package api

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

	"geniusrun/backend/internal/garmin"
)

type authResponse struct {
	Status  string `json:"status"` // "authenticated" | "mfa_required" | "failed"
	Message string `json:"message"`
}

func authStatusString(s garmin.AuthStatus) string {
	switch s {
	case garmin.AuthSuccess:
		return "authenticated"
	case garmin.AuthMFARequired:
		return "mfa_required"
	case garmin.AuthFailed:
		return "failed"
	default:
		return "unknown"
	}
}

// recordAuthResult updates the in-memory auth status/message for userID,
// and -- on a successful authentication -- persists that this account has
// connected to Garmin at least once (store.MarkGarminConnected), which is
// what the login gate actually checks (the in-memory auth status resets on
// every backend restart; this doesn't).
func (s *Server) recordAuthResult(ctx context.Context, userID int64, res garmin.AuthResult) {
	s.mu.Lock()
	s.userAuthStatus[userID] = res.Status
	s.userAuthMessage[userID] = res.Message
	s.mu.Unlock()

	if res.Status == garmin.AuthSuccess {
		if err := s.DB.MarkGarminConnected(ctx, userID); err != nil {
			log.Printf("api: mark garmin connected for user %d: %v", userID, err)
		}
	}
}

func (s *Server) handleAuthLogin(w http.ResponseWriter, r *http.Request) {
	userID := userIDFromContext(r.Context())
	client, err := s.garminFor(r.Context(), userID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	res, err := client.Authenticate(r.Context())
	if err != nil {
		writeError(w, http.StatusBadGateway, err.Error())
		return
	}
	s.recordAuthResult(r.Context(), userID, res)
	writeJSON(w, http.StatusOK, authResponse{Status: authStatusString(res.Status), Message: res.Message})
}

func (s *Server) handleAuthMFA(w http.ResponseWriter, r *http.Request) {
	userID := userIDFromContext(r.Context())
	var body struct {
		Code string `json:"code"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}
	if body.Code == "" {
		writeError(w, http.StatusBadRequest, "code is required")
		return
	}

	client, err := s.garminFor(r.Context(), userID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	res, err := client.CompleteMFA(r.Context(), body.Code)
	if err != nil {
		writeError(w, http.StatusBadGateway, err.Error())
		return
	}
	s.recordAuthResult(r.Context(), userID, res)
	writeJSON(w, http.StatusOK, authResponse{Status: authStatusString(res.Status), Message: res.Message})
}

func (s *Server) handleAuthStatus(w http.ResponseWriter, r *http.Request) {
	userID := userIDFromContext(r.Context())
	s.mu.Lock()
	status, msg := s.userAuthStatus[userID], s.userAuthMessage[userID]
	s.mu.Unlock()
	writeJSON(w, http.StatusOK, authResponse{Status: authStatusString(status), Message: msg})
}