// Copyright 2015 CoreOS, Inc.
//
// 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 etcdserver

import (
	"bytes"

	"github.com/coreos/etcd/Godeps/_workspace/src/github.com/gogo/protobuf/proto"
	"github.com/coreos/etcd/Godeps/_workspace/src/golang.org/x/net/context"
	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
	dstorage "github.com/coreos/etcd/storage"
)

type V3DemoServer interface {
	V3DemoDo(ctx context.Context, r pb.InternalRaftRequest) proto.Message
}

func (s *EtcdServer) V3DemoDo(ctx context.Context, r pb.InternalRaftRequest) proto.Message {
	switch {
	case r.Range != nil:
		return doRange(s.kv, r.Range)
	case r.Put != nil:
		return doPut(s.kv, r.Put)
	case r.DeleteRange != nil:
		return doDeleteRange(s.kv, r.DeleteRange)
	case r.Txn != nil:
		var index int64
		rt := r.Txn

		ok := true
		for _, c := range rt.Compare {
			kvs, rev, err := s.kv.Range(c.Key, nil, 1, 0)
			if err != nil {
				ok = false
				break
			}
			index = rev
			kv := kvs[0]

			// -1 is less, 0 is equal, 1 is greater
			var result int
			switch c.Target {
			case pb.Compare_VALUE:
				result = bytes.Compare(kv.Value, c.Value)
			case pb.Compare_CREATE:
				result = compareInt64(kv.CreateIndex, c.CreateIndex)
			case pb.Compare_MOD:
				result = compareInt64(kv.ModIndex, c.ModIndex)
			case pb.Compare_VERSION:
				result = compareInt64(kv.Version, c.Version)
			}

			switch c.Result {
			case pb.Compare_EQUAL:
				if result != 0 {
					ok = false
				}
			case pb.Compare_GREATER:
				if result != 1 {
					ok = false
				}
			case pb.Compare_LESS:
				if result != -1 {
					ok = false
				}
			}

			if !ok {
				break
			}
		}

		var reqs []*pb.RequestUnion
		if ok {
			reqs = rt.Success
		} else {
			reqs = rt.Failure
		}
		resps := make([]*pb.ResponseUnion, len(reqs))
		for i := range reqs {
			resps[i] = doUnion(s.kv, reqs[i])
		}
		if len(resps) != 0 {
			index += 1
		}

		txnResp := &pb.TxnResponse{}
		txnResp.Header = &pb.ResponseHeader{}
		txnResp.Header.Index = index
		txnResp.Responses = resps
		txnResp.Succeeded = ok
		return txnResp
	default:
		panic("not implemented")
	}
}

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

func doPut(kv dstorage.KV, p *pb.PutRequest) *pb.PutResponse {
	resp := &pb.PutResponse{}
	resp.Header = &pb.ResponseHeader{}
	rev := kv.Put(p.Key, p.Value)
	resp.Header.Index = rev
	return resp
}

func doRange(kv dstorage.KV, r *pb.RangeRequest) *pb.RangeResponse {
	resp := &pb.RangeResponse{}
	resp.Header = &pb.ResponseHeader{}
	kvs, rev, err := kv.Range(r.Key, r.RangeEnd, r.Limit, 0)
	if err != nil {
		panic("not handled error")
	}

	resp.Header.Index = rev
	for i := range kvs {
		resp.Kvs = append(resp.Kvs, &kvs[i])
	}
	return resp
}

func doDeleteRange(kv dstorage.KV, dr *pb.DeleteRangeRequest) *pb.DeleteRangeResponse {
	resp := &pb.DeleteRangeResponse{}
	resp.Header = &pb.ResponseHeader{}
	_, rev := kv.DeleteRange(dr.Key, dr.RangeEnd)
	resp.Header.Index = rev
	return resp
}

func doUnion(kv dstorage.KV, union *pb.RequestUnion) *pb.ResponseUnion {
	switch {
	case union.RequestRange != nil:
		return &pb.ResponseUnion{ResponseRange: doRange(kv, union.RequestRange)}
	case union.RequestPut != nil:
		return &pb.ResponseUnion{ResponsePut: doPut(kv, union.RequestPut)}
	case union.RequestDeleteRange != nil:
		return &pb.ResponseUnion{ResponseDeleteRange: doDeleteRange(kv, union.RequestDeleteRange)}
	default:
		// empty union
		return nil
	}
}