remindme.go

package commands

import (
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"regexp"
	"strings"
	"time"

	"github.com/BryanSLam/discord-bot/util"
	dg "github.com/bwmarrin/discordgo"
	"github.com/go-redis/redis"
)

func init() {
	// Run once at 6:00 AM from Monday-Friday
	cronner.AddFunc("00 06 * * MON-FRI", todaysReminders)
}

// NewRemindmeCommand TODO: @doc
func NewRemindmeCommand() *Command {
	return &Command{
		Match: func(s string) bool {
			return regexp.MustCompile(`(?i)^!remindme [\w ]+ (0?[1-9]|1[012])/(0?[1-9]|[12][0-9]|3[01])/(\d\d)$`).MatchString(s)
		},
		Fn: Remindme,
	}
}

// Set up redis table in a way where the keys are the dates of when to pull a reminder
// and the value is an array of events that need to be reminded on that date

// Remindme creates a reminder entry into datastore (Redis)
func Remindme(drw io.ReadWriter, logger *util.Logger, m map[string]interface{}) {
	buf, err := ioutil.ReadAll(drw)
	if err != nil {
		drw.Write([]byte(err.Error()))
		return
	}

	mc := m["messageCreate"].(*dg.MessageCreate)
	channelID := mc.ChannelID

	slice := strings.Split(string(buf), " ")
	date := slice[len(slice)-1]
	// grab message string in between command and date
	msgSlice := slice[1 : len(slice)-1]
	msg := strings.Join(msgSlice, " ")
	reminder := fmt.Sprintf("%s~*REMINDER %s: %s", channelID, mc.Author.Mention(), msg)

	err = addReminder(reminder, date)
	if err != nil {
		drw.Write([]byte(err.Error()))
		logger.Trace("Remindme request failed: " + err.Error())
		return
	}

	drw.Write([]byte("Reminder set for " + date + " at 6:00 AM"))
}

// addReminder will function as a stack; pushing new reminder messages for the date key.
// The date should be in the form mm/dd/yy.
func addReminder(message string, date string) error {
	dateCheck, _ := time.Parse(dateFormat, date)
	future := time.Date(dateCheck.Year(), dateCheck.Month(), dateCheck.Day(), 0, 0, 0, 0, pst)
	if future.Before(time.Now().In(pst)) {
		return errors.New("Date has already passed")
	}

	redisClient.RPush(dateCheck.Format(redisDateFormat), message)
	return nil
}

// getReminders will fetch reminder messages datastore for the given date
func getReminders(date string) ([]string, error) {
	_, err := redisClient.LRange(date, 0, -1).Result()
	if err == redis.Nil {
		return nil, errors.New("no reminders for date: " + date)
	}
	reminders := redisClient.LRange(date, 0, -1).Val()

	redisClient.Del(date)
	return reminders, nil
}

// Function run during the daily reminder check
func todaysReminders() {
	dgSession, _ := dg.New("Bot " + token)

	todaysDate := time.Now().In(pst).Format(redisDateFormat)
	reminders, _ := getReminders(todaysDate)
	dgSession.Open()
	defer dgSession.Close()

	for _, reminder := range reminders {
		split := strings.Split(reminder, "~*")
		channel := split[0]
		dgSession.ChannelMessageSend(channel, split[1])
	}
}