commit 24c9f21743174ff0bea72f42159502748951edba
Author: Michael Zhang <iptq@protonmail.com>
Date:   Sun Oct 11 14:32:58 2020 -0500

    initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..92f116f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+/subscribe-bot
+/db
+/config.toml
diff --git a/bot.go b/bot.go
new file mode 100644
index 0000000..0924574
--- /dev/null
+++ b/bot.go
@@ -0,0 +1,117 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"log"
+	"reflect"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/bwmarrin/discordgo"
+)
+
+type Bot struct {
+	*discordgo.Session
+	mentionRe *regexp.Regexp
+	db        *Db
+	requests  chan int
+}
+
+func NewBot(token string, db *Db, requests chan int) (bot *Bot, err error) {
+	s, err := discordgo.New("Bot " + token)
+	if err != nil {
+		return
+	}
+
+	err = s.Open()
+	if err != nil {
+		return
+	}
+	log.Println("connected to discord")
+
+	re, err := regexp.Compile("\\s*<@\\!?" + s.State.User.ID + ">\\s*")
+	if err != nil {
+		return
+	}
+
+	bot = &Bot{s, re, db, requests}
+	s.AddHandler(bot.errWrap(bot.newMessageHandler))
+	return
+}
+
+func (bot *Bot) errWrap(fn interface{}) interface{} {
+	val := reflect.ValueOf(fn)
+	origType := reflect.TypeOf(fn)
+	origTypeIn := make([]reflect.Type, origType.NumIn())
+	for i := 0; i < origType.NumIn(); i++ {
+		origTypeIn[i] = origType.In(i)
+	}
+	newType := reflect.FuncOf(origTypeIn, []reflect.Type{}, false)
+	newFunc := reflect.MakeFunc(newType, func(args []reflect.Value) (result []reflect.Value) {
+		res := val.Call(args)
+		if len(res) > 0 && !res[0].IsNil() {
+			err := res[0].Interface().(error)
+			if err != nil {
+				msg := fmt.Sprintf("error: %s", err)
+				channel, _ := bot.UserChannelCreate("100443064228646912")
+				id, _ := bot.ChannelMessageSend(channel.ID, msg)
+				log.Println(id, msg)
+			}
+		}
+		return []reflect.Value{}
+	})
+	return newFunc.Interface()
+}
+
+func (bot *Bot) newMessageHandler(s *discordgo.Session, m *discordgo.MessageCreate) (err error) {
+	mentionsMe := false
+	for _, user := range m.Mentions {
+		if user.ID == s.State.User.ID {
+			mentionsMe = true
+			break
+		}
+	}
+
+	if !mentionsMe {
+		return
+	}
+
+	msg := bot.mentionRe.ReplaceAllString(m.Content, " ")
+	msg = strings.Trim(msg, " ")
+
+	parts := strings.Split(msg, " ")
+	switch strings.ToLower(parts[0]) {
+	case "track":
+		if len(parts) < 2 {
+			err = errors.New("fucked up")
+			return
+		}
+
+		var mapperId int
+		mapperId, err = strconv.Atoi(parts[1])
+		if err != nil {
+			return
+		}
+
+		err = bot.db.ChannelTrackMapper(m.ChannelID, mapperId, 3)
+		if err != nil {
+			return
+		}
+
+		go func() {
+			time.Sleep(refreshInterval)
+			bot.requests <- mapperId
+		}()
+
+		bot.MessageReactionAdd(m.ChannelID, m.ID, "\xf0\x9f\x91\x8d")
+	}
+
+	return
+}
+
+func (bot *Bot) Close() {
+	bot.Session.Close()
+}
diff --git a/config.go b/config.go
new file mode 100644
index 0000000..6a842fe
--- /dev/null
+++ b/config.go
@@ -0,0 +1,37 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+
+	"github.com/BurntSushi/toml"
+)
+
+type Config struct {
+	BotToken     string `toml:"bot_token"`
+	ClientId     int    `toml:"client_id"`
+	ClientSecret string `toml:"client_secret"`
+}
+
+func ReadConfig(path string) (config Config, err error) {
+	file, err := os.Open(path)
+	if err != nil {
+		err = fmt.Errorf("couldn't open file %s: %w", path, err)
+		return
+	}
+
+	data, err := ioutil.ReadAll(file)
+	if err != nil {
+		err = fmt.Errorf("couldn't read data from %s: %w", path, err)
+		return
+	}
+
+	err = toml.Unmarshal(data, &config)
+	if err != nil {
+		err = fmt.Errorf("couldn't parse config data from %s: %w", path, err)
+		return
+	}
+
+	return
+}
diff --git a/db.go b/db.go
new file mode 100644
index 0000000..21823dd
--- /dev/null
+++ b/db.go
@@ -0,0 +1,240 @@
+package main
+
+// Database is laid out like this:
+// mapper/<mapper_id>/trackers/<channel_id> -> priority
+// mapper/<mapper_id>/latestEvent
+// channel/<channel_id>/tracks/<mapper_id> -> priority
+
+import (
+	"strconv"
+
+	bolt "go.etcd.io/bbolt"
+)
+
+var (
+	LATEST_EVENT = []byte("latestEvent")
+)
+
+type Db struct {
+	*bolt.DB
+	api *Osuapi
+}
+
+func OpenDb(path string, api *Osuapi) (db *Db, err error) {
+	inner, err := bolt.Open(path, 0666, nil)
+	db = &Db{inner, api}
+	return
+}
+
+// Loop over channels that are tracking this specific mapper
+func (db *Db) IterTrackingChannels(mapperId int, fn func(channelId string) error) (err error) {
+	err = db.DB.View(func(tx *bolt.Tx) error {
+		mapper := getMapper(tx, mapperId)
+		if mapper == nil {
+			return nil
+		}
+
+		trackers := mapper.Bucket([]byte("trackers"))
+		if trackers == nil {
+			return nil
+		}
+
+		c := trackers.Cursor()
+		for k, _ := c.First(); k != nil; k, _ = c.Next() {
+			channelId := string(k)
+			err := fn(channelId)
+			if err != nil {
+				return err
+			}
+		}
+
+		return nil
+	})
+
+	return
+}
+
+// Loop over tracked mappers
+func (db *Db) IterTrackedMappers(fn func(userId int) error) (err error) {
+	err = db.DB.View(func(tx *bolt.Tx) error {
+		mappers := tx.Bucket([]byte("mapper"))
+		if mappers == nil {
+			return nil
+		}
+
+		c := mappers.Cursor()
+		for k, _ := c.First(); k != nil; k, _ = c.Next() {
+			userId, err := strconv.Atoi(string(k))
+			if err != nil {
+				return err
+			}
+
+			err = fn(userId)
+			if err != nil {
+				return err
+			}
+		}
+
+		return nil
+	})
+
+	return
+}
+
+// Get a list of channels that are tracking this mapper
+func (db *Db) GetMapperTrackers(userId int) (trackersList []string) {
+	trackersList = make([]string, 0)
+	db.DB.View(func(tx *bolt.Tx) error {
+		mapper, err := getMapperMut(tx, userId)
+		if err != nil {
+			return err
+		}
+
+		trackers := mapper.Bucket([]byte("trackers"))
+		if trackers == nil {
+			return nil
+		}
+
+		c := trackers.Cursor()
+		for k, _ := c.First(); k != nil; k, _ = c.Next() {
+			channelId := string(k)
+			trackersList = append(trackersList, channelId)
+		}
+
+		return nil
+	})
+	return
+}
+
+// Update the latest event of a mapper to the given one
+func (db *Db) UpdateMapperLatestEvent(userId int, eventId int) (err error) {
+	err = db.DB.Update(func(tx *bolt.Tx) error {
+		mapper, err := getMapperMut(tx, userId)
+		if err != nil {
+			return err
+		}
+
+		err = mapper.Put(LATEST_EVENT, []byte(strconv.Itoa(eventId)))
+		if err != nil {
+			return err
+		}
+
+		return nil
+	})
+	return
+}
+
+// Get the latest event ID of this mapper, if they have one
+func (db *Db) MapperLastEvent(userId int) (has bool, id int) {
+	has = false
+	id = -1
+	db.DB.View(func(tx *bolt.Tx) error {
+		mapper := getMapper(tx, userId)
+		if mapper == nil {
+			return nil
+		}
+
+		lastEventId := mapper.Get(LATEST_EVENT)
+		if lastEventId == nil {
+			return nil
+		}
+
+		var err error
+		id, err = strconv.Atoi(string(lastEventId))
+		if err != nil {
+			return nil
+		}
+
+		has = true
+		return nil
+	})
+
+	return
+}
+
+// Start tracking a new mapper (if they're not already tracked)
+func (db *Db) ChannelTrackMapper(channelId string, mapperId int, priority int) (err error) {
+	events, err := db.api.GetUserEvents(mapperId, 1, 0)
+	if err != nil {
+		return
+	}
+
+	err = db.Batch(func(tx *bolt.Tx) error {
+		{
+			mapper, err := getMapperMut(tx, mapperId)
+			if err != nil {
+				return err
+			}
+
+			if len(events) > 0 {
+				latestEventId := strconv.Itoa(events[0].ID)
+				mapper.Put(LATEST_EVENT, []byte(latestEventId))
+			}
+
+			trackers, err := mapper.CreateBucketIfNotExists([]byte("trackers"))
+			if err != nil {
+				return err
+			}
+
+			err = trackers.Put([]byte(channelId), []byte(strconv.Itoa(priority)))
+			if err != nil {
+				return err
+			}
+		}
+		{
+			channels, err := tx.CreateBucketIfNotExists([]byte("channels"))
+			if err != nil {
+				return err
+			}
+
+			channel, err := channels.CreateBucketIfNotExists([]byte(channelId))
+			if err != nil {
+				return err
+			}
+
+			tracks, err := channel.CreateBucketIfNotExists([]byte("tracks"))
+			if err != nil {
+				return err
+			}
+
+			err = tracks.Put([]byte(strconv.Itoa(mapperId)), []byte(strconv.Itoa(priority)))
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+	return
+}
+
+func (db *Db) Close() {
+	db.DB.Close()
+}
+
+func getMapper(tx *bolt.Tx, userId int) (mapper *bolt.Bucket) {
+	mappers := tx.Bucket([]byte("mapper"))
+	if mappers == nil {
+		return nil
+	}
+
+	mapper = mappers.Bucket([]byte(strconv.Itoa(userId)))
+	if mapper == nil {
+		return nil
+	}
+
+	return
+}
+
+func getMapperMut(tx *bolt.Tx, userId int) (mapper *bolt.Bucket, err error) {
+	mappers, err := tx.CreateBucketIfNotExists([]byte("mapper"))
+	if err != nil {
+		return
+	}
+
+	mapper, err = mappers.CreateBucketIfNotExists([]byte(strconv.Itoa(userId)))
+	if err != nil {
+		return
+	}
+
+	return
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..d7b76e0
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,10 @@
+module subscribe-bot
+
+go 1.14
+
+require (
+	github.com/BurntSushi/toml v0.3.1
+	github.com/bwmarrin/discordgo v0.22.0
+	go.etcd.io/bbolt v1.3.5
+	golang.org/x/sync v0.0.0-20201008141435-b3e1573b7520
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..e39543c
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,13 @@
+github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/bwmarrin/discordgo v0.22.0 h1:uBxY1HmlVCsW1IuaPjpCGT6A2DBwRn0nvOguQIxDdFM=
+github.com/bwmarrin/discordgo v0.22.0/go.mod h1:c1WtWUGN6nREDmzIpyTp/iD3VYt4Fpx+bVyfBG7JE+M=
+github.com/gorilla/websocket v1.4.0 h1:WDFjx/TMzVgy9VdMMQi2K2Emtwi2QcUQsztZ/zLaH/Q=
+github.com/gorilla/websocket v1.4.0/go.mod h1:E7qHFY5m1UJ88s3WnNqhKjPHQ0heANvMoAMk2YaljkQ=
+go.etcd.io/bbolt v1.3.5 h1:XAzx9gjCb0Rxj7EoqcClPD1d5ZBxZJk0jbuoPHenBt0=
+go.etcd.io/bbolt v1.3.5/go.mod h1:G5EMThwa9y8QZGBClrRx5EY+Yw9kAhnjy3bSjsnlVTQ=
+golang.org/x/crypto v0.0.0-20181030102418-4d3f4d9ffa16 h1:y6ce7gCWtnH+m3dCjzQ1PCuwl28DDIc3VNnvY29DlIA=
+golang.org/x/crypto v0.0.0-20181030102418-4d3f4d9ffa16/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/sync v0.0.0-20201008141435-b3e1573b7520 h1:Bx6FllMpG4NWDOfhMBz1VR2QYNp/SAOHPIAsaVmxfPo=
+golang.org/x/sync v0.0.0-20201008141435-b3e1573b7520/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20200202164722-d101bd2416d5/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..e023296
--- /dev/null
+++ b/main.go
@@ -0,0 +1,63 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+)
+
+var exit_chan = make(chan int)
+
+func main() {
+	configPath := flag.String("config", "config.toml", "Path to the config file (defaults to config.toml)")
+	flag.Parse()
+
+	config, err := ReadConfig(*configPath)
+
+	requests := make(chan int)
+
+	api := NewOsuapi(&config)
+
+	db, err := OpenDb("db", api)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	bot, err := NewBot(config.BotToken, db, requests)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	go RunScraper(bot, db, api, requests)
+
+	signal_chan := make(chan os.Signal, 1)
+	signal.Notify(signal_chan,
+		syscall.SIGHUP,
+		syscall.SIGINT,
+		syscall.SIGTERM,
+		syscall.SIGQUIT)
+	go func() {
+		for {
+			s := <-signal_chan
+			switch s {
+			case syscall.SIGHUP:
+				fallthrough
+			case syscall.SIGINT:
+				fallthrough
+			case syscall.SIGTERM:
+				fallthrough
+			case syscall.SIGQUIT:
+				exit_chan <- 0
+			default:
+				exit_chan <- 1
+			}
+		}
+	}()
+	code := <-exit_chan
+
+	db.Close()
+	bot.Close()
+	os.Exit(code)
+}
diff --git a/models.go b/models.go
new file mode 100644
index 0000000..b8db5a4
--- /dev/null
+++ b/models.go
@@ -0,0 +1,32 @@
+package main
+
+type Event struct {
+	CreatedAt string `json:"created_at"`
+	ID        int    `json:"id"`
+	Type      string `json:"type"`
+
+	// type: achievement
+	Achievement Achievement `json:"achievement,omitempty"`
+
+	// type: beatmapsetApprove
+	// type: beatmapsetDelete
+	// type: beatmapsetRevive
+	// type: beatmapsetUpdate
+	// type: beatmapsetUpload
+	Beatmapset Beatmapset `json:"beatmapset,omitempty"`
+
+	User User `json:"user,omitempty"`
+}
+
+type Achievement struct{}
+
+type Beatmapset struct {
+	Title string `json:"title"`
+	URL   string `json:"url"`
+}
+
+type User struct {
+	Username         string `json:"username"`
+	URL              string `json:"url"`
+	PreviousUsername string `json:"previousUsername,omitempty"`
+}
diff --git a/osuapi.go b/osuapi.go
new file mode 100644
index 0000000..97a3778
--- /dev/null
+++ b/osuapi.go
@@ -0,0 +1,126 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"strings"
+	"time"
+
+	"golang.org/x/sync/semaphore"
+)
+
+const BASE_URL = "https://osu.ppy.sh/api/v2"
+
+type Osuapi struct {
+	lock         *semaphore.Weighted
+	token        string
+	expires      time.Time
+	clientId     int
+	clientSecret string
+}
+
+func NewOsuapi(config *Config) *Osuapi {
+	// want to cap at around 1000 requests a minute, OSU cap is 1200
+	lock := semaphore.NewWeighted(1000)
+	return &Osuapi{lock, "", time.Now(), config.ClientId, config.ClientSecret}
+}
+
+func (api *Osuapi) Token() (token string, err error) {
+	if time.Now().Before(api.expires) {
+		token = api.token
+		return
+	}
+
+	data := fmt.Sprintf(
+		"client_id=%d&client_secret=%s&grant_type=client_credentials&scope=public",
+		api.clientId,
+		api.clientSecret,
+	)
+
+	resp, err := http.Post("https://osu.ppy.sh/oauth/token", "application/x-www-form-urlencoded", strings.NewReader(data))
+	if err != nil {
+		return
+	}
+
+	var osuToken OsuToken
+	respBody, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return
+	}
+
+	err = json.Unmarshal(respBody, &osuToken)
+	if err != nil {
+		return
+	}
+
+	log.Println("got new access token", osuToken.AccessToken[:12]+"...")
+	api.token = osuToken.AccessToken
+	api.expires = time.Now().Add(time.Duration(osuToken.ExpiresIn) * time.Second)
+	token = api.token
+	return
+}
+
+func (api *Osuapi) Request(action string, url string, result interface{}) (err error) {
+	err = api.lock.Acquire(context.TODO(), 1)
+	if err != nil {
+		return
+	}
+	apiUrl := BASE_URL + url
+	req, err := http.NewRequest(action, apiUrl, nil)
+
+	token, err := api.Token()
+	if err != nil {
+		return
+	}
+
+	req.Header.Add("Authorization", "Bearer "+token)
+	if err != nil {
+		return
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return
+	}
+	data, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return
+	}
+
+	err = json.Unmarshal(data, result)
+	if err != nil {
+		return
+	}
+
+	// release the lock after 1 minute
+	go func() {
+		time.Sleep(time.Minute)
+		api.lock.Release(1)
+	}()
+	return
+}
+
+func (api *Osuapi) GetUserEvents(userId int, limit int, offset int) (events []Event, err error) {
+	url := fmt.Sprintf(
+		"/users/%d/recent_activity?limit=%d&offset=%d",
+		userId,
+		limit,
+		offset,
+	)
+	err = api.Request("GET", url, &events)
+	if err != nil {
+		return
+	}
+
+	return
+}
+
+type OsuToken struct {
+	TokenType   string `json:"token_type"`
+	ExpiresIn   int    `json:"expires_in"`
+	AccessToken string `json:"access_token"`
+}
diff --git a/scrape.go b/scrape.go
new file mode 100644
index 0000000..16ae8fd
--- /dev/null
+++ b/scrape.go
@@ -0,0 +1,120 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"time"
+)
+
+var (
+	refreshInterval = 60 * time.Second
+)
+
+func RunScraper(bot *Bot, db *Db, api *Osuapi, requests chan int) {
+	// start timers
+	go startTimers(db, requests)
+
+	for userId := range requests {
+		log.Println("scraping", userId)
+		newMaps, err := getNewMaps(db, api, userId)
+		if err != nil {
+			log.Println("err getting new maps:", err)
+			exit_chan <- 1
+		}
+
+		db.IterTrackingChannels(userId, func(channelId string) error {
+			for _, beatmap := range newMaps {
+				bot.ChannelMessageSend(channelId, fmt.Sprintf("new beatmap event [%s](%s)", beatmap.Title, beatmap.URL))
+			}
+			return nil
+		})
+
+		// wait a minute and put them back into the queue
+		go func() {
+			time.Sleep(refreshInterval)
+			requests <- userId
+		}()
+	}
+}
+
+func getNewMaps(db *Db, api *Osuapi, userId int) (newMaps []Beatmapset, err error) {
+	// see if there's a last event
+	hasLastEvent, lastEventId := db.MapperLastEvent(userId)
+	newMaps = make([]Beatmapset, 0)
+	var (
+		events            []Event
+		newLatestEvent    = 0
+		updateLatestEvent = false
+	)
+	if hasLastEvent {
+		log.Printf("last event id for %d is %d\n", userId, lastEventId)
+		offset := 0
+
+	loop:
+		for {
+			log.Println("loading user events from", offset)
+			events, err = api.GetUserEvents(userId, 50, offset)
+			if err != nil {
+				err = fmt.Errorf("couldn't load events for user %d, offset %d: %w", userId, offset, err)
+				return
+			}
+			if len(events) == 0 {
+				break
+			}
+
+			for _, event := range events {
+				if event.ID == lastEventId {
+					break loop
+				}
+
+				if event.ID > newLatestEvent {
+					updateLatestEvent = true
+					newLatestEvent = event.ID
+				}
+
+				if event.Type == "beatmapsetUpload" ||
+					event.Type == "beatmapsetRevive" ||
+					event.Type == "beatmapsetUpdate" {
+					newMaps = append(newMaps, event.Beatmapset)
+				}
+			}
+
+			offset += len(events)
+		}
+	} else {
+		log.Printf("no last event id found for %d\n", userId)
+		events, err = api.GetUserEvents(userId, 50, 0)
+		if err != nil {
+			return
+		}
+
+		for _, event := range events {
+			if event.ID > newLatestEvent {
+				updateLatestEvent = true
+				newLatestEvent = event.ID
+			}
+
+			if event.Type == "beatmapsetUpload" ||
+				event.Type == "beatmapsetRevive" ||
+				event.Type == "beatmapsetUpdate" {
+				newMaps = append(newMaps, event.Beatmapset)
+			}
+		}
+	}
+
+	if updateLatestEvent {
+		err = db.UpdateMapperLatestEvent(userId, newLatestEvent)
+		if err != nil {
+			return
+		}
+	}
+
+	return
+}
+
+func startTimers(db *Db, requests chan int) {
+	db.IterTrackedMappers(func(userId int) error {
+		requests <- userId
+		return nil
+	})
+}