Handle `%s` format string for URL in `BROWSER` variable

The `BROWSER` environment variable might contain a `%s` format string
that should be replaced by the URL to open. If it's present perform the
replacement. Otherwise, append the URL to the `BROWSER` command as
before.

1 files changed, 19 insertions, 1 deletions

diff --git a/browserenv.go b/browserenv.go
index f0a6dd8..3f463a2 100644
--- a/browserenv.go
+++ b/browserenv.go
@@ -6,6 +6,8 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
+	"strings"
 
 	"github.com/pkg/browser"
 )
@@ -13,6 +15,8 @@ import (
 var Stderr io.Writer = os.Stderr
 var Stdout io.Writer = os.Stdout
 
+var percentS = regexp.MustCompile("%s[[:^alpha:]]?")
+
 func OpenFile(path string) error {
 	envCommand := envBrowserCommand()
 	if envCommand != "" {
@@ -73,8 +77,22 @@ func browserCommand(command, url string) *exec.Cmd {
 	shell := shellArgs[0]
 	args := shellArgs[1:]
 
-	command = fmtBrowserCommand(command, url)
+	if browserCommandIncludesURL(command) {
+		command = fmtWithURL(command, url)
+	} else {
+		command = fmtBrowserCommand(command, url)
+	}
+
 	args = append(args, command)
 
 	return exec.Command(shell, args...)
 }
+
+func browserCommandIncludesURL(command string) bool {
+	return percentS.MatchString(command)
+}
+
+func fmtWithURL(command, url string) string {
+	// TODO: shellescape URL
+	return strings.ReplaceAll(command, "%s", url)
+}