Add "network delete" service command

And add all the infrastructure required to stop and delete networks.

References: https://todo.sr.ht/~emersion/soju/17

db.go

@@ -215,6 +215,29 @@ func (db *DB) StoreNetwork(username string, network *Network) error {
 	return err
 }
 
+func (db *DB) DeleteNetwork(id int64) error {
+	db.lock.Lock()
+	defer db.lock.Unlock()
+
+	tx, err := db.db.Begin()
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback()
+
+	_, err = tx.Exec("DELETE FROM Network WHERE id = ?", id)
+	if err != nil {
+		return err
+	}
+
+	_, err = tx.Exec("DELETE FROM Channel WHERE network = ?", id)
+	if err != nil {
+		return err
+	}
+
+	return tx.Commit()
+}
+
 func (db *DB) ListChannels(networkID int64) ([]Channel, error) {
 	db.lock.RLock()
 	defer db.lock.RUnlock()

service.go

@@ -97,6 +97,11 @@ func init() {
 					desc:   "show a list of saved networks and their current status",
 					handle: handleServiceNetworkStatus,
 				},
+				"delete": {
+					usage:  "<name>",
+					desc:   "delete a network",
+					handle: handleServiceNetworkDelete,
+				},
 			},
 		},
 	}
@@ -143,9 +148,14 @@ func handleServiceHelp(dc *downstreamConn, params []string) error {
 	return nil
 }
 
-func handleServiceCreateNetwork(dc *downstreamConn, params []string) error {
+func newFlagSet() *flag.FlagSet {
 	fs := flag.NewFlagSet("", flag.ContinueOnError)
 	fs.SetOutput(ioutil.Discard)
+	return fs
+}
+
+func handleServiceCreateNetwork(dc *downstreamConn, params []string) error {
+	fs := newFlagSet()
 	addr := fs.String("addr", "", "")
 	name := fs.String("name", "", "")
 	username := fs.String("username", "", "")
@@ -177,7 +187,7 @@ func handleServiceCreateNetwork(dc *downstreamConn, params []string) error {
 		return fmt.Errorf("could not create network: %v", err)
 	}
 
-	sendServicePRIVMSG(dc, fmt.Sprintf("created network %s successfully", network.GetName()))
+	sendServicePRIVMSG(dc, fmt.Sprintf("created network %q", network.GetName()))
 	return nil
 }
 
@@ -204,3 +214,21 @@ func handleServiceNetworkStatus(dc *downstreamConn, params []string) error {
 	})
 	return nil
 }
+
+func handleServiceNetworkDelete(dc *downstreamConn, params []string) error {
+	if len(params) != 1 {
+		return fmt.Errorf("expected exactly one argument")
+	}
+
+	net := dc.user.getNetwork(params[0])
+	if net == nil {
+		return fmt.Errorf("unknown network %q", params[0])
+	}
+
+	if err := dc.user.deleteNetwork(net.ID); err != nil {
+		return err
+	}
+
+	sendServicePRIVMSG(dc, fmt.Sprintf("deleted network %q", net.GetName()))
+	return nil
+}

user.go

@@ -39,6 +39,7 @@ type network struct {
 	Network
 	user    *user
 	ring    *Ring
+	stopped chan struct{}
 
 	lock    sync.Mutex
 	conn    *upstreamConn
@@ -50,6 +51,7 @@ func newNetwork(user *user, record *Network) *network {
 		Network: *record,
 		user:    user,
 		ring:    NewRing(user.srv.RingCap),
+		stopped: make(chan struct{}),
 		history: make(map[string]uint64),
 	}
 }
@@ -57,6 +59,13 @@ func newNetwork(user *user, record *Network) *network {
 func (net *network) run() {
 	var lastTry time.Time
 	for {
+		select {
+		case <-net.stopped:
+			return
+		default:
+			// This space is intentionally left blank
+		}
+
 		if dur := time.Now().Sub(lastTry); dur < retryConnectMinDelay {
 			delay := retryConnectMinDelay - dur
 			net.user.srv.Logger.Printf("waiting %v before trying to reconnect to %q", delay.Truncate(time.Second), net.Addr)
@@ -92,6 +101,19 @@ func (net *network) upstream() *upstreamConn {
 	return net.conn
 }
 
+func (net *network) Stop() {
+	select {
+	case <-net.stopped:
+		return
+	default:
+		close(net.stopped)
+	}
+
+	if uc := net.upstream(); uc != nil {
+		uc.Close()
+	}
+}
+
 type user struct {
 	User
 	srv *Server
@@ -265,3 +287,27 @@ func (u *user) createNetwork(net *Network) (*network, error) {
 	go network.run()
 	return network, nil
 }
+
+func (u *user) deleteNetwork(id int64) error {
+	for i, net := range u.networks {
+		if net.ID != id {
+			continue
+		}
+
+		if err := u.srv.db.DeleteNetwork(net.ID); err != nil {
+			return err
+		}
+
+		u.forEachDownstream(func(dc *downstreamConn) {
+			if dc.network != nil && dc.network == net {
+				dc.Close()
+			}
+		})
+
+		net.Stop()
+		u.networks = append(u.networks[:i], u.networks[i+1:]...)
+		return nil
+	}
+
+	panic("tried deleting a non-existing network")
+}