feat: add discord-bot service

src/discord-bot/BUILD.bazel

@@ -3,11 +3,15 @@ load("@io_bazel_rules_docker//go:image.bzl", "go_image")
 
 go_library(
     name = "discord-bot_lib",
-    srcs = ["discordbot.go"],
+    srcs = [
+        "discordbot.go",
+        "listener.go",
+    ],
     importpath = "github.com/roleypoly/roleypoly/src/discord-bot",
     visibility = ["//visibility:private"],
     deps = [
         "//src/common/version",
+        "//src/discord-bot/internal/strings",
         "@com_github_bwmarrin_discordgo//:discordgo",
         "@com_github_joho_godotenv//autoload",
         "@com_github_lampjaw_discordclient//:discordclient",
@@ -16,13 +20,13 @@ go_library(
 )
 
 go_binary(
-    name = "discord-bot_bin",
+    name = "discord-bot",
     embed = [":discord-bot_lib"],
     visibility = ["//visibility:private"],
 )
 
 go_image(
-    name = "discord-bot",
+    name = "image",
     embed = [":discord-bot_lib"],
-    visibility = ["//visibility:public"],
+    visibility = ["//visibility:private"],
 )

src/discord-bot/discordbot.go

@@ -3,6 +3,7 @@ package main
 import (
 	"os"
 	"os/signal"
+	"regexp"
 	"strings"
 	"syscall"
 
@@ -13,15 +14,21 @@ import (
 	"k8s.io/klog"
 )
 
+var (
+	botToken    = os.Getenv("DISCORD_BOT_TOKEN")
+	botClientID = os.Getenv("DISCORD_CLIENT_ID")
+	rootUsers   = strings.Split(os.Getenv("ROOT_USERS"), ",")
+	allowedBots = strings.Split(os.Getenv("ALLOWED_BOTS"), ",")
+	appURL      = os.Getenv("PUBLIC_URL")
+
+	selfMention = regexp.MustCompile("<@!?" + botClientID + ">")
+)
+
 func main() {
 	klog.Info(version.StartupInfo("discord-bot"))
 
-	botToken := os.Getenv("DISCORD_BOT_TOKEN")
-	botClientID := os.Getenv("DISCORD_CLIENT_ID")
-	rootUsers := strings.Split(os.Getenv("ROOT_USERS"), ",")
-
 	discordClient := discordclient.NewDiscordClient(botToken, rootUsers[0], botClientID)
-	discordClient.GatewayIntents = discordgo.IntentsNone
+	discordClient.GatewayIntents = discordgo.IntentsGuildMessages
 
 	messageChannel, err := discordClient.Listen(-1)
 	if err != nil {
@@ -30,14 +37,21 @@ func main() {
 
 	defer awaitExit()
 
-	go processMessages(messageChannel)
+	l := listener{
+		client: discordClient,
+	}
+
+	go l.processMessages(messageChannel)
 }
 
-func processMessages(messageChannel <-chan discordclient.Message) {
-	for {
-		message := <-messageChannel
-		klog.Infoln("message: ", message.Message())
+func isBotAllowlisted(userID string) bool {
+	for _, id := range allowedBots {
+		if id == userID {
+			return true
+		}
 	}
+
+	return false
 }
 
 func awaitExit() {

src/discord-bot/internal/strings/BUILD.bazel

@@ -0,0 +1,11 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "strings",
+    srcs = [
+        "renderer.go",
+        "strings.go",
+    ],
+    importpath = "github.com/roleypoly/roleypoly/src/discord-bot/internal/strings",
+    visibility = ["//src/discord-bot:__subpackages__"],
+)

src/discord-bot/internal/strings/renderer.go

@@ -0,0 +1,13 @@
+package strings
+
+import (
+	"bytes"
+	"text/template"
+)
+
+// Render a template to string
+func Render(tmpl *template.Template, data interface{}) string {
+	buffer := &bytes.Buffer{}
+	tmpl.Execute(buffer, data)
+	return buffer.String()
+}

src/discord-bot/internal/strings/strings.go

@@ -0,0 +1,44 @@
+package strings
+
+import (
+	"text/template"
+)
+
+var (
+	// MentionResponse is a template that requires strings AppURL and GuildID.
+	MentionResponse = template.Must(
+		template.New("MentionResponse").Parse(
+			`:beginner: Assign your roles here! {{ .AppURL }}/s/{{ .GuildID }}`,
+		),
+	)
+
+	RootStats = template.Must(
+		template.New("RootStats").Parse(`🐈
+**People Stats**
+<:blank:676216695375003650>🙎‍♀️ **Total Users:** {{ .Users }}
+<:blank:676216695375003650>👨‍👩‍👦‍👦 **Total Guilds:** {{ .Guilds }}
+<:blank:676216695375003650>🦺 **Total Roles:** {{ .Roles }}
+
+**Bot Stats**
+<:blank:676216695375003650>🔩 **Total Shards:** {{ .Shards }}
+<:blank:676216695375003650>⚙️ **Revision:** {{ .GitCommit }} ({{ .GitBranch }})
+<:blank:676216695375003650>⏰ **Built at** {{ .BuildDate }}
+`,
+		),
+	)
+)
+
+type MentionResponseData struct {
+	AppURL  string
+	GuildID string
+}
+
+type RootStatsData struct {
+	Users     int
+	Guilds    int
+	Roles     int
+	Shards    int
+	GitCommit string
+	GitBranch string
+	BuildDate string
+}

src/discord-bot/listener.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"github.com/lampjaw/discordclient"
+	"k8s.io/klog"
+
+	"github.com/roleypoly/roleypoly/src/discord-bot/internal/strings"
+)
+
+type listener struct {
+	client *discordclient.DiscordClient
+}
+
+func (l *listener) processMessages(messageChannel <-chan discordclient.Message) {
+	for {
+		go l.handle(<-messageChannel)
+	}
+}
+
+func (l *listener) handle(message discordclient.Message) {
+	// Only if it's a message create
+	if message.Type() != discordclient.MessageTypeCreate {
+		return
+	}
+
+	// Only if it's an allowed bot
+	if message.IsBot() && !isBotAllowlisted(message.UserID()) {
+		return
+	}
+
+	// Only if it has the right mention
+	if !selfMention.MatchString(message.RawMessage()) {
+		return
+	}
+
+	l.defaultResponse(message)
+}
+
+func (l *listener) defaultResponse(message discordclient.Message) {
+	channel := message.Channel()
+	guild, err := message.ResolveGuildID()
+	if err != nil {
+		klog.Warning("failed to fetch guild, ", err)
+	}
+
+	l.client.SendMessage(
+		channel,
+		strings.Render(
+			strings.MentionResponse,
+			strings.MentionResponseData{GuildID: guild, AppURL: appURL},
+		),
+	)
+}