From c0015e89c0749aa26ba71824e85904a2e0e85c9e Mon Sep 17 00:00:00 2001
From: Charles Iliya Krempeaux <iamreiver@gmail.com>
Date: Thu, 11 Jul 2019 21:27:37 -0700
Subject: [PATCH] calltrace

---
 calltrace.go              | 62 +++++++++++++++++++++++++++++++++++++++
 default_writing_router.go |  4 +++
 pretty_writing_router.go  |  9 ++++++
 3 files changed, 75 insertions(+)
 create mode 100644 calltrace.go

diff --git a/calltrace.go b/calltrace.go
new file mode 100644
index 0000000..0451887
--- /dev/null
+++ b/calltrace.go
@@ -0,0 +1,62 @@
+package flog
+
+import (
+	"fmt"
+	"runtime"
+	"strings"
+)
+
+func calltrace() []string {
+
+	const max = 10
+
+	var frames *runtime.Frames
+	{
+		var buffer [max]uintptr
+
+		var pc []uintptr = buffer[:]
+
+		n := runtime.Callers(0, pc)
+		if 0 >= n {
+			return nil
+		}
+		pc = pc[:n]
+		frames = runtime.CallersFrames(pc)
+	}
+
+	var trace []string
+	{
+		var buffer [max]string
+		trace = buffer[:0]
+
+		var more bool = true
+		for more {
+			var frame runtime.Frame
+
+			frame, more = frames.Next()
+			switch frame.Function {
+			case "runtime.Callers":
+				continue
+			default:
+				if strings.HasPrefix(frame.Function, "github.com/reiver/go-flog.") {
+					continue
+				}
+			}
+
+			var filename string = frame.File
+			if index := strings.LastIndex(filename, "/"); 0 <= index {
+				filename = filename[1+index:]
+			}
+
+			s := fmt.Sprintf("%s():%s:%d", frame.Function, filename, frame.Line)
+
+			trace = append(trace, s)
+
+			if !more {
+				break
+			}
+		}
+	}
+
+	return trace
+}
diff --git a/default_writing_router.go b/default_writing_router.go
index 46d9125..6254270 100644
--- a/default_writing_router.go
+++ b/default_writing_router.go
@@ -63,6 +63,10 @@ func (router *DefaultWritingRouter) Route(message string, context map[string]int
 	p = dotquote.AppendString(p, message, "text")
 	p = append(p, ' ')
 	p = dotquote.AppendString(p, time.Now().String(), "when")
+	if trace := calltrace(); nil != trace {
+		p = append(p, ' ')
+		p = dotquote.AppendStrings(p, trace, "calltrace")
+	}
 
 	// If we have an error, then get the error.Error() into the log too.
 	if errorFieldValue, ok := context["~error"]; ok {
diff --git a/pretty_writing_router.go b/pretty_writing_router.go
index 37b03e9..1df9615 100644
--- a/pretty_writing_router.go
+++ b/pretty_writing_router.go
@@ -41,6 +41,7 @@ func (router *PrettyWritingRouter) Route(message string, context map[string]inte
 	const STYLE_MESSAGE   = "\x1b[44;37;1m" // BG BLUE,   FG WHITE,  BOLD
 	const STYLE_DEFAULT   = "\033[95m"      // HEADER
 	const STYLE_RESET     = "\033[0m"       // RESET
+	const STYLE_CALLTRACE = "\033[40;36;1m" // BG BLACK,  FG CYAN,   BOLD
 
 	str := ""
 
@@ -101,6 +102,14 @@ func (router *PrettyWritingRouter) Route(message string, context map[string]inte
 		str = fmt.Sprintf("%s\t%s%s%s=%s%#v%s", str, style, key, STYLE_RESET, style, value, STYLE_RESET)
 	}
 
+	if trace := calltrace(); nil != trace {
+		str = fmt.Sprintf("%s\t⟨⟨", str)
+		for _, s := range trace {
+			str = fmt.Sprintf("%s %s%s%s,", str, STYLE_CALLTRACE, s, STYLE_RESET)
+		}
+		str = fmt.Sprintf("%s ⟩⟩", str)
+	}
+
 	fmt.Fprintln(router.writer, str)
 
 //@TODO: Should this be checking for errors from fmt.Fprintln()?