// Copyright 2017 The etcd 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 leasing

import (
	"bytes"

	v3pb "go.etcd.io/etcd/api/v3/etcdserverpb"
	v3 "go.etcd.io/etcd/client/v3"
)

func compareInt64(a, b int64) int {
	switch {
	case a < b:
		return -1
	case a > b:
		return 1
	default:
		return 0
	}
}

func evalCmp(resp *v3.GetResponse, tcmp v3.Cmp) bool {
	var result int
	if len(resp.Kvs) != 0 {
		kv := resp.Kvs[0]
		switch tcmp.Target {
		case v3pb.Compare_VALUE:
			if tv, _ := tcmp.TargetUnion.(*v3pb.Compare_Value); tv != nil {
				result = bytes.Compare(kv.Value, tv.Value)
			}
		case v3pb.Compare_CREATE:
			if tv, _ := tcmp.TargetUnion.(*v3pb.Compare_CreateRevision); tv != nil {
				result = compareInt64(kv.CreateRevision, tv.CreateRevision)
			}
		case v3pb.Compare_MOD:
			if tv, _ := tcmp.TargetUnion.(*v3pb.Compare_ModRevision); tv != nil {
				result = compareInt64(kv.ModRevision, tv.ModRevision)
			}
		case v3pb.Compare_VERSION:
			if tv, _ := tcmp.TargetUnion.(*v3pb.Compare_Version); tv != nil {
				result = compareInt64(kv.Version, tv.Version)
			}
		}
	}
	switch tcmp.Result {
	case v3pb.Compare_EQUAL:
		return result == 0
	case v3pb.Compare_NOT_EQUAL:
		return result != 0
	case v3pb.Compare_GREATER:
		return result > 0
	case v3pb.Compare_LESS:
		return result < 0
	}
	return true
}

func gatherOps(ops []v3.Op) (ret []v3.Op) {
	for _, op := range ops {
		if !op.IsTxn() {
			ret = append(ret, op)
			continue
		}
		_, thenOps, elseOps := op.Txn()
		ret = append(ret, gatherOps(append(thenOps, elseOps...))...)
	}
	return ret
}

func gatherResponseOps(resp []*v3pb.ResponseOp, ops []v3.Op) (ret []v3.Op) {
	for i, op := range ops {
		if !op.IsTxn() {
			ret = append(ret, op)
			continue
		}
		_, thenOps, elseOps := op.Txn()
		if txnResp := resp[i].GetResponseTxn(); txnResp.Succeeded {
			ret = append(ret, gatherResponseOps(txnResp.Responses, thenOps)...)
		} else {
			ret = append(ret, gatherResponseOps(txnResp.Responses, elseOps)...)
		}
	}
	return ret
}

func copyHeader(hdr *v3pb.ResponseHeader) *v3pb.ResponseHeader {
	h := *hdr
	return &h
}

func closeAll(chs []chan<- struct{}) {
	for _, ch := range chs {
		close(ch)
	}
}