package apperr

import (
	"errors"

	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

// Error 表示网关内部统一业务错误。
type Error struct {
	Status  int
	Code    string
	Message string
}

func (e *Error) Error() string {
	return e.Message
}

// New 构造一个统一错误，便于 HTTP 层直接映射。
func New(status int, code string, message string) *Error {
	return &Error{
		Status:  status,
		Code:    code,
		Message: message,
	}
}

// Resolve 将任意错误转换成统一 HTTP 状态码和错误码。
func Resolve(err error) (statusCode int, code string, message string) {
	if err == nil {
		return 200, "ok", "ok"
	}

	var appErr *Error
	if errors.As(err, &appErr) {
		return appErr.Status, appErr.Code, appErr.Message
	}

	grpcStatus, ok := status.FromError(err)
	if !ok {
		return 500, "internal_error", "internal server error"
	}

	switch grpcStatus.Code() {
	case codes.InvalidArgument:
		return 400, "bad_request", grpcStatus.Message()
	case codes.Unauthenticated, codes.PermissionDenied:
		return 401, "unauthorized", grpcStatus.Message()
	case codes.NotFound:
		return 404, "not_found", grpcStatus.Message()
	case codes.DeadlineExceeded:
		return 504, "upstream_timeout", "upstream request timeout"
	default:
		return 502, "upstream_error", grpcStatus.Message()
	}
}