// Copyright 2023 Versity Software
// This file is 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 gwcli

import (
	"fmt"
	"io/fs"
	"math"

	"github.com/urfave/cli/v2"
	"github.com/versity/versitygw/backend/meta"
	"github.com/versity/versitygw/backend/posix"
)

var (
	chownuid, chowngid   bool
	bucketlinks          bool
	versioningDir        string
	dirPerms             uint
	sidecar              string
	nometa               bool
	forceNoTmpFile       bool
	forceNoCopyFileRange bool
	enableODirect        bool
	actionsConcurrency   int
	ioBufferSize         int
	defaultEtag          string
	dataIntegrityEtag    bool
)

// PosixCommand returns the "posix" subcommand, common to all versitygw
// binaries.
func PosixCommand() *cli.Command {
	return &cli.Command{
		Name:  "posix",
		Usage: "posix filesystem storage backend",
		Description: `Any posix filesystem that supports extended attributes. The top level
directory for the gateway must be provided. All sub directories of the
top level directory are treated as buckets, and all files/directories
below the "bucket directory" are treated as the objects. The object
name is split on "/" separator to translate to posix storage.
For example:
top level: /mnt/fs/gwroot
bucket: mybucket
object: a/b/c/myobject
will be translated into the file /mnt/fs/gwroot/mybucket/a/b/c/myobject`,
		Action: runPosix,
		Flags: []cli.Flag{
			&cli.BoolFlag{
				Name:        "chuid",
				Usage:       "chown newly created files and directories to client account UID",
				EnvVars:     []string{"VGW_CHOWN_UID"},
				Destination: &chownuid,
			},
			&cli.BoolFlag{
				Name:        "chgid",
				Usage:       "chown newly created files and directories to client account GID",
				EnvVars:     []string{"VGW_CHOWN_GID"},
				Destination: &chowngid,
			},
			&cli.BoolFlag{
				Name:        "bucketlinks",
				Usage:       "allow symlinked directories at bucket level to be treated as buckets",
				EnvVars:     []string{"VGW_BUCKET_LINKS"},
				Destination: &bucketlinks,
			},
			&cli.StringFlag{
				Name:        "versioning-dir",
				Usage:       "the directory path to enable bucket versioning",
				EnvVars:     []string{"VGW_VERSIONING_DIR"},
				Destination: &versioningDir,
			},
			&cli.UintFlag{
				Name:        "dir-perms",
				Usage:       "default directory permissions for new directories",
				EnvVars:     []string{"VGW_DIR_PERMS"},
				Destination: &dirPerms,
				DefaultText: "0755",
				Value:       0755,
			},
			&cli.StringFlag{
				Name:        "sidecar",
				Usage:       "use provided sidecar directory to store metadata",
				EnvVars:     []string{"VGW_META_SIDECAR"},
				Destination: &sidecar,
			},
			&cli.IntFlag{
				Name:        "concurrency",
				Usage:       "maximum concurrent actions allowed",
				EnvVars:     []string{"VGW_POSIX_CONCURRENCY"},
				Value:       5000,
				Destination: &actionsConcurrency,
			},
			&cli.IntFlag{
				Name:        "io-buffer-size",
				Usage:       "buffer size in bytes used by POSIX put/get/part read and write paths (<=0 uses backend default 1MiB)",
				EnvVars:     []string{"VGW_POSIX_IO_BUFFER_SIZE"},
				Value:       1024 * 1024,
				Destination: &ioBufferSize,
			},
			&cli.BoolFlag{
				Name:        "nometa",
				Usage:       "disable metadata storage",
				EnvVars:     []string{"VGW_META_NONE"},
				Destination: &nometa,
			},
			&cli.BoolFlag{
				Name:        "disableotmp",
				Usage:       "disable O_TMPFILE support for new objects",
				EnvVars:     []string{"VGW_DISABLE_OTMP"},
				Destination: &forceNoTmpFile,
			},
			&cli.BoolFlag{
				Name:        "disable-copy-file-range",
				Usage:       "explicitly copy multipart upload parts instead of using copy_file_range (which may hang with some NFS servers)",
				EnvVars:     []string{"VGW_DISABLE_COPY_FILE_RANGE"},
				Destination: &forceNoCopyFileRange,
			},
			&cli.BoolFlag{
				Name:        "enable-odirect",
				Usage:       "enable best-effort O_DIRECT for object data reads/writes",
				EnvVars:     []string{"VGW_ENABLE_O_DIRECT"},
				Destination: &enableODirect,
			},
			&cli.StringFlag{
				Name:        "default-etag",
				Usage:       "default ETag value returned for objects that do not have a stored etag attribute (e.g. files placed on the filesystem outside of versitygw)",
				EnvVars:     []string{"VGW_DEFAULT_ETAG"},
				Destination: &defaultEtag,
			},
			&cli.BoolFlag{
				Name:        "data-integrity-etag",
				Usage:       "use data-integrity checksum-derived ETags instead of MD5-based ETags (PUT object ETag, multipart part ETags, and completed multipart object ETag)",
				EnvVars:     []string{"VGW_DATA_INTEGRITY_ETAG"},
				Destination: &dataIntegrityEtag,
			},
		},
	}
}

func runPosix(ctx *cli.Context) error {
	if ctx.NArg() == 0 {
		return fmt.Errorf("no directory provided for operation")
	}

	gwroot := (ctx.Args().Get(0))

	if dirPerms > math.MaxUint32 {
		return fmt.Errorf("invalid directory permissions: %d", dirPerms)
	}

	if nometa && sidecar != "" {
		return fmt.Errorf("cannot use both nometa and sidecar metadata")
	}

	if actionsConcurrency <= 0 {
		return fmt.Errorf("concurrency must be positive, got %d", actionsConcurrency)
	}

	opts := posix.PosixOpts{
		ChownUID:             chownuid,
		ChownGID:             chowngid,
		BucketLinks:          bucketlinks,
		VersioningDir:        versioningDir,
		NewDirPerm:           fs.FileMode(dirPerms),
		ForceNoTmpFile:       forceNoTmpFile,
		ForceNoCopyFileRange: forceNoCopyFileRange,
		EnableODirect:        enableODirect,
		ValidateBucketNames:  DisableStrictBucketNames,
		Concurrency:          actionsConcurrency,
		IOBufferSize:         ioBufferSize,
		CopyObjectThreshold:  CopyObjectThreshold,
		DefaultEtag:          defaultEtag,
		DataIntegrityEtag:    dataIntegrityEtag,
	}

	var ms meta.MetadataStorer
	switch {
	case sidecar != "":
		sc, err := meta.NewSideCar(sidecar)
		if err != nil {
			return fmt.Errorf("failed to init sidecar metadata: %w", err)
		}
		ms = sc
		opts.SideCarDir = sidecar
	case nometa:
		ms = meta.NoMeta{}
	default:
		ms = meta.XattrMeta{}
		err := meta.XattrMeta{}.Test(gwroot)
		if err != nil {
			return fmt.Errorf("xattr check failed: %w", err)
		}
	}

	be, err := posix.New(gwroot, ms, opts)
	if err != nil {
		return fmt.Errorf("failed to init posix backend: %w", err)
	}

	return RunGateway(ctx.Context, be)
}