Added logging

vendor/github.com/op/go-logging/log_windows.go

@@ -0,0 +1,107 @@
+// +build windows
+// Copyright 2013, Örjan Persson. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package logging
+
+import (
+	"bytes"
+	"io"
+	"log"
+	"syscall"
+)
+
+var (
+	kernel32DLL                 = syscall.NewLazyDLL("kernel32.dll")
+	setConsoleTextAttributeProc = kernel32DLL.NewProc("SetConsoleTextAttribute")
+)
+
+// Character attributes
+// Note:
+// -- The attributes are combined to produce various colors (e.g., Blue + Green will create Cyan).
+//    Clearing all foreground or background colors results in black; setting all creates white.
+// See https://msdn.microsoft.com/en-us/library/windows/desktop/ms682088(v=vs.85).aspx#_win32_character_attributes.
+const (
+	fgBlack     = 0x0000
+	fgBlue      = 0x0001
+	fgGreen     = 0x0002
+	fgCyan      = 0x0003
+	fgRed       = 0x0004
+	fgMagenta   = 0x0005
+	fgYellow    = 0x0006
+	fgWhite     = 0x0007
+	fgIntensity = 0x0008
+	fgMask      = 0x000F
+)
+
+var (
+	colors = []uint16{
+		INFO:     fgWhite,
+		CRITICAL: fgMagenta,
+		ERROR:    fgRed,
+		WARNING:  fgYellow,
+		NOTICE:   fgGreen,
+		DEBUG:    fgCyan,
+	}
+	boldcolors = []uint16{
+		INFO:     fgWhite | fgIntensity,
+		CRITICAL: fgMagenta | fgIntensity,
+		ERROR:    fgRed | fgIntensity,
+		WARNING:  fgYellow | fgIntensity,
+		NOTICE:   fgGreen | fgIntensity,
+		DEBUG:    fgCyan | fgIntensity,
+	}
+)
+
+type file interface {
+	Fd() uintptr
+}
+
+// LogBackend utilizes the standard log module.
+type LogBackend struct {
+	Logger *log.Logger
+	Color  bool
+
+	// f is set to a non-nil value if the underlying writer which logs writes to
+	// implements the file interface. This makes us able to colorise the output.
+	f file
+}
+
+// NewLogBackend creates a new LogBackend.
+func NewLogBackend(out io.Writer, prefix string, flag int) *LogBackend {
+	b := &LogBackend{Logger: log.New(out, prefix, flag)}
+
+	// Unfortunately, the API used only takes an io.Writer where the Windows API
+	// need the actual fd to change colors.
+	if f, ok := out.(file); ok {
+		b.f = f
+	}
+
+	return b
+}
+
+func (b *LogBackend) Log(level Level, calldepth int, rec *Record) error {
+	if b.Color && b.f != nil {
+		buf := &bytes.Buffer{}
+		setConsoleTextAttribute(b.f, colors[level])
+		buf.Write([]byte(rec.Formatted(calldepth + 1)))
+		err := b.Logger.Output(calldepth+2, buf.String())
+		setConsoleTextAttribute(b.f, fgWhite)
+		return err
+	}
+	return b.Logger.Output(calldepth+2, rec.Formatted(calldepth+1))
+}
+
+// setConsoleTextAttribute sets the attributes of characters written to the
+// console screen buffer by the WriteFile or WriteConsole function.
+// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms686047(v=vs.85).aspx.
+func setConsoleTextAttribute(f file, attribute uint16) bool {
+	ok, _, _ := setConsoleTextAttributeProc.Call(f.Fd(), uintptr(attribute), 0)
+	return ok != 0
+}
+
+func doFmtVerbLevelColor(layout string, level Level, output io.Writer) {
+	// TODO not supported on Windows since the io.Writer here is actually a
+	// bytes.Buffer.
+}