//go:build linux
// +build linux

/*
Copyright 2021 The Kubernetes 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 mount

import (
	"fmt"
	"strconv"
	"strings"

	"k8s.io/klog/v2"
	utilexec "k8s.io/utils/exec"
)

const (
	blockDev = "blockdev"
)

// ResizeFs Provides support for resizing file systems
type ResizeFs struct {
	exec utilexec.Interface
}

// NewResizeFs returns new instance of resizer
func NewResizeFs(exec utilexec.Interface) *ResizeFs {
	return &ResizeFs{exec: exec}
}

// Resize perform resize of file system
func (resizefs *ResizeFs) Resize(devicePath string, deviceMountPath string) (bool, error) {
	format, err := getDiskFormat(resizefs.exec, devicePath)
	if err != nil {
		formatErr := fmt.Errorf("ResizeFS.Resize - error checking format for device %s: %v", devicePath, err)
		return false, formatErr
	}

	// If disk has no format, there is no need to resize the disk because mkfs.*
	// by default will use whole disk anyways.
	if format == "" {
		return false, nil
	}

	klog.V(3).Infof("ResizeFS.Resize - Expanding mounted volume %s", devicePath)
	switch format {
	case "ext3", "ext4":
		return resizefs.extResize(devicePath)
	case "xfs":
		return resizefs.xfsResize(deviceMountPath)
	case "btrfs":
		return resizefs.btrfsResize(deviceMountPath)
	}
	return false, fmt.Errorf("ResizeFS.Resize - resize of format %s is not supported for device %s mounted at %s", format, devicePath, deviceMountPath)
}

func (resizefs *ResizeFs) extResize(devicePath string) (bool, error) {
	output, err := resizefs.exec.Command("resize2fs", devicePath).CombinedOutput()
	if err == nil {
		klog.V(2).Infof("Device %s resized successfully", devicePath)
		return true, nil
	}

	resizeError := fmt.Errorf("resize of device %s failed: %v. resize2fs output: %s", devicePath, err, string(output))
	return false, resizeError
}

func (resizefs *ResizeFs) xfsResize(deviceMountPath string) (bool, error) {
	args := []string{"-d", deviceMountPath}
	output, err := resizefs.exec.Command("xfs_growfs", args...).CombinedOutput()

	if err == nil {
		klog.V(2).Infof("Device %s resized successfully", deviceMountPath)
		return true, nil
	}

	resizeError := fmt.Errorf("resize of device %s failed: %v. xfs_growfs output: %s", deviceMountPath, err, string(output))
	return false, resizeError
}

func (resizefs *ResizeFs) btrfsResize(deviceMountPath string) (bool, error) {
	args := []string{"filesystem", "resize", "max", deviceMountPath}
	output, err := resizefs.exec.Command("btrfs", args...).CombinedOutput()

	if err == nil {
		klog.V(2).Infof("Device %s resized successfully", deviceMountPath)
		return true, nil
	}

	resizeError := fmt.Errorf("resize of device %s failed: %v. btrfs output: %s", deviceMountPath, err, string(output))
	return false, resizeError
}

func (resizefs *ResizeFs) NeedResize(devicePath string, deviceMountPath string) (bool, error) {
	// Do nothing if device is mounted as readonly
	readonly, err := resizefs.getDeviceRO(devicePath)
	if err != nil {
		return false, err
	}

	if readonly {
		klog.V(3).Infof("ResizeFs.needResize - no resize possible since filesystem %s is readonly", devicePath)
		return false, nil
	}

	deviceSize, err := resizefs.getDeviceSize(devicePath)
	if err != nil {
		return false, err
	}
	var fsSize, blockSize uint64
	format, err := getDiskFormat(resizefs.exec, devicePath)
	if err != nil {
		formatErr := fmt.Errorf("ResizeFS.Resize - error checking format for device %s: %v", devicePath, err)
		return false, formatErr
	}

	// If disk has no format, there is no need to resize the disk because mkfs.*
	// by default will use whole disk anyways.
	if format == "" {
		return false, nil
	}

	klog.V(3).Infof("ResizeFs.needResize - checking mounted volume %s", devicePath)
	switch format {
	case "ext3", "ext4":
		blockSize, fsSize, err = resizefs.getExtSize(devicePath)
		klog.V(5).Infof("Ext size: filesystem size=%d, block size=%d", fsSize, blockSize)
	case "xfs":
		blockSize, fsSize, err = resizefs.getXFSSize(deviceMountPath)
		klog.V(5).Infof("Xfs size: filesystem size=%d, block size=%d, err=%v", fsSize, blockSize, err)
	case "btrfs":
		blockSize, fsSize, err = resizefs.getBtrfsSize(devicePath)
		klog.V(5).Infof("Btrfs size: filesystem size=%d, block size=%d, err=%v", fsSize, blockSize, err)
	default:
		klog.Errorf("Not able to parse given filesystem info. fsType: %s, will not resize", format)
		return false, fmt.Errorf("Could not parse fs info on given filesystem format: %s. Supported fs types are: xfs, ext3, ext4", format)
	}
	if err != nil {
		return false, err
	}
	// Tolerate one block difference, just in case of rounding errors somewhere.
	klog.V(5).Infof("Volume %s: device size=%d, filesystem size=%d, block size=%d", devicePath, deviceSize, fsSize, blockSize)
	if deviceSize <= fsSize+blockSize {
		return false, nil
	}
	return true, nil
}

func (resizefs *ResizeFs) getDeviceSize(devicePath string) (uint64, error) {
	output, err := resizefs.exec.Command(blockDev, "--getsize64", devicePath).CombinedOutput()
	outStr := strings.TrimSpace(string(output))
	if err != nil {
		return 0, fmt.Errorf("failed to read size of device %s: %s: %s", devicePath, err, outStr)
	}
	size, err := strconv.ParseUint(outStr, 10, 64)
	if err != nil {
		return 0, fmt.Errorf("failed to parse size of device %s %s: %s", devicePath, outStr, err)
	}
	return size, nil
}

func (resizefs *ResizeFs) getDeviceRO(devicePath string) (bool, error) {
	output, err := resizefs.exec.Command(blockDev, "--getro", devicePath).CombinedOutput()
	outStr := strings.TrimSpace(string(output))
	if err != nil {
		return false, fmt.Errorf("failed to get readonly bit from device %s: %s: %s", devicePath, err, outStr)
	}
	switch outStr {
	case "0":
		return false, nil
	case "1":
		return true, nil
	default:
		return false, fmt.Errorf("Failed readonly device check. Expected 1 or 0, got '%s'", outStr)
	}
}

func (resizefs *ResizeFs) getExtSize(devicePath string) (uint64, uint64, error) {
	output, err := resizefs.exec.Command("dumpe2fs", "-h", devicePath).CombinedOutput()
	if err != nil {
		return 0, 0, fmt.Errorf("failed to read size of filesystem on %s: %s: %s", devicePath, err, string(output))
	}

	blockSize, blockCount, _ := resizefs.parseFsInfoOutput(string(output), ":", "block size", "block count")

	if blockSize == 0 {
		return 0, 0, fmt.Errorf("could not find block size of device %s", devicePath)
	}
	if blockCount == 0 {
		return 0, 0, fmt.Errorf("could not find block count of device %s", devicePath)
	}
	return blockSize, blockSize * blockCount, nil
}

func (resizefs *ResizeFs) getXFSSize(devicePath string) (uint64, uint64, error) {
	output, err := resizefs.exec.Command("xfs_io", "-c", "statfs", devicePath).CombinedOutput()
	if err != nil {
		return 0, 0, fmt.Errorf("failed to read size of filesystem on %s: %s: %s", devicePath, err, string(output))
	}

	blockSize, blockCount, _ := resizefs.parseFsInfoOutput(string(output), "=", "geom.bsize", "geom.datablocks")

	if blockSize == 0 {
		return 0, 0, fmt.Errorf("could not find block size of device %s", devicePath)
	}
	if blockCount == 0 {
		return 0, 0, fmt.Errorf("could not find block count of device %s", devicePath)
	}
	return blockSize, blockSize * blockCount, nil
}

func (resizefs *ResizeFs) getBtrfsSize(devicePath string) (uint64, uint64, error) {
	output, err := resizefs.exec.Command("btrfs", "inspect-internal", "dump-super", "-f", devicePath).CombinedOutput()
	if err != nil {
		return 0, 0, fmt.Errorf("failed to read size of filesystem on %s: %s: %s", devicePath, err, string(output))
	}

	blockSize, totalBytes, _ := resizefs.parseBtrfsInfoOutput(string(output), "sectorsize", "total_bytes")

	if blockSize == 0 {
		return 0, 0, fmt.Errorf("could not find block size of device %s", devicePath)
	}
	if totalBytes == 0 {
		return 0, 0, fmt.Errorf("could not find total size of device %s", devicePath)
	}
	return blockSize, totalBytes, nil
}

func (resizefs *ResizeFs) parseBtrfsInfoOutput(cmdOutput string, blockSizeKey string, totalBytesKey string) (uint64, uint64, error) {
	lines := strings.Split(cmdOutput, "\n")
	var blockSize, blockCount uint64
	var err error

	for _, line := range lines {
		tokens := strings.Fields(line)
		if len(tokens) != 2 {
			continue
		}
		key, value := strings.ToLower(strings.TrimSpace(tokens[0])), strings.ToLower(strings.TrimSpace(tokens[1]))

		if key == blockSizeKey {
			blockSize, err = strconv.ParseUint(value, 10, 64)
			if err != nil {
				return 0, 0, fmt.Errorf("failed to parse block size %s: %s", value, err)
			}
		}
		if key == totalBytesKey {
			blockCount, err = strconv.ParseUint(value, 10, 64)
			if err != nil {
				return 0, 0, fmt.Errorf("failed to parse total size %s: %s", value, err)
			}
		}
	}
	return blockSize, blockCount, err
}

func (resizefs *ResizeFs) parseFsInfoOutput(cmdOutput string, spliter string, blockSizeKey string, blockCountKey string) (uint64, uint64, error) {
	lines := strings.Split(cmdOutput, "\n")
	var blockSize, blockCount uint64
	var err error

	for _, line := range lines {
		tokens := strings.Split(line, spliter)
		if len(tokens) != 2 {
			continue
		}
		key, value := strings.ToLower(strings.TrimSpace(tokens[0])), strings.ToLower(strings.TrimSpace(tokens[1]))
		if key == blockSizeKey {
			blockSize, err = strconv.ParseUint(value, 10, 64)
			if err != nil {
				return 0, 0, fmt.Errorf("failed to parse block size %s: %s", value, err)
			}
		}
		if key == blockCountKey {
			blockCount, err = strconv.ParseUint(value, 10, 64)
			if err != nil {
				return 0, 0, fmt.Errorf("failed to parse block count %s: %s", value, err)
			}
		}
	}
	return blockSize, blockCount, err
}
