dumpsterChat/examples/steamfree/main.go

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/gorilla/websocket"
)

// ---- config from env ----

var (
	botToken    string
	host        string
	channelID   string
	pollMinutes int
	seen        = map[string]bool{} // appid -> posted
)

// ---- dumpsterChat WS protocol ----

type Event struct {
	Type    string          `json:"type"`
	Payload json.RawMessage `json:"payload"`
}

// ---- Steam API response ----

type FeaturedCategories struct {
	Specials FeaturedList `json:"specials"`
}

type FeaturedList struct {
	Items []FeaturedItem `json:"items"`
}

type FeaturedItem struct {
	ID            int    `json:"id"`
	Name          string `json:"name"`
	DiscountPct   int    `json:"discount_percent"`
	FinalPrice    int    `json:"final_price"`   // in cents
	OriginalPrice int    `json:"original_price"` // in cents
}

func main() {
	botToken = os.Getenv("BOT_TOKEN")
	if botToken == "" {
		log.Fatal("BOT_TOKEN required (create a bot in the dumpsterChat store)")
	}
	host = os.Getenv("DUMPSTER_HOST")
	if host == "" {
		host = "localhost:8080"
	}
	channelID = os.Getenv("CHANNEL_ID")
	if channelID == "" {
		log.Fatal("CHANNEL_ID required (the channel to post free games to)")
	}
	pollMinutes = 30
	if m := os.Getenv("POLL_MINUTES"); m != "" {
		if v, err := strconv.Atoi(m); err == nil && v > 0 {
			pollMinutes = v
		}
	}

	// Connect to dumpsterChat
	u := url.URL{
		Scheme:   "ws",
		Host:     host,
		Path:     "/ws/bot",
		RawQuery: "token=" + botToken,
	}

	log.Printf("SteamFree bot connecting to %s", u.String())

	c, _, err := websocket.DefaultDialer.Dial(u.String(), nil)
	if err != nil {
		log.Fatal("dial:", err)
	}
	defer c.Close()

	log.Println("SteamFree bot connected!")

	// First poll immediately, then on ticker
	poll(c)

	ticker := time.NewTicker(time.Duration(pollMinutes) * time.Minute)
	defer ticker.Stop()

	// Keep connection alive by reading (we don't need to react to events)
	go func() {
		for {
			_, _, err := c.ReadMessage()
			if err != nil {
				log.Println("ws read:", err)
				return
			}
		}
	}()

	for range ticker.C {
		poll(c)
	}
}

func poll(c *websocket.Conn) {
	log.Println("Polling Steam for free games...")

	games, err := fetchFreeGames()
	if err != nil {
		log.Println("fetch error:", err)
		return
	}

	newCount := 0
	for _, g := range games {
		if seen[strconv.Itoa(g.ID)] {
			continue
		}
		seen[strconv.Itoa(g.ID)] = true
		newCount++

		msg := formatGame(g)
		sendMessage(c, channelID, msg)
		log.Printf("Posted: %s (was $%.2f, now FREE)", g.Name, float64(g.OriginalPrice)/100)
		time.Sleep(500 * time.Millisecond) // be polite to the WS
	}

	if newCount == 0 {
		log.Println("No new free games found")
	} else {
		log.Printf("Posted %d new free games", newCount)
	}
}

func fetchFreeGames() ([]FeaturedItem, error) {
	client := &http.Client{Timeout: 15 * time.Second}
	resp, err := client.Get("https://store.steampowered.com/api/featuredcategories?cc=us&l=english")
	if err != nil {
		return nil, fmt.Errorf("steam api: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		return nil, fmt.Errorf("steam api: status %d", resp.StatusCode)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("read body: %w", err)
	}

	var cats FeaturedCategories
	if err := json.Unmarshal(body, &cats); err != nil {
		return nil, fmt.Errorf("parse json: %w", err)
	}

	// Filter: 100% discount and actually had a price (not permanent free-to-play)
	var free []FeaturedItem
	for _, item := range cats.Specials.Items {
		if item.DiscountPct == 100 && item.OriginalPrice > 0 {
			free = append(free, item)
		}
	}

	return free, nil
}

func formatGame(g FeaturedItem) string {
	storeURL := fmt.Sprintf("https://store.steampowered.com/app/%d", g.ID)

	var b strings.Builder
	fmt.Fprintf(&b, "🎮 **FREE ON STEAM** 🎮\n")
	fmt.Fprintf(&b, "**%s**\n", g.Name)
	fmt.Fprintf(&b, "~~$%.2f~~ → **FREE**\n", float64(g.OriginalPrice)/100)
	fmt.Fprintf(&b, "%s", storeURL)

	return b.String()
}

func sendMessage(c *websocket.Conn, channelID, content string) {
	msg := map[string]interface{}{
		"type": "SEND_MESSAGE",
		"payload": map[string]string{
			"channel_id": channelID,
			"content":    content,
		},
	}
	data, _ := json.Marshal(msg)
	c.WriteMessage(websocket.TextMessage, data)
}