// Copyright 2015 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 etcdserver

import (
	"strconv"
	"strings"
	"time"

	"github.com/coreos/etcd/auth"
	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
	"github.com/coreos/etcd/lease"
	"github.com/coreos/etcd/lease/leasehttp"
	"github.com/coreos/etcd/mvcc"
	"golang.org/x/net/context"
	"google.golang.org/grpc/metadata"
)

const (
	// the max request size that raft accepts.
	// TODO: make this a flag? But we probably do not want to
	// accept large request which might block raft stream. User
	// specify a large value might end up with shooting in the foot.
	maxRequestBytes = 1.5 * 1024 * 1024

	// max timeout for waiting a v3 request to go through raft.
	maxV3RequestTimeout = 5 * time.Second
)

type RaftKV interface {
	Range(ctx context.Context, r *pb.RangeRequest) (*pb.RangeResponse, error)
	Put(ctx context.Context, r *pb.PutRequest) (*pb.PutResponse, error)
	DeleteRange(ctx context.Context, r *pb.DeleteRangeRequest) (*pb.DeleteRangeResponse, error)
	Txn(ctx context.Context, r *pb.TxnRequest) (*pb.TxnResponse, error)
	Compact(ctx context.Context, r *pb.CompactionRequest) (*pb.CompactionResponse, error)
}

type Lessor interface {
	// LeaseGrant sends LeaseGrant request to raft and apply it after committed.
	LeaseGrant(ctx context.Context, r *pb.LeaseGrantRequest) (*pb.LeaseGrantResponse, error)
	// LeaseRevoke sends LeaseRevoke request to raft and apply it after committed.
	LeaseRevoke(ctx context.Context, r *pb.LeaseRevokeRequest) (*pb.LeaseRevokeResponse, error)

	// LeaseRenew renews the lease with given ID. The renewed TTL is returned. Or an error
	// is returned.
	LeaseRenew(id lease.LeaseID) (int64, error)
}

type Authenticator interface {
	AuthEnable(ctx context.Context, r *pb.AuthEnableRequest) (*pb.AuthEnableResponse, error)
	AuthDisable(ctx context.Context, r *pb.AuthDisableRequest) (*pb.AuthDisableResponse, error)
	Authenticate(ctx context.Context, r *pb.AuthenticateRequest) (*pb.AuthenticateResponse, error)
	UserAdd(ctx context.Context, r *pb.AuthUserAddRequest) (*pb.AuthUserAddResponse, error)
	UserDelete(ctx context.Context, r *pb.AuthUserDeleteRequest) (*pb.AuthUserDeleteResponse, error)
	UserChangePassword(ctx context.Context, r *pb.AuthUserChangePasswordRequest) (*pb.AuthUserChangePasswordResponse, error)
	UserGrantRole(ctx context.Context, r *pb.AuthUserGrantRoleRequest) (*pb.AuthUserGrantRoleResponse, error)
	UserGet(ctx context.Context, r *pb.AuthUserGetRequest) (*pb.AuthUserGetResponse, error)
	UserRevokeRole(ctx context.Context, r *pb.AuthUserRevokeRoleRequest) (*pb.AuthUserRevokeRoleResponse, error)
	RoleAdd(ctx context.Context, r *pb.AuthRoleAddRequest) (*pb.AuthRoleAddResponse, error)
	RoleGrantPermission(ctx context.Context, r *pb.AuthRoleGrantPermissionRequest) (*pb.AuthRoleGrantPermissionResponse, error)
	RoleGet(ctx context.Context, r *pb.AuthRoleGetRequest) (*pb.AuthRoleGetResponse, error)
	RoleRevokePermission(ctx context.Context, r *pb.AuthRoleRevokePermissionRequest) (*pb.AuthRoleRevokePermissionResponse, error)
	RoleDelete(ctx context.Context, r *pb.AuthRoleDeleteRequest) (*pb.AuthRoleDeleteResponse, error)
}

func (s *EtcdServer) Range(ctx context.Context, r *pb.RangeRequest) (*pb.RangeResponse, error) {
	if r.Serializable {
		user, err := s.usernameFromCtx(ctx)
		if err != nil {
			return nil, err
		}
		hdr := &pb.RequestHeader{Username: user}
		if !s.AuthStore().IsRangePermitted(hdr, string(r.Key), string(r.RangeEnd)) {
			return nil, auth.ErrPermissionDenied
		}
		return s.applyV3.Range(noTxn, r)
	}

	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{Range: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.RangeResponse), nil
}

func (s *EtcdServer) Put(ctx context.Context, r *pb.PutRequest) (*pb.PutResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{Put: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.PutResponse), nil
}

func (s *EtcdServer) DeleteRange(ctx context.Context, r *pb.DeleteRangeRequest) (*pb.DeleteRangeResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{DeleteRange: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.DeleteRangeResponse), nil
}

func (s *EtcdServer) Txn(ctx context.Context, r *pb.TxnRequest) (*pb.TxnResponse, error) {
	if isTxnSerializable(r) {
		return s.applyV3.Txn(r)
	}

	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{Txn: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.TxnResponse), nil
}

func isTxnSerializable(r *pb.TxnRequest) bool {
	for _, u := range r.Success {
		if r := u.GetRequestRange(); r == nil || !r.Serializable {
			return false
		}
	}
	for _, u := range r.Failure {
		if r := u.GetRequestRange(); r == nil || !r.Serializable {
			return false
		}
	}
	return true
}

func (s *EtcdServer) Compact(ctx context.Context, r *pb.CompactionRequest) (*pb.CompactionResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{Compaction: r})
	if r.Physical && result != nil && result.physc != nil {
		<-result.physc
		// The compaction is done deleting keys; the hash is now settled
		// but the data is not necessarily committed. If there's a crash,
		// the hash may revert to a hash prior to compaction completing
		// if the compaction resumes. Force the finished compaction to
		// commit so it won't resume following a crash.
		s.be.ForceCommit()
	}
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	resp := result.resp.(*pb.CompactionResponse)
	if resp == nil {
		resp = &pb.CompactionResponse{}
	}
	if resp.Header == nil {
		resp.Header = &pb.ResponseHeader{}
	}
	resp.Header.Revision = s.kv.Rev()
	return resp, nil
}

func (s *EtcdServer) LeaseGrant(ctx context.Context, r *pb.LeaseGrantRequest) (*pb.LeaseGrantResponse, error) {
	// no id given? choose one
	for r.ID == int64(lease.NoLease) {
		// only use positive int64 id's
		r.ID = int64(s.reqIDGen.Next() & ((1 << 63) - 1))
	}
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{LeaseGrant: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.LeaseGrantResponse), nil
}

func (s *EtcdServer) LeaseRevoke(ctx context.Context, r *pb.LeaseRevokeRequest) (*pb.LeaseRevokeResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{LeaseRevoke: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.LeaseRevokeResponse), nil
}

func (s *EtcdServer) LeaseRenew(id lease.LeaseID) (int64, error) {
	ttl, err := s.lessor.Renew(id)
	if err == nil {
		return ttl, nil
	}
	if err != lease.ErrNotPrimary {
		return -1, err
	}

	// renewals don't go through raft; forward to leader manually
	leader := s.cluster.Member(s.Leader())
	for i := 0; i < 5 && leader == nil; i++ {
		// wait an election
		dur := time.Duration(s.Cfg.ElectionTicks) * time.Duration(s.Cfg.TickMs) * time.Millisecond
		select {
		case <-time.After(dur):
			leader = s.cluster.Member(s.Leader())
		case <-s.done:
			return -1, ErrStopped
		}
	}
	if leader == nil || len(leader.PeerURLs) == 0 {
		return -1, ErrNoLeader
	}

	for _, url := range leader.PeerURLs {
		lurl := url + "/leases"
		ttl, err = leasehttp.RenewHTTP(id, lurl, s.peerRt, s.Cfg.peerDialTimeout())
		if err == nil {
			break
		}
	}
	return ttl, err
}

func (s *EtcdServer) Alarm(ctx context.Context, r *pb.AlarmRequest) (*pb.AlarmResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{Alarm: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AlarmResponse), nil
}

func (s *EtcdServer) AuthEnable(ctx context.Context, r *pb.AuthEnableRequest) (*pb.AuthEnableResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthEnable: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthEnableResponse), nil
}

func (s *EtcdServer) AuthDisable(ctx context.Context, r *pb.AuthDisableRequest) (*pb.AuthDisableResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthDisable: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthDisableResponse), nil
}

func (s *EtcdServer) Authenticate(ctx context.Context, r *pb.AuthenticateRequest) (*pb.AuthenticateResponse, error) {
	st, err := s.AuthStore().GenSimpleToken()
	if err != nil {
		return nil, err
	}

	internalReq := &pb.InternalAuthenticateRequest{
		Name:        r.Name,
		Password:    r.Password,
		SimpleToken: st,
	}

	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{Authenticate: internalReq})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthenticateResponse), nil
}

func (s *EtcdServer) UserAdd(ctx context.Context, r *pb.AuthUserAddRequest) (*pb.AuthUserAddResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthUserAdd: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthUserAddResponse), nil
}

func (s *EtcdServer) UserDelete(ctx context.Context, r *pb.AuthUserDeleteRequest) (*pb.AuthUserDeleteResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthUserDelete: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthUserDeleteResponse), nil
}

func (s *EtcdServer) UserChangePassword(ctx context.Context, r *pb.AuthUserChangePasswordRequest) (*pb.AuthUserChangePasswordResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthUserChangePassword: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthUserChangePasswordResponse), nil
}

func (s *EtcdServer) UserGrantRole(ctx context.Context, r *pb.AuthUserGrantRoleRequest) (*pb.AuthUserGrantRoleResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthUserGrantRole: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthUserGrantRoleResponse), nil
}

func (s *EtcdServer) UserGet(ctx context.Context, r *pb.AuthUserGetRequest) (*pb.AuthUserGetResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthUserGet: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthUserGetResponse), nil
}

func (s *EtcdServer) UserRevokeRole(ctx context.Context, r *pb.AuthUserRevokeRoleRequest) (*pb.AuthUserRevokeRoleResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthUserRevokeRole: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthUserRevokeRoleResponse), nil
}

func (s *EtcdServer) RoleAdd(ctx context.Context, r *pb.AuthRoleAddRequest) (*pb.AuthRoleAddResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthRoleAdd: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthRoleAddResponse), nil
}

func (s *EtcdServer) RoleGrantPermission(ctx context.Context, r *pb.AuthRoleGrantPermissionRequest) (*pb.AuthRoleGrantPermissionResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthRoleGrantPermission: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthRoleGrantPermissionResponse), nil
}

func (s *EtcdServer) RoleGet(ctx context.Context, r *pb.AuthRoleGetRequest) (*pb.AuthRoleGetResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthRoleGet: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthRoleGetResponse), nil
}

func (s *EtcdServer) RoleRevokePermission(ctx context.Context, r *pb.AuthRoleRevokePermissionRequest) (*pb.AuthRoleRevokePermissionResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthRoleRevokePermission: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthRoleRevokePermissionResponse), nil
}

func (s *EtcdServer) RoleDelete(ctx context.Context, r *pb.AuthRoleDeleteRequest) (*pb.AuthRoleDeleteResponse, error) {
	result, err := s.processInternalRaftRequest(ctx, pb.InternalRaftRequest{AuthRoleDelete: r})
	if err != nil {
		return nil, err
	}
	if result.err != nil {
		return nil, result.err
	}
	return result.resp.(*pb.AuthRoleDeleteResponse), nil
}

func (s *EtcdServer) isValidSimpleToken(token string) bool {
	splitted := strings.Split(token, ".")
	if len(splitted) != 2 {
		return false
	}
	index, err := strconv.Atoi(splitted[1])
	if err != nil {
		return false
	}

	// CAUTION: below index synchronization is required because this node
	// might not receive and apply the log entry of Authenticate() RPC.
	authApplied := false
	for i := 0; i < 10; i++ {
		if uint64(index) <= s.getAppliedIndex() {
			authApplied = true
			break
		}

		time.Sleep(100 * time.Millisecond)
	}

	if !authApplied {
		plog.Errorf("timeout of waiting Authenticate() RPC")
		return false
	}

	return true
}

func (s *EtcdServer) usernameFromCtx(ctx context.Context) (string, error) {
	md, ok := metadata.FromContext(ctx)
	if !ok {
		return "", nil
	}

	ts, tok := md["token"]
	if !tok {
		return "", nil
	}

	token := ts[0]
	if !s.isValidSimpleToken(token) {
		return "", ErrInvalidAuthToken
	}

	username, uok := s.AuthStore().UsernameFromToken(token)
	if !uok {
		plog.Warningf("invalid auth token: %s", token)
		return "", ErrInvalidAuthToken
	}
	return username, nil
}

func (s *EtcdServer) processInternalRaftRequest(ctx context.Context, r pb.InternalRaftRequest) (*applyResult, error) {
	r.Header = &pb.RequestHeader{
		ID: s.reqIDGen.Next(),
	}
	username, err := s.usernameFromCtx(ctx)
	if err != nil {
		return nil, err
	}
	r.Header.Username = username

	data, err := r.Marshal()
	if err != nil {
		return nil, err
	}

	if len(data) > maxRequestBytes {
		return nil, ErrRequestTooLarge
	}

	id := r.ID
	if id == 0 {
		id = r.Header.ID
	}
	ch := s.w.Register(id)

	cctx, cancel := context.WithTimeout(ctx, maxV3RequestTimeout)
	defer cancel()

	s.r.Propose(cctx, data)

	select {
	case x := <-ch:
		return x.(*applyResult), nil
	case <-cctx.Done():
		s.w.Trigger(id, nil) // GC wait
		return nil, cctx.Err()
	case <-s.done:
		return nil, ErrStopped
	}
}

// Watchable returns a watchable interface attached to the etcdserver.
func (s *EtcdServer) Watchable() mvcc.Watchable { return s.KV() }