// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

package mount

import (
	"fmt"
	"os"

	"github.com/talos-systems/go-blockdevice/blockdevice"
	"golang.org/x/sys/unix"

	"github.com/talos-systems/talos/internal/app/machined/pkg/runtime"
	"github.com/talos-systems/talos/internal/app/machined/pkg/runtime/disk"
	"github.com/talos-systems/talos/pkg/machinery/constants"
)

// SystemMountPointsForDevice returns the mountpoints required to boot the system.
// This function is called exclusively during installations ( both image
// creation and bare metall installs ). This is why we want to look up
// device by specified disk as well as why we don't want to grow any
// filesystems.
func SystemMountPointsForDevice(devpath string, opts ...Option) (mountpoints *Points, err error) {
	mountpoints = NewMountPoints()

	bd, err := blockdevice.Open(devpath)
	if err != nil {
		return nil, err
	}

	defer bd.Close() // nolint:errcheck

	for _, name := range []string{constants.EphemeralPartitionLabel, constants.BootPartitionLabel, constants.EFIPartitionLabel, constants.StatePartitionLabel} {
		mountpoint, err := SystemMountPointForLabel(bd, name, opts...)
		if err != nil {
			return nil, err
		}

		mountpoints.Set(name, mountpoint)
	}

	return mountpoints, nil
}

// SystemMountPointForLabel returns a mount point for the specified device and label.
// nolint:gocyclo
func SystemMountPointForLabel(device *blockdevice.BlockDevice, label string, opts ...Option) (mountpoint *Point, err error) {
	var target string

	switch label {
	case constants.EphemeralPartitionLabel:
		target = constants.EphemeralMountPoint
	case constants.BootPartitionLabel:
		target = constants.BootMountPoint
	case constants.EFIPartitionLabel:
		target = constants.EFIMountPoint
	case constants.StatePartitionLabel:
		target = constants.StateMountPoint
	default:
		return nil, fmt.Errorf("unknown label: %q", label)
	}

	partition, err := device.GetPartition(label)
	if err != nil && err != os.ErrNotExist {
		return nil, err
	}

	if partition == nil {
		// A boot partitition is not required.
		if label == constants.BootPartitionLabel {
			return nil, nil
		}

		return nil, fmt.Errorf("failed to find device with label %s: %w", label, err)
	}

	fsType, err := partition.Filesystem()
	if err != nil {
		return nil, err
	}

	partPath, err := partition.Path()
	if err != nil {
		return nil, err
	}

	mountpoint = NewMountPoint(partPath, target, fsType, unix.MS_NOATIME, "", opts...)

	return mountpoint, nil
}

// SystemPartitionMount mounts a system partition by the label.
func SystemPartitionMount(r runtime.Runtime, label string, opts ...Option) (err error) {
	device := r.State().Machine().Disk(disk.WithPartitionLabel(label))
	if device == nil {
		return fmt.Errorf("failed to find device with partition labeled %s", label)
	}

	mountpoints := NewMountPoints()

	mountpoint, err := SystemMountPointForLabel(device.BlockDevice, label, opts...)
	if err != nil {
		return err
	}

	if mountpoint == nil {
		return fmt.Errorf("no mountpoints for label %q", label)
	}

	mountpoints.Set(label, mountpoint)

	if err = Mount(mountpoints); err != nil {
		return err
	}

	return nil
}

// SystemPartitionUnmount unmounts a system partition by the label.
func SystemPartitionUnmount(r runtime.Runtime, label string) (err error) {
	device := r.State().Machine().Disk(disk.WithPartitionLabel(label))
	if device == nil {
		return fmt.Errorf("failed to find device with partition labeled %s", label)
	}

	mountpoints := NewMountPoints()

	mountpoint, err := SystemMountPointForLabel(device.BlockDevice, label)
	if err != nil {
		return err
	}

	if mountpoint == nil {
		return fmt.Errorf("no mountpoints for label %q", label)
	}

	mountpoints.Set(label, mountpoint)

	if err = Unmount(mountpoints); err != nil {
		return err
	}

	return nil
}