Go server

main.go

package main

import (
    "fmt"
    "log"
    "math/rand"
    "net/http"
    "time"
)

const DateLogFormat = "2006-01-02 15:04:05.000 -07:00"

func main() {
    log.SetFlags(0)
    log.SetOutput(new(logger))

    server := provideServer()

    log.Printf("Listening on %s...\n", server.Addr)
    log.Fatal(server.ListenAndServe())
}

type logger struct{}

func (writer logger) Write(bytes []byte) (int, error) {
    return fmt.Print(time.Now().Format(DateLogFormat) + " " + string(bytes))
}

type loggingResponseWriter struct {
    http.ResponseWriter
    statusCode int 
}

func NewLoggingResponseWriter(w http.ResponseWriter) *loggingResponseWriter {
    return &loggingResponseWriter{w, http.StatusOK}
}

func (lrw *loggingResponseWriter) WriteHeader(code int) {
    lrw.statusCode = code
    lrw.ResponseWriter.WriteHeader(code)
}

type Handler func(http.ResponseWriter, *http.Request) error
type AuthenticationHandler func(http.ResponseWriter, *http.Request) error

// intercept takes an authentication handler and a custom http handler
// and calls them respectively then logs the result.
// This function does not and should not mutate the response writer whatsoever
func intercept(handle Handler, authenticate AuthenticationHandler) http.HandlerFunc {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        id := rand.Int()
        before := time.Now()
        b := before.Format(DateLogFormat)
        fmt.Printf("%s - %d [%s] \"%s %s %s\" Received Request\n", r.RemoteAddr, id, b, r.Method, r.URL.String(), r.Proto)

        lrw := NewLoggingResponseWriter(w)

        if err := authenticate(lrw, r); err != nil {
            statusCode := lrw.statusCode
            a := time.Now().Format(DateLogFormat)
            fmt.Printf("%s - %d [%s] \"%s %s %s\" %d %dms Error Response: %s\n", r.RemoteAddr, id, a, r.Method, r.URL.String(), r.Proto, statusCode, time.Since(before), err.Error())
            return
        }   

        err := handle(lrw, r)
        statusCode := lrw.statusCode

        after := time.Now()
        a := after.Format(DateLogFormat)

        if err != nil {
            fmt.Printf("%s - %d [%s] \"%s %s %s\" %d %dms Error Response: %s\n", r.RemoteAddr, id, a, r.Method, r.URL.String(), r.Proto, statusCode, time.Since(before), err.Error())
            return
        }   

        fmt.Printf("%s - %d [%s] \"%s %s %s\" %d %dms Responded Successfully\n",
            r.RemoteAddr, id, a, r.Method, r.URL.String(), r.Proto, statusCode, time.Since(before))
    })  
}