// 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 clientv3

import (
	"github.com/coreos/etcd/Godeps/_workspace/src/golang.org/x/net/context"
	"github.com/coreos/etcd/Godeps/_workspace/src/google.golang.org/grpc"
	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
)

type (
	PutResponse         pb.PutResponse
	RangeResponse       pb.RangeResponse
	GetResponse         pb.RangeResponse
	DeleteRangeResponse pb.DeleteRangeResponse
	DeleteResponse      pb.DeleteRangeResponse
	TxnResponse         pb.TxnResponse
)

type KV interface {
	// PUT puts a key-value pair into etcd.
	// Note that key,value can be plain bytes array and string is
	// an immutable representation of that bytes array.
	// To get a string of bytes, do string([]byte(0x10, 0x20)).
	Put(key, val string) (*PutResponse, error)

	// Range gets the keys [key, end) in the range at rev.
	// If revev <=0, range gets the keys at currentRev.
	// Limit limits the number of keys returned.
	// If the required rev is compacted, ErrCompacted will be returned.
	Range(key, end string, limit, rev int64, sort *SortOption) (*RangeResponse, error)

	// Get is like Range. A shortcut for ranging single key like [key, key+1).
	Get(key, rev int64) (*GetResponse, error)

	// DeleteRange deletes the given range [key, end).
	DeleteRange(key, end string) (*DeleteRangeResponse, error)

	// Delete is like DeleteRange. A shortcut for deleting single key like [key, key+1).
	Delete(key string) (*DeleteResponse, error)

	// Compact compacts etcd KV history before the given rev.
	Compact(rev int64) error

	// Txn creates a transaction.
	Txn() Txn
}

//
// Tx.If(
//  CmpValue(k1, ">", v1),
//  CmpVersion(k1, "=", 2)
// ).Then(
//  OpPut(k2,v2), OpPut(k3,v3)
// ).Else(
//  OpPut(k4,v4), OpPut(k5,v5)
// ).Commit()
type Txn interface {
	// If takes a list of comparison. If all comparisons passed in succeed,
	// the operations passed into Then() will be executed. Or the operations
	// passed into Else() will be executed.
	If(cs ...Compare) Txn

	// Then takes a list of operations. The Ops list will be executed, if the
	// comparisons passed in If() succeed.
	Then(ops ...Op) Txn

	// Else takes a list of operations. The Ops list will be executed, if the
	// comparisons passed in If() fail.
	Else(ops ...Op) Txn

	// Commit tries to commit the transaction.
	Commit() (*TxnResponse, error)

	// TODO: add a Do for shortcut the txn without any condition?
}

type kv struct {
	conn   *grpc.ClientConn // conn in-use
	remote pb.KVClient

	c *Client
}

func (kv *kv) Range(key, end string, limit, rev int64, sort *SortOption) (*pb.RangeResponse, error) {
	r, err := kv.do(OpRange(key, end, limit, rev, sort))
	if err != nil {
		return nil, err
	}
	return r.GetResponseRange(), nil
}

func (kv *kv) do(op Op) (*pb.ResponseUnion, error) {
	for {
		var err error
		switch op.t {
		// TODO: handle other ops
		case tRange:
			var resp *pb.RangeResponse
			// TODO: setup sorting
			r := &pb.RangeRequest{Key: op.key, RangeEnd: op.end, Limit: op.limit, Revision: op.rev}
			resp, err = kv.remote.Range(context.TODO(), r)
			if err == nil {
				return &pb.ResponseUnion{Response: &pb.ResponseUnion_ResponseRange{resp}}, nil
			}
		default:
			panic("Unknown op")
		}

		if isRPCError(err) {
			return nil, err
		}

		newConn, cerr := kv.c.retryConnection(kv.conn, err)
		if cerr != nil {
			// TODO: return client lib defined connection error
			return nil, cerr
		}
		kv.conn = newConn
		kv.remote = pb.NewKVClient(kv.conn)
	}
}