// Copyright 2016 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 v3rpc

import (
	"crypto/sha256"
	"io"

	"github.com/coreos/etcd/etcdserver"
	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
	"github.com/coreos/etcd/mvcc"
	"github.com/coreos/etcd/mvcc/backend"
	"github.com/coreos/etcd/pkg/types"
	"github.com/coreos/etcd/version"
	"golang.org/x/net/context"
)

type KVGetter interface {
	KV() mvcc.ConsistentWatchableKV
}

type BackendGetter interface {
	Backend() backend.Backend
}

type Alarmer interface {
	Alarm(ctx context.Context, ar *pb.AlarmRequest) (*pb.AlarmResponse, error)
}

type RaftStatusGetter interface {
	Index() uint64
	Term() uint64
	Leader() types.ID
}

type maintenanceServer struct {
	rg  RaftStatusGetter
	kg  KVGetter
	bg  BackendGetter
	a   Alarmer
	hdr header
}

func NewMaintenanceServer(s *etcdserver.EtcdServer) pb.MaintenanceServer {
	return &maintenanceServer{rg: s, kg: s, bg: s, a: s, hdr: newHeader(s)}
}

func (ms *maintenanceServer) Defragment(ctx context.Context, sr *pb.DefragmentRequest) (*pb.DefragmentResponse, error) {
	plog.Noticef("starting to defragment the storage backend...")
	err := ms.bg.Backend().Defrag()
	if err != nil {
		plog.Errorf("failed to defragment the storage backend (%v)", err)
		return nil, err
	}
	plog.Noticef("finished defragmenting the storage backend")
	return &pb.DefragmentResponse{}, nil
}

func (ms *maintenanceServer) Snapshot(sr *pb.SnapshotRequest, srv pb.Maintenance_SnapshotServer) error {
	snap := ms.bg.Backend().Snapshot()
	pr, pw := io.Pipe()

	defer pr.Close()

	go func() {
		snap.WriteTo(pw)
		if err := snap.Close(); err != nil {
			plog.Errorf("error closing snapshot (%v)", err)
		}
		pw.Close()
	}()

	// send file data
	h := sha256.New()
	br := int64(0)
	buf := make([]byte, 32*1024)
	sz := snap.Size()
	for br < sz {
		n, err := io.ReadFull(pr, buf)
		if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
			return togRPCError(err)
		}
		br += int64(n)
		resp := &pb.SnapshotResponse{
			RemainingBytes: uint64(sz - br),
			Blob:           buf[:n],
		}
		if err = srv.Send(resp); err != nil {
			return togRPCError(err)
		}
		h.Write(buf[:n])
	}

	// send sha
	sha := h.Sum(nil)
	hresp := &pb.SnapshotResponse{RemainingBytes: 0, Blob: sha}
	if err := srv.Send(hresp); err != nil {
		return togRPCError(err)
	}

	return nil
}

func (ms *maintenanceServer) Hash(ctx context.Context, r *pb.HashRequest) (*pb.HashResponse, error) {
	h, rev, err := ms.kg.KV().Hash()
	if err != nil {
		return nil, togRPCError(err)
	}
	resp := &pb.HashResponse{Header: &pb.ResponseHeader{Revision: rev}, Hash: h}
	ms.hdr.fill(resp.Header)
	return resp, nil
}

func (ms *maintenanceServer) Alarm(ctx context.Context, ar *pb.AlarmRequest) (*pb.AlarmResponse, error) {
	return ms.a.Alarm(ctx, ar)
}

func (ms *maintenanceServer) Status(ctx context.Context, ar *pb.StatusRequest) (*pb.StatusResponse, error) {
	resp := &pb.StatusResponse{
		Header:    &pb.ResponseHeader{Revision: ms.hdr.rev()},
		Version:   version.Version,
		DbSize:    ms.bg.Backend().Size(),
		Leader:    uint64(ms.rg.Leader()),
		RaftIndex: ms.rg.Index(),
		RaftTerm:  ms.rg.Term(),
	}
	ms.hdr.fill(resp.Header)
	return resp, nil
}
