From 161e241f53763790382b6e69b886b7683e1643cd Mon Sep 17 00:00:00 2001
From: Tom Hudson <mail@tomnomnom.com>
Date: Sat, 3 Sep 2016 15:49:56 +0100
Subject: [PATCH] Adds version information to builds; fixes #19

---
 CHANGELOG.mkd  |  3 ++-
 README.mkd     |  1 +
 main.go        | 17 ++++++++++++++++-
 script/release |  2 +-
 url.go         |  3 ++-
 5 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.mkd b/CHANGELOG.mkd
index 0f2701e..9b385f0 100644
--- a/CHANGELOG.mkd
+++ b/CHANGELOG.mkd
@@ -1,8 +1,9 @@
 # Changelog
 
-## HEAD
+## 0.3.3
 - Slightly improved error reporting when ungronning
 - 20 second timeout on HTTP(s) requests (thanks @gummiboll!)
+- Version information added at build time + `--version` option (issue #19)
 
 ## 0.3.2
 - Adds handling of `--` lines produced by grep -A etc (issue #15)
diff --git a/README.mkd b/README.mkd
index 73ffeb0..c228a63 100644
--- a/README.mkd
+++ b/README.mkd
@@ -183,6 +183,7 @@ Usage:
 Options:
   -u, --ungron     Reverse the operation (turn assignments back into JSON)
   -m, --monochrome Monochrome (don't colorize output)
+      --version    Print version information
 
 Exit Codes:
   0 OK
diff --git a/main.go b/main.go
index 0cdf2eb..409c748 100644
--- a/main.go
+++ b/main.go
@@ -15,6 +15,7 @@ import (
 	"github.com/pkg/errors"
 )
 
+// Exit codes
 const (
 	exitOK = iota
 	exitOpenFile
@@ -25,6 +26,7 @@ const (
 	exitJSONEncode
 )
 
+// Output colors
 var (
 	strColor   = color.New(color.FgYellow)
 	braceColor = color.New(color.FgMagenta)
@@ -33,6 +35,10 @@ var (
 	boolColor  = color.New(color.FgCyan)
 )
 
+// gronVersion stores the current gron version, set at build
+// time with the ldflags -X option
+var gronVersion = "dev"
+
 func init() {
 	flag.Usage = func() {
 		h := "Transform JSON (from a file, URL, or stdin) into discrete assignments to make it greppable\n\n"
@@ -42,7 +48,8 @@ func init() {
 
 		h += "Options:\n"
 		h += "  -u, --ungron     Reverse the operation (turn assignments back into JSON)\n"
-		h += "  -m, --monochrome Monochrome (don't colorize output)\n\n"
+		h += "  -m, --monochrome Monochrome (don't colorize output)\n"
+		h += "      --version    Print version information\n\n"
 
 		h += "Exit Codes:\n"
 		h += fmt.Sprintf("  %d\t%s\n", exitOK, "OK")
@@ -68,15 +75,23 @@ func main() {
 	var (
 		ungronFlag     bool
 		monochromeFlag bool
+		versionFlag    bool
 	)
 
 	flag.BoolVar(&ungronFlag, "ungron", false, "Turn statements into JSON instead")
 	flag.BoolVar(&ungronFlag, "u", false, "Turn statements into JSON instead")
 	flag.BoolVar(&monochromeFlag, "monochrome", false, "Monochrome (don't colorize output)")
 	flag.BoolVar(&monochromeFlag, "m", false, "Monochrome (don't colorize output)")
+	flag.BoolVar(&versionFlag, "version", false, "Print version information")
 
 	flag.Parse()
 
+	// Print version information
+	if versionFlag {
+		fmt.Printf("gron version %s\n", gronVersion)
+		os.Exit(exitOK)
+	}
+
 	var raw io.Reader
 
 	filename := flag.Arg(0)
diff --git a/script/release b/script/release
index 33b8fb0..34a2d1e 100755
--- a/script/release
+++ b/script/release
@@ -52,7 +52,7 @@ for ARCH in "amd64" "386"; do
 
         rm -f ${BINFILE}
 
-        GOOS=${OS} GOARCH=${ARCH} go build github.com/${USER}/${REPO}
+        GOOS=${OS} GOARCH=${ARCH} go build -ldflags "-X main.gronVersion=${VERSION}" github.com/${USER}/${REPO}
 
         if [[ "${OS}" == "windows" ]]; then
             ARCHIVE="${BINARY}-${OS}-${ARCH}-${VERSION}.zip"
diff --git a/url.go b/url.go
index 14a203d..b357093 100644
--- a/url.go
+++ b/url.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"bufio"
+	"fmt"
 	"io"
 	"net/http"
 	"strings"
@@ -21,7 +22,7 @@ func getURL(url string) (io.Reader, error) {
 	if err != nil {
 		return nil, err
 	}
-	req.Header.Set("User-Agent", "gron/0.2")
+	req.Header.Set("User-Agent", fmt.Sprintf("gron/%s", gronVersion))
 	req.Header.Set("Accept", "application/json")
 
 	resp, err := client.Do(req)