package term
import (
"bytes"
"fmt"
"io"
"sync"
"github.com/go-kit/kit/log"
)
// Color represents an ANSI color. The zero value is Default.
type Color uint8
// ANSI colors.
const (
Default = Color(iota)
Black
DarkRed
DarkGreen
Brown
DarkBlue
DarkMagenta
DarkCyan
Gray
DarkGray
Red
Green
Yellow
Blue
Magenta
Cyan
White
numColors
)
// For more on ANSI escape codes see
// https://en.wikipedia.org/wiki/ANSI_escape_code. See in particular
// https://en.wikipedia.org/wiki/ANSI_escape_code#Colors.
var (
resetColorBytes = []byte("\x1b[39;49;22m")
fgColorBytes [][]byte
bgColorBytes [][]byte
)
func init() {
// Default
fgColorBytes = append(fgColorBytes, []byte("\x1b[39m"))
bgColorBytes = append(bgColorBytes, []byte("\x1b[49m"))
// dark colors
for color := Black; color < DarkGray; color++ {
fgColorBytes = append(fgColorBytes, []byte(fmt.Sprintf("\x1b[%dm", 30+color-Black)))
bgColorBytes = append(bgColorBytes, []byte(fmt.Sprintf("\x1b[%dm", 40+color-Black)))
}
// bright colors
for color := DarkGray; color < numColors; color++ {
fgColorBytes = append(fgColorBytes, []byte(fmt.Sprintf("\x1b[%d;1m", 30+color-DarkGray)))
bgColorBytes = append(bgColorBytes, []byte(fmt.Sprintf("\x1b[%d;1m", 40+color-DarkGray)))
}
}
// FgBgColor represents a foreground and background color.
type FgBgColor struct {
Fg, Bg Color
}
func (c FgBgColor) isZero() bool {
return c.Fg == Default && c.Bg == Default
}
// NewColorLogger returns a Logger which writes colored logs to w. ANSI color
// codes for the colors returned by color are added to the formatted output
// from the Logger returned by newLogger and the combined result written to w.
func NewColorLogger(w io.Writer, newLogger func(io.Writer) log.Logger, color func(keyvals ...interface{}) FgBgColor) log.Logger {
if color == nil {
panic("color func nil")
}
return &colorLogger{
w: w,
newLogger: newLogger,
color: color,
bufPool: sync.Pool{New: func() interface{} { return &loggerBuf{} }},
noColorLogger: newLogger(w),
}
}
type colorLogger struct {
w io.Writer
newLogger func(io.Writer) log.Logger
color func(keyvals ...interface{}) FgBgColor
bufPool sync.Pool
noColorLogger log.Logger
}
func (l *colorLogger) Log(keyvals ...interface{}) error {
color := l.color(keyvals...)
if color.isZero() {
return l.noColorLogger.Log(keyvals...)
}
lb := l.getLoggerBuf()
defer l.putLoggerBuf(lb)
if color.Fg != Default {
lb.buf.Write(fgColorBytes[color.Fg])
}
if color.Bg != Default {
lb.buf.Write(bgColorBytes[color.Bg])
}
err := lb.logger.Log(keyvals...)
if err != nil {
return err
}
if color.Fg != Default || color.Bg != Default {
lb.buf.Write(resetColorBytes)
}
_, err = io.Copy(l.w, lb.buf)
return err
}
type loggerBuf struct {
buf *bytes.Buffer
logger log.Logger
}
func (l *colorLogger) getLoggerBuf() *loggerBuf {
lb := l.bufPool.Get().(*loggerBuf)
if lb.buf == nil {
lb.buf = &bytes.Buffer{}
lb.logger = l.newLogger(lb.buf)
} else {
lb.buf.Reset()
}
return lb
}
func (l *colorLogger) putLoggerBuf(cb *loggerBuf) {
l.bufPool.Put(cb)
}