add: reimplement discord bot

1 files changed, 203 insertions, 3 deletions

diff --git a/internal/bot/bot.go b/internal/bot/bot.go
index 1c8182d..4fb8fc8 100644
--- a/internal/bot/bot.go
+++ b/internal/bot/bot.go
@@ -1,8 +1,208 @@
 package bot
 
-import "fmt"
+import (
+	"errors"
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"strings"
+	"syscall"
+	"time"
+
+	"github.com/bwmarrin/discordgo"
+
+	"github.com/hachem-wtf/benson/internal/config"
+	"github.com/hachem-wtf/benson/internal/modrinth"
+)
 
 func Run() error {
-	fmt.Println("benson bot — not yet implemented")
-	return nil
+	cfg, err := config.Load()
+	if err != nil {
+		if os.IsNotExist(err) {
+			return fmt.Errorf("no config found — run `benson setup` to create one")
+		}
+		return fmt.Errorf("failed to load %s: %w", config.Path(), err)
+	}
+
+	api, err := config.LoadAPI()
+	if err != nil {
+		if os.IsNotExist(err) {
+			return fmt.Errorf("no bot token found — run `benson setup` to create one")
+		}
+		return fmt.Errorf("failed to load %s: %w", config.APIPath(), err)
+	}
+	if api.Token == "" {
+		return errors.New("config/api.json: token is empty")
+	}
+	if cfg.ChannelID == "" {
+		return errors.New("config/config.json: channel_id is empty")
+	}
+
+	session, err := discordgo.New("Bot " + api.Token)
+	if err != nil {
+		return err
+	}
+	session.Identify.Intents = discordgo.IntentsGuilds | discordgo.IntentsGuildMessages
+
+	ready := make(chan struct{})
+	session.AddHandler(func(s *discordgo.Session, r *discordgo.Ready) {
+		log.Printf("[OK] Logged in as %s", r.User.String())
+		close(ready)
+	})
+
+	if err := session.Open(); err != nil {
+		return err
+	}
+	defer session.Close()
+
+	<-ready
+
+	client := modrinth.NewClient()
+	checkAndReport(session, cfg, client)
+
+	interval := time.Duration(cfg.CheckIntervalMinutes) * time.Minute
+	if interval <= 0 {
+		interval = time.Hour
+	}
+	ticker := time.NewTicker(interval)
+	defer ticker.Stop()
+
+	stop := make(chan os.Signal, 1)
+	signal.Notify(stop, os.Interrupt, syscall.SIGTERM)
+
+	log.Printf("checking every %s — press Ctrl+C to stop", interval)
+
+	for {
+		select {
+		case <-ticker.C:
+			checkAndReport(session, cfg, client)
+		case <-stop:
+			log.Println("shutting down")
+			return nil
+		}
+	}
+}
+
+type report struct {
+	noCompatible          []string
+	newlyCompatible       []string
+	stillCompatibleUpdate []string
+}
+
+func checkAndReport(session *discordgo.Session, cfg *config.Config, client *modrinth.Client) {
+	rep := checkMods(cfg, client)
+
+	embed := buildEmbed(cfg, rep)
+	if embed == nil {
+		return
+	}
+
+	if _, err := session.ChannelMessageSendEmbed(cfg.ChannelID, embed); err != nil {
+		log.Println("[Discord] failed to send update:", err)
+		return
+	}
+	log.Println("[Discord] update message sent.")
+}
+
+func checkMods(cfg *config.Config, client *modrinth.Client) report {
+	cache, err := config.LoadCache()
+	if err != nil {
+		log.Println("[Cache] failed to load:", err)
+		cache = config.Cache{}
+	}
+	newCache := config.Cache{}
+
+	var rep report
+	for _, slug := range cfg.ModrinthMods {
+		versions, err := client.GetVersions(slug)
+		if err != nil {
+			log.Printf("[Modrinth] failed for %s: %v", slug, err)
+			continue
+		}
+
+		latest := modrinth.LatestVersion(versions)
+		compatible := modrinth.CompatibleVersion(versions, cfg.MinecraftVersion, "")
+
+		cached := cache[slug]
+
+		state := config.ModState{}
+		if compatible != nil {
+			state.Compatible = compatible.ID
+		}
+		if latest != nil {
+			state.Latest = latest.ID
+		}
+		newCache[slug] = state
+
+		switch {
+		case compatible == nil:
+			rep.noCompatible = append(rep.noCompatible, slug)
+		case cached.Compatible == "":
+			rep.newlyCompatible = append(rep.newlyCompatible, slug)
+		case latest != nil && latest.ID != cached.Latest:
+			rep.stillCompatibleUpdate = append(rep.stillCompatibleUpdate, slug)
+		}
+	}
+
+	if err := config.SaveCache(newCache); err != nil {
+		log.Println("[Cache] failed to save:", err)
+	}
+	return rep
+}
+
+const (
+	colorGood = 0x22C55E // green — everything compatible
+	colorWarn = 0xEF4444 // red — something has no compatible build
+)
+
+func buildEmbed(cfg *config.Config, rep report) *discordgo.MessageEmbed {
+	if len(rep.noCompatible) == 0 && len(rep.newlyCompatible) == 0 && len(rep.stillCompatibleUpdate) == 0 {
+		return nil
+	}
+
+	color := colorGood
+	if len(rep.noCompatible) > 0 {
+		color = colorWarn
+	}
+
+	var fields []*discordgo.MessageEmbedField
+	if f := section("🎉  Now compatible", rep.newlyCompatible); f != nil {
+		fields = append(fields, f)
+	}
+	if f := section("🟢  Updated (still compatible)", rep.stillCompatibleUpdate); f != nil {
+		fields = append(fields, f)
+	}
+	if f := section("❌  No compatible version", rep.noCompatible); f != nil {
+		fields = append(fields, f)
+	}
+
+	return &discordgo.MessageEmbed{
+		Author: &discordgo.MessageEmbedAuthor{
+			Name: "Modrinth compatibility",
+		},
+		Description: fmt.Sprintf("Fabric · Minecraft `%s`", cfg.MinecraftVersion),
+		Color:       color,
+		Fields:      fields,
+		Timestamp:   time.Now().Format(time.RFC3339),
+		Footer: &discordgo.MessageEmbedFooter{
+			Text: fmt.Sprintf("Benson · tracking %d mods", len(cfg.ModrinthMods)),
+		},
+	}
+}
+
+func section(name string, slugs []string) *discordgo.MessageEmbedField {
+	if len(slugs) == 0 {
+		return nil
+	}
+
+	var b strings.Builder
+	for _, slug := range slugs {
+		fmt.Fprintf(&b, "[`%s`](https://modrinth.com/mod/%s)\n", slug, slug)
+	}
+
+	return &discordgo.MessageEmbedField{
+		Name:  name,
+		Value: strings.TrimRight(b.String(), "\n"),
+	}
 }