titlebot-ng-ng/voteServer/main.go

package main

import (
	"database/sql"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"sync"
	"time"

	"github.com/nbd-wtf/go-nostr"
	"github.com/nbd-wtf/go-nostr/nip19"
	_ "github.com/mattn/go-sqlite3"
	"gopkg.in/yaml.v2"
)

type Submission struct {
	Submitter      string `json:"submitter"`
	SubmissionTime int64  `json:"submission_time"`
	Submission     string `json:"submission"`
}

type SubmissionBuffer struct {
	Submissions []Submission
	Mtx         sync.Mutex
}

type User struct {
	UserName      string `json:"user_name"`
	DisplayName   string `json:"display_name"`
	LastActive    int64  `json:"last_active"`
	NumberOfPosts int    `json:"number_of_posts"`
	LastSeen      int64  `json:"last_seen"`
}

type UserData struct {
	Users          map[string]User `json:"users"`
	MostRecentPost int64           `json:"most_recent_post"`
}

type Vote struct {
	VoterDisplayName   string `json:"voter_display_name"`
	SelectedSubmission string `json:"selected_submission"`
	Submitter          string `json:"submitter"`
	SubmissionTime     int64  `json:"submission_time"`
	VoteTimestamp      int64  `json:"vote_timestamp"`
}

type UserMap struct {
	Users          map[string]User
	MostRecentPost int64
	Mtx            sync.RWMutex
}

type Config struct {
	RoomID            string `yaml:"room_id"`
	VoteActivityHours int    `yaml:"vote_activity_hours"`
	VoteHost          string `yaml:"vote_host"`
	VotePath          string `yaml:"vote_path"`
}

type Room struct {
	Config   *Config
	Slug     string
	DB       *sql.DB
	SubBuffer *SubmissionBuffer
	UserMap  *UserMap
}

// --- Nostr auth types ---

type SignedLinkRequest struct {
	DisplayName string `json:"display_name"`
	Npub        string `json:"npub"`
	SignedEvent json.RawMessage `json:"signed_event"` // full signed Nostr event
}

type ChallengeRequest struct {
	Npub string `json:"npub"` // bech32 npub or hex pubkey
}

type SignedVoteRequest struct {
	Npub             string          `json:"npub"`
	Challenge        string          `json:"challenge"`
	SelectedSubmission string        `json:"selected_submission"`
	Submitter        string          `json:"submitter"`
	SubmissionTime   int64           `json:"submission_time"`
	SignedEvent      json.RawMessage `json:"signed_event"` // full signed Nostr event
}

func loadConfig(configPath string) (*Config, error) {
	data, err := os.ReadFile(configPath)
	if err != nil {
		return nil, fmt.Errorf("failed to read config file: %w", err)
	}

	var config Config
	err = yaml.Unmarshal(data, &config)
	if err != nil {
		return nil, fmt.Errorf("failed to parse config: %w", err)
	}

	if config.VoteActivityHours == 0 {
		config.VoteActivityHours = 72
	}

	if config.VoteHost == "" {
		config.VoteHost = "localhost"
	}

	return &config, nil
}

func loadConfigs() ([]*Config, error) {
	var configs []*Config

	files, err := filepath.Glob(filepath.Join("..", "configs", "*.yaml"))
	if err == nil && len(files) > 0 {
		for _, f := range files {
			if strings.Contains(filepath.Base(f), "example") {
				continue
			}
			c, err := loadConfig(f)
			if err != nil {
				log.Printf("Error loading config %s: %v", f, err)
				continue
			}
			configs = append(configs, c)
		}
	}

	if len(configs) == 0 {
		c, err := loadConfig(filepath.Join("..", "config.yaml"))
		if err != nil {
			return nil, err
		}
		configs = append(configs, c)
	}

	return configs, nil
}

func loadRoomSlugs() map[string]string {
	data, err := os.ReadFile(filepath.Join("..", "room_slugs.json"))
	if err != nil {
		return nil
	}
	var slugs map[string]string
	if err := json.Unmarshal(data, &slugs); err != nil {
		return nil
	}
	return slugs
}

func slugify(s string) string {
	var b strings.Builder
	lastDash := false
	for _, r := range strings.ToLower(s) {
		if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') {
			b.WriteRune(r)
			lastDash = false
		} else if !lastDash {
			b.WriteByte('-')
			lastDash = true
		}
	}
	return strings.Trim(b.String(), "-")
}

func roomSlug(config *Config, slugs map[string]string) string {
	if config.VotePath != "" {
		return config.VotePath
	}
	if slugs != nil {
		if slug, ok := slugs[config.RoomID]; ok && slug != "" {
			return slug
		}
	}
	return slugify(config.RoomID)
}

func safeDBName(roomID string, prefix string) string {
	re := regexp.MustCompile(`[^a-zA-Z0-9_-]`)
	safe := re.ReplaceAllString(roomID, "_")
	return fmt.Sprintf("%s_%s.db", prefix, safe)
}

func initDB(dbPath string) (*sql.DB, error) {
	db, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		return nil, fmt.Errorf("failed to open database: %w", err)
	}

	_, err = db.Exec(`
		CREATE TABLE IF NOT EXISTS votes (
			id INTEGER PRIMARY KEY AUTOINCREMENT,
			voter_display_name TEXT NOT NULL,
			selected_submission TEXT NOT NULL,
			submitter TEXT,
			submission_time INTEGER,
			vote_timestamp INTEGER NOT NULL,
			UNIQUE(voter_display_name)
		)
	`)
	if err != nil {
		return nil, fmt.Errorf("failed to create votes table: %w", err)
	}

	_, err = db.Exec(`
		CREATE TABLE IF NOT EXISTS nostr_links (
			id INTEGER PRIMARY KEY AUTOINCREMENT,
			npub_hex TEXT NOT NULL,
			display_name TEXT NOT NULL,
			linked_at INTEGER NOT NULL,
			UNIQUE(npub_hex),
			UNIQUE(display_name)
		)
	`)
	if err != nil {
		return nil, fmt.Errorf("failed to create nostr_links table: %w", err)
	}

	_, err = db.Exec(`
		CREATE TABLE IF NOT EXISTS nostr_challenges (
			id INTEGER PRIMARY KEY AUTOINCREMENT,
			npub_hex TEXT NOT NULL,
			challenge TEXT NOT NULL,
			created_at INTEGER NOT NULL,
			expires_at INTEGER NOT NULL,
			used INTEGER DEFAULT 0
		)
	`)
	if err != nil {
		return nil, fmt.Errorf("failed to create nostr_challenges table: %w", err)
	}

	return db, nil
}

// --- Nostr helpers ---

func decodeNpub(npub string) (string, error) {
	prefix, extracted, err := nip19.Decode(npub)
	if err != nil {
		return "", fmt.Errorf("failed to decode npub: %w", err)
	}
	if prefix != "npub" {
		return "", fmt.Errorf("expected npub prefix, got %s", prefix)
	}
	hexKey, ok := extracted.(string)
	if !ok {
		return "", fmt.Errorf("unexpected type from npub decode")
	}
	return hexKey, nil
}

func parsePubkey(input string) (string, error) {
	input = strings.TrimSpace(input)
	if strings.HasPrefix(input, "npub1") {
		return decodeNpub(input)
	}
	// Assume hex
	cleaned := strings.TrimPrefix(input, "0x")
	if len(cleaned) != 64 {
		return "", fmt.Errorf("invalid pubkey: expected 64 hex characters, got %d", len(cleaned))
	}
	if _, err := hex.DecodeString(cleaned); err != nil {
		return "", fmt.Errorf("invalid hex pubkey: %w", err)
	}
	return cleaned, nil
}

func verifySignedEvent(signedEventJSON json.RawMessage, expectedPubkey string) (*nostr.Event, error) {
	var evt nostr.Event
	if err := json.Unmarshal(signedEventJSON, &evt); err != nil {
		return nil, fmt.Errorf("failed to parse signed event: %w", err)
	}

	if evt.PubKey != expectedPubkey {
		return nil, fmt.Errorf("event pubkey %s does not match expected %s", evt.PubKey, expectedPubkey)
	}

	ok, err := evt.CheckSignature()
	if err != nil {
		return nil, fmt.Errorf("signature verification error: %w", err)
	}
	if !ok {
		return nil, fmt.Errorf("invalid signature")
	}

	return &evt, nil
}

func decodeNpubEndpoint(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}
	body, err := io.ReadAll(r.Body)
	if err != nil {
		http.Error(w, "Failed to read request", http.StatusBadRequest)
		return
	}
	defer r.Body.Close()

	var req struct {
		Npub string `json:"npub"`
	}
	if err := json.Unmarshal(body, &req); err != nil {
		http.Error(w, "Invalid request", http.StatusBadRequest)
		return
	}

	hexKey, err := decodeNpub(req.Npub)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]string{"hex": hexKey})
}

func encodeNpubEndpoint(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}
	body, err := io.ReadAll(r.Body)
	if err != nil {
		http.Error(w, "Failed to read request", http.StatusBadRequest)
		return
	}
	defer r.Body.Close()

	var req struct {
		Hex string `json:"hex"`
	}
	if err := json.Unmarshal(body, &req); err != nil {
		http.Error(w, "Invalid request", http.StatusBadRequest)
		return
	}

	npub, err := nip19.EncodePublicKey(req.Hex)
	if err != nil {
		http.Error(w, fmt.Sprintf("Failed to encode: %v", err), http.StatusBadRequest)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]string{"npub": npub})
}

func cleanExpiredChallenges(db *sql.DB) {
	_, err := db.Exec(`DELETE FROM nostr_challenges WHERE expires_at < ?`, time.Now().Unix())
	if err != nil {
		log.Printf("Error cleaning expired challenges: %v", err)
	}
}

// --- Routes ---

func main() {
	configs, err := loadConfigs()
	if err != nil {
		log.Fatalf("Failed to load configs: %v", err)
	}

	slugs := loadRoomSlugs()

	var rooms []*Room
	usedSlugs := make(map[string]bool)
	for _, config := range configs {
		slug := roomSlug(config, slugs)
		if usedSlugs[slug] {
			log.Printf("Skipping room %s: slug /%s already in use by another config", config.RoomID, slug)
			continue
		}
		usedSlugs[slug] = true

		dbName := safeDBName(config.RoomID, "votes")
		dbPath := filepath.Join("..", dbName)
		db, err := initDB(dbPath)
		if err != nil {
			log.Printf("Database initialization failed for %s: %v", config.RoomID, err)
			continue
		}
		defer db.Close()

		room := &Room{
			Config:    config,
			Slug:      slug,
			DB:        db,
			SubBuffer: &SubmissionBuffer{},
			UserMap:   &UserMap{Users: make(map[string]User)},
		}
		rooms = append(rooms, room)

		go collectSubmissions(room)
		go collectUserList(room)
		go cleanExpiredChallengesLoop(room)

		base := "/" + room.Slug
		http.HandleFunc(base+"/", serveHTML)
		http.HandleFunc(base+"/css.css", serveCSS)
		http.HandleFunc(base+"/js.js", serveJS)
		http.HandleFunc(base+"/submissions", serveSubmissions(room.SubBuffer))
		http.HandleFunc(base+"/getVotes", getVotes(room))
		http.HandleFunc(base+"/link", serveLinkHTML)
		http.HandleFunc(base+"/linkNpub", linkNpub(room))
		http.HandleFunc(base+"/challenge", challenge(room))
		http.HandleFunc(base+"/verifyVote", verifyVote(room))
		http.HandleFunc(base+"/decode_npub", decodeNpubEndpoint)
		http.HandleFunc(base+"/encode_npub", encodeNpubEndpoint)

		log.Printf("Vote server serving room '%s' under %s (db %s)", config.RoomID, base, dbPath)
	}

	if len(rooms) == 1 {
		http.HandleFunc("/submissions", serveSubmissions(rooms[0].SubBuffer))
		http.HandleFunc("/getVotes", getVotes(rooms[0]))
		http.HandleFunc("/link", serveLinkHTML)
		http.HandleFunc("/linkNpub", linkNpub(rooms[0]))
		http.HandleFunc("/challenge", challenge(rooms[0]))
		http.HandleFunc("/verifyVote", verifyVote(rooms[0]))
		http.HandleFunc("/decode_npub", decodeNpubEndpoint)
		http.HandleFunc("/encode_npub", encodeNpubEndpoint)
	}

	http.HandleFunc("/", indexHandler(rooms))

	log.Println("Vote server starting on :9081")
	log.Fatal(http.ListenAndServe(":9081", nil))
}

func cleanExpiredChallengesLoop(room *Room) {
	ticker := time.NewTicker(5 * time.Minute)
	defer ticker.Stop()
	for range ticker.C {
		cleanExpiredChallenges(room.DB)
	}
}

func indexHandler(rooms []*Room) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		if len(rooms) == 1 {
			http.Redirect(w, r, "/"+rooms[0].Slug+"/", http.StatusFound)
			return
		}
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		fmt.Fprintln(w, "<!DOCTYPE html><html><head><meta charset='utf-8'><title>Pick a Title!</title></head><body>")
		fmt.Fprintln(w, "<h1>Pick a Title!</h1>")
		fmt.Fprintln(w, "<ul>")
		for _, room := range rooms {
			fmt.Fprintf(w, "<li><a href='/%s/'>%s</a></li>\n", room.Slug, room.Slug)
		}
		fmt.Fprintln(w, "</ul></body></html>")
	}
}

func serveHTML(w http.ResponseWriter, r *http.Request) {
	htmlPath := filepath.Join("htm", "ndx.html")
	http.ServeFile(w, r, htmlPath)
}

func serveCSS(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/css")
	cssPath := filepath.Join("htm", "css.css")
	http.ServeFile(w, r, cssPath)
}

func serveJS(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/javascript")
	jsPath := filepath.Join("htm", "js.js")
	http.ServeFile(w, r, jsPath)
}

func serveLinkHTML(w http.ResponseWriter, r *http.Request) {
	htmlPath := filepath.Join("htm", "link.html")
	http.ServeFile(w, r, htmlPath)
}

func serveSubmissions(subBuffer *SubmissionBuffer) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		subBuffer.Mtx.Lock()
		defer subBuffer.Mtx.Unlock()

		w.Header().Set("Content-Type", "application/json")
		err := json.NewEncoder(w).Encode(subBuffer)
		if err != nil {
			log.Printf("Error encoding submissions: %v", err)
			http.Error(w, "Failed to encode submissions", http.StatusInternalServerError)
			return
		}
	}
}

func collectSubmissions(room *Room) {
	ticker := time.NewTicker(30 * time.Second)
	defer ticker.Stop()

	fetchSubmissions(room)

	for range ticker.C {
		fetchSubmissions(room)
	}
}

func fetchSubmissions(room *Room) {
	url := fmt.Sprintf("http://localhost:9080/%s/subs", room.Slug)
	resp, err := http.Get(url)
	if err != nil {
		log.Printf("Error fetching submissions: %v", err)
		return
	}
	defer resp.Body.Close()

	var fetchedBuffer SubmissionBuffer
	err = json.NewDecoder(resp.Body).Decode(&fetchedBuffer)
	if err != nil {
		log.Printf("Error decoding submissions: %v", err)
		return
	}

	room.SubBuffer.Mtx.Lock()
	room.SubBuffer.Submissions = fetchedBuffer.Submissions
	room.SubBuffer.Mtx.Unlock()

	log.Printf("Fetched %d submissions", len(fetchedBuffer.Submissions))
}

func collectUserList(room *Room) {
	ticker := time.NewTicker(30 * time.Second)
	defer ticker.Stop()

	fetchUserList(room)

	for range ticker.C {
		fetchUserList(room)
	}
}

func fetchUserList(room *Room) {
	url := fmt.Sprintf("http://localhost:9080/%s/users", room.Slug)
	resp, err := http.Get(url)
	if err != nil {
		log.Printf("Error fetching users: %v", err)
		return
	}
	defer resp.Body.Close()

	var userData UserData
	err = json.NewDecoder(resp.Body).Decode(&userData)
	if err != nil {
		log.Printf("Error decoding users: %v", err)
		return
	}

	room.UserMap.Mtx.Lock()
	room.UserMap.Users = userData.Users
	room.UserMap.MostRecentPost = userData.MostRecentPost
	room.UserMap.Mtx.Unlock()

	log.Printf("Fetched %d users (most recent post: %d)", len(userData.Users), userData.MostRecentPost)
}

// --- Old getVotes endpoint (kept for backward compat) ---

func getVotes(room *Room) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
			return
		}

		body, err := io.ReadAll(r.Body)
		if err != nil {
			log.Printf("Error reading request body: %v", err)
			http.Error(w, "Failed to read request", http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		var vote Vote
		err = json.Unmarshal(body, &vote)
		if err != nil {
			log.Printf("Error parsing vote: %v", err)
			http.Error(w, "Invalid vote format", http.StatusBadRequest)
			return
		}

		if vote.VoterDisplayName == "" {
			http.Error(w, "Voter display name is required", http.StatusBadRequest)
			return
		}
		if vote.SelectedSubmission == "" {
			http.Error(w, "Selected submission is required", http.StatusBadRequest)
			return
		}

		room.UserMap.Mtx.RLock()
		var userFound bool
		for _, user := range room.UserMap.Users {
			if user.DisplayName == vote.VoterDisplayName {
				userFound = true
				break
			}
		}
		room.UserMap.Mtx.RUnlock()

		if !userFound {
			log.Printf("Vote rejected: User '%s' not found in database", vote.VoterDisplayName)
			http.Error(w, "User not found. Please enter your Matrix display name exactly as it appears in the room.", http.StatusForbidden)
			return
		}

		vote.VoteTimestamp = time.Now().Unix()

		err = saveVote(room.DB, vote)
		if err != nil {
			log.Printf("Error saving vote: %v", err)
			http.Error(w, "Failed to save vote", http.StatusInternalServerError)
			return
		}

		log.Printf("Vote accepted (legacy): %s voted for '%s'", vote.VoterDisplayName, vote.SelectedSubmission)

		w.WriteHeader(http.StatusOK)
		w.Write([]byte("Vote recorded successfully"))
	}
}

// --- Nostr auth endpoints ---

func linkNpub(room *Room) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
			return
		}

		body, err := io.ReadAll(r.Body)
		if err != nil {
			http.Error(w, "Failed to read request", http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		var req SignedLinkRequest
		if err := json.Unmarshal(body, &req); err != nil {
			http.Error(w, "Invalid request format", http.StatusBadRequest)
			return
		}

		if req.DisplayName == "" {
			http.Error(w, "Display name is required", http.StatusBadRequest)
			return
		}

		npubHex, err := parsePubkey(req.Npub)
		if err != nil {
			http.Error(w, fmt.Sprintf("Invalid npub: %v", err), http.StatusBadRequest)
			return
		}

		evt, err := verifySignedEvent(req.SignedEvent, npubHex)
		if err != nil {
			http.Error(w, fmt.Sprintf("Signature verification failed: %v", err), http.StatusForbidden)
			return
		}

		expectedMsg := buildLinkMessage(npubHex, req.DisplayName, room.Slug)
		if evt.Content != expectedMsg {
			http.Error(w, "Signed message does not match expected linking message", http.StatusForbidden)
			return
		}

		// Check that the Matrix display name exists in the user database
		room.UserMap.Mtx.RLock()
		var userFound bool
		for _, user := range room.UserMap.Users {
			if user.DisplayName == req.DisplayName {
				userFound = true
				break
			}
		}
		room.UserMap.Mtx.RUnlock()

		if !userFound {
			http.Error(w, "Matrix display name not found in this room's user list", http.StatusForbidden)
			return
		}

		// Store the link
		_, err = room.DB.Exec(`
			INSERT OR REPLACE INTO nostr_links (npub_hex, display_name, linked_at)
			VALUES (?, ?, ?)
		`, npubHex, req.DisplayName, time.Now().Unix())
		if err != nil {
			log.Printf("Error storing npub link: %v", err)
			http.Error(w, "Failed to store link", http.StatusInternalServerError)
			return
		}

		log.Printf("Npub linked: %s -> Matrix user '%s'", npubHex[:16]+"...", req.DisplayName)
		w.WriteHeader(http.StatusOK)
		w.Write([]byte("Linked successfully"))
	}
}

func buildLinkMessage(npubHex, displayName, slug string) string {
	return fmt.Sprintf("Link npub %s to Matrix user %s for room %s", npubHex, displayName, slug)
}

func challenge(room *Room) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
			return
		}

		body, err := io.ReadAll(r.Body)
		if err != nil {
			http.Error(w, "Failed to read request", http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		var req ChallengeRequest
		if err := json.Unmarshal(body, &req); err != nil {
			http.Error(w, "Invalid request format", http.StatusBadRequest)
			return
		}

		npubHex, err := parsePubkey(req.Npub)
		if err != nil {
			http.Error(w, fmt.Sprintf("Invalid npub: %v", err), http.StatusBadRequest)
			return
		}

		// Check that this npub is linked
		var displayName string
		err = room.DB.QueryRow(`SELECT display_name FROM nostr_links WHERE npub_hex = ?`, npubHex).Scan(&displayName)
		if err == sql.ErrNoRows {
			http.Error(w, "Npub not linked. Please link your npub first.", http.StatusNotFound)
			return
		}
		if err != nil {
			http.Error(w, "Database error", http.StatusInternalServerError)
			return
		}

		// Generate challenge message (this is what the user will sign)
		now := time.Now().Unix()
		challengeMsg := fmt.Sprintf("Vote at %d in room %s", now, room.Slug)

		_, err = room.DB.Exec(`
			INSERT INTO nostr_challenges (npub_hex, challenge, created_at, expires_at)
			VALUES (?, ?, ?, ?)
		`, npubHex, challengeMsg, now, now+300) // 5 minute expiry
		if err != nil {
			log.Printf("Error storing challenge: %v", err)
			http.Error(w, "Failed to store challenge", http.StatusInternalServerError)
			return
		}

		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]string{
			"challenge":    challengeMsg,
			"display_name": displayName,
		})
	}
}

func verifyVote(room *Room) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
			return
		}

		body, err := io.ReadAll(r.Body)
		if err != nil {
			http.Error(w, "Failed to read request", http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		var req SignedVoteRequest
		if err := json.Unmarshal(body, &req); err != nil {
			http.Error(w, "Invalid request format", http.StatusBadRequest)
			return
		}

		if req.SelectedSubmission == "" {
			http.Error(w, "Selected submission is required", http.StatusBadRequest)
			return
		}

		npubHex, err := parsePubkey(req.Npub)
		if err != nil {
			http.Error(w, fmt.Sprintf("Invalid npub: %v", err), http.StatusBadRequest)
			return
		}

		// Verify the signed event
		evt, err := verifySignedEvent(req.SignedEvent, npubHex)
		if err != nil {
			http.Error(w, fmt.Sprintf("Signature verification failed: %v", err), http.StatusForbidden)
			return
		}

		// Look up the challenge and linked display name
		var displayName string
		err = room.DB.QueryRow(`
			SELECT display_name FROM nostr_links WHERE npub_hex = ?
		`, npubHex).Scan(&displayName)
		if err == sql.ErrNoRows {
			http.Error(w, "Npub not linked", http.StatusForbidden)
			return
		}
		if err != nil {
			http.Error(w, "Database error", http.StatusInternalServerError)
			return
		}

		// Verify the challenge exists, is unused, and hasn't expired
		var challengeCount int
		err = room.DB.QueryRow(`
			SELECT COUNT(*) FROM nostr_challenges
			WHERE npub_hex = ? AND challenge = ? AND used = 0 AND expires_at > ?
		`, npubHex, req.Challenge, time.Now().Unix()).Scan(&challengeCount)
		if err != nil || challengeCount == 0 {
			http.Error(w, "Invalid or expired challenge", http.StatusForbidden)
			return
		}

		// Verify the signed event content is the challenge message
		if evt.Content != req.Challenge {
			http.Error(w, "Signed message does not match the challenge", http.StatusForbidden)
			return
		}

		// Mark challenge as used
		_, err = room.DB.Exec(`
			UPDATE nostr_challenges SET used = 1
			WHERE npub_hex = ? AND challenge = ? AND used = 0
		`, npubHex, req.Challenge)
		if err != nil {
			log.Printf("Error marking challenge used: %v", err)
		}

		// Record the vote
		vote := Vote{
			VoterDisplayName:   displayName,
			SelectedSubmission: req.SelectedSubmission,
			Submitter:          req.Submitter,
			SubmissionTime:     req.SubmissionTime,
			VoteTimestamp:      time.Now().Unix(),
		}

		err = saveVote(room.DB, vote)
		if err != nil {
			log.Printf("Error saving vote: %v", err)
			http.Error(w, "Failed to save vote", http.StatusInternalServerError)
			return
		}

		log.Printf("Vote accepted: %s (npub %s...) voted for '%s'", displayName, npubHex[:16], req.SelectedSubmission)

		w.WriteHeader(http.StatusOK)
		w.Write([]byte("Vote recorded successfully"))
	}
}

func saveVote(db *sql.DB, vote Vote) error {
	_, err := db.Exec(`
		INSERT OR REPLACE INTO votes (
			voter_display_name,
			selected_submission,
			submitter,
			submission_time,
			vote_timestamp
		) VALUES (?, ?, ?, ?, ?)
	`, vote.VoterDisplayName, vote.SelectedSubmission, vote.Submitter, vote.SubmissionTime, vote.VoteTimestamp)

	if err != nil {
		return fmt.Errorf("failed to save vote: %w", err)
	}

	return nil
}