package drivers

import (
	"errors"
	"fmt"
	"io/fs"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"github.com/lxc/incus/v6/internal/linux"
	"github.com/lxc/incus/v6/internal/migration"
	deviceConfig "github.com/lxc/incus/v6/internal/server/device/config"
	localMigration "github.com/lxc/incus/v6/internal/server/migration"
	"github.com/lxc/incus/v6/internal/server/operations"
	internalUtil "github.com/lxc/incus/v6/internal/util"
	"github.com/lxc/incus/v6/shared/api"
	"github.com/lxc/incus/v6/shared/revert"
	"github.com/lxc/incus/v6/shared/subprocess"
	"github.com/lxc/incus/v6/shared/util"
	"github.com/lxc/incus/v6/shared/validate"
)

var (
	cephfsVersion string
	cephfsLoaded  bool
)

type cephfs struct {
	common
}

// load is used to run one-time action per-driver rather than per-pool.
func (d *cephfs) load() error {
	// Register the patches.
	d.patches = map[string]func() error{
		"storage_lvm_skipactivation":                         nil,
		"storage_missing_snapshot_records":                   nil,
		"storage_delete_old_snapshot_records":                nil,
		"storage_zfs_drop_block_volume_filesystem_extension": nil,
		"storage_prefix_bucket_names_with_project":           nil,
	}

	// Done if previously loaded.
	if cephfsLoaded {
		return nil
	}

	// Validate the required binaries.
	for _, tool := range []string{"ceph", "rbd"} {
		_, err := exec.LookPath(tool)
		if err != nil {
			return fmt.Errorf("Required tool '%s' is missing", tool)
		}
	}

	// Detect and record the version.
	if cephfsVersion == "" {
		out, err := subprocess.RunCommand("rbd", "--version")
		if err != nil {
			return err
		}

		out = strings.TrimSpace(out)

		fields := strings.Split(out, " ")
		if strings.HasPrefix(out, "ceph version ") && len(fields) > 2 {
			cephfsVersion = fields[2]
		} else {
			cephfsVersion = out
		}
	}

	cephfsLoaded = true
	return nil
}

// isRemote returns true indicating this driver uses remote storage.
func (d *cephfs) isRemote() bool {
	return true
}

// Info returns the pool driver information.
func (d *cephfs) Info() Info {
	return Info{
		Name:                         "cephfs",
		Version:                      cephfsVersion,
		DefaultVMBlockFilesystemSize: deviceConfig.DefaultVMBlockFilesystemSize,
		OptimizedImages:              false,
		PreservesInodes:              false,
		Remote:                       d.isRemote(),
		VolumeTypes:                  []VolumeType{VolumeTypeCustom},
		VolumeMultiNode:              d.isRemote(),
		BlockBacking:                 false,
		RunningCopyFreeze:            false,
		DirectIO:                     true,
		MountedRoot:                  true,
	}
}

// FillConfig populates the storage pool's configuration file with the default values.
func (d *cephfs) FillConfig() error {
	if d.config["cephfs.cluster_name"] == "" {
		d.config["cephfs.cluster_name"] = CephDefaultCluster
	}

	if d.config["cephfs.user.name"] == "" {
		d.config["cephfs.user.name"] = CephDefaultUser
	}

	return nil
}

// Create is called during pool creation and is effectively using an empty driver struct.
// WARNING: The Create() function cannot rely on any of the struct attributes being set.
func (d *cephfs) Create() error {
	revert := revert.New()
	defer revert.Fail()

	err := d.FillConfig()
	if err != nil {
		return err
	}

	// Config validation.
	if d.config["source"] == "" {
		return fmt.Errorf("Missing required source name/path")
	}

	if d.config["cephfs.path"] != "" && d.config["cephfs.path"] != d.config["source"] {
		return fmt.Errorf("cephfs.path must match the source")
	}

	d.config["cephfs.path"] = d.config["source"]

	// Parse the namespace / path.
	fsName, fsPath, _ := strings.Cut(d.config["cephfs.path"], "/")
	fsPath = "/" + fsPath

	// If the filesystem already exists, disallow keys associated to creating the filesystem.
	fsExists, err := d.fsExists(d.config["cephfs.cluster_name"], d.config["cephfs.user.name"], fsName)
	if err != nil {
		return fmt.Errorf("Failed to check if %q CephFS exists: %w", fsName, err)
	}

	if fsExists {
		for _, key := range []string{"create_missing", "osd_pg_num", "meta_pool", "data_pool"} {
			cephfsSourceKey := fmt.Sprintf("cephfs.%s", key)
			if d.config[cephfsSourceKey] != "" {
				return fmt.Errorf("Invalid config key %q: CephFS filesystem already exists", cephfsSourceKey)
			}
		}
	} else {
		createMissing := util.IsTrue(d.config["cephfs.create_missing"])
		if !createMissing {
			return fmt.Errorf("The requested %q CephFS doesn't exist", fsName)
		}

		// Set the pg_num to 32 because we need to specify something, but ceph will automatically change it if necessary.
		pgNum := d.config["cephfs.osd_pg_num"]
		if pgNum == "" {
			d.config["cephfs.osd_pg_num"] = "32"
		}

		// Create the meta and data pools if necessary.
		for _, key := range []string{"cephfs.meta_pool", "cephfs.data_pool"} {
			pool := d.config[key]

			if pool == "" {
				return fmt.Errorf("Missing required key %q for creating cephfs osd pool", key)
			}

			osdPoolExists, err := d.osdPoolExists(d.config["cephfs.cluster_name"], d.config["cephfs.user.name"], pool)
			if err != nil {
				return fmt.Errorf("Failed to check if %q OSD Pool exists: %w", pool, err)
			}

			if !osdPoolExists {
				// Create new osd pool.
				_, err := subprocess.RunCommand("ceph",
					"--name", fmt.Sprintf("client.%s", d.config["cephfs.user.name"]),
					"--cluster", d.config["cephfs.cluster_name"],
					"osd",
					"pool",
					"create",
					pool,
					d.config["cephfs.osd_pg_num"],
				)
				if err != nil {
					return fmt.Errorf("Failed to create ceph OSD pool %q: %w", pool, err)
				}

				revert.Add(func() {
					// Delete the OSD pool.
					_, _ = subprocess.RunCommand("ceph",
						"--name", fmt.Sprintf("client.%s", d.config["cephfs.user.name"]),
						"--cluster", d.config["cephfs.cluster_name"],
						"osd",
						"pool",
						"delete",
						pool,
						pool,
						"--yes-i-really-really-mean-it",
					)
				})
			}
		}

		// Create the filesystem.
		_, err := subprocess.RunCommand("ceph",
			"--name", fmt.Sprintf("client.%s", d.config["cephfs.user.name"]),
			"--cluster", d.config["cephfs.cluster_name"],
			"fs",
			"new",
			fsName,
			d.config["cephfs.meta_pool"],
			d.config["cephfs.data_pool"],
		)
		if err != nil {
			return fmt.Errorf("Failed to create CephFS %q: %w", fsName, err)
		}

		revert.Add(func() {
			// Set the FS to fail so that we can remove it.
			_, _ = subprocess.RunCommand("ceph",
				"--name", fmt.Sprintf("client.%s", d.config["cephfs.user.name"]),
				"--cluster", d.config["cephfs.cluster_name"],
				"fs",
				"fail",
				fsName,
			)

			// Delete the FS.
			_, _ = subprocess.RunCommand("ceph",
				"--name", fmt.Sprintf("client.%s", d.config["cephfs.user.name"]),
				"--cluster", d.config["cephfs.cluster_name"],
				"fs",
				"rm",
				fsName,
				"--yes-i-really-mean-it",
			)
		})
	}

	// Create a temporary mountpoint.
	mountPath, err := os.MkdirTemp("", "incus_cephfs_")
	if err != nil {
		return fmt.Errorf("Failed to create temporary directory under: %w", err)
	}

	defer func() { _ = os.RemoveAll(mountPath) }()

	err = os.Chmod(mountPath, 0o700)
	if err != nil {
		return fmt.Errorf("Failed to chmod '%s': %w", mountPath, err)
	}

	mountPoint := filepath.Join(mountPath, "mount")

	err = os.Mkdir(mountPoint, 0o700)
	if err != nil {
		return fmt.Errorf("Failed to create directory '%s': %w", mountPoint, err)
	}

	// Collect Ceph information.
	clusterName := d.config["cephfs.cluster_name"]
	userName := d.config["cephfs.user.name"]

	fsid, err := CephFsid(clusterName)
	if err != nil {
		return err
	}

	monitors, err := CephMonitors(clusterName)
	if err != nil {
		return err
	}

	key, err := CephKeyring(clusterName, userName)
	if err != nil {
		return err
	}

	srcPath, options := CephBuildMount(
		userName,
		key,
		fsid,
		monitors,
		fsName, "/",
	)

	// Mount the pool.
	err = TryMount(srcPath, mountPoint, "ceph", 0, strings.Join(options, ","))
	if err != nil {
		return err
	}

	defer func() { _, _ = forceUnmount(mountPoint) }()

	// Create the path if missing.
	err = os.MkdirAll(filepath.Join(mountPoint, fsPath), 0o755)
	if err != nil {
		return fmt.Errorf("Failed to create directory '%s': %w", filepath.Join(mountPoint, fsPath), err)
	}

	// Check that the existing path is empty.
	ok, _ := internalUtil.PathIsEmpty(filepath.Join(mountPoint, fsPath))
	if !ok {
		return fmt.Errorf("Only empty CephFS paths can be used as a storage pool")
	}

	revert.Success()

	return nil
}

// Delete clears any local and remote data related to this driver instance.
func (d *cephfs) Delete(op *operations.Operation) error {
	// Parse the namespace / path.
	fsName, fsPath, _ := strings.Cut(d.config["cephfs.path"], "/")
	fsPath = "/" + fsPath

	// Create a temporary mountpoint.
	mountPath, err := os.MkdirTemp("", "incus_cephfs_")
	if err != nil {
		return fmt.Errorf("Failed to create temporary directory under: %w", err)
	}

	defer func() { _ = os.RemoveAll(mountPath) }()

	err = os.Chmod(mountPath, 0o700)
	if err != nil {
		return fmt.Errorf("Failed to chmod '%s': %w", mountPath, err)
	}

	mountPoint := filepath.Join(mountPath, "mount")
	err = os.Mkdir(mountPoint, 0o700)
	if err != nil {
		return fmt.Errorf("Failed to create directory '%s': %w", mountPoint, err)
	}

	// Collect Ceph information.
	clusterName := d.config["cephfs.cluster_name"]
	userName := d.config["cephfs.user.name"]

	fsid, err := CephFsid(clusterName)
	if err != nil {
		return err
	}

	monitors, err := CephMonitors(clusterName)
	if err != nil {
		return err
	}

	key, err := CephKeyring(clusterName, userName)
	if err != nil {
		return err
	}

	srcPath, options := CephBuildMount(
		userName,
		key,
		fsid,
		monitors,
		fsName, "/",
	)

	// Mount the pool.
	err = TryMount(srcPath, mountPoint, "ceph", 0, strings.Join(options, ","))
	if err != nil {
		return err
	}

	defer func() { _, _ = forceUnmount(mountPoint) }()

	// On delete, wipe everything in the directory.
	err = wipeDirectory(GetPoolMountPath(d.name))
	if err != nil {
		return err
	}

	// Delete the pool from the parent.
	if util.PathExists(filepath.Join(mountPoint, fsPath)) {
		// Delete the path itself.
		if fsPath != "" && fsPath != "/" {
			err = os.Remove(filepath.Join(mountPoint, fsPath))
			if err != nil && !errors.Is(err, fs.ErrNotExist) {
				return fmt.Errorf("Failed to remove directory '%s': %w", filepath.Join(mountPoint, fsPath), err)
			}
		}
	}

	// Make sure the existing pool is unmounted.
	_, err = d.Unmount()
	if err != nil {
		return err
	}

	return nil
}

// Validate checks that all provide keys are supported and that no conflicting or missing configuration is present.
func (d *cephfs) Validate(config map[string]string) error {
	rules := map[string]func(value string) error{
		"cephfs.cluster_name":    validate.IsAny,
		"cephfs.fscache":         validate.Optional(validate.IsBool),
		"cephfs.path":            validate.IsAny,
		"cephfs.user.name":       validate.IsAny,
		"cephfs.create_missing":  validate.Optional(validate.IsBool),
		"cephfs.osd_pg_num":      validate.Optional(validate.IsInt64),
		"cephfs.meta_pool":       validate.IsAny,
		"cephfs.data_pool":       validate.IsAny,
		"volatile.pool.pristine": validate.IsAny,
	}

	return d.validatePool(config, rules, nil)
}

// Update applies any driver changes required from a configuration change.
func (d *cephfs) Update(changedConfig map[string]string) error {
	return nil
}

// Mount brings up the driver and sets it up to be used.
func (d *cephfs) Mount() (bool, error) {
	// Check if already mounted.
	if linux.IsMountPoint(GetPoolMountPath(d.name)) {
		return false, nil
	}

	// Parse the namespace / path.
	fsName, fsPath, _ := strings.Cut(d.config["cephfs.path"], "/")
	fsPath = "/" + fsPath

	// Collect Ceph information.
	clusterName := d.config["cephfs.cluster_name"]
	userName := d.config["cephfs.user.name"]

	fsid, err := CephFsid(clusterName)
	if err != nil {
		return false, err
	}

	monitors, err := CephMonitors(clusterName)
	if err != nil {
		return false, err
	}

	key, err := CephKeyring(clusterName, userName)
	if err != nil {
		return false, err
	}

	srcPath, options := CephBuildMount(
		userName,
		key,
		fsid,
		monitors,
		fsName,
		fsPath,
	)

	// Mount the pool.
	err = TryMount(srcPath, GetPoolMountPath(d.name), "ceph", 0, strings.Join(options, ","))
	if err != nil {
		return false, err
	}

	return true, nil
}

// Unmount clears any of the runtime state of the driver.
func (d *cephfs) Unmount() (bool, error) {
	return forceUnmount(GetPoolMountPath(d.name))
}

// GetResources returns the pool resource usage information.
func (d *cephfs) GetResources() (*api.ResourcesStoragePool, error) {
	return genericVFSGetResources(d)
}

// MigrationTypes returns the supported migration types and options supported by the driver.
func (d *cephfs) MigrationTypes(contentType ContentType, refresh bool, copySnapshots bool, clusterMove bool, storageMove bool) []localMigration.Type {
	var rsyncFeatures []string

	// Do not pass compression argument to rsync if the associated
	// config key, that is rsync.compression, is set to false.
	if util.IsFalse(d.Config()["rsync.compression"]) {
		rsyncFeatures = []string{"delete", "bidirectional"}
	} else {
		rsyncFeatures = []string{"delete", "compress", "bidirectional"}
	}

	if contentType != ContentTypeFS {
		return nil
	}

	// Do not support xattr transfer on cephfs
	return []localMigration.Type{
		{
			FSType:   migration.MigrationFSType_RSYNC,
			Features: rsyncFeatures,
		},
	}
}
