{}) bool {
	channel := message.Channel
	from := message.User.Name

	var dur, dur2 time.Duration
	t, err := p.when.Parse(message.Body, time.Now())
	// Allowing err to fallthrough for other parsing
	if t != nil && err == nil {
		t2 := t.Time.Sub(time.Now()).String()
		message.Body = string(message.Body[0:t.Index]) + t2 + string(message.Body[t.Index+len(t.Text):])
		log.Debug().
			Str("body", message.Body).
			Str("text", t.Text).
			Msg("Got time request")
	}
	parts := strings.Fields(message.Body)

	if len(parts) >= 5 {
		if strings.ToLower(parts[0]) == "remind" {
			who := parts[1]
			if who == "me" {
				who = from
			}

			dur, err = time.ParseDuration(parts[3])
			if err != nil {
				p.bot.Send(c, bot.Message, channel, "Easy cowboy, not sure I can parse that duration. Try something like '1.5h' or '2h45m'.")
				return true
			}

			operator := strings.ToLower(parts[2])
			doConfirm := true

			if operator == "in" || operator == "at" || operator == "on" {
				//one off reminder
				//remind Who in dur blah
				when := time.Now().UTC().Add(dur)
				what := strings.Join(parts[4:], " ")

				p.addReminder(&Reminder{
					From:    from,
					Who:     who,
					What:    what,
					When:    when,
					Channel: channel,
				})

			} else if operator == "every" && strings.ToLower(parts[4]) == "for" {
				//batch add, especially for reminding msherms to buy a kit
				//remind Who every dur for dur2 blah
				dur2, err = time.ParseDuration(parts[5])
				if err != nil {
					log.Error().Err(err)
					p.bot.Send(c, bot.Message, channel, "Easy cowboy, not sure I can parse that duration. Try something like '1.5h' or '2h45m'.")
					return true
				}

				when := time.Now().UTC().Add(dur)
				endTime := time.Now().UTC().Add(dur2)
				what := strings.Join(parts[6:], " ")

				max := p.config.GetInt("Reminder.MaxBatchAdd", 10)
				for i := 0; when.Before(endTime); i++ {
					if i >= max {
						p.bot.Send(c, bot.Message, channel, "Easy cowboy, that's a lot of reminders. I'll add some of them.")
						doConfirm = false
						break
					}

					p.addReminder(&Reminder{
						From:    from,
						Who:     who,
						What:    what,
						When:    when,
						Channel: channel,
					})

					when = when.Add(dur)
				}
			} else {
				p.bot.Send(c, bot.Message, channel, "Easy cowboy, not sure I comprehend What you're asking.")
				return true
			}

			if doConfirm && from == who {
				p.bot.Send(c, bot.Message, channel, fmt.Sprintf("Okay. I'll remind you."))
			} else if doConfirm {
				p.bot.Send(c, bot.Message, channel, fmt.Sprintf("Sure %s, I'll remind %s.", from, who))
			}

			p.queueUpNextReminder()

			return true
		}
	} else if len(parts) >= 2 && strings.ToLower(parts[0]) == "list" && strings.ToLower(parts[1]) == "reminders" {
		var response string
		var err error
		if len(parts) == 2 {
			response, err = p.getAllRemindersFormatted(channel)
		} else if len(parts) == 4 {
			if strings.ToLower(parts[2]) == "to" {
				response, err = p.getAllRemindersToMeFormatted(channel, strings.ToLower(parts[3]))
			} else if strings.ToLower(parts[2]) == "From" {
				response, err = p.getAllRemindersFromMeFormatted(channel, strings.ToLower(parts[3]))
			}
		}
		if err != nil {
			p.bot.Send(c, bot.Message, channel, "listing failed.")
		} else {
			p.bot.Send(c, bot.Message, channel, response)
		}
		return true
	} else if len(parts) == 3 && strings.ToLower(parts[0]) == "cancel" && strings.ToLower(parts[1]) == "reminder" {
		id, err := strconv.ParseUint(parts[2], 10, 64)
		if err != nil {
			p.bot.Send(c, bot.Message, channel, fmt.Sprintf("couldn't parse ID: %s", parts[2]))

		} else {
			err := p.deleteReminder(id)
			if err == nil {
				p.bot.Send(c, bot.Message, channel, fmt.Sprintf("successfully canceled reminder: %s", parts[2]))
			} else {
				p.bot.Send(c, bot.Message, channel, fmt.Sprintf("failed to find and cancel reminder: %s", parts[2]))
			}
		}
		return true
	}

	return false
}

func (p *ReminderPlugin) help(c bot.Connector, kind bot.Kind, message msg.Message, args ...interface{}) bool {
	p.bot.Send(c, bot.Message, message.Channel, "Pester someone with a reminder. Try \"remind <user> in <duration> message\".\n\nUnsure about duration syntax? Check https://golang.org/pkg/time/#ParseDuration")
	return true
}

func (p *ReminderPlugin) getNextReminder() *Reminder {
	p.mutex.Lock()
	defer p.mutex.Unlock()

	reminder := Reminder{}
	res, err := p.store.FindAggregate(Reminder{}, &bh.Query{}, "")
	if err != nil {
		log.Error().Err(err)
		return nil
	}
	if len(res) == 0 {
		log.Error().Msg("No next reminder in system.")
		return nil
	}
	res[0].Max("RemindWhen", &reminder)

	return &reminder
}

func (p *ReminderPlugin) addReminder(reminder *Reminder) error {
	p.mutex.Lock()
	defer p.mutex.Unlock()
	err := p.store.Insert(bh.NextSequence(), reminder)
	if err != nil {
		log.Error().Err(err).Msgf("error creating reminder")
		return err
	}
	return nil
}

func (p *ReminderPlugin) deleteReminder(id uint64) error {
	p.mutex.Lock()
	defer p.mutex.Unlock()
	err := p.store.Delete(id, Reminder{})
	return err
}

func (p *ReminderPlugin) getRemindersFormatted(filter, who string) (string, error) {
	max := p.config.GetInt("Reminder.MaxList", 25)

	p.mutex.Lock()
	defer p.mutex.Unlock()

	q := bh.Where(filter).Eq(who)
	if filter == "" || who == "" {
		q = &bh.Query{}
	}
	total, err := p.store.Count(Reminder{}, q)
	if err != nil {
		log.Error().Err(err)
		return "", nil
	}

	if total == 0 {
		return "no pending reminders", nil
	}

	reminders := []Reminder{}
	err = p.store.Find(&reminders, q.SortBy("ID").Limit(max))
	if err != nil {
		log.Error().Err(err)
		return "", nil
	}
	txt := ""
	for counter, reminder := range reminders {
		txt += fmt.Sprintf("%d) %s -> %s :: %s @ %s (%d)\n", counter, reminder.From, reminder.Who, reminder.What, reminder.When, reminder.ID)
		counter++
	}

	remaining := total - max
	if remaining > 0 {
		txt += fmt.Sprintf("...%d more...\n", remaining)
	}

	return txt, nil
}

func (p *ReminderPlugin) getAllRemindersFormatted(channel string) (string, error) {
	return p.getRemindersFormatted("", "")
}

func (p *ReminderPlugin) getAllRemindersFromMeFormatted(channel, me string) (string, error) {
	return p.getRemindersFormatted("FromWho", me)
}

func (p *ReminderPlugin) getAllRemindersToMeFormatted(channel, me string) (string, error) {
	return p.getRemindersFormatted("ToWho", me)
}

func (p *ReminderPlugin) queueUpNextReminder() {
	nextReminder := p.getNextReminder()

	if nextReminder != nil {
		p.timer.Reset(nextReminder.When.Sub(time.Now().UTC()))
	}
}

func reminderer(c bot.Connector, p *ReminderPlugin) {
	for {
		<-p.timer.C

		reminder := p.getNextReminder()

		if reminder != nil && time.Now().UTC().After(reminder.When) {
			var message string
			if reminder.From == reminder.Who {
				reminder.From = "you"
				message = fmt.Sprintf("Hey %s, you wanted to be reminded: %s", reminder.Who, reminder.What)
			} else {
				message = fmt.Sprintf("Hey %s, %s wanted you to be reminded: %s", reminder.Who, reminder.From, reminder.What)
			}

			p.bot.Send(c, bot.Message, reminder.Channel, message)
			smsPlugin := sms.New(p.bot)
			if err := smsPlugin.Send(reminder.Who, message); err != nil {
				log.Error().Err(err).Msgf("could not send reminder")
			}

			if err := p.deleteReminder(reminder.ID); err != nil {
				log.Fatal().
					Uint64("ID", reminder.ID).
					Err(err).
					Msg("this will cause problems, we need to stop now.")
			}
		}

		p.queueUpNextReminder()
	}
}