package handler

import (
	"encoding/json"
	"net/http"
	"strings"

	"github.com/prabhupadasays/spsays-bff/internal/middleware"
	"github.com/prabhupadasays/spsays-bff/internal/repository"
	"github.com/prabhupadasays/spsays-bff/internal/service"
	"github.com/prabhupadasays/spsays-bff/pkg/response"
)

// PushHandler serves Web Push subscription management. The VAPID public key
// is handed to the browser so it can subscribe; subscriptions are stored per
// user. All routes require auth.
type PushHandler struct {
	push *service.PushSender // optional — nil when VAPID isn't configured
	repo *repository.PushRepo
}

func NewPushHandler(push *service.PushSender, repo *repository.PushRepo) *PushHandler {
	return &PushHandler{push: push, repo: repo}
}

// Key — GET /push/key. Returns the VAPID public key + whether push is on.
func (h *PushHandler) Key(w http.ResponseWriter, r *http.Request) {
	response.JSON(w, http.StatusOK, struct {
		PublicKey string `json:"public_key"`
		Enabled   bool   `json:"enabled"`
	}{
		PublicKey: h.push.PublicKey(),
		Enabled:   h.push.Enabled(),
	})
}

type subscribeReq struct {
	Endpoint string `json:"endpoint"`
	Keys     struct {
		P256dh string `json:"p256dh"`
		Auth   string `json:"auth"`
	} `json:"keys"`
}

// Subscribe — POST /push/subscribe. Stores (or refreshes) the caller's push
// subscription. Body is the browser PushSubscription JSON.
func (h *PushHandler) Subscribe(w http.ResponseWriter, r *http.Request) {
	if h.repo == nil || !h.push.Enabled() {
		response.Error(w, http.StatusServiceUnavailable, "push not configured")
		return
	}
	uid := middleware.UserID(r.Context())
	var req subscribeReq
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		response.Error(w, http.StatusBadRequest, "invalid JSON body")
		return
	}
	if req.Endpoint == "" || req.Keys.P256dh == "" || req.Keys.Auth == "" {
		response.Error(w, http.StatusBadRequest, "missing subscription fields")
		return
	}
	if err := h.repo.Upsert(r.Context(), uid, req.Endpoint, req.Keys.P256dh, req.Keys.Auth, r.UserAgent()); err != nil {
		response.Error(w, http.StatusInternalServerError, "could not save subscription")
		return
	}
	response.NoContent(w)
}

type unsubscribeReq struct {
	Endpoint string `json:"endpoint"`
}

// Unsubscribe — POST /push/unsubscribe. Removes a subscription by endpoint.
func (h *PushHandler) Unsubscribe(w http.ResponseWriter, r *http.Request) {
	if h.repo == nil {
		response.NoContent(w)
		return
	}
	var req unsubscribeReq
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || strings.TrimSpace(req.Endpoint) == "" {
		response.Error(w, http.StatusBadRequest, "missing endpoint")
		return
	}
	if err := h.repo.DeleteByEndpoint(r.Context(), req.Endpoint); err != nil {
		response.Error(w, http.StatusInternalServerError, "could not remove subscription")
		return
	}
	response.NoContent(w)
}