/*
Copyright 2024 The Ceph-CSI 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 group

import (
	"context"
	"errors"
	"fmt"

	"github.com/ceph/go-ceph/rados"
	librbd "github.com/ceph/go-ceph/rbd"
	"github.com/container-storage-interface/spec/lib/go/csi"
	"github.com/csi-addons/spec/lib/go/volumegroup"

	rbderrors "github.com/ceph/ceph-csi/internal/rbd/errors"
	"github.com/ceph/ceph-csi/internal/rbd/types"
	"github.com/ceph/ceph-csi/internal/util"
	"github.com/ceph/ceph-csi/internal/util/log"
)

// volumeGroup handles all requests for 'rbd group' operations.
type volumeGroup struct {
	commonVolumeGroup

	// volumes is a list of rbd-images that are part of the group. The ID
	// of each volume is stored in the journal.
	volumes []types.Volume

	// volumeToFree contains Volumes that were resolved during
	// GetVolumeGroup. The volumes slice can be updated independently of
	// this by calling AddVolume (Volumes are allocated elsewhere), and
	// RemoveVolume (need to keep track of the allocated Volume).
	volumesToFree []types.Volume
}

// verify that volumeGroup implements the VolumeGroup and Stringer interfaces.
var (
	_ types.VolumeGroup = &volumeGroup{}
	_ fmt.Stringer      = &volumeGroup{}
)

// GetVolumeGroup initializes a new VolumeGroup object that can be used
// to manage an `rbd group`.
// If the .GetName() function returns an error, the VolumeGroup does not exist
// yet. It is needed to call .Create() in that case first.
func GetVolumeGroup(
	ctx context.Context,
	id string,
	csiDriver string,
	creds *util.Credentials,
	volumeResolver types.VolumeResolver,
) (types.VolumeGroup, error) {
	vg := &volumeGroup{}
	err := vg.initCommonVolumeGroup(ctx, id, csiDriver, creds)
	if err != nil {
		return nil, fmt.Errorf("failed to initialize volume group with id %q: %w", id, err)
	}

	attrs, err := vg.getVolumeGroupAttributes(ctx)
	if err != nil {
		if errors.Is(err, rbderrors.ErrGroupNotFound) {
			log.ErrorLog(ctx, "%v, returning empty volume group %q", vg, err)

			return vg, err
		}

		return nil, fmt.Errorf("failed to get volume attributes for id %q: %w", vg, err)
	}

	var volumes []types.Volume
	// it is needed to free the previously allocated volumes
	defer func() {
		// volumesToFree is empty in case of an error, let .Destroy() handle it otherwise
		if len(vg.volumesToFree) > 0 {
			return
		}

		for _, v := range volumes {
			v.Destroy(ctx)
		}
	}()
	for volID := range attrs.VolumeMap {
		vol, err := volumeResolver.GetVolumeByID(ctx, volID)
		if err != nil {
			return nil, fmt.Errorf("failed to get attributes for volume group id %q: %w", id, err)
		}

		volumes = append(volumes, vol)
	}

	vg.volumes = volumes
	// all allocated volumes need to be free'd at Destroy() time
	vg.volumesToFree = volumes

	log.DebugLog(ctx, "GetVolumeGroup(%s) returns %+v", id, *vg)

	return vg, nil
}

// ToCSI creates a CSI-Addons type for the VolumeGroup.
func (vg *volumeGroup) ToCSI(ctx context.Context) (*volumegroup.VolumeGroup, error) {
	volumes, err := vg.ListVolumes(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to list volumes for volume group %q: %w", vg, err)
	}

	csiVolumes := make([]*csi.Volume, len(volumes))
	for i, vol := range volumes {
		csiVolumes[i], err = vol.ToCSI(ctx)
		if err != nil {
			return nil, fmt.Errorf("failed to convert volume %q to CSI type: %w", vol, err)
		}
	}

	id, err := vg.GetID(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to get id for volume group %q: %w", vg, err)
	}

	// TODO: maybe store the VolumeContext in the journal?
	vgContext := map[string]string{}

	return &volumegroup.VolumeGroup{
		VolumeGroupId:      id,
		VolumeGroupContext: vgContext,
		Volumes:            csiVolumes,
	}, nil
}

// Destroy frees the resources used by the volumeGroup.
func (vg *volumeGroup) Destroy(ctx context.Context) {
	// free the volumes that were allocated in GetVolumeGroup()
	if len(vg.volumesToFree) > 0 {
		for _, volume := range vg.volumesToFree {
			volume.Destroy(ctx)
		}
		vg.volumesToFree = make([]types.Volume, 0)
	}

	vg.commonVolumeGroup.Destroy(ctx)
}

func (vg *volumeGroup) Create(ctx context.Context) error {
	name, err := vg.GetName(ctx)
	if err != nil {
		return fmt.Errorf("missing name to create volume group: %w", err)
	}

	ioctx, err := vg.GetIOContext(ctx)
	if err != nil {
		return err
	}

	err = librbd.GroupCreate(ioctx, name)
	if err != nil {
		if !errors.Is(err, librbd.ErrExist) {
			return fmt.Errorf("failed to create volume group %q: %w", name, err)
		}

		log.DebugLog(ctx, "ignoring error while creating volume group %q: %v", vg, err)
	}

	log.DebugLog(ctx, "volume group %q has been created", vg)

	return nil
}

func (vg *volumeGroup) Delete(ctx context.Context) error {
	name, err := vg.GetName(ctx)
	if err != nil {
		return err
	}

	ioctx, err := vg.GetIOContext(ctx)
	if err != nil {
		return err
	}

	err = librbd.GroupRemove(ioctx, name)
	if err != nil && !errors.Is(err, rados.ErrNotFound) {
		return fmt.Errorf("failed to remove volume group %q: %w", vg, err)
	}

	log.DebugLog(ctx, "volume group %q has been removed", vg)

	return vg.commonVolumeGroup.Delete(ctx)
}

func (vg *volumeGroup) AddVolume(ctx context.Context, vol types.Volume) error {
	err := vol.AddToGroup(ctx, vg)
	if err != nil {
		return fmt.Errorf("failed to add volume %q to volume group %q: %w", vol, vg, err)
	}

	vg.volumes = append(vg.volumes, vol)

	volID, err := vol.GetID(ctx)
	if err != nil {
		return err
	}

	pool, err := vg.GetPool(ctx)
	if err != nil {
		return err
	}

	id, err := vg.GetID(ctx)
	if err != nil {
		return err
	}

	csiID := util.CSIIdentifier{}
	err = csiID.DecomposeCSIID(id)
	if err != nil {
		return fmt.Errorf("failed to decompose volume group id %q: %w", id, err)
	}

	toAdd := map[string]string{
		volID: "",
	}

	j, err := vg.getJournal(ctx)
	if err != nil {
		return err
	}

	err = j.AddVolumesMapping(ctx, pool, csiID.ObjectUUID, toAdd)
	if err != nil {
		return fmt.Errorf("failed to add mapping for volume %q to volume group id %q: %w",
			volID, id, err)
	}

	return nil
}

func (vg *volumeGroup) RemoveVolume(ctx context.Context, vol types.Volume) error {
	// volume was already removed from the group
	if len(vg.volumes) == 0 {
		return nil
	}

	err := vol.RemoveFromGroup(ctx, vg)
	if err != nil {
		if !errors.Is(err, librbd.ErrNotExist) {
			return fmt.Errorf("failed to remove volume %q from volume group %q: %w", vol, vg, err)
		}
		log.DebugLog(ctx, "volume %q doesn't exist in group", vol)
	}

	// toRemove contain the ID of the volume that is removed from the group
	toRemove, err := vol.GetID(ctx)
	if err != nil {
		return fmt.Errorf("failed to get volume id for %q: %w", vol, err)
	}

	// volumes is the updated list, without the volume that was removed
	volumes := make([]types.Volume, 0)
	var id string
	for _, v := range vg.volumes {
		id, err = v.GetID(ctx)
		if err != nil {
			return err
		}

		if id == toRemove {
			// do not add the volume to the list
			continue
		}

		volumes = append(volumes, v)
	}

	// update the list of volumes
	vg.volumes = volumes

	pool, err := vg.GetPool(ctx)
	if err != nil {
		return err
	}

	id, err = vg.GetID(ctx)
	if err != nil {
		return err
	}

	csiID := util.CSIIdentifier{}
	err = csiID.DecomposeCSIID(id)
	if err != nil {
		return fmt.Errorf("failed to decompose volume group id %q: %w", id, err)
	}

	mapping := []string{
		toRemove,
	}

	j, err := vg.getJournal(ctx)
	if err != nil {
		return err
	}

	err = j.RemoveVolumesMapping(ctx, pool, csiID.ObjectUUID, mapping)
	if err != nil {
		return fmt.Errorf("failed to remove mapping for volume %q to volume group id %q: %w",
			toRemove, id, err)
	}

	return nil
}

func (vg *volumeGroup) ListVolumes(ctx context.Context) ([]types.Volume, error) {
	return vg.volumes, nil
}

// CreateSnapshots makes consistent snapshots of all the volumes in the volume group.
func (vg *volumeGroup) CreateSnapshots(
	ctx context.Context,
	cr *util.Credentials,
	name string,
) ([]types.Snapshot, error) {
	group, err := vg.GetName(ctx)
	if err != nil {
		return nil, err
	}

	ioctx, err := vg.GetIOContext(ctx)
	if err != nil {
		return nil, err
	}

	err = librbd.GroupSnapCreate(ioctx, group, name)
	if err != nil {
		if !errors.Is(err, librbd.ErrExist) {
			return nil, fmt.Errorf("failed to create volume group snapshot %q: %w", name, err)
		}

		log.DebugLog(ctx, "ignoring error while creating volume group snapshot %q: %v", vg, err)
	}
	defer func() {
		// always remove the groups-snapshot on function exit, it is not used anymore afterwards
		cleanupErr := librbd.GroupSnapRemove(ioctx, group, name)
		if cleanupErr != nil {
			log.ErrorLog(ctx, "failed to remove temporary volume group snapshot %q: %v",
				name, cleanupErr)
		}
	}()

	info, err := librbd.GroupSnapGetInfo(ioctx, group, name)
	if err != nil {
		return nil, fmt.Errorf("failed to get info for volume group snapshot %q: %w",
			vg.String()+"@"+name, err)
	}

	snapshots := make([]types.Snapshot, len(info.Snapshots))
	defer func() {
		// free all created snapshot objects in case of a failure
		if err == nil {
			return
		}

		for _, snapshot := range snapshots {
			snapshot.Destroy(ctx)
		}
	}()

	// Loop though all the RBD-snapshots in the group, and find the volume
	// that was used to create the snapshot. Once found, use the volume to
	// create a new RBD-image from the RBD-snapshot.
	for i, snap := range info.Snapshots {
		for _, volume := range vg.volumes {
			var volName string

			volName, err = volume.GetName(ctx)
			if err != nil {
				return nil, fmt.Errorf(
					"failed to get name for volume %q: %w", volume, err)
			}
			if volName != snap.Name {
				// the volume isn't the snapshot-source, continue with the next one
				continue
			}

			// yay, volume for the RBD-snapshot found!
			snapName := fmt.Sprintf("%s-snap-%d", group, i)
			snapshots[i], err = volume.NewSnapshotByID(ctx, cr, snapName, snap.SnapID)
			if err != nil {
				return nil, fmt.Errorf(
					"failed to create snapshot for image %q with snapshot id %d: %w",
					snap.Name, snap.SnapID, err)
			}

			// done, no need to try more volumes in the loop
			break
		}
	}

	return snapshots, nil
}
