refactor: shared service layer, default IRC port, smaller functions

Wire up service.Service in HTTP handlers and delegate cleanupUser to
svc.BroadcastQuit for consistent quit/part logic across transports.
Default IRC_LISTEN_ADDR to :6667, remove unused import, fix all lint
issues (dogsled, funcorder, wrapcheck, varnamelen, nolintlint).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/ircserver/conn.go

@@ -3,7 +3,6 @@ package ircserver
 import (
 	"bufio"
 	"context"
-	"encoding/json"
 	"fmt"
 	"log/slog"
 	"net"
@@ -15,6 +14,7 @@ import (
 	"git.eeqj.de/sneak/neoirc/internal/broker"
 	"git.eeqj.de/sneak/neoirc/internal/config"
 	"git.eeqj.de/sneak/neoirc/internal/db"
+	"git.eeqj.de/sneak/neoirc/internal/service"
 	"git.eeqj.de/sneak/neoirc/pkg/irc"
 )
 
@@ -30,6 +30,10 @@ const (
 	minPasswordLen = 8
 )
 
+// cmdHandler is the signature for registered IRC command
+// handlers.
+type cmdHandler func(ctx context.Context, msg *Message)
+
 // Conn represents a single IRC client TCP connection.
 type Conn struct {
 	conn      net.Conn
@@ -37,7 +41,9 @@ type Conn struct {
 	database  *db.Database
 	brk       *broker.Broker
 	cfg       *config.Config
+	svc       *service.Service
 	serverSfx string
+	commands  map[string]cmdHandler
 
 	mu        sync.Mutex
 	nick      string
@@ -65,6 +71,7 @@ func newConn(
 	database *db.Database,
 	brk *broker.Broker,
 	cfg *config.Config,
+	svc *service.Service,
 ) *Conn {
 	host, _, _ := net.SplitHostPort(tcpConn.RemoteAddr().String())
 
@@ -73,16 +80,57 @@ func newConn(
 		srvName = "neoirc"
 	}
 
-	return &Conn{ //nolint:exhaustruct // zero-value defaults
+	conn := &Conn{ //nolint:exhaustruct // zero-value defaults
 		conn:      tcpConn,
 		log:       log,
 		database:  database,
 		brk:       brk,
 		cfg:       cfg,
+		svc:       svc,
 		serverSfx: srvName,
 		remoteIP:  host,
 		hostname:  resolveHost(ctx, host),
 	}
+
+	conn.commands = conn.buildCommandMap()
+
+	return conn
+}
+
+// buildCommandMap returns a map from IRC command strings
+// to handler functions.
+func (c *Conn) buildCommandMap() map[string]cmdHandler {
+	return map[string]cmdHandler{
+		irc.CmdPing: func(_ context.Context, msg *Message) {
+			c.handlePing(msg)
+		},
+		"PONG":         func(context.Context, *Message) {},
+		irc.CmdNick:    c.handleNick,
+		irc.CmdPrivmsg: c.handlePrivmsg,
+		irc.CmdNotice:  c.handlePrivmsg,
+		irc.CmdJoin:    c.handleJoin,
+		irc.CmdPart:    c.handlePart,
+		irc.CmdQuit: func(_ context.Context, msg *Message) {
+			c.handleQuit(msg)
+		},
+		irc.CmdTopic:  c.handleTopic,
+		irc.CmdMode:   c.handleMode,
+		irc.CmdNames:  c.handleNames,
+		irc.CmdList:   func(ctx context.Context, _ *Message) { c.handleList(ctx) },
+		irc.CmdWhois:  c.handleWhois,
+		irc.CmdWho:    c.handleWho,
+		irc.CmdLusers: func(ctx context.Context, _ *Message) { c.handleLusers(ctx) },
+		irc.CmdMotd:   func(context.Context, *Message) { c.deliverMOTD() },
+		irc.CmdOper:   c.handleOper,
+		irc.CmdAway:   c.handleAway,
+		irc.CmdKick:   c.handleKick,
+		irc.CmdPass:   c.handlePassPostReg,
+		"INVITE":      c.handleInvite,
+		"CAP": func(_ context.Context, msg *Message) {
+			c.handleCAP(msg)
+		},
+		"USERHOST": c.handleUserhost,
+	}
 }
 
 // resolveHost does a reverse DNS lookup, returning the IP
@@ -145,71 +193,14 @@ func (c *Conn) cleanup(ctx context.Context) {
 	c.mu.Unlock()
 
 	if wasRegistered && sessID > 0 {
-		c.broadcastQuit(ctx, nick, "Connection closed")
-		c.database.DeleteSession(ctx, sessID) //nolint:errcheck,gosec
+		c.svc.BroadcastQuit(
+			ctx, sessID, nick, "Connection closed",
+		)
 	}
 
 	c.conn.Close() //nolint:errcheck,gosec
 }
 
-func (c *Conn) broadcastQuit(
-	ctx context.Context,
-	nick, reason string,
-) {
-	channels, err := c.database.GetSessionChannels(
-		ctx, c.sessionID,
-	)
-	if err != nil {
-		return
-	}
-
-	notified := make(map[int64]bool)
-
-	for _, ch := range channels {
-		chID, getErr := c.database.GetChannelByName(
-			ctx, ch.Name,
-		)
-		if getErr != nil {
-			continue
-		}
-
-		memberIDs, memErr := c.database.GetChannelMemberIDs(
-			ctx, chID,
-		)
-		if memErr != nil {
-			continue
-		}
-
-		for _, mid := range memberIDs {
-			if mid == c.sessionID || notified[mid] {
-				continue
-			}
-
-			notified[mid] = true
-		}
-	}
-
-	body, _ := json.Marshal([]string{reason}) //nolint:errchkjson
-
-	for sid := range notified {
-		dbID, _, insErr := c.database.InsertMessage(
-			ctx, irc.CmdQuit, nick, "", nil, body, nil,
-		)
-		if insErr != nil {
-			continue
-		}
-
-		_ = c.database.EnqueueToSession(ctx, sid, dbID)
-		c.brk.Notify(sid)
-	}
-
-	// Part from all channels so they get cleaned up.
-	for _, ch := range channels {
-		c.database.PartChannel(ctx, ch.ID, c.sessionID) //nolint:errcheck,gosec
-		c.database.DeleteChannelIfEmpty(ctx, ch.ID)     //nolint:errcheck,gosec
-	}
-}
-
 // send writes a formatted IRC line to the connection.
 func (c *Conn) send(line string) {
 	_ = c.conn.SetWriteDeadline(
@@ -261,9 +252,8 @@ func (c *Conn) hostmask() string {
 	return c.nick + "!" + user + "@" + host
 }
 
-// handleMessage dispatches a parsed IRC message.
-//
-//nolint:cyclop // dispatch table is inherently branchy
+// handleMessage dispatches a parsed IRC message using
+// the command handler map.
 func (c *Conn) handleMessage(
 	ctx context.Context,
 	msg *Message,
@@ -276,57 +266,17 @@ func (c *Conn) handleMessage(
 		return
 	}
 
-	switch msg.Command {
-	case irc.CmdPing:
-		c.handlePing(msg)
-	case "PONG":
-		// Silently accept.
-	case irc.CmdNick:
-		c.handleNick(ctx, msg)
-	case irc.CmdPrivmsg, irc.CmdNotice:
-		c.handlePrivmsg(ctx, msg)
-	case irc.CmdJoin:
-		c.handleJoin(ctx, msg)
-	case irc.CmdPart:
-		c.handlePart(ctx, msg)
-	case irc.CmdQuit:
-		c.handleQuit(msg)
-	case irc.CmdTopic:
-		c.handleTopic(ctx, msg)
-	case irc.CmdMode:
-		c.handleMode(ctx, msg)
-	case irc.CmdNames:
-		c.handleNames(ctx, msg)
-	case irc.CmdList:
-		c.handleList(ctx)
-	case irc.CmdWhois:
-		c.handleWhois(ctx, msg)
-	case irc.CmdWho:
-		c.handleWho(ctx, msg)
-	case irc.CmdLusers:
-		c.handleLusers(ctx)
-	case irc.CmdMotd:
-		c.deliverMOTD()
-	case irc.CmdOper:
-		c.handleOper(ctx, msg)
-	case irc.CmdAway:
-		c.handleAway(ctx, msg)
-	case irc.CmdKick:
-		c.handleKick(ctx, msg)
-	case irc.CmdPass:
-		c.handlePassPostReg(ctx, msg)
-	case "INVITE":
-		c.handleInvite(ctx, msg)
-	case "CAP":
-		c.handleCAP(msg)
-	case "USERHOST":
-		c.handleUserhost(ctx, msg)
-	default:
+	handler, ok := c.commands[msg.Command]
+	if !ok {
 		c.sendNumeric(
 			irc.ErrUnknownCommand,
 			msg.Command, "Unknown command",
 		)
+
+		return
 	}
+
+	handler(ctx, msg)
 }
 
 // handlePreRegistration handles messages before the