beaver/color/color.go

package color

import (
	"fmt"
	"strconv"
	"strings"
)

// Color defines a custom color object which is defined by SGR parameters.
type Color struct {
	Attrs []Attribute
}

// Attribute defines a single SGR Code
type Attribute int

const escape = "\x1b"

// Logger attributes
const (
	Reset Attribute = iota
	Bold
	Faint
	Italic
	Underline
	BlinkSlow
	BlinkRapid
	ReverseVideo
	Concealed
	CrossedOut
)

// Foreground text colors
const (
	FgBlack Attribute = iota + 30
	FgRed
	FgGreen
	FgYellow
	FgBlue
	FgMagenta
	FgCyan
	FgWhite
)

// Foreground Hi-Intensity text colors
const (
	FgHiBlack Attribute = iota + 90
	FgHiRed
	FgHiGreen
	FgHiYellow
	FgHiBlue
	FgHiMagenta
	FgHiCyan
	FgHiWhite
)

// Background text colors
const (
	BgBlack Attribute = iota + 40
	BgRed
	BgGreen
	BgYellow
	BgBlue
	BgMagenta
	BgCyan
	BgWhite
)

// Background Hi-Intensity text colors
const (
	BgHiBlack Attribute = iota + 100
	BgHiRed
	BgHiGreen
	BgHiYellow
	BgHiBlue
	BgHiMagenta
	BgHiCyan
	BgHiWhite
)

// New returns a new Color with attrs Attributes
func New(attrs ...Attribute) *Color {
	return &Color{Attrs: attrs}
}

// Add adds new Attributes to a Color
func (c *Color) Add(attrs ...Attribute) {
	for _, attr := range attrs {
		has := false
		for _, att := range c.Attrs {
			if attr == att {
				has = true
				break
			}
		}
		if !has {
			c.Attrs = append(c.Attrs, attr)
		}
	}
}

// String returns a string representation of the sum of a Color's Attributes
func (c *Color) String() string {
	attrs := 0
	for _, attr := range c.Attrs {
		attrs += int(attr)
	}
	return fmt.Sprintf("%d", attrs)
}

func (c *Color) sequence() string {
	format := make([]string, len(c.Attrs))
	for i, v := range c.Attrs {
		format[i] = strconv.Itoa(int(v))
	}

	return strings.Join(format, ";")
}

func (c *Color) wrap(s string) string {
	return c.format() + s + c.unformat()
}

func (c *Color) format() string {
	return fmt.Sprintf("%s[%sm", escape, c.sequence())
}

func (c *Color) unformat() string {
	return fmt.Sprintf("%s[%dm", escape, Reset)
}

func (c *Color) Format(text string) string {
	if len(c.Attrs) > 0 {
		return c.wrap(text)
	}
	return text
}

// ParseLevel parses a string and returns a Beaver Level's Color, defaulting to Info
func ParseLevel(level string) *Color {
	switch strings.ToUpper(level) {
	case "T", "TRACE":
		return Trace
	case "D", "DEBUG":
		return Debug
	case "I", "INFO":
		return Info
	case "W", "WARN":
		return Warn
	case "E", "ERROR":
		return Error
	case "F", "FATAL":
		return Fatal
	}
	return Info
}

var (
	Trace   = New(Bold, FgCyan)
	Debug   = New(Bold, FgBlue)
	Info    = New(Bold, FgGreen)
	Warn    = New(Bold, FgYellow)
	Error   = New(Bold, FgRed)
	Fatal   = New(Bold, BgRed)
	Default = New()
	Time    = Default
	Stack   = Default
)