fix(ui): list IPs in reverse chronological order

- Fix #730

internal/models/history.go

@@ -18,16 +18,16 @@ type HistoryEvent struct { // current and previous ips
 
 // GetPreviousIPs returns an antichronological list of previous
 // IP addresses if there is any.
-func (h History) GetPreviousIPs() []netip.Addr {
+func (h History) GetPreviousIPs() (previousIPs []netip.Addr) {
 	if len(h) <= 1 {
 		return nil
 	}
-	IPs := make([]netip.Addr, len(h)-1)
-	const two = 2
-	for i := len(h) - two; i >= 0; i-- {
-		IPs[i] = h[i].IP
+	previousIPs = make([]netip.Addr, len(h)-1)
+	mostRecentPreviousIPIndex := len(h) - 2 //nolint:gomnd
+	for i := range previousIPs {
+		previousIPs[i] = h[mostRecentPreviousIPIndex-i].IP
 	}
-	return IPs
+	return previousIPs
 }
 
 // GetCurrentIP returns the current IP address (latest in history).

internal/models/history_test.go

@@ -1,12 +1,58 @@
 package models
 
 import (
+	"net/netip"
 	"testing"
 	"time"
 
 	"github.com/stretchr/testify/assert"
 )
 
+func Test_GetPreviousIPs(t *testing.T) {
+	t.Parallel()
+	testCases := map[string]struct {
+		h           History
+		previousIPs []netip.Addr
+	}{
+		"empty_history": {
+			h: History{},
+		},
+		"single_event": {
+			h: History{
+				{IP: netip.MustParseAddr("1.2.3.4")},
+			},
+		},
+		"two_events": {
+			h: History{
+				{IP: netip.MustParseAddr("1.2.3.4")},
+				{IP: netip.MustParseAddr("5.6.7.8")}, // last one
+			},
+			previousIPs: []netip.Addr{
+				netip.MustParseAddr("1.2.3.4"),
+			},
+		},
+		"three_events": {
+			h: History{
+				{IP: netip.MustParseAddr("1.2.3.4")},
+				{IP: netip.MustParseAddr("5.6.7.8")},
+				{IP: netip.MustParseAddr("9.6.7.8")}, // last one
+			},
+			previousIPs: []netip.Addr{
+				netip.MustParseAddr("5.6.7.8"),
+				netip.MustParseAddr("1.2.3.4"),
+			},
+		},
+	}
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+			previousIPs := testCase.h.GetPreviousIPs()
+			assert.Equal(t, testCase.previousIPs, previousIPs)
+		})
+	}
+}
+
 func Test_GetDurationSinceSuccess(t *testing.T) {
 	t.Parallel()
 	tests := map[string]struct {