glchat/internal/server/errors.go

package server

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

	"glchat/internal/auth"
	"glchat/internal/httpx"
	"glchat/internal/permissions"
	"glchat/internal/store"
)

// apiError — доменная ошибка с кодом для клиента (AGENT.md 8.5).
type apiError struct {
	Status  int    `json:"-"`
	Code    string `json:"code"`
	Message string `json:"message"`
	cause   error
}

func (e apiError) Error() string { return e.Code + ": " + e.Message }
func (e apiError) Unwrap() error { return e.cause }

// newAPIError подбирает код и статус по доменной ошибке.
func newAPIError(err error) apiError {
	candidate := apiError{Status: http.StatusInternalServerError, Code: "internal.error", Message: "internal error", cause: err}
	switch {
	case errors.Is(err, auth.ErrInvalidCredentials):
		candidate.Status, candidate.Code, candidate.Message = http.StatusUnauthorized, "auth.invalid_credentials", "invalid credentials"
	case errors.Is(err, auth.ErrTOTPRequired):
		candidate.Status, candidate.Code, candidate.Message = http.StatusUnauthorized, "auth.2fa_required", "two-factor code required"
	case errors.Is(err, auth.ErrTOTPInvalid):
		candidate.Status, candidate.Code, candidate.Message = http.StatusBadRequest, "auth.totp_invalid", "invalid two-factor code"
	case errors.Is(err, auth.ErrInstanceAdminTOTP):
		candidate.Status, candidate.Code = http.StatusForbidden, "auth.2fa_enrollment_required"
		candidate.Message = "instance administrator must enable two-factor authentication: run `glchat totp-setup --email <admin>` on the server"
	case errors.Is(err, auth.ErrUserBanned):
		candidate.Status, candidate.Code = http.StatusForbidden, "user.banned"
		candidate.Message = "account is banned on this instance"
	case errors.Is(err, auth.ErrSessionExpired):
		candidate.Status, candidate.Code, candidate.Message = http.StatusUnauthorized, "auth.session_expired", "session expired"
	case errors.Is(err, auth.ErrStepUpRequired):
		candidate.Status, candidate.Code = http.StatusForbidden, "auth.step_up_required"
		candidate.Message = "step-up authentication required"
	case errors.Is(err, auth.ErrUsernameTaken):
		candidate.Status, candidate.Code, candidate.Message = http.StatusConflict, "auth.username_taken", "username is already taken"
	case errors.Is(err, auth.ErrEmailTaken):
		candidate.Status, candidate.Code, candidate.Message = http.StatusConflict, "auth.email_taken", "email is already registered"
	case errors.Is(err, auth.ErrRegistrationOff):
		candidate.Status, candidate.Code = http.StatusForbidden, "auth.registration_disabled"
		candidate.Message = "registration is disabled"
	case errors.Is(err, auth.ErrWeakPassword):
		candidate.Status, candidate.Code, candidate.Message = http.StatusUnprocessableEntity, "auth.weak_password", err.Error()
	case errors.Is(err, auth.ErrInvalidUsername):
		candidate.Status, candidate.Code, candidate.Message = http.StatusUnprocessableEntity, "auth.invalid_username", err.Error()
	case errors.Is(err, auth.ErrTOTPAlreadyEnabled):
		candidate.Status, candidate.Code = http.StatusConflict, "auth.2fa_already_enabled"
		candidate.Message = "two-factor authentication is already enabled"
	case errors.Is(err, auth.ErrNoTOTPSecret):
		candidate.Status, candidate.Code = http.StatusBadRequest, "auth.2fa_not_configured"
		candidate.Message = "two-factor authentication is not configured"
	case errors.Is(err, store.ErrNotFound):
		candidate.Status, candidate.Code, candidate.Message = http.StatusNotFound, "not_found", "resource not found"
	case errors.Is(err, store.ErrConflict):
		candidate.Status, candidate.Code, candidate.Message = http.StatusConflict, "conflict", "resource already exists"
	case errors.Is(err, permissions.ErrDenied):
		candidate.Status, candidate.Code, candidate.Message = http.StatusForbidden, "perm.denied", "permission denied"
	}
	return candidate
}

// writeAPIError отдаёт ошибку в едином формате с машиночитаемым кодом.
func writeAPIError(w http.ResponseWriter, err error) {
	apiErr := newAPIError(err)
	if apiErr.Status >= http.StatusInternalServerError {
		// Неожиданную ошибку пишем в лог: клиент видит «internal error», а
		// разобраться без текста ошибки невозможно (AGENT.md 9.4).
		slog.Error("unexpected API error", slog.String("code", apiErr.Code), slog.Any("error", err))
		apiErr.Message = "internal error"
	}
	httpx.WriteJSON(w, apiErr.Status, map[string]any{
		"error": map[string]any{
			"code":    apiErr.Code,
			"message": apiErr.Message,
		},
	})
}

// writeHumaAPIError отдаёт ошибку chi-ручки: huma-ошибки уже несут код и
// статус, доменные ошибки переводит writeAPIError (AGENT.md 8.5).
func writeHumaAPIError(w http.ResponseWriter, err error) {
	var apiErr *humaAPIError
	if errors.As(err, &apiErr) {
		httpx.WriteJSON(w, apiErr.status, map[string]any{
			"error": map[string]any{"code": apiErr.code, "message": apiErr.message},
		})
		return
	}
	writeAPIError(w, err)
}

// writeJSON пишет успешный ответ (все текущие ручки возвращают 200).
func writeJSON(w http.ResponseWriter, body any) {
	httpx.WriteJSON(w, http.StatusOK, body)
}

// decodeBody читает JSON-тело с ограничением размера.
func decodeBody(w http.ResponseWriter, r *http.Request, dst any) bool {
	if r.Body == nil {
		writeAPIError(w, errors.New("empty request body"))
		return false
	}
	decoder := json.NewDecoder(http.MaxBytesReader(w, r.Body, 1<<20))
	decoder.DisallowUnknownFields()
	if err := decoder.Decode(dst); err != nil {
		httpx.WriteJSON(w, http.StatusBadRequest, map[string]any{
			"error": map[string]any{"code": "request.bad", "message": "malformed json body"},
		})
		return false
	}
	return true
}