/**
# Copyright (c) 2022, NVIDIA CORPORATION.  All rights reserved.
#
# 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 edits

import (
	"os"

	"tags.cncf.io/container-device-interface/pkg/cdi"
	"tags.cncf.io/container-device-interface/specs-go"

	"github.com/opencontainers/runc/libcontainer/devices"

	"github.com/NVIDIA/nvidia-container-toolkit/internal/discover"
)

type device discover.Device

// toEdits converts a discovered device to CDI Container Edits.
func (d device) toEdits() (*cdi.ContainerEdits, error) {
	deviceNode, err := d.toSpec()
	if err != nil {
		return nil, err
	}

	e := cdi.ContainerEdits{
		ContainerEdits: &specs.ContainerEdits{
			DeviceNodes: []*specs.DeviceNode{deviceNode},
		},
	}
	return &e, nil
}

// toSpec converts a discovered Device to a CDI Spec Device. Note
// that missing info is filled in when edits are applied by querying the Device node.
func (d device) toSpec() (*specs.DeviceNode, error) {
	// The HostPath field was added in the v0.5.0 CDI specification.
	// The cdi package uses strict unmarshalling when loading specs from file causing failures for
	// unexpected fields.
	// Since the behaviour for HostPath == "" and HostPath == Path are equivalent, we clear HostPath
	// if it is equal to Path to ensure compatibility with the widest range of specs.
	hostPath := d.HostPath

	if hostPath == d.Path {
		hostPath = ""
	}
	s := specs.DeviceNode{
		HostPath: hostPath,
		Path:     d.Path,
		FileMode: d.getFileMode(),
	}

	return &s, nil
}

// getFileMode returns the filemode of the host device node associated with the discovered device.
// If this fails, a nil filemode is returned.
func (d device) getFileMode() *os.FileMode {
	path := d.HostPath
	if path == "" {
		path = d.Path
	}
	dn, err := devices.DeviceFromPath(path, "rwm")
	if err != nil {
		// return nil, fmt.Errorf("failed to get device information for %q: %w", path, err)
		return nil
	}

	return &dn.FileMode
}