Initial commit

logger.go

@@ -0,0 +1,56 @@
+package logger
+
+import (
+	"log"
+	"os"
+)
+
+var Write *conditionalLogger
+
+func init() {
+	Write = &conditionalLogger{
+		consoleLogger: log.New(os.Stdout, "", log.LstdFlags),
+	}
+}
+
+type conditionalLogger struct {
+	hasErrorOccurred bool
+	fileLogger       *log.Logger
+	consoleLogger    *log.Logger
+	logFile          *os.File
+}
+
+func (c *conditionalLogger) Log(v ...interface{}) {
+	if c.hasErrorOccurred {
+		c.fileLogger.Println(v...)
+	} else {
+		c.consoleLogger.Println(v...)
+	}
+}
+
+func (c *conditionalLogger) Logf(format string, v ...interface{}) {
+	if c.hasErrorOccurred {
+		c.fileLogger.Printf(format, v...)
+	} else {
+		c.consoleLogger.Printf(format, v...)
+	}
+}
+
+func (c *conditionalLogger) Error(v ...interface{}) {
+	c.initFileLoggerIfNecessary()
+	c.fileLogger.Println(v...)
+}
+
+func (c *conditionalLogger) Errorf(format string, v ...interface{}) {
+	c.initFileLoggerIfNecessary()
+	c.fileLogger.Printf(format, v...)
+}
+
+// Private helper method to initialize the file logger if an error occurs.
+func (c *conditionalLogger) initFileLoggerIfNecessary() {
+	if !c.hasErrorOccurred {
+		c.logFile, _ = os.OpenFile("log.txt", os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
+		c.fileLogger = log.New(c.logFile, "", log.LstdFlags)
+		c.hasErrorOccurred = true
+	}
+}