From f5617dadf3105899e95469185f52459bc90c5633 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Tue, 28 Aug 2018 11:17:05 +0100
Subject: [PATCH] fs/accounting: factor out eta and percent calculations and
 write tests

---
 fs/accounting/accounting.go | 19 +++-----------
 fs/accounting/stats.go      | 37 +++++++++++++++++++++++++++
 fs/accounting/stats_test.go | 51 +++++++++++++++++++++++++++++++++++++
 3 files changed, 91 insertions(+), 16 deletions(-)
 create mode 100644 fs/accounting/stats_test.go

diff --git a/fs/accounting/accounting.go b/fs/accounting/accounting.go
index 3068b4253..a3746f5e9 100644
--- a/fs/accounting/accounting.go
+++ b/fs/accounting/accounting.go
@@ -229,26 +229,13 @@ func (acc *Account) speed() (bps, current float64) {
 // eta returns the ETA of the current operation,
 // rounded to full seconds.
 // If the ETA cannot be determined 'ok' returns false.
-func (acc *Account) eta() (eta time.Duration, ok bool) {
-	if acc == nil || acc.size <= 0 {
+func (acc *Account) eta() (etaDuration time.Duration, ok bool) {
+	if acc == nil {
 		return 0, false
 	}
 	acc.statmu.Lock()
 	defer acc.statmu.Unlock()
-	if acc.bytes == 0 {
-		return 0, false
-	}
-	left := acc.size - acc.bytes
-	if left <= 0 {
-		return 0, true
-	}
-	avg := acc.avg
-	if avg <= 0 {
-		return 0, false
-	}
-	seconds := float64(left) / avg
-
-	return time.Second * time.Duration(seconds), true
+	return eta(acc.bytes, acc.size, acc.avg)
 }
 
 // String produces stats for this file
diff --git a/fs/accounting/stats.go b/fs/accounting/stats.go
index 1e795fd45..f7863ad29 100644
--- a/fs/accounting/stats.go
+++ b/fs/accounting/stats.go
@@ -140,6 +140,43 @@ func (s *StatsInfo) RemoteStats(in rc.Params) (out rc.Params, err error) {
 	return out, nil
 }
 
+// eta returns the ETA of the current operation,
+// rounded to full seconds.
+// If the ETA cannot be determined 'ok' returns false.
+func eta(size, total int64, rate float64) (eta time.Duration, ok bool) {
+	if total <= 0 || size < 0 || rate <= 0 {
+		return 0, false
+	}
+	remaining := total - size
+	if remaining < 0 {
+		return 0, false
+	}
+	seconds := float64(remaining) / rate
+	return time.Second * time.Duration(seconds), true
+}
+
+// etaString returns the ETA of the current operation,
+// rounded to full seconds.
+// If the ETA cannot be determined it returns "-"
+func etaString(done, total int64, rate float64) string {
+	d, ok := eta(done, total, rate)
+	if !ok {
+		return "-"
+	}
+	return d.String()
+}
+
+// percent returns a/b as a percentage rounded to the nearest integer
+// as a string
+//
+// if the percentage is invalid it returns "-"
+func percent(a int64, b int64) string {
+	if a < 0 || b <= 0 {
+		return "-"
+	}
+	return fmt.Sprintf("%d%%", int(float64(a)*100/float64(b)+0.5))
+}
+
 // String convert the StatsInfo to a string for printing
 func (s *StatsInfo) String() string {
 	s.mu.RLock()
diff --git a/fs/accounting/stats_test.go b/fs/accounting/stats_test.go
new file mode 100644
index 000000000..d7f5e852f
--- /dev/null
+++ b/fs/accounting/stats_test.go
@@ -0,0 +1,51 @@
+package accounting
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestETA(t *testing.T) {
+	for _, test := range []struct {
+		size, total int64
+		rate        float64
+		wantETA     time.Duration
+		wantOK      bool
+		wantString  string
+	}{
+		{size: 0, total: 100, rate: 1.0, wantETA: 100 * time.Second, wantOK: true, wantString: "1m40s"},
+		{size: 50, total: 100, rate: 1.0, wantETA: 50 * time.Second, wantOK: true, wantString: "50s"},
+		{size: 100, total: 100, rate: 1.0, wantETA: 0 * time.Second, wantOK: true, wantString: "0s"},
+		{size: -1, total: 100, rate: 1.0, wantETA: 0, wantOK: false, wantString: "-"},
+		{size: 200, total: 100, rate: 1.0, wantETA: 0, wantOK: false, wantString: "-"},
+		{size: 10, total: -1, rate: 1.0, wantETA: 0, wantOK: false, wantString: "-"},
+		{size: 10, total: 20, rate: 0.0, wantETA: 0, wantOK: false, wantString: "-"},
+		{size: 10, total: 20, rate: -1.0, wantETA: 0, wantOK: false, wantString: "-"},
+		{size: 0, total: 0, rate: 1.0, wantETA: 0, wantOK: false, wantString: "-"},
+	} {
+		t.Run(fmt.Sprintf("size=%d/total=%d/rate=%f", test.size, test.total, test.rate), func(t *testing.T) {
+			gotETA, gotOK := eta(test.size, test.total, test.rate)
+			assert.Equal(t, test.wantETA, gotETA)
+			assert.Equal(t, test.wantOK, gotOK)
+			gotString := etaString(test.size, test.total, test.rate)
+			assert.Equal(t, test.wantString, gotString)
+		})
+	}
+}
+
+func TestPercentage(t *testing.T) {
+	assert.Equal(t, percent(0, 1000), "0%")
+	assert.Equal(t, percent(1, 1000), "0%")
+	assert.Equal(t, percent(9, 1000), "1%")
+	assert.Equal(t, percent(500, 1000), "50%")
+	assert.Equal(t, percent(1000, 1000), "100%")
+	assert.Equal(t, percent(1E8, 1E9), "10%")
+	assert.Equal(t, percent(1E8, 1E9), "10%")
+	assert.Equal(t, percent(0, 0), "-")
+	assert.Equal(t, percent(100, -100), "-")
+	assert.Equal(t, percent(-100, 100), "-")
+	assert.Equal(t, percent(-100, -100), "-")
+}