package user

import (
	"encoding/json"
	"log/slog"
	"net/http"

	"github.com/food-ai/backend/internal/infra/middleware"
)

const maxRequestBodySize = 1 << 20 // 1 MB

type Handler struct {
	service *Service
}

func NewHandler(service *Service) *Handler {
	return &Handler{service: service}
}

func (h *Handler) Get(w http.ResponseWriter, r *http.Request) {
	userID := middleware.UserIDFromCtx(r.Context())
	if userID == "" {
		writeErrorJSON(w, r, http.StatusUnauthorized, "unauthorized")
		return
	}

	u, err := h.service.GetProfile(r.Context(), userID)
	if err != nil {
		writeErrorJSON(w, r, http.StatusNotFound, "user not found")
		return
	}

	writeJSON(w, http.StatusOK, u)
}

func (h *Handler) Update(w http.ResponseWriter, r *http.Request) {
	userID := middleware.UserIDFromCtx(r.Context())
	if userID == "" {
		writeErrorJSON(w, r, http.StatusUnauthorized, "unauthorized")
		return
	}

	r.Body = http.MaxBytesReader(w, r.Body, maxRequestBodySize)
	var req UpdateProfileRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeErrorJSON(w, r, http.StatusBadRequest, "invalid request body")
		return
	}

	u, err := h.service.UpdateProfile(r.Context(), userID, req)
	if err != nil {
		writeErrorJSON(w, r, http.StatusBadRequest, err.Error())
		return
	}

	writeJSON(w, http.StatusOK, u)
}

type errorResponse struct {
	Error     string `json:"error"`
	RequestID string `json:"request_id,omitempty"`
}

func writeErrorJSON(w http.ResponseWriter, r *http.Request, status int, msg string) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	if encodeErr := json.NewEncoder(w).Encode(errorResponse{
		Error:     msg,
		RequestID: middleware.RequestIDFromCtx(r.Context()),
	}); encodeErr != nil {
		slog.ErrorContext(r.Context(), "failed to write error response", "err", encodeErr)
	}
}

func writeJSON(w http.ResponseWriter, status int, v interface{}) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	if err := json.NewEncoder(w).Encode(v); err != nil {
		slog.Error("failed to write JSON response", "err", err)
	}
}