package log

import (
	"github.com/mattn/go-isatty"
	"os"
)

type Colorer interface {
	Black(s string) string
	Red(s string) string
	Green(s string) string
	Yellow(s string) string
	Blue(s string) string
	Magenta(s string) string
	Cyan(s string) string
	White(s string) string
	Grey(s string) string
}

func NewColorer() Colorer {
	return &colorer{}
}

type clr string

const (
	black   clr = "\x1b[30m"
	red     clr = "\x1b[31m"
	green   clr = "\x1b[32m"
	yellow  clr = "\x1b[33m"
	blue    clr = "\x1b[34m"
	magenta clr = "\x1b[35m"
	cyan    clr = "\x1b[36m"
	white   clr = "\x1b[37m"
	grey    clr = "\x1b[90m"
)

var (
	// NoColor defines if the output is colorized or not. It's dynamically set to
	// false or true based on the stdout's file descriptor referring to a terminal
	// or not. It's also set to true if the NO_COLOR environment variable is
	// set (regardless of its value). This is a global option and affects all
	// colors. For more control over each Color block use the methods
	// DisableColor() individually.
	noColor = noColorIsSet() || os.Getenv("TERM") == "dumb" ||
		(!isatty.IsTerminal(os.Stdout.Fd()) && !isatty.IsCygwinTerminal(os.Stdout.Fd()))
)

// noColorIsSet returns true if the environment variable NO_COLOR is set to a non-empty string.
func noColorIsSet() bool {
	return os.Getenv("NO_COLOR") != ""
}

func (c clr) f(s string) string {
	if noColorIsSet() || noColor {
		return s
	}
	return string(c) + s + "\x1b[0m"
}

type colorer struct{}

func (c *colorer) Black(s string) string   { return black.f(s) }
func (c *colorer) Red(s string) string     { return red.f(s) }
func (c *colorer) Green(s string) string   { return green.f(s) }
func (c *colorer) Yellow(s string) string  { return yellow.f(s) }
func (c *colorer) Blue(s string) string    { return blue.f(s) }
func (c *colorer) Magenta(s string) string { return magenta.f(s) }
func (c *colorer) Cyan(s string) string    { return cyan.f(s) }
func (c *colorer) White(s string) string   { return white.f(s) }
func (c *colorer) Grey(s string) string    { return grey.f(s) }