Count the lines from the terminal, not from ACI

Count the number of lines output on the terminal wrt the terminal width
so that we can go up the right amount.

azure/aci.go

@@ -27,6 +27,7 @@ import (
 	"github.com/Azure/azure-sdk-for-go/services/containerinstance/mgmt/2018-10-01/containerinstance"
 	"github.com/Azure/go-autorest/autorest"
 	"github.com/Azure/go-autorest/autorest/to"
+	"github.com/buger/goterm"
 	tm "github.com/buger/goterm"
 	"github.com/gobwas/ws"
 	"github.com/gobwas/ws/wsutil"
@@ -242,7 +243,8 @@ func getACIContainerLogs(ctx context.Context, aciContext store.AciContext, conta
 }
 
 func streamLogs(ctx context.Context, aciContext store.AciContext, containerGroupName, containerName string, out io.Writer) error {
-	lastOutput := 0
+	terminalWidth := goterm.Width()
+	numLines := 0
 	for {
 		select {
 		case <-ctx.Done():
@@ -260,14 +262,20 @@ func streamLogs(ctx context.Context, aciContext store.AciContext, containerGroup
 			// the kind of logs ACI is giving us. Hopefully Azue will give us
 			// a real logs streaming api soon.
 			b := aec.EmptyBuilder
-			b = b.Up(uint(lastOutput))
+			b = b.Up(uint(numLines))
 			fmt.Fprint(out, b.Column(0).ANSI)
 
 			for i := 0; i < currentOutput-1; i++ {
 				fmt.Fprintln(out, logLines[i])
 			}
 
-			lastOutput = currentOutput - 1
+			numLines = 0
+			for i := 0; i < currentOutput-1; i++ {
+				numLines++
+				if len(logLines[i]) > terminalWidth {
+					numLines += len(logLines[i]) / terminalWidth
+				}
+			}
 
 			time.Sleep(2 * time.Second)
 		}