justcaptcha/internal/handlers/handlers.go

package handlers

import (
	"fmt"
	"image/jpeg"
	"justcaptcha/internal/server"
	"justcaptcha/pkg/captcha"
	"justcaptcha/pkg/captcha/inmemdb"
	"justcaptcha/pkg/dwcaptcha"
	"net/http"
	"time"
)

const errMsgWrongAnswer = "An answer provided was wrong"
const errMsgImageNotFound = "cannot get an image for a non-existing CAPTCHA"

type CaptchaHandlers struct {
	expiry time.Duration
}

func New(expiry time.Duration) *CaptchaHandlers {
	inmemdb.SetExpiry(expiry)
	return &CaptchaHandlers{expiry: expiry}
}

func (h *CaptchaHandlers) New(w http.ResponseWriter, r *http.Request) {
	dc := dwcaptcha.NewDwellingCaptcha(h.expiry)
	_, id := inmemdb.New(r.RemoteAddr, dc)
	w.WriteHeader(http.StatusCreated)
	fmt.Fprint(w, id)
}

func (h *CaptchaHandlers) Image(w http.ResponseWriter, r *http.Request) {
	captchaID := captcha.ID(server.GetURLParam(r, "captcha"))
	captchaStyle := r.URL.Query().Get("style")

	captchaImage := inmemdb.Image(captchaID, captchaStyle)
	if captchaImage == nil {
		http.Error(w, errMsgImageNotFound, http.StatusNotFound)
		return
	}

	w.Header().Add("Content-Disposition", "inline; filename=\""+string(captchaID)+"\"")

	jpeg.Encode(w, *captchaImage, &jpeg.Options{Quality: 20})
}

func (h *CaptchaHandlers) Solve(w http.ResponseWriter, r *http.Request) {
	captchaID := captcha.ID(server.GetURLParam(r, "captcha"))

	r.ParseForm()
	answer := captcha.Answer(r.FormValue("answer"))

	if ok := inmemdb.Solve(captchaID, answer); !ok {
		http.Error(w, errMsgWrongAnswer, http.StatusForbidden)
		return
	}

	w.WriteHeader(http.StatusAccepted)
}

func (h *CaptchaHandlers) IsSolved(w http.ResponseWriter, r *http.Request) {
	captchaID := captcha.ID(server.GetURLParam(r, "captcha"))
	isJustRemove := r.URL.Query().Has("remove")

	if isJustRemove {
		inmemdb.Remove(captchaID)
		w.WriteHeader(http.StatusNoContent)
		return
	}

	if solved := inmemdb.IsSolved(captchaID); !solved {
		http.Error(w, errMsgWrongAnswer, http.StatusForbidden)
		return
	}

	w.WriteHeader(http.StatusNoContent)
}