package main

import (
	"bytes"
	"io"
	"strings"
)

const (
	colorReset   = "\033[0m"
	colorDim     = "\033[2m"
	colorCyan    = "\033[36m"
	colorBlue    = "\033[94m"
	colorGreen   = "\033[32m"
	colorYellow  = "\033[33m"
	colorRed     = "\033[31m"
	colorMagenta = "\033[35m"
)

type colorLineWriter struct {
	w   io.Writer
	buf []byte
}

func newColorLineWriter(w io.Writer) *colorLineWriter {
	return &colorLineWriter{w: w, buf: make([]byte, 0, 1024)}
}

func (c *colorLineWriter) Write(p []byte) (int, error) {
	c.buf = append(c.buf, p...)
	for {
		i := bytes.IndexByte(c.buf, '\n')
		if i < 0 {
			break
		}
		line := c.buf[:i]
		if _, err := c.w.Write([]byte(colorizeLine(string(line)) + "\n")); err != nil {
			return 0, err
		}
		c.buf = c.buf[i+1:]
	}
	return len(p), nil
}

func colorizeLine(line string) string {
	lower := strings.ToLower(line)
	lineColor := colorCyan
	switch {
	case strings.Contains(lower, "error") || strings.Contains(lower, "failed") || strings.Contains(lower, "disconnected"):
		lineColor = colorRed
	case strings.Contains(lower, "warn"):
		lineColor = colorYellow
	case strings.Contains(lower, "connected") || strings.Contains(lower, "listening") || strings.Contains(lower, "started"):
		lineColor = colorGreen
	case strings.Contains(lower, "public key") || strings.Contains(lower, "ipv6") || strings.Contains(lower, "interface"):
		lineColor = colorBlue
	case strings.Contains(lower, "sandbox"):
		lineColor = colorMagenta
	}

	if len(line) > 20 && line[4] == '/' && line[7] == '/' && line[10] == ' ' && line[13] == ':' && line[16] == ':' {
		timestamp := line[:19]
		rest := strings.TrimLeft(line[19:], " ")
		return colorDim + timestamp + colorReset + " " + lineColor + rest + colorReset
	}
	return lineColor + line + colorReset
}