/**
# 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 discover

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/NVIDIA/nvidia-container-toolkit/internal/config/image"
	"github.com/NVIDIA/nvidia-container-toolkit/internal/info/drm"
	"github.com/NVIDIA/nvidia-container-toolkit/internal/info/proc"
	"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
	"github.com/NVIDIA/nvidia-container-toolkit/internal/lookup"
	"github.com/NVIDIA/nvidia-container-toolkit/internal/lookup/cuda"
	"github.com/NVIDIA/nvidia-container-toolkit/internal/lookup/root"
)

// NewDRMNodesDiscoverer returns a discoverer for the DRM device nodes associated with the specified visible devices.
//
// TODO: The logic for creating DRM devices should be consolidated between this
// and the logic for generating CDI specs for a single device. This is only used
// when applying OCI spec modifications to an incoming spec in "legacy" mode.
func NewDRMNodesDiscoverer(logger logger.Interface, devices image.VisibleDevices, devRoot string, nvidiaCDIHookPath string) (Discover, error) {
	drmDeviceNodes, err := newDRMDeviceDiscoverer(logger, devices, devRoot)
	if err != nil {
		return nil, fmt.Errorf("failed to create DRM device discoverer: %v", err)
	}

	drmByPathSymlinks := newCreateDRMByPathSymlinks(logger, drmDeviceNodes, devRoot, nvidiaCDIHookPath)

	discover := Merge(drmDeviceNodes, drmByPathSymlinks)
	return discover, nil
}

// NewGraphicsMountsDiscoverer creates a discoverer for the mounts required by graphics tools such as vulkan.
func NewGraphicsMountsDiscoverer(logger logger.Interface, driver *root.Driver, nvidiaCDIHookPath string) (Discover, error) {
	libraries := newGraphicsLibrariesDiscoverer(logger, driver, nvidiaCDIHookPath)

	configs := NewMounts(
		logger,
		driver.Configs(),
		driver.Root,
		[]string{
			"glvnd/egl_vendor.d/10_nvidia.json",
			"egl/egl_external_platform.d/15_nvidia_gbm.json",
			"egl/egl_external_platform.d/10_nvidia_wayland.json",
			"nvidia/nvoptix.bin",
			"X11/xorg.conf.d/10-nvidia.conf",
			"X11/xorg.conf.d/nvidia-drm-outputclass.conf",
		},
	)

	discover := Merge(
		libraries,
		configs,
		newVulkanConfigsDiscover(logger, driver),
	)

	return discover, nil
}

// newVulkanConfigsDiscover creates a discoverer for vulkan ICD files.
// For these files we search the standard driver config paths as well as the
// driver root itself. This allows us to support GKE installations where the
// vulkan ICD files are at {{ .driverRoot }}/vulkan instead of in /etc/vulkan.
func newVulkanConfigsDiscover(logger logger.Interface, driver *root.Driver) Discover {
	locator := lookup.First(driver.Configs(), driver.Files())
	return &mountsToContainerPath{
		logger:  logger,
		locator: locator,
		required: []string{
			"vulkan/icd.d/nvidia_icd.json",
			"vulkan/icd.d/nvidia_layers.json",
			"vulkan/implicit_layer.d/nvidia_layers.json",
		},
		containerRoot: "/etc",
	}
}

type graphicsDriverLibraries struct {
	Discover
	logger            logger.Interface
	nvidiaCDIHookPath string
}

var _ Discover = (*graphicsDriverLibraries)(nil)

func newGraphicsLibrariesDiscoverer(logger logger.Interface, driver *root.Driver, nvidiaCDIHookPath string) Discover {
	cudaLibRoot, cudaVersionPattern := getCUDALibRootAndVersionPattern(logger, driver)

	libraries := NewMounts(
		logger,
		driver.Libraries(),
		driver.Root,
		[]string{
			// The libnvidia-egl-gbm and libnvidia-egl-wayland libraries do not
			// have the RM version. Use the *.* pattern to match X.Y.Z versions.
			"libnvidia-egl-gbm.so.*.*",
			"libnvidia-egl-wayland.so.*.*",
			// We include the following libraries to have them available for
			// symlink creation below:
			// If CDI injection is used, these should already be detected as:
			// * libnvidia-allocator.so.RM_VERSION
			// * libnvidia-vulkan-producer.so.RM_VERSION
			// but need to be handled for the legacy case too.
			"libnvidia-allocator.so." + cudaVersionPattern,
			"libnvidia-vulkan-producer.so." + cudaVersionPattern,
		},
	)

	xorgLibraries := NewMounts(
		logger,
		lookup.NewFileLocator(
			lookup.WithLogger(logger),
			lookup.WithRoot(driver.Root),
			lookup.WithSearchPaths(buildXOrgSearchPaths(cudaLibRoot)...),
			lookup.WithCount(1),
		),
		driver.Root,
		[]string{
			"nvidia_drv.so",
			"libglxserver_nvidia.so." + cudaVersionPattern,
		},
	)

	return &graphicsDriverLibraries{
		Discover:          Merge(libraries, xorgLibraries),
		logger:            logger,
		nvidiaCDIHookPath: nvidiaCDIHookPath,
	}
}

// Mounts discovers the required libraries and filters out libnvidia-allocator.so.
// The library libnvidia-allocator.so is already handled by either the *.RM_VERSION
// injection or by libnvidia-container. We therefore filter it out here as a
// workaround for the case where libnvidia-container will re-mount this in the
// container, which causes issues with shared mount propagation.
func (d graphicsDriverLibraries) Mounts() ([]Mount, error) {
	mounts, err := d.Discover.Mounts()
	if err != nil {
		return nil, fmt.Errorf("failed to get library mounts: %v", err)
	}

	var filtered []Mount
	for _, mount := range mounts {
		if d.isDriverLibrary(filepath.Base(mount.Path), "libnvidia-allocator.so") {
			continue
		}
		filtered = append(filtered, mount)
	}
	return filtered, nil
}

// Create necessary library symlinks for graphics drivers
func (d graphicsDriverLibraries) Hooks() ([]Hook, error) {
	mounts, err := d.Discover.Mounts()
	if err != nil {
		return nil, fmt.Errorf("failed to get library mounts: %v", err)
	}

	var links []string
	for _, mount := range mounts {
		dir, filename := filepath.Split(mount.Path)
		switch {
		case d.isDriverLibrary(filename, "libnvidia-allocator.so"):
			// gbm/nvidia-drm_gbm.so is a symlink to ../libnvidia-allocator.so.1 which
			// in turn symlinks to libnvidia-allocator.so.RM_VERSION.
			// The libnvidia-allocator.so.1 -> libnvidia-allocator.so.RM_VERSION symlink
			// is created when ldconfig is run against the container and there
			// is no explicit need to create it.
			// create gbm/nvidia-drm_gbm.so -> ../libnvidia-allocate.so.1 symlink
			linkPath := filepath.Join(dir, "gbm", "nvidia-drm_gbm.so")
			links = append(links, fmt.Sprintf("%s::%s", "../libnvidia-allocator.so.1", linkPath))
		case d.isDriverLibrary(filename, "libnvidia-vulkan-producer.so"):
			// libnvidia-vulkan-producer.so is a drirect symlink to libnvidia-vulkan-producer.so.RM_VERSION
			// create libnvidia-vulkan-producer.so -> libnvidia-vulkan-producer.so.RM_VERSION symlink
			linkPath := filepath.Join(dir, "libnvidia-vulkan-producer.so")
			links = append(links, fmt.Sprintf("%s::%s", filename, linkPath))
		case d.isDriverLibrary(filename, "libglxserver_nvidia.so"):
			// libglxserver_nvidia.so is a directl symlink to libglxserver_nvidia.so.RM_VERSION
			// create libglxserver_nvidia.so -> libglxserver_nvidia.so.RM_VERSION symlink
			linkPath := filepath.Join(dir, "libglxserver_nvidia.so")
			links = append(links, fmt.Sprintf("%s::%s", filename, linkPath))
		}
	}
	if len(links) == 0 {
		return nil, nil
	}

	hooks := CreateCreateSymlinkHook(d.nvidiaCDIHookPath, links)

	return hooks.Hooks()
}

// isDriverLibrary checks whether the specified filename is a specific driver library.
func (d graphicsDriverLibraries) isDriverLibrary(filename string, libraryName string) bool {
	// TODO: Instead of `.*.*` we could use the driver version.
	pattern := strings.TrimSuffix(libraryName, ".") + ".*.*"
	match, _ := filepath.Match(pattern, filename)
	return match
}

// getCUDALibRootAndVersionPattern returns the parent directory and the version
// suffix of the libcuda.so.*.* library at the driver root.
// If the library cannot be located an empty root is returned.
// If the version string cannot be extracted, the generic *.* pattern is returned.
func getCUDALibRootAndVersionPattern(logger logger.Interface, driver *root.Driver) (string, string) {
	libCudaPaths, err := cuda.New(
		driver.Libraries(),
	).Locate(".*.*")
	if err != nil {
		logger.Warningf("failed to locate libcuda.so: %v; using *.*", err)
		return "", "*.*"
	}
	libcudaPath := libCudaPaths[0]

	libRoot := filepath.Dir(libcudaPath)
	version := strings.TrimPrefix(filepath.Base(libcudaPath), "libcuda.so.")
	if version == "" {
		logger.Warningf("failed to extract version from %v; using *.*", libcudaPath)
		version = "*.*"
	}

	return driver.RelativeToRoot(libRoot), version
}

// buildXOrgSearchPaths returns the ordered list of search paths for XOrg files.
func buildXOrgSearchPaths(libRoot string) []string {
	var paths []string
	if libRoot != "" {
		paths = append(paths,
			filepath.Join(libRoot, "nvidia/xorg"),
			filepath.Join(libRoot, "xorg", "modules", "drivers"),
			filepath.Join(libRoot, "xorg", "modules", "extensions"),
			filepath.Join(libRoot, "xorg", "modules/updates", "drivers"),
			filepath.Join(libRoot, "xorg", "modules/updates", "extensions"),
		)
	}

	return append(paths,
		filepath.Join("/usr/lib/xorg", "modules", "drivers"),
		filepath.Join("/usr/lib/xorg", "modules", "extensions"),
		filepath.Join("/usr/lib/xorg", "modules/updates", "drivers"),
		filepath.Join("/usr/lib/xorg", "modules/updates", "extensions"),
		filepath.Join("/usr/lib64/xorg", "modules", "drivers"),
		filepath.Join("/usr/lib64/xorg", "modules", "extensions"),
		filepath.Join("/usr/lib64/xorg", "modules/updates", "drivers"),
		filepath.Join("/usr/lib64/xorg", "modules/updates", "extensions"),
		filepath.Join("/usr/X11R6/lib", "modules", "drivers"),
		filepath.Join("/usr/X11R6/lib", "modules", "extensions"),
		filepath.Join("/usr/X11R6/lib", "modules/updates", "drivers"),
		filepath.Join("/usr/X11R6/lib", "modules/updates", "extensions"),
		filepath.Join("/usr/X11R6/lib64", "modules", "drivers"),
		filepath.Join("/usr/X11R6/lib64", "modules", "extensions"),
		filepath.Join("/usr/X11R6/lib64", "modules/updates", "drivers"),
		filepath.Join("/usr/X11R6/lib64", "modules/updates", "extensions"),
	)
}

type drmDevicesByPath struct {
	None
	logger            logger.Interface
	nvidiaCDIHookPath string
	devRoot           string
	devicesFrom       Discover
}

// newCreateDRMByPathSymlinks creates a discoverer for a hook to create the by-path symlinks for DRM devices discovered by the specified devices discoverer
func newCreateDRMByPathSymlinks(logger logger.Interface, devices Discover, devRoot string, nvidiaCDIHookPath string) Discover {
	d := drmDevicesByPath{
		logger:            logger,
		nvidiaCDIHookPath: nvidiaCDIHookPath,
		devRoot:           devRoot,
		devicesFrom:       devices,
	}

	return &d
}

// Hooks returns a hook to create the symlinks from the required CSV files
func (d drmDevicesByPath) Hooks() ([]Hook, error) {
	devices, err := d.devicesFrom.Devices()
	if err != nil {
		return nil, fmt.Errorf("failed to discover devices for by-path symlinks: %v", err)
	}
	if len(devices) == 0 {
		return nil, nil
	}
	links, err := d.getSpecificLinkArgs(devices)
	if err != nil {
		return nil, fmt.Errorf("failed to determine specific links: %v", err)
	}
	if len(links) == 0 {
		return nil, nil
	}

	var args []string
	for _, l := range links {
		args = append(args, "--link", l)
	}

	hook := CreateNvidiaCDIHook(
		d.nvidiaCDIHookPath,
		"create-symlinks",
		args...,
	)

	return []Hook{hook}, nil
}

// getSpecificLinkArgs returns the required specific links that need to be created
func (d drmDevicesByPath) getSpecificLinkArgs(devices []Device) ([]string, error) {
	selectedDevices := make(map[string]bool)
	for _, d := range devices {
		selectedDevices[filepath.Base(d.HostPath)] = true
	}

	linkLocator := lookup.NewFileLocator(
		lookup.WithLogger(d.logger),
		lookup.WithRoot(d.devRoot),
	)
	candidates, err := linkLocator.Locate("/dev/dri/by-path/pci-*-*")
	if err != nil {
		d.logger.Warningf("Failed to locate by-path links: %v; ignoring", err)
		return nil, nil
	}

	var links []string
	for _, c := range candidates {
		device, err := os.Readlink(c)
		if err != nil {
			d.logger.Warningf("Failed to evaluate symlink %v; ignoring", c)
			continue
		}

		if selectedDevices[filepath.Base(device)] {
			d.logger.Debugf("adding device symlink %v -> %v", c, device)
			links = append(links, fmt.Sprintf("%v::%v", device, c))
		}
	}

	return links, nil
}

// newDRMDeviceDiscoverer creates a discoverer for the DRM devices associated with the requested devices.
func newDRMDeviceDiscoverer(logger logger.Interface, devices image.VisibleDevices, devRoot string) (Discover, error) {
	allDevices := NewCharDeviceDiscoverer(
		logger,
		devRoot,
		[]string{
			"/dev/dri/card*",
			"/dev/dri/renderD*",
		},
	)

	filter, err := newDRMDeviceFilter(devices, devRoot)
	if err != nil {
		return nil, fmt.Errorf("failed to construct DRM device filter: %v", err)
	}

	// We return a discoverer that applies the DRM device filter created above to all discovered DRM device nodes.
	d := newFilteredDiscoverer(
		logger,
		allDevices,
		filter,
	)

	return d, err
}

// newDRMDeviceFilter creates a filter that matches DRM devices nodes for the visible devices.
func newDRMDeviceFilter(devices image.VisibleDevices, devRoot string) (Filter, error) {
	gpuInformationPaths, err := proc.GetInformationFilePaths(devRoot)
	if err != nil {
		return nil, fmt.Errorf("failed to read GPU information: %v", err)
	}

	var selectedBusIds []string
	for _, f := range gpuInformationPaths {
		info, err := proc.ParseGPUInformationFile(f)
		if err != nil {
			return nil, fmt.Errorf("failed to parse %v: %v", f, err)
		}
		uuid := info[proc.GPUInfoGPUUUID]
		busID := info[proc.GPUInfoBusLocation]
		minor := info[proc.GPUInfoDeviceMinor]

		if devices.Has(minor) || devices.Has(uuid) || devices.Has(busID) {
			selectedBusIds = append(selectedBusIds, busID)
		}
	}

	filter := make(selectDeviceByPath)
	for _, busID := range selectedBusIds {
		drmDeviceNodes, err := drm.GetDeviceNodesByBusID(busID)
		if err != nil {
			return nil, fmt.Errorf("failed to determine DRM devices for %v: %v", busID, err)
		}
		for _, drmDeviceNode := range drmDeviceNodes {
			filter[drmDeviceNode] = true
		}
	}

	return filter, nil
}

// selectDeviceByPath is a filter that allows devices to be selected by the path
type selectDeviceByPath map[string]bool

var _ Filter = (*selectDeviceByPath)(nil)

// DeviceIsSelected determines whether the device's path has been selected
func (s selectDeviceByPath) DeviceIsSelected(device Device) bool {
	return s[device.Path]
}

// MountIsSelected is always true
func (s selectDeviceByPath) MountIsSelected(Mount) bool {
	return true
}

// HookIsSelected is always true
func (s selectDeviceByPath) HookIsSelected(Hook) bool {
	return true
}
