/**
# Copyright (c) 2021-2022, 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 crio

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

	log "github.com/sirupsen/logrus"
	cli "github.com/urfave/cli/v2"

	"github.com/NVIDIA/nvidia-container-toolkit/internal/config"
	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/engine/crio"
	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/ocihook"
	"github.com/NVIDIA/nvidia-container-toolkit/tools/container"
)

const (
	Name = "crio"

	defaultConfigMode = "hook"

	// Hook-based settings
	defaultHooksDir     = "/usr/share/containers/oci/hooks.d"
	defaultHookFilename = "oci-nvidia-hook.json"

	// Config-based settings
	DefaultConfig      = "/etc/crio/crio.conf"
	DefaultSocket      = "/var/run/crio/crio.sock"
	DefaultRestartMode = "systemd"
)

// Options defines the cri-o specific options.
type Options struct {
	configMode string

	// hook-specific options
	hooksDir     string
	hookFilename string
}

func Flags(opts *Options) []cli.Flag {
	flags := []cli.Flag{
		&cli.StringFlag{
			Name:        "hooks-dir",
			Usage:       "path to the cri-o hooks directory",
			Value:       defaultHooksDir,
			Destination: &opts.hooksDir,
			EnvVars:     []string{"CRIO_HOOKS_DIR"},
			DefaultText: defaultHooksDir,
		},
		&cli.StringFlag{
			Name:        "hook-filename",
			Usage:       "filename of the cri-o hook that will be created / removed in the hooks directory",
			Value:       defaultHookFilename,
			Destination: &opts.hookFilename,
			EnvVars:     []string{"CRIO_HOOK_FILENAME"},
			DefaultText: defaultHookFilename,
		},
		&cli.StringFlag{
			Name:        "config-mode",
			Usage:       "the configuration mode to use. One of [hook | config]",
			Value:       defaultConfigMode,
			Destination: &opts.configMode,
			EnvVars:     []string{"CRIO_CONFIG_MODE"},
		},
	}

	return flags
}

// Setup installs the prestart hook required to launch GPU-enabled containers
func Setup(c *cli.Context, o *container.Options, co *Options) error {
	log.Infof("Starting 'setup' for %v", c.App.Name)

	switch co.configMode {
	case "hook":
		return setupHook(o, co)
	case "config":
		return setupConfig(o)
	default:
		return fmt.Errorf("invalid config-mode '%v'", co.configMode)
	}
}

// setupHook installs the prestart hook required to launch GPU-enabled containers
func setupHook(o *container.Options, co *Options) error {
	log.Infof("Installing prestart hook")

	hookPath := filepath.Join(co.hooksDir, co.hookFilename)
	err := ocihook.CreateHook(hookPath, filepath.Join(o.RuntimeDir, config.NVIDIAContainerRuntimeHookExecutable))
	if err != nil {
		return fmt.Errorf("error creating hook: %v", err)
	}

	return nil
}

// setupConfig updates the cri-o config for the NVIDIA container runtime
func setupConfig(o *container.Options) error {
	log.Infof("Updating config file")

	cfg, err := crio.New(
		crio.WithPath(o.Config),
	)
	if err != nil {
		return fmt.Errorf("unable to load config: %v", err)
	}

	err = o.Configure(cfg)
	if err != nil {
		return fmt.Errorf("unable to configure cri-o: %v", err)
	}

	err = RestartCrio(o)
	if err != nil {
		return fmt.Errorf("unable to restart crio: %v", err)
	}

	return nil
}

// Cleanup removes the specified prestart hook
func Cleanup(c *cli.Context, o *container.Options, co *Options) error {
	log.Infof("Starting 'cleanup' for %v", c.App.Name)

	switch co.configMode {
	case "hook":
		return cleanupHook(co)
	case "config":
		return cleanupConfig(o)
	default:
		return fmt.Errorf("invalid config-mode '%v'", co.configMode)
	}
}

// cleanupHook removes the prestart hook
func cleanupHook(co *Options) error {
	log.Infof("Removing prestart hook")

	hookPath := filepath.Join(co.hooksDir, co.hookFilename)
	err := os.Remove(hookPath)
	if err != nil {
		return fmt.Errorf("error removing hook '%v': %v", hookPath, err)
	}

	return nil
}

// cleanupConfig removes the NVIDIA container runtime from the cri-o config
func cleanupConfig(o *container.Options) error {
	log.Infof("Reverting config file modifications")

	cfg, err := crio.New(
		crio.WithPath(o.Config),
	)
	if err != nil {
		return fmt.Errorf("unable to load config: %v", err)
	}

	err = o.Unconfigure(cfg)
	if err != nil {
		return fmt.Errorf("unable to unconfigure cri-o: %v", err)
	}

	err = RestartCrio(o)
	if err != nil {
		return fmt.Errorf("unable to restart crio: %v", err)
	}

	return nil
}

// RestartCrio restarts crio depending on the value of restartModeFlag
func RestartCrio(o *container.Options) error {
	return o.Restart("crio", func(string) error { return fmt.Errorf("supporting crio via signal is unsupported") })
}