Fix #135

internal/version/version.go

@@ -0,0 +1,88 @@
+package version
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+)
+
+// GetMessage returns a message for the user describing if there is a newer version
+// available. It should only be called once the tunnel is established.
+func GetMessage(version, commitShort string, client *http.Client) (message string, err error) {
+	if version == "latest" {
+		// Find # of commits between current commit and latest commit
+		commitsSince, err := getCommitsSince(client, commitShort)
+		if err != nil {
+			return "", fmt.Errorf("cannot get version information: %w", err)
+		} else if commitsSince == 0 {
+			return fmt.Sprintf("You are running on the bleeding edge of %s!", version), nil
+		}
+		commits := "commits"
+		if commitsSince == 1 {
+			commits = "commit"
+		}
+		return fmt.Sprintf("You are running %d %s behind the most recent %s", commitsSince, commits, version), nil
+	}
+	tagName, name, releaseTime, err := getLatestRelease(client)
+	if err != nil {
+		return "", fmt.Errorf("cannot get version information: %w", err)
+	}
+	if tagName == version {
+		return fmt.Sprintf("You are running the latest release %s", version), nil
+	}
+	timeSinceRelease := formatDuration(time.Since(releaseTime))
+	return fmt.Sprintf("There is a new release %s (%s) created %s ago",
+			tagName, name, timeSinceRelease),
+		nil
+}
+
+func formatDuration(duration time.Duration) string {
+	switch {
+	case duration < time.Minute:
+		seconds := int(duration.Round(time.Second).Seconds())
+		if seconds < 2 {
+			return fmt.Sprintf("%d second", seconds)
+		}
+		return fmt.Sprintf("%d seconds", seconds)
+	case duration <= time.Hour:
+		minutes := int(duration.Round(time.Minute).Minutes())
+		if minutes == 1 {
+			return "1 minute"
+		}
+		return fmt.Sprintf("%d minutes", minutes)
+	case duration < 48*time.Hour:
+		hours := int(duration.Truncate(time.Hour).Hours())
+		return fmt.Sprintf("%d hours", hours)
+	default:
+		days := int(duration.Truncate(time.Hour).Hours() / 24)
+		return fmt.Sprintf("%d days", days)
+	}
+}
+
+func getLatestRelease(client *http.Client) (tagName, name string, time time.Time, err error) {
+	releases, err := getGithubReleases(client)
+	if err != nil {
+		return "", "", time, err
+	}
+	for _, release := range releases {
+		if release.Prerelease {
+			continue
+		}
+		return release.TagName, release.Name, release.PublishedAt, nil
+	}
+	return "", "", time, fmt.Errorf("no releases found")
+}
+
+func getCommitsSince(client *http.Client, commitShort string) (n int, err error) {
+	commits, err := getGithubCommits(client)
+	if err != nil {
+		return 0, err
+	}
+	for i := range commits {
+		if commits[i].Sha[:7] == commitShort {
+			return n, nil
+		}
+		n++
+	}
+	return 0, fmt.Errorf("no commit matching %q was found", commitShort)
+}