// Copyright 2025 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 apply

import (
	"context"

	"github.com/coreos/go-semver/semver"
	"go.uber.org/zap"

	pb "go.etcd.io/etcd/api/v3/etcdserverpb"
	"go.etcd.io/etcd/api/v3/membershippb"
	"go.etcd.io/etcd/client/pkg/v3/types"
	"go.etcd.io/etcd/pkg/v3/traceutil"
	"go.etcd.io/etcd/server/v3/auth"
	"go.etcd.io/etcd/server/v3/etcdserver/api"
	"go.etcd.io/etcd/server/v3/etcdserver/api/membership"
	mvcctxn "go.etcd.io/etcd/server/v3/etcdserver/txn"
	"go.etcd.io/etcd/server/v3/etcdserver/version"
	"go.etcd.io/etcd/server/v3/lease"
	"go.etcd.io/etcd/server/v3/storage/mvcc"
)

type applierV3backend struct {
	options ApplierOptions
}

func newApplierV3Backend(opts ApplierOptions) applierV3 {
	return &applierV3backend{
		options: opts,
	}
}

func (a *applierV3backend) Apply(r *pb.InternalRaftRequest, shouldApplyV3 membership.ShouldApplyV3, applyFunc applyFunc) *Result {
	return applyFunc(r, shouldApplyV3)
}

func (a *applierV3backend) Put(p *pb.PutRequest) (resp *pb.PutResponse, trace *traceutil.Trace, err error) {
	return mvcctxn.Put(context.TODO(), a.options.Logger, a.options.Lessor, a.options.KV, p)
}

func (a *applierV3backend) DeleteRange(dr *pb.DeleteRangeRequest) (*pb.DeleteRangeResponse, *traceutil.Trace, error) {
	return mvcctxn.DeleteRange(context.TODO(), a.options.Logger, a.options.KV, dr)
}

func (a *applierV3backend) Range(r *pb.RangeRequest) (*pb.RangeResponse, *traceutil.Trace, error) {
	return mvcctxn.Range(context.TODO(), a.options.Logger, a.options.KV, r, true)
}

func (a *applierV3backend) Txn(rt *pb.TxnRequest) (*pb.TxnResponse, *traceutil.Trace, error) {
	return mvcctxn.Txn(context.TODO(), a.options.Logger, rt, a.options.TxnModeWriteWithSharedBuffer, a.options.KV, a.options.Lessor)
}

func (a *applierV3backend) Compaction(compaction *pb.CompactionRequest) (*pb.CompactionResponse, <-chan struct{}, *traceutil.Trace, error) {
	resp := &pb.CompactionResponse{}
	resp.Header = &pb.ResponseHeader{}
	ctx, trace := traceutil.EnsureTrace(context.TODO(), a.options.Logger, "compact",
		traceutil.Field{Key: "revision", Value: compaction.Revision},
	)

	ch, err := a.options.KV.Compact(trace, compaction.Revision)
	if err != nil {
		return nil, ch, nil, err
	}
	// get the current revision. which key to get is not important.
	rr, _ := a.options.KV.Range(ctx, []byte("compaction"), nil, mvcc.RangeOptions{})
	resp.Header.Revision = rr.Rev
	return resp, ch, trace, err
}

func (a *applierV3backend) LeaseGrant(lc *pb.LeaseGrantRequest) (*pb.LeaseGrantResponse, error) {
	l, err := a.options.Lessor.Grant(lease.LeaseID(lc.ID), lc.TTL)
	resp := &pb.LeaseGrantResponse{}
	if err == nil {
		resp.ID = int64(l.ID)
		resp.TTL = l.TTL()
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) LeaseRevoke(lc *pb.LeaseRevokeRequest) (*pb.LeaseRevokeResponse, error) {
	err := a.options.Lessor.Revoke(lease.LeaseID(lc.ID))
	return &pb.LeaseRevokeResponse{Header: a.newHeader()}, err
}

func (a *applierV3backend) LeaseCheckpoint(lc *pb.LeaseCheckpointRequest) (*pb.LeaseCheckpointResponse, error) {
	for _, c := range lc.Checkpoints {
		err := a.options.Lessor.Checkpoint(lease.LeaseID(c.ID), c.Remaining_TTL)
		if err != nil {
			return &pb.LeaseCheckpointResponse{Header: a.newHeader()}, err
		}
	}
	return &pb.LeaseCheckpointResponse{Header: a.newHeader()}, nil
}

func (a *applierV3backend) Alarm(ar *pb.AlarmRequest) (*pb.AlarmResponse, error) {
	resp := &pb.AlarmResponse{}

	switch ar.Action {
	case pb.AlarmRequest_GET:
		resp.Alarms = a.options.AlarmStore.Get(ar.Alarm)
	case pb.AlarmRequest_ACTIVATE:
		if ar.Alarm == pb.AlarmType_NONE {
			break
		}
		m := a.options.AlarmStore.Activate(types.ID(ar.MemberID), ar.Alarm)
		if m == nil {
			break
		}
		resp.Alarms = append(resp.Alarms, m)
		alarms.WithLabelValues(types.ID(ar.MemberID).String(), m.Alarm.String()).Inc()
	case pb.AlarmRequest_DEACTIVATE:
		m := a.options.AlarmStore.Deactivate(types.ID(ar.MemberID), ar.Alarm)
		if m == nil {
			break
		}
		resp.Alarms = append(resp.Alarms, m)
		alarms.WithLabelValues(types.ID(ar.MemberID).String(), m.Alarm.String()).Dec()
	default:
		return nil, nil
	}
	return resp, nil
}

func (a *applierV3backend) AuthEnable() (*pb.AuthEnableResponse, error) {
	err := a.options.AuthStore.AuthEnable()
	if err != nil {
		return nil, err
	}
	return &pb.AuthEnableResponse{Header: a.newHeader()}, nil
}

func (a *applierV3backend) AuthDisable() (*pb.AuthDisableResponse, error) {
	a.options.AuthStore.AuthDisable()
	return &pb.AuthDisableResponse{Header: a.newHeader()}, nil
}

func (a *applierV3backend) AuthStatus() (*pb.AuthStatusResponse, error) {
	enabled := a.options.AuthStore.IsAuthEnabled()
	authRevision := a.options.AuthStore.Revision()
	return &pb.AuthStatusResponse{Header: a.newHeader(), Enabled: enabled, AuthRevision: authRevision}, nil
}

func (a *applierV3backend) Authenticate(r *pb.InternalAuthenticateRequest) (*pb.AuthenticateResponse, error) {
	ctx := context.WithValue(context.WithValue(context.Background(), auth.AuthenticateParamIndex{}, a.options.ConsistentIndex.ConsistentIndex()), auth.AuthenticateParamSimpleTokenPrefix{}, r.SimpleToken)
	resp, err := a.options.AuthStore.Authenticate(ctx, r.Name, r.Password)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) UserAdd(r *pb.AuthUserAddRequest) (*pb.AuthUserAddResponse, error) {
	resp, err := a.options.AuthStore.UserAdd(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) UserDelete(r *pb.AuthUserDeleteRequest) (*pb.AuthUserDeleteResponse, error) {
	resp, err := a.options.AuthStore.UserDelete(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) UserChangePassword(r *pb.AuthUserChangePasswordRequest) (*pb.AuthUserChangePasswordResponse, error) {
	resp, err := a.options.AuthStore.UserChangePassword(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) UserGrantRole(r *pb.AuthUserGrantRoleRequest) (*pb.AuthUserGrantRoleResponse, error) {
	resp, err := a.options.AuthStore.UserGrantRole(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) UserGet(r *pb.AuthUserGetRequest) (*pb.AuthUserGetResponse, error) {
	resp, err := a.options.AuthStore.UserGet(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) UserRevokeRole(r *pb.AuthUserRevokeRoleRequest) (*pb.AuthUserRevokeRoleResponse, error) {
	resp, err := a.options.AuthStore.UserRevokeRole(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) RoleAdd(r *pb.AuthRoleAddRequest) (*pb.AuthRoleAddResponse, error) {
	resp, err := a.options.AuthStore.RoleAdd(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) RoleGrantPermission(r *pb.AuthRoleGrantPermissionRequest) (*pb.AuthRoleGrantPermissionResponse, error) {
	resp, err := a.options.AuthStore.RoleGrantPermission(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) RoleGet(r *pb.AuthRoleGetRequest) (*pb.AuthRoleGetResponse, error) {
	resp, err := a.options.AuthStore.RoleGet(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) RoleRevokePermission(r *pb.AuthRoleRevokePermissionRequest) (*pb.AuthRoleRevokePermissionResponse, error) {
	resp, err := a.options.AuthStore.RoleRevokePermission(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) RoleDelete(r *pb.AuthRoleDeleteRequest) (*pb.AuthRoleDeleteResponse, error) {
	resp, err := a.options.AuthStore.RoleDelete(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) UserList(r *pb.AuthUserListRequest) (*pb.AuthUserListResponse, error) {
	resp, err := a.options.AuthStore.UserList(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) RoleList(r *pb.AuthRoleListRequest) (*pb.AuthRoleListResponse, error) {
	resp, err := a.options.AuthStore.RoleList(r)
	if resp != nil {
		resp.Header = a.newHeader()
	}
	return resp, err
}

func (a *applierV3backend) ClusterVersionSet(r *membershippb.ClusterVersionSetRequest, shouldApplyV3 membership.ShouldApplyV3) {
	prevVersion := a.options.Cluster.Version()
	newVersion := semver.Must(semver.NewVersion(r.Ver))
	a.options.Cluster.SetVersion(newVersion, api.UpdateCapability, shouldApplyV3)
	// Force snapshot after cluster version downgrade.
	if prevVersion != nil && newVersion.LessThan(*prevVersion) {
		lg := a.options.Logger
		if lg != nil {
			lg.Info("Cluster version downgrade detected, forcing snapshot",
				zap.String("prev-cluster-version", prevVersion.String()),
				zap.String("new-cluster-version", newVersion.String()),
			)
		}
		a.options.SnapshotServer.ForceSnapshot()
	}
}

func (a *applierV3backend) ClusterMemberAttrSet(r *membershippb.ClusterMemberAttrSetRequest, shouldApplyV3 membership.ShouldApplyV3) {
	a.options.Cluster.UpdateAttributes(
		types.ID(r.Member_ID),
		membership.Attributes{
			Name:       r.MemberAttributes.Name,
			ClientURLs: r.MemberAttributes.ClientUrls,
		},
		shouldApplyV3,
	)
}

func (a *applierV3backend) DowngradeInfoSet(r *membershippb.DowngradeInfoSetRequest, shouldApplyV3 membership.ShouldApplyV3) {
	d := version.DowngradeInfo{Enabled: false}
	if r.Enabled {
		d = version.DowngradeInfo{Enabled: true, TargetVersion: r.Ver}
	}
	a.options.Cluster.SetDowngradeInfo(&d, shouldApplyV3)
}

func (a *applierV3backend) newHeader() *pb.ResponseHeader {
	return &pb.ResponseHeader{
		ClusterId: uint64(a.options.Cluster.ID()),
		MemberId:  uint64(a.options.RaftStatus.MemberID()),
		Revision:  a.options.KV.Rev(),
		RaftTerm:  a.options.RaftStatus.Term(),
	}
}