golang-utils/utils/http/helpers/helpers.go

package helpers

import (
	"errors"
	"fmt"
	"log"
	"net/http"
	"os"
	"regexp"
	"runtime"
	"strconv"
	"time"

	"github.com/vladimirok5959/golang-server-sessions/session"
)

// func HandlerApplicationStatus() http.Handler
// func HandlerBuildInFile(data, contentType string) http.Handler
// func MinifyHtmlCode(str string) string
// func RespondAsBadRequest(w http.ResponseWriter, r *http.Request, err error)
// func RespondAsMethodNotAllowed(w http.ResponseWriter, r *http.Request)
// func SessionStart(w http.ResponseWriter, r *http.Request) (*session.Session, error)
// func SetLanguageCookie(w http.ResponseWriter, r *http.Request) error

var mHtml = regexp.MustCompile(`>[\n\t\r\s]+<`)
var mHtmlLeft = regexp.MustCompile(`>[\n\t\r\s]+`)
var mHtmlRight = regexp.MustCompile(`[\n\t\r\s]+<`)

func HandlerApplicationStatus() http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			RespondAsMethodNotAllowed(w, r)
			return
		}
		var m runtime.MemStats
		runtime.ReadMemStats(&m)
		memory := fmt.Sprintf(
			`{"alloc":"%v","total_alloc":"%v","sys":"%v","num_gc":"%v"}`,
			m.Alloc, m.TotalAlloc, m.Sys, m.NumGC,
		)
		w.Header().Set("Content-Type", "application/json")
		if _, err := w.Write([]byte(fmt.Sprintf(`{"routines":%d,"memory":%s}`, runtime.NumGoroutine(), memory))); err != nil {
			log.Printf("%s\n", err.Error())
		}
	})
}

func HandlerBuildInFile(data, contentType string) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			RespondAsMethodNotAllowed(w, r)
			return
		}
		w.Header().Set("Content-Type", contentType)
		if _, err := w.Write([]byte(data)); err != nil {
			fmt.Printf("%s\n", err.Error())
		}
	})
}

func MinifyHtmlCode(str string) string {
	str = mHtml.ReplaceAllString(str, "><")
	str = mHtmlLeft.ReplaceAllString(str, ">")
	str = mHtmlRight.ReplaceAllString(str, "<")
	return str
}

func RespondAsBadRequest(w http.ResponseWriter, r *http.Request, err error) {
	if err != nil {
		log.Printf("%s\n", err.Error())
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusBadRequest)
		if _, e := w.Write([]byte(`{"error":"` + strconv.Quote(err.Error()) + `"}`)); e != nil {
			log.Printf("%s\n", e.Error())
		}
	} else {
		w.WriteHeader(http.StatusBadRequest)
	}
}

func RespondAsMethodNotAllowed(w http.ResponseWriter, r *http.Request) {
	w.WriteHeader(http.StatusMethodNotAllowed)
}

// Example:
//
// sess := helpers.SessionStart(w, r)
//
// defer sess.Close()
func SessionStart(w http.ResponseWriter, r *http.Request) (*session.Session, error) {
	sess, err := session.New(w, r, "/tmp")
	if err != nil && !errors.Is(err, os.ErrNotExist) {
		log.Printf("%s\n", err.Error())
	}
	return sess, err
}

func SetLanguageCookie(w http.ResponseWriter, r *http.Request) error {
	var clang string
	if c, err := r.Cookie("lang"); err == nil {
		clang = c.Value
	}
	// if err := r.ParseForm(); err != nil {
	// 	RespondAsBadRequest(w, r, err)
	// 	return err
	// }
	lang := r.Form.Get("lang")
	if lang != "" && lang != clang {
		http.SetCookie(w, &http.Cookie{
			Name:     "lang",
			Value:    lang,
			Expires:  time.Now().Add(365 * 24 * time.Hour),
			HttpOnly: true,
		})
	}
	return nil
}