solher/zest

package zest

import (
    "log"
    "net/http"
    "os"
    "time"

    "github.com/codegangsta/negroni"
)

// Logger is a middleware handler that logs the request as it goes in and the response as it goes out.
type Logger struct {
    // Logger inherits from log.Logger used to log messages with the Logger middleware.
    *log.Logger
}

// NewLogger returns a new Logger instance
func NewLogger() *Logger {
    return &Logger{log.New(os.Stdout, "\n[Zest] ", 0)}
}

func (l *Logger) ServeHTTP(rw http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
    path := r.URL.Path
    // start timer
    start := time.Now()

    clientIP := r.RemoteAddr
    method := r.Method
    methodColor := colorForMethod(method)

    // process request
    next(rw, r)

    // stop timer
    end := time.Now()
    latency := end.Sub(start)

    res := rw.(negroni.ResponseWriter)
    statusCode := res.Status()
    statusColor := colorForStatus(statusCode)

    l.Printf("%v | %s %3d %s | %v | %s | %s %s %s %s",
        end.Format("2006/01/02 - 15:04:05"),
        statusColor, statusCode, reset,
        latency,
        clientIP,
        methodColor, method, reset,
        path,
    )
}

var (
    green   = string([]byte{27, 91, 57, 55, 59, 52, 50, 109})
    white   = string([]byte{27, 91, 57, 48, 59, 52, 55, 109})
    yellow  = string([]byte{27, 91, 57, 55, 59, 52, 51, 109})
    red     = string([]byte{27, 91, 57, 55, 59, 52, 49, 109})
    blue    = string([]byte{27, 91, 57, 55, 59, 52, 52, 109})
    magenta = string([]byte{27, 91, 57, 55, 59, 52, 53, 109})
    cyan    = string([]byte{27, 91, 57, 55, 59, 52, 54, 109})
    reset   = string([]byte{27, 91, 48, 109})
)

func colorForStatus(code int) string {
    switch {
    case code >= 200 && code < 300:
        return green
    case code >= 300 && code < 400:
        return white
    case code >= 400 && code < 500:
        return yellow
    default:
        return red
    }
}

func colorForMethod(method string) string {
    switch method {
    case "GET":
        return blue
    case "POST":
        return cyan
    case "PUT":
        return yellow
    case "DELETE":
        return red
    case "PATCH":
        return green
    case "HEAD":
        return magenta
    case "OPTIONS":
        return white
    default:
        return reset
    }
}