From 51290b4f9292d89523bf32797c30ea3b8c579915 Mon Sep 17 00:00:00 2001
From: Noah Petherbridge <root@kirsle.net>
Date: Tue, 10 Apr 2018 19:09:13 -0700
Subject: [PATCH] No colors for non-interactive shells

---
 formatter.go  | 2 +-
 golog.go      | 9 +++++++++
 golog_test.go | 2 ++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/formatter.go b/formatter.go
index a355d7d..d7bf82a 100644
--- a/formatter.go
+++ b/formatter.go
@@ -49,7 +49,7 @@ func (l *Logger) Format(level logLevel, tmpl string, args ...interface{}) string
 	}
 
 	// Find the theme color to use.
-	if l.Config.Colors != NoColor {
+	if interactive && l.Config.Colors != NoColor {
 		var (
 			primary   ThemeColor
 			secondary ThemeColor
diff --git a/golog.go b/golog.go
index 64836b9..fff201b 100644
--- a/golog.go
+++ b/golog.go
@@ -1,8 +1,11 @@
 package golog
 
 import (
+	"os"
 	"sync"
 	"text/template"
+
+	"golang.org/x/crypto/ssh/terminal"
 )
 
 // An internal map of named loggers. This allows for GetLogger() to be called
@@ -11,10 +14,16 @@ import (
 var (
 	loggers     map[string]*Logger
 	loggerMutex sync.Mutex
+
+	interactive bool // is an interactive shell
 )
 
 func init() {
 	loggers = map[string]*Logger{}
+
+	// Detect if we're running in an interactive shell, so we can globally
+	// disable colors when redirecting to a log file.
+	interactive = terminal.IsTerminal(int(os.Stdout.Fd()))
 }
 
 // Logger stores the configuration for a named logger instance.
diff --git a/golog_test.go b/golog_test.go
index 239f7a4..1ae9a87 100644
--- a/golog_test.go
+++ b/golog_test.go
@@ -3,6 +3,8 @@ package golog
 import "testing"
 
 func TestColors(t *testing.T) {
+	interactive = true // fake an interactive TTY to test color outputs
+
 	log := GetLogger("test")
 
 	// Helper function to emit all the log types.