justcaptcha/internal/handlers/handlers.go

package handlers

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

const errMsgNotFound = "CAPTCHA with such ID doesn't exist"
const errMsgWrongAnswer = "An answer provided was wrong"
const errMsgFailedToGenImage = "failed to generate an image for a CAPTCHA"
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, err := inmemdb.Image(captchaID, captchaStyle)
	if err != nil {
		w.WriteHeader(http.StatusNotFound)
		fmt.Fprint(w, errMsgImageNotFound)
		return
	}

	if captchaImage == nil {
		w.WriteHeader(http.StatusInternalServerError)
		fmt.Fprint(w, errMsgFailedToGenImage)
		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"))

	ok, err := inmemdb.Solve(captchaID, answer)
	if err != nil {
		w.WriteHeader(http.StatusNotFound)
		fmt.Fprint(w, errMsgNotFound)
		return
	}

	if !ok {
		w.WriteHeader(http.StatusForbidden)
		fmt.Fprint(w, errMsgWrongAnswer)
		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")

	w.WriteHeader(http.StatusNoContent)

	if isJustRemove {
		inmemdb.Remove(captchaID)
		return
	}

	solved, err := inmemdb.IsSolved(captchaID)
	if err != nil {
		w.WriteHeader(http.StatusNotFound)
		fmt.Fprint(w, errMsgNotFound)
		return
	}

	if !solved {
		w.WriteHeader(http.StatusForbidden)
		fmt.Fprint(w, errMsgWrongAnswer)
	}
}