package handler

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

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

// ReminderHandler serves the sādhana-reminder preference + the timezone the
// scheduler fires against. All routes require auth.
type ReminderHandler struct {
	svc *service.ReminderService
}

func NewReminderHandler(svc *service.ReminderService) *ReminderHandler {
	return &ReminderHandler{svc: svc}
}

type reminderPrefResp struct {
	Enabled bool `json:"enabled"`
}

// GetPrefs — GET /sadhna/reminders. Whether reminders are on for the caller.
func (h *ReminderHandler) GetPrefs(w http.ResponseWriter, r *http.Request) {
	uid := middleware.UserID(r.Context())
	enabled, err := h.svc.Enabled(r.Context(), uid)
	if err != nil {
		response.Error(w, http.StatusInternalServerError, "could not load reminder preference")
		return
	}
	response.JSON(w, http.StatusOK, reminderPrefResp{Enabled: enabled})
}

// UpdatePrefs — PUT /sadhna/reminders { enabled }. Toggles reminders.
func (h *ReminderHandler) UpdatePrefs(w http.ResponseWriter, r *http.Request) {
	uid := middleware.UserID(r.Context())
	var req struct {
		Enabled bool `json:"enabled"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		response.Error(w, http.StatusBadRequest, "invalid JSON body")
		return
	}
	if err := h.svc.SetEnabled(r.Context(), uid, req.Enabled); err != nil {
		response.Error(w, http.StatusInternalServerError, "could not update reminder preference")
		return
	}
	response.JSON(w, http.StatusOK, reminderPrefResp{Enabled: req.Enabled})
}

// SetTimezone — POST /sadhna/timezone { timezone }. The browser reports its
// IANA zone so reminders fire at local time.
func (h *ReminderHandler) SetTimezone(w http.ResponseWriter, r *http.Request) {
	uid := middleware.UserID(r.Context())
	var req struct {
		Timezone string `json:"timezone"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		response.Error(w, http.StatusBadRequest, "invalid JSON body")
		return
	}
	if err := h.svc.SetTimezone(r.Context(), uid, req.Timezone); err != nil {
		if errors.Is(err, service.ErrInvalidTimezone) {
			response.Error(w, http.StatusBadRequest, "invalid timezone")
			return
		}
		response.Error(w, http.StatusInternalServerError, "could not save timezone")
		return
	}
	response.NoContent(w)
}