Error handling. Vendoring

Signed-off-by: Ettore Dreucci <ettore.dreucci@gmail.com>

vendor/gopkg.in/tucnak/telebot.v2/poller.go

@@ -0,0 +1,106 @@
+package telebot
+
+import (
+	"time"
+
+	"github.com/pkg/errors"
+)
+
+var (
+	ErrCouldNotUpdate = errors.New("getUpdates() failed")
+)
+
+// Poller is a provider of Updates.
+//
+// All pollers must implement Poll(), which accepts bot
+// pointer and subscription channel and start polling
+// synchronously straight away.
+type Poller interface {
+	// Poll is supposed to take the bot object
+	// subscription channel and start polling
+	// for Updates immediately.
+	//
+	// Poller must listen for stop constantly and close
+	// it as soon as it's done polling.
+	Poll(b *Bot, updates chan Update, stop chan struct{})
+}
+
+// MiddlewarePoller is a special kind of poller that acts
+// like a filter for updates. It could be used for spam
+// handling, banning or whatever.
+//
+// For heavy middleware, use increased capacity.
+//
+type MiddlewarePoller struct {
+	Capacity int // Default: 1
+	Poller   Poller
+	Filter   func(*Update) bool
+}
+
+// NewMiddlewarePoller wait for it... constructs a new middleware poller.
+func NewMiddlewarePoller(original Poller, filter func(*Update) bool) *MiddlewarePoller {
+	return &MiddlewarePoller{
+		Poller: original,
+		Filter: filter,
+	}
+}
+
+// Poll sieves updates through middleware filter.
+func (p *MiddlewarePoller) Poll(b *Bot, dest chan Update, stop chan struct{}) {
+	cap := 1
+	if p.Capacity > 1 {
+		cap = p.Capacity
+	}
+
+	middle := make(chan Update, cap)
+	stopPoller := make(chan struct{})
+
+	go p.Poller.Poll(b, middle, stopPoller)
+
+	for {
+		select {
+		// call to stop
+		case <-stop:
+			stopPoller <- struct{}{}
+
+		// poller is done
+		case <-stopPoller:
+			close(stop)
+			return
+
+		case upd := <-middle:
+			if p.Filter(&upd) {
+				dest <- upd
+			}
+		}
+	}
+}
+
+// LongPoller is a classic LongPoller with timeout.
+type LongPoller struct {
+	Timeout time.Duration
+
+	LastUpdateID int
+}
+
+// Poll does long polling.
+func (p *LongPoller) Poll(b *Bot, dest chan Update, stop chan struct{}) {
+	go func(stop chan struct{}) {
+		<-stop
+		close(stop)
+	}(stop)
+
+	for {
+		updates, err := b.getUpdates(p.LastUpdateID+1, p.Timeout)
+
+		if err != nil {
+			b.debug(ErrCouldNotUpdate)
+			continue
+		}
+
+		for _, update := range updates {
+			p.LastUpdateID = update.ID
+			dest <- update
+		}
+	}
+}