package app

import (
	"context"
	"crypto/subtle"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"strconv"
	"time"

	"evening_detective_server/internal/repos/teams_repo"
	"evening_detective_server/internal/services/game_service"
)

// TeamRegistrationHandler принимает webhook Яндекс Форм отдельно от пользовательского JWT.
func TeamRegistrationHandler(token string, register func(context.Context, int, string, game_service.Registration) (int, error)) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		w.Header().Set("Cache-Control", "no-store")
		fail := func(code int, message string) {
			w.WriteHeader(code)
			_ = json.NewEncoder(w).Encode(map[string]string{"error": message})
		}
		if token == "" {
			fail(http.StatusServiceUnavailable, "Интеграция регистрации не настроена")
			return
		}
		if subtle.ConstantTimeCompare([]byte(r.Header.Get("Authorization")), []byte("Bearer "+token)) != 1 {
			fail(http.StatusUnauthorized, "Неверный токен интеграции")
			return
		}
		gameID, err := strconv.ParseInt(r.PathValue("id"), 10, 32)
		deliveryID := r.Header.Get("X-Delivery-Id")
		if err != nil || gameID <= 0 || deliveryID == "" || len(deliveryID) > 255 {
			fail(http.StatusBadRequest, "Требуются ID игры и заголовок X-Delivery-Id (до 255 байт)")
			return
		}
		decoder := json.NewDecoder(http.MaxBytesReader(w, r.Body, 16<<10))
		decoder.DisallowUnknownFields()
		var registration game_service.Registration
		if err := decoder.Decode(&registration); err != nil {
			fail(http.StatusBadRequest, "Некорректный JSON регистрации")
			return
		}
		if err := decoder.Decode(new(any)); err != io.EOF {
			fail(http.StatusBadRequest, "Ожидается один JSON-объект")
			return
		}
		ctx, cancel := context.WithTimeout(r.Context(), 4*time.Second)
		defer cancel()
		id, err := register(ctx, int(gameID), deliveryID, registration)
		switch {
		case errors.Is(err, game_service.ErrInvalidRegistration):
			fail(http.StatusBadRequest, err.Error())
		case errors.Is(err, teams_repo.ErrRegistrationClosed):
			fail(http.StatusConflict, err.Error())
		case err != nil:
			fail(http.StatusInternalServerError, "Не удалось зарегистрировать команду")
		default:
			_ = json.NewEncoder(w).Encode(map[string]int{"id": id})
		}
	})
}