fix: revert .golangci.yml to main, fix all lint issues in code

- Restore original .golangci.yml from main (no linter config changes)
- Reduce complexity in dispatchCommand via command map pattern
- Extract helpers in api.go: respondError, internalError, normalizeChannel,
  handleCreateUserError, handleChangeNickError, partAndCleanup, broadcastTopic
- Split PollMessages into buildPollPath + decodePollResponse
- Add t.Parallel() to all tests, make subtests independent
- Extract test fx providers into named functions to reduce funlen
- Use mutex to serialize viper access in parallel tests
- Extract PRIVMSG constant, add nolint for gosec false positives
- Split long test functions into focused test cases
- Add blank lines before expressions per wsl_v5

internal/handlers/api.go

@@ -49,8 +49,8 @@ func (s *Handlers) requireAuth(
 ) (int64, string, bool) {
 	uid, nick, err := s.authUser(r)
 	if err != nil {
-		s.respondJSON(w, r,
-			map[string]string{"error": "unauthorized"},
+		s.respondError(w, r,
+			"unauthorized",
 			http.StatusUnauthorized)
 
 		return 0, "", false
@@ -120,10 +120,8 @@ func (s *Handlers) HandleCreateSession() http.HandlerFunc {
 
 		err := json.NewDecoder(r.Body).Decode(&req)
 		if err != nil {
-			s.respondJSON(w, r,
-				map[string]string{
-					"error": "invalid request body",
-				},
+			s.respondError(w, r,
+				"invalid request body",
 				http.StatusBadRequest)
 
 			return
@@ -132,10 +130,8 @@ func (s *Handlers) HandleCreateSession() http.HandlerFunc {
 		req.Nick = strings.TrimSpace(req.Nick)
 
 		if !validNickRe.MatchString(req.Nick) {
-			s.respondJSON(w, r,
-				map[string]string{
-					"error": "invalid nick format",
-				},
+			s.respondError(w, r,
+				"invalid nick format",
 				http.StatusBadRequest)
 
 			return
@@ -145,21 +141,7 @@ func (s *Handlers) HandleCreateSession() http.HandlerFunc {
 			r.Context(), req.Nick,
 		)
 		if err != nil {
-			if strings.Contains(err.Error(), "UNIQUE") {
-				s.respondJSON(w, r,
-					map[string]string{
-						"error": "nick already taken",
-					},
-					http.StatusConflict)
-
-				return
-			}
-
-			s.log.Error("create user failed", "error", err)
-
-			s.respondJSON(w, r,
-				map[string]string{"error": "internal error"},
-				http.StatusInternalServerError)
+			s.handleCreateUserError(w, r, err)
 
 			return
 		}
@@ -170,6 +152,36 @@ func (s *Handlers) HandleCreateSession() http.HandlerFunc {
 	}
 }
 
+func (s *Handlers) respondError(
+	w http.ResponseWriter,
+	r *http.Request,
+	msg string,
+	code int,
+) {
+	s.respondJSON(w, r,
+		map[string]string{"error": msg}, code)
+}
+
+func (s *Handlers) handleCreateUserError(
+	w http.ResponseWriter,
+	r *http.Request,
+	err error,
+) {
+	if strings.Contains(err.Error(), "UNIQUE") {
+		s.respondError(w, r,
+			"nick already taken",
+			http.StatusConflict)
+
+		return
+	}
+
+	s.log.Error("create user failed", "error", err)
+
+	s.respondError(w, r,
+		"internal error",
+		http.StatusInternalServerError)
+}
+
 // HandleState returns the current user's info and channels.
 func (s *Handlers) HandleState() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
@@ -184,8 +196,8 @@ func (s *Handlers) HandleState() http.HandlerFunc {
 		if err != nil {
 			s.log.Error("list channels failed", "error", err)
 
-			s.respondJSON(w, r,
-				map[string]string{"error": "internal error"},
+			s.respondError(w, r,
+				"internal error",
 				http.StatusInternalServerError)
 
 			return
@@ -215,8 +227,8 @@ func (s *Handlers) HandleListAllChannels() http.HandlerFunc {
 				"list all channels failed", "error", err,
 			)
 
-			s.respondJSON(w, r,
-				map[string]string{"error": "internal error"},
+			s.respondError(w, r,
+				"internal error",
 				http.StatusInternalServerError)
 
 			return
@@ -240,10 +252,8 @@ func (s *Handlers) HandleChannelMembers() http.HandlerFunc {
 			r.Context(), name,
 		)
 		if err != nil {
-			s.respondJSON(w, r,
-				map[string]string{
-					"error": "channel not found",
-				},
+			s.respondError(w, r,
+				"channel not found",
 				http.StatusNotFound)
 
 			return
@@ -257,8 +267,8 @@ func (s *Handlers) HandleChannelMembers() http.HandlerFunc {
 				"channel members failed", "error", err,
 			)
 
-			s.respondJSON(w, r,
-				map[string]string{"error": "internal error"},
+			s.respondError(w, r,
+				"internal error",
 				http.StatusInternalServerError)
 
 			return
@@ -299,8 +309,8 @@ func (s *Handlers) HandleGetMessages() http.HandlerFunc {
 				"poll messages failed", "error", err,
 			)
 
-			s.respondJSON(w, r,
-				map[string]string{"error": "internal error"},
+			s.respondError(w, r,
+				"internal error",
 				http.StatusInternalServerError)
 
 			return
@@ -350,8 +360,8 @@ func (s *Handlers) longPoll(
 	if err != nil {
 		s.log.Error("poll messages failed", "error", err)
 
-		s.respondJSON(w, r,
-			map[string]string{"error": "internal error"},
+		s.respondError(w, r,
+			"internal error",
 			http.StatusInternalServerError)
 
 		return
@@ -382,10 +392,8 @@ func (s *Handlers) HandleSendCommand() http.HandlerFunc {
 
 		err := json.NewDecoder(r.Body).Decode(&req)
 		if err != nil {
-			s.respondJSON(w, r,
-				map[string]string{
-					"error": "invalid request body",
-				},
+			s.respondError(w, r,
+				"invalid request body",
 				http.StatusBadRequest)
 
 			return
@@ -397,10 +405,8 @@ func (s *Handlers) HandleSendCommand() http.HandlerFunc {
 		req.To = strings.TrimSpace(req.To)
 
 		if req.Command == "" {
-			s.respondJSON(w, r,
-				map[string]string{
-					"error": "command required",
-				},
+			s.respondError(w, r,
+				"command required",
 				http.StatusBadRequest)
 
 			return
@@ -476,8 +482,8 @@ func (s *Handlers) handlePrivmsg(
 	bodyLines func() []string,
 ) {
 	if to == "" {
-		s.respondJSON(w, r,
-			map[string]string{"error": "to field required"},
+		s.respondError(w, r,
+			"to field required",
 			http.StatusBadRequest)
 
 		return
@@ -485,8 +491,8 @@ func (s *Handlers) handlePrivmsg(
 
 	lines := bodyLines()
 	if len(lines) == 0 {
-		s.respondJSON(w, r,
-			map[string]string{"error": "body required"},
+		s.respondError(w, r,
+			"body required",
 			http.StatusBadRequest)
 
 		return
@@ -514,8 +520,8 @@ func (s *Handlers) handleChannelMsg(
 		r.Context(), to,
 	)
 	if err != nil {
-		s.respondJSON(w, r,
-			map[string]string{"error": "channel not found"},
+		s.respondError(w, r,
+			"channel not found",
 			http.StatusNotFound)
 
 		return
@@ -529,8 +535,8 @@ func (s *Handlers) handleChannelMsg(
 			"get channel members failed", "error", err,
 		)
 
-		s.respondJSON(w, r,
-			map[string]string{"error": "internal error"},
+		s.respondError(w, r,
+			"internal error",
 			http.StatusInternalServerError)
 
 		return
@@ -542,8 +548,8 @@ func (s *Handlers) handleChannelMsg(
 	if err != nil {
 		s.log.Error("send message failed", "error", err)
 
-		s.respondJSON(w, r,
-			map[string]string{"error": "internal error"},
+		s.respondError(w, r,
+			"internal error",
 			http.StatusInternalServerError)
 
 		return
@@ -565,8 +571,8 @@ func (s *Handlers) handleDirectMsg(
 		r.Context(), to,
 	)
 	if err != nil {
-		s.respondJSON(w, r,
-			map[string]string{"error": "user not found"},
+		s.respondError(w, r,
+			"user not found",
 			http.StatusNotFound)
 
 		return
@@ -583,8 +589,8 @@ func (s *Handlers) handleDirectMsg(
 	if err != nil {
 		s.log.Error("send dm failed", "error", err)
 
-		s.respondJSON(w, r,
-			map[string]string{"error": "internal error"},
+		s.respondError(w, r,
+			"internal error",
 			http.StatusInternalServerError)
 
 		return
@@ -595,6 +601,27 @@ func (s *Handlers) handleDirectMsg(
 		http.StatusCreated)
 }
 
+func normalizeChannel(name string) string {
+	if !strings.HasPrefix(name, "#") {
+		return "#" + name
+	}
+
+	return name
+}
+
+func (s *Handlers) internalError(
+	w http.ResponseWriter,
+	r *http.Request,
+	msg string,
+	err error,
+) {
+	s.log.Error(msg, "error", err)
+
+	s.respondError(w, r,
+		"internal error",
+		http.StatusInternalServerError)
+}
+
 func (s *Handlers) handleJoin(
 	w http.ResponseWriter,
 	r *http.Request,
@@ -602,23 +629,18 @@ func (s *Handlers) handleJoin(
 	nick, to string,
 ) {
 	if to == "" {
-		s.respondJSON(w, r,
-			map[string]string{"error": "to field required"},
+		s.respondError(w, r,
+			"to field required",
 			http.StatusBadRequest)
 
 		return
 	}
 
-	channel := to
-	if !strings.HasPrefix(channel, "#") {
-		channel = "#" + channel
-	}
+	channel := normalizeChannel(to)
 
 	if !validChannelRe.MatchString(channel) {
-		s.respondJSON(w, r,
-			map[string]string{
-				"error": "invalid channel name",
-			},
+		s.respondError(w, r,
+			"invalid channel name",
 			http.StatusBadRequest)
 
 		return
@@ -628,13 +650,8 @@ func (s *Handlers) handleJoin(
 		r.Context(), channel,
 	)
 	if err != nil {
-		s.log.Error(
-			"get/create channel failed", "error", err,
-		)
-
-		s.respondJSON(w, r,
-			map[string]string{"error": "internal error"},
-			http.StatusInternalServerError)
+		s.internalError(w, r,
+			"get/create channel failed", err)
 
 		return
 	}
@@ -643,11 +660,8 @@ func (s *Handlers) handleJoin(
 		r.Context(), chID, uid,
 	)
 	if err != nil {
-		s.log.Error("join channel failed", "error", err)
-
-		s.respondJSON(w, r,
-			map[string]string{"error": "internal error"},
-			http.StatusInternalServerError)
+		s.internalError(w, r,
+			"join channel failed", err)
 
 		return
 	}
@@ -676,31 +690,36 @@ func (s *Handlers) handlePart(
 	body json.RawMessage,
 ) {
 	if to == "" {
-		s.respondJSON(w, r,
-			map[string]string{"error": "to field required"},
+		s.respondError(w, r,
+			"to field required",
 			http.StatusBadRequest)
 
 		return
 	}
 
-	channel := to
-	if !strings.HasPrefix(channel, "#") {
-		channel = "#" + channel
-	}
+	channel := normalizeChannel(to)
 
 	chID, err := s.params.Database.GetChannelByName(
 		r.Context(), channel,
 	)
 	if err != nil {
-		s.respondJSON(w, r,
-			map[string]string{
-				"error": "channel not found",
-			},
+		s.respondError(w, r,
+			"channel not found",
 			http.StatusNotFound)
 
 		return
 	}
 
+	s.partAndCleanup(w, r, chID, uid, nick, channel, body)
+}
+
+func (s *Handlers) partAndCleanup(
+	w http.ResponseWriter,
+	r *http.Request,
+	chID, uid int64,
+	nick, channel string,
+	body json.RawMessage,
+) {
 	memberIDs, _ := s.params.Database.GetChannelMemberIDs(
 		r.Context(), chID,
 	)
@@ -709,15 +728,12 @@ func (s *Handlers) handlePart(
 		r, "PART", nick, channel, body, memberIDs,
 	)
 
-	err = s.params.Database.PartChannel(
+	err := s.params.Database.PartChannel(
 		r.Context(), chID, uid,
 	)
 	if err != nil {
-		s.log.Error("part channel failed", "error", err)
-
-		s.respondJSON(w, r,
-			map[string]string{"error": "internal error"},
-			http.StatusInternalServerError)
+		s.internalError(w, r,
+			"part channel failed", err)
 
 		return
 	}
@@ -743,10 +759,8 @@ func (s *Handlers) handleNick(
 ) {
 	lines := bodyLines()
 	if len(lines) == 0 {
-		s.respondJSON(w, r,
-			map[string]string{
-				"error": "body required (new nick)",
-			},
+		s.respondError(w, r,
+			"body required (new nick)",
 			http.StatusBadRequest)
 
 		return
@@ -755,8 +769,8 @@ func (s *Handlers) handleNick(
 	newNick := strings.TrimSpace(lines[0])
 
 	if !validNickRe.MatchString(newNick) {
-		s.respondJSON(w, r,
-			map[string]string{"error": "invalid nick"},
+		s.respondError(w, r,
+			"invalid nick",
 			http.StatusBadRequest)
 
 		return
@@ -776,21 +790,7 @@ func (s *Handlers) handleNick(
 		r.Context(), uid, newNick,
 	)
 	if err != nil {
-		if strings.Contains(err.Error(), "UNIQUE") {
-			s.respondJSON(w, r,
-				map[string]string{
-					"error": "nick already in use",
-				},
-				http.StatusConflict)
-
-			return
-		}
-
-		s.log.Error("change nick failed", "error", err)
-
-		s.respondJSON(w, r,
-			map[string]string{"error": "internal error"},
-			http.StatusInternalServerError)
+		s.handleChangeNickError(w, r, err)
 
 		return
 	}
@@ -804,6 +804,22 @@ func (s *Handlers) handleNick(
 		http.StatusOK)
 }
 
+func (s *Handlers) handleChangeNickError(
+	w http.ResponseWriter,
+	r *http.Request,
+	err error,
+) {
+	if strings.Contains(err.Error(), "UNIQUE") {
+		s.respondError(w, r,
+			"nick already in use",
+			http.StatusConflict)
+
+		return
+	}
+
+	s.internalError(w, r, "change nick failed", err)
+}
+
 func (s *Handlers) broadcastNick(
 	r *http.Request,
 	uid int64,
@@ -858,8 +874,8 @@ func (s *Handlers) handleTopic(
 	bodyLines func() []string,
 ) {
 	if to == "" {
-		s.respondJSON(w, r,
-			map[string]string{"error": "to field required"},
+		s.respondError(w, r,
+			"to field required",
 			http.StatusBadRequest)
 
 		return
@@ -867,43 +883,40 @@ func (s *Handlers) handleTopic(
 
 	lines := bodyLines()
 	if len(lines) == 0 {
-		s.respondJSON(w, r,
-			map[string]string{
-				"error": "body required (topic text)",
-			},
+		s.respondError(w, r,
+			"body required (topic text)",
 			http.StatusBadRequest)
 
 		return
 	}
 
 	topic := strings.Join(lines, " ")
-
-	channel := to
-	if !strings.HasPrefix(channel, "#") {
-		channel = "#" + channel
-	}
+	channel := normalizeChannel(to)
 
 	err := s.params.Database.SetTopic(
 		r.Context(), channel, topic,
 	)
 	if err != nil {
-		s.log.Error("set topic failed", "error", err)
-
-		s.respondJSON(w, r,
-			map[string]string{"error": "internal error"},
-			http.StatusInternalServerError)
+		s.internalError(w, r, "set topic failed", err)
 
 		return
 	}
 
+	s.broadcastTopic(w, r, nick, channel, topic, body)
+}
+
+func (s *Handlers) broadcastTopic(
+	w http.ResponseWriter,
+	r *http.Request,
+	nick, channel, topic string,
+	body json.RawMessage,
+) {
 	chID, err := s.params.Database.GetChannelByName(
 		r.Context(), channel,
 	)
 	if err != nil {
-		s.respondJSON(w, r,
-			map[string]string{
-				"error": "channel not found",
-			},
+		s.respondError(w, r,
+			"channel not found",
 			http.StatusNotFound)
 
 		return
@@ -991,10 +1004,8 @@ func (s *Handlers) HandleGetHistory() http.HandlerFunc {
 
 		target := r.URL.Query().Get("target")
 		if target == "" {
-			s.respondJSON(w, r,
-				map[string]string{
-					"error": "target required",
-				},
+			s.respondError(w, r,
+				"target required",
 				http.StatusBadRequest)
 
 			return
@@ -1019,8 +1030,8 @@ func (s *Handlers) HandleGetHistory() http.HandlerFunc {
 				"get history failed", "error", err,
 			)
 
-			s.respondJSON(w, r,
-				map[string]string{"error": "internal error"},
+			s.respondError(w, r,
+				"internal error",
 				http.StatusInternalServerError)
 
 			return