Huge refactor to have everything working with socket.io

It fixes lots of bugs, can fallback to long polling, resize viewport of
terminals and share clients state of the session, so they all see the
same thing.

services/client.go

@@ -0,0 +1,60 @@
+package services
+
+import "github.com/googollee/go-socket.io"
+
+type ViewPort struct {
+	Rows uint
+	Cols uint
+}
+
+type Client struct {
+	SO       socketio.Socket
+	ViewPort ViewPort
+}
+
+func (c *Client) ResizeViewPort(cols, rows uint) {
+	c.ViewPort.Rows = rows
+	c.ViewPort.Cols = cols
+}
+
+func NewClient(so socketio.Socket, session *Session) *Client {
+	so.Join(session.Id)
+
+	c := &Client{SO: so}
+
+	so.On("terminal in", func(name, data string) {
+		// User wrote something on the terminal. Need to write it to the instance terminal
+		instance := GetInstance(session, name)
+		if len(data) > 0 {
+			instance.Conn.Conn.Write([]byte(data))
+		}
+	})
+
+	so.On("viewport resize", func(cols, rows uint) {
+		// User resized his viewport
+		c.ResizeViewPort(cols, rows)
+		vp := session.GetSmallestViewPort()
+		// Resize all terminals in the session
+		wsServer.BroadcastTo(session.Id, "viewport resize", vp.Cols, vp.Rows)
+		for _, instance := range session.Instances {
+			instance.ResizeTerminal(vp.Cols, vp.Rows)
+		}
+	})
+	so.On("disconnection", func() {
+		// Client has disconnected. Remove from session and recheck terminal sizes.
+		for i, cl := range session.Clients {
+			if cl.SO.Id() == c.SO.Id() {
+				session.Clients = append(session.Clients[:i], session.Clients[i+1:]...)
+				break
+			}
+		}
+		vp := session.GetSmallestViewPort()
+		// Resize all terminals in the session
+		wsServer.BroadcastTo(session.Id, "viewport resize", vp.Cols, vp.Rows)
+		for _, instance := range session.Instances {
+			instance.ResizeTerminal(vp.Cols, vp.Rows)
+		}
+	})
+
+	return c
+}