// Copyright 2021-2025 The Connect Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package connect

import "fmt"

// An IdempotencyLevel is a value that declares how "idempotent" an RPC is. This
// value can affect RPC behaviors, such as determining whether it is safe to
// retry a request, or what kinds of request modalities are allowed for a given
// procedure.
type IdempotencyLevel int

// NOTE: For simplicity, these should be kept in sync with the values of the
// google.protobuf.MethodOptions.IdempotencyLevel enumeration.

const (
	// IdempotencyUnknown is the default idempotency level. A procedure with
	// this idempotency level may not be idempotent. This is appropriate for
	// any kind of procedure.
	IdempotencyUnknown IdempotencyLevel = 0

	// IdempotencyNoSideEffects is the idempotency level that specifies that a
	// given call has no side-effects. This is equivalent to [RFC 9110 § 9.2.1]
	// "safe" methods in terms of semantics. This procedure should not mutate
	// any state. This idempotency level is appropriate for queries, or anything
	// that would be suitable for an HTTP GET request. In addition, due to the
	// lack of side-effects, such a procedure would be suitable to retry and
	// expect that the results will not be altered by preceding attempts.
	//
	// [RFC 9110 § 9.2.1]: https://www.rfc-editor.org/rfc/rfc9110.html#section-9.2.1
	IdempotencyNoSideEffects IdempotencyLevel = 1

	// IdempotencyIdempotent is the idempotency level that specifies that a
	// given call is "idempotent", such that multiple instances of the same
	// request to this procedure would have the same side-effects as a single
	// request. This is equivalent to [RFC 9110 § 9.2.2] "idempotent" methods.
	// This level is a subset of the previous level. This idempotency level is
	// appropriate for any procedure that is safe to retry multiple times
	// and be guaranteed that the response and side-effects will not be altered
	// as a result of multiple attempts, for example, entity deletion requests.
	//
	// [RFC 9110 § 9.2.2]: https://www.rfc-editor.org/rfc/rfc9110.html#section-9.2.2
	IdempotencyIdempotent IdempotencyLevel = 2
)

func (i IdempotencyLevel) String() string {
	switch i {
	case IdempotencyUnknown:
		return "idempotency_unknown"
	case IdempotencyNoSideEffects:
		return "no_side_effects"
	case IdempotencyIdempotent:
		return "idempotent"
	}
	return fmt.Sprintf("idempotency_%d", i)
}
