add a "version" command with various outputs, including the git hash and tag

2 files changed, 71 insertions, 2 deletions

diff --git a/commands/root.go b/commands/root.go
index 5bb2b504..797ae949 100644
--- a/commands/root.go
+++ b/commands/root.go
@@ -17,8 +17,6 @@ var repo repository.ClockedRepo
 
 // RootCmd represents the base command when called without any subcommands
 var RootCmd = &cobra.Command{
-	Version: "0.4.0",
-
 	Use:   rootCommandName,
 	Short: "A bug tracker embedded in Git",
 	Long: `git-bug is a bug tracker embedded in git.
diff --git a/commands/version.go b/commands/version.go
new file mode 100644
index 00000000..b4dc008e
--- /dev/null
+++ b/commands/version.go
@@ -0,0 +1,71 @@
+package commands
+
+import (
+	"fmt"
+	"runtime"
+
+	"github.com/spf13/cobra"
+)
+
+// These variables are initialized externally during the build. See the Makefile.
+var GitCommit string
+var GitLastTag string
+var GitExactTag string
+
+var (
+	versionNumber bool
+	versionCommit bool
+	versionAll    bool
+)
+
+func runVersionCmd(cmd *cobra.Command, args []string) {
+	if versionAll {
+		fmt.Printf("%s version: %s\n", rootCommandName, RootCmd.Version)
+		fmt.Printf("System version: %s/%s\n", runtime.GOARCH, runtime.GOOS)
+		fmt.Printf("Golang version: %s\n", runtime.Version())
+		return
+	}
+
+	if versionNumber {
+		fmt.Println(RootCmd.Version)
+		return
+	}
+
+	if versionCommit {
+		fmt.Println(GitCommit)
+		return
+	}
+
+	fmt.Printf("%s version: %s\n", rootCommandName, RootCmd.Version)
+}
+
+var versionCmd = &cobra.Command{
+	Use:   "version",
+	Short: "Show git-bug version information",
+	Run:   runVersionCmd,
+}
+
+func init() {
+	if GitExactTag == "undefined" {
+		GitExactTag = ""
+	}
+
+	RootCmd.Version = GitLastTag
+
+	if GitExactTag == "" {
+		RootCmd.Version = fmt.Sprintf("%s-dev-%.10s", RootCmd.Version, GitCommit)
+	}
+
+	RootCmd.AddCommand(versionCmd)
+	versionCmd.Flags().SortFlags = false
+
+	versionCmd.Flags().BoolVarP(&versionNumber, "number", "n", false,
+		"Only show the version number",
+	)
+	versionCmd.Flags().BoolVarP(&versionCommit, "commit", "c", false,
+		"Only show the commit hash",
+	)
+	versionCmd.Flags().BoolVarP(&versionAll, "all", "a", false,
+		"Show all version informations",
+	)
+}