package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"regexp"
	"strings"
	"time"

	"github.com/docopt/docopt-go"
	"github.com/ghodss/yaml"
	"github.com/kubernetes-incubator/node-feature-discovery/source"
	"github.com/kubernetes-incubator/node-feature-discovery/source/cpuid"
	"github.com/kubernetes-incubator/node-feature-discovery/source/fake"
	"github.com/kubernetes-incubator/node-feature-discovery/source/iommu"
	"github.com/kubernetes-incubator/node-feature-discovery/source/kernel"
	"github.com/kubernetes-incubator/node-feature-discovery/source/memory"
	"github.com/kubernetes-incubator/node-feature-discovery/source/network"
	"github.com/kubernetes-incubator/node-feature-discovery/source/panic_fake"
	"github.com/kubernetes-incubator/node-feature-discovery/source/pci"
	"github.com/kubernetes-incubator/node-feature-discovery/source/pstate"
	"github.com/kubernetes-incubator/node-feature-discovery/source/rdt"
	"github.com/kubernetes-incubator/node-feature-discovery/source/selinux"
	"github.com/kubernetes-incubator/node-feature-discovery/source/storage"
	api "k8s.io/api/core/v1"
	meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	k8sclient "k8s.io/client-go/kubernetes"
	restclient "k8s.io/client-go/rest"
)

const (
	// ProgramName is the canonical name of this discovery program.
	ProgramName = "node-feature-discovery"

	// Namespace is the prefix for all published labels.
	labelNs = "feature.node.kubernetes.io/"

	// Namespace is the prefix for all published labels.
	annotationNs = "nfd.node.kubernetes.io/"

	// NodeNameEnv is the environment variable that contains this node's name.
	NodeNameEnv = "NODE_NAME"
)

var (
	version     = "" // Must not be const, set using ldflags at build time
	labelPrefix = labelNs + "nfd-"
)

// package loggers
var (
	stdoutLogger = log.New(os.Stdout, "", log.LstdFlags)
	stderrLogger = log.New(os.Stderr, "", log.LstdFlags)
)

// Global config
type NFDConfig struct {
	Sources struct {
		Pci *pci.NFDConfig `json:"pci,omitempty"`
	} `json:"sources,omitempty"`
}

var config = NFDConfig{}

// Labels are a Kubernetes representation of discovered features.
type Labels map[string]string

// Annotations are used for NFD-related node metadata
type Annotations map[string]string

// APIHelpers represents a set of API helpers for Kubernetes
type APIHelpers interface {
	// GetClient returns a client
	GetClient() (*k8sclient.Clientset, error)

	// GetNode returns the Kubernetes node on which this container is running.
	GetNode(*k8sclient.Clientset) (*api.Node, error)

	// RemoveLabels removes labels from the supplied node that contain the
	// search string provided. In order to publish the changes, the node must
	// subsequently be updated via the API server using the client library.
	RemoveLabels(*api.Node, string)

	// AddLabels adds new NFD labels to the node object.
	// In order to publish the labels, the node must be subsequently updated via the
	// API server using the client library.
	AddLabels(*api.Node, Labels)

	// Add annotations
	AddAnnotations(*api.Node, Annotations)

	// UpdateNode updates the node via the API server using a client.
	UpdateNode(*k8sclient.Clientset, *api.Node) error
}

// Command line arguments
type Args struct {
	labelWhiteList string
	configFile     string
	noPublish      bool
	options        string
	oneshot        bool
	sleepInterval  time.Duration
	sources        []string
}

func main() {
	// Assert that the version is known
	if version == "" {
		stderrLogger.Fatalf("main.version not set! Set -ldflags \"-X main.version `git describe --tags --dirty --always`\" during build or run.")
	}
	stdoutLogger.Printf("Node Feature Discovery %s", version)

	// Parse command-line arguments.
	args := argsParse(nil)

	// Parse config
	err := configParse(args.configFile, args.options)
	if err != nil {
		stderrLogger.Print(err)
	}

	// Configure the parameters for feature discovery.
	enabledSources, labelWhiteList, err := configureParameters(args.sources, args.labelWhiteList)
	if err != nil {
		stderrLogger.Fatalf("error occurred while configuring parameters: %s", err.Error())
	}

	helper := APIHelpers(k8sHelpers{})

	for {
		// Get the set of feature labels.
		labels := createFeatureLabels(enabledSources, labelWhiteList)

		// Update the node with the feature labels.
		err = updateNodeWithFeatureLabels(helper, args.noPublish, labels)
		if err != nil {
			stderrLogger.Fatalf("error occurred while updating node with feature labels: %s", err.Error())
		}

		if args.oneshot {
			break
		}

		if args.sleepInterval > 0 {
			time.Sleep(args.sleepInterval)
		} else {
			// Sleep forever
			select {}
		}
	}
}

// argsParse parses the command line arguments passed to the program.
// The argument argv is passed only for testing purposes.
func argsParse(argv []string) (args Args) {
	usage := fmt.Sprintf(`%s.

  Usage:
  %s [--no-publish] [--sources=<sources>] [--label-whitelist=<pattern>]
     [--oneshot | --sleep-interval=<seconds>] [--config=<path>]
     [--options=<config>]
  %s -h | --help
  %s --version

  Options:
  -h --help                   Show this screen.
  --version                   Output version and exit.
  --config=<path>             Config file to use.
                              [Default: /etc/kubernetes/node-feature-discovery/node-feature-discovery.conf]
  --options=<config>          Specify config options from command line. Config
                              options are specified in the same format as in the
                              config file (i.e. json or yaml). These options
                              will override settings read from the config file.
                              [Default: ]
  --sources=<sources>         Comma separated list of feature sources.
                              [Default: cpuid,iommu,kernel,memory,network,pci,pstate,rdt,selinux,storage]
  --no-publish                Do not publish discovered features to the
                              cluster-local Kubernetes API server.
  --label-whitelist=<pattern> Regular expression to filter label names to
                              publish to the Kubernetes API server. [Default: ]
  --oneshot                   Label once and exit.
  --sleep-interval=<seconds>  Time to sleep between re-labeling. Non-positive
                              value implies no re-labeling (i.e. infinite
                              sleep). [Default: 60s]`,
		ProgramName,
		ProgramName,
		ProgramName,
		ProgramName,
	)

	arguments, _ := docopt.Parse(usage, argv, true,
		fmt.Sprintf("%s %s", ProgramName, version), false)

	// Parse argument values as usable types.
	var err error
	args.configFile = arguments["--config"].(string)
	args.noPublish = arguments["--no-publish"].(bool)
	args.options = arguments["--options"].(string)
	args.sources = strings.Split(arguments["--sources"].(string), ",")
	args.labelWhiteList = arguments["--label-whitelist"].(string)
	args.oneshot = arguments["--oneshot"].(bool)
	args.sleepInterval, err = time.ParseDuration(arguments["--sleep-interval"].(string))

	// Check that sleep interval has a sane value
	if err != nil {
		stderrLogger.Fatalf("invalid --sleep-interval specified: %s", err.Error())
	}
	if args.sleepInterval > 0 && args.sleepInterval < time.Second {
		stderrLogger.Printf("WARNING: too short sleep-intervall specified (%s), forcing to 1s", args.sleepInterval.String())
		args.sleepInterval = time.Second
	}

	return args
}

// Parse configuration options
func configParse(filepath string, overrides string) error {
	config.Sources.Pci = &pci.Config

	data, err := ioutil.ReadFile(filepath)
	if err != nil {
		return fmt.Errorf("Failed to read config file: %s", err)
	}

	// Read config file
	err = yaml.Unmarshal(data, &config)
	if err != nil {
		return fmt.Errorf("Failed to parse config file: %s", err)
	}

	// Parse config overrides
	err = yaml.Unmarshal([]byte(overrides), &config)
	if err != nil {
		return fmt.Errorf("Failed to parse --options: %s", err)
	}

	return nil
}

// configureParameters returns all the variables required to perform feature
// discovery based on command line arguments.
func configureParameters(sourcesWhiteList []string, labelWhiteListStr string) (enabledSources []source.FeatureSource, labelWhiteList *regexp.Regexp, err error) {
	// A map for lookup
	sourcesWhiteListMap := map[string]struct{}{}
	for _, s := range sourcesWhiteList {
		sourcesWhiteListMap[strings.TrimSpace(s)] = struct{}{}
	}

	// Configure feature sources.
	allSources := []source.FeatureSource{
		cpuid.Source{},
		fake.Source{},
		iommu.Source{},
		kernel.Source{},
		memory.Source{},
		network.Source{},
		panic_fake.Source{},
		pci.Source{},
		pstate.Source{},
		rdt.Source{},
		selinux.Source{},
		storage.Source{},
	}

	enabledSources = []source.FeatureSource{}
	for _, s := range allSources {
		if _, enabled := sourcesWhiteListMap[s.Name()]; enabled {
			enabledSources = append(enabledSources, s)
		}
	}

	// Compile labelWhiteList regex
	labelWhiteList, err = regexp.Compile(labelWhiteListStr)
	if err != nil {
		stderrLogger.Printf("error parsing whitelist regex (%s): %s", labelWhiteListStr, err)
		return nil, nil, err
	}

	return enabledSources, labelWhiteList, nil
}

// createFeatureLabels returns the set of feature labels from the enabled
// sources and the whitelist argument.
func createFeatureLabels(sources []source.FeatureSource, labelWhiteList *regexp.Regexp) (labels Labels) {
	labels = Labels{}

	// Do feature discovery from all configured sources.
	for _, source := range sources {
		labelsFromSource, err := getFeatureLabels(source)
		if err != nil {
			stderrLogger.Printf("discovery failed for source [%s]: %s", source.Name(), err.Error())
			stderrLogger.Printf("continuing ...")
			continue
		}

		for name, value := range labelsFromSource {
			// Log discovered feature.
			stdoutLogger.Printf("%s = %s", name, value)
			// Skip if label doesn't match labelWhiteList
			if !labelWhiteList.Match([]byte(name)) {
				stderrLogger.Printf("%s does not match the whitelist (%s) and will not be published.", name, labelWhiteList.String())
				continue
			}
			labels[name] = value
		}
	}
	return labels
}

// updateNodeWithFeatureLabels updates the node with the feature labels, unless
// disabled via --no-publish flag.
func updateNodeWithFeatureLabels(helper APIHelpers, noPublish bool, labels Labels) error {
	if !noPublish {
		// Advertise NFD version as an annotation
		annotations := Annotations{"version": version}

		err := advertiseFeatureLabels(helper, labels, annotations)
		if err != nil {
			stderrLogger.Printf("failed to advertise labels: %s", err.Error())
			return err
		}
	}
	return nil
}

// getFeatureLabels returns node labels for features discovered by the
// supplied source.
func getFeatureLabels(source source.FeatureSource) (labels Labels, err error) {
	defer func() {
		if r := recover(); r != nil {
			stderrLogger.Printf("panic occurred during discovery of source [%s]: %v", source.Name(), r)
			err = fmt.Errorf("%v", r)
		}
	}()

	labels = Labels{}
	features, err := source.Discover()
	if err != nil {
		return nil, err
	}
	for k := range features {
		labels[fmt.Sprintf("%s-%s", source.Name(), k)] = fmt.Sprintf("%v", features[k])
	}
	return labels, nil
}

// advertiseFeatureLabels advertises the feature labels to a Kubernetes node
// via the API server.
func advertiseFeatureLabels(helper APIHelpers, labels Labels, annotations Annotations) error {
	cli, err := helper.GetClient()
	if err != nil {
		stderrLogger.Printf("can't get kubernetes client: %s", err.Error())
		return err
	}

	// Get the current node.
	node, err := helper.GetNode(cli)
	if err != nil {
		stderrLogger.Printf("failed to get node: %s", err.Error())
		return err
	}

	// Remove labels with our prefix
	helper.RemoveLabels(node, labelPrefix)
	// Also, remove all labels with the old prefix, and the old version label
	helper.RemoveLabels(node, "node.alpha.kubernetes-incubator.io/nfd")
	helper.RemoveLabels(node, "node.alpha.kubernetes-incubator.io/node-feature-discovery")

	// Add labels to the node object.
	helper.AddLabels(node, labels)

	// Add annotations
	helper.AddAnnotations(node, annotations)

	// Send the updated node to the apiserver.
	err = helper.UpdateNode(cli, node)
	if err != nil {
		stderrLogger.Printf("can't update node: %s", err.Error())
		return err
	}

	return nil
}

// Implements main.APIHelpers
type k8sHelpers struct{}

func (h k8sHelpers) GetClient() (*k8sclient.Clientset, error) {
	// Set up an in-cluster K8S client.
	config, err := restclient.InClusterConfig()
	if err != nil {
		return nil, err
	}
	clientset, err := k8sclient.NewForConfig(config)
	if err != nil {
		return nil, err
	}
	return clientset, nil
}

func (h k8sHelpers) GetNode(cli *k8sclient.Clientset) (*api.Node, error) {
	// Get the pod name and pod namespace from the env variables
	nodeName := os.Getenv(NodeNameEnv)
	stdoutLogger.Printf("%s: %s", NodeNameEnv, nodeName)

	// Get the node object using node name
	node, err := cli.Core().Nodes().Get(nodeName, meta_v1.GetOptions{})
	if err != nil {
		stderrLogger.Printf("can't get node: %s", err.Error())
		return nil, err
	}

	return node, nil
}

// RemoveLabels searches through all labels on Node n and removes
// any where the key contain the search string.
func (h k8sHelpers) RemoveLabels(n *api.Node, search string) {
	for k := range n.Labels {
		if strings.Contains(k, search) {
			delete(n.Labels, k)
		}
	}
}

func (h k8sHelpers) AddLabels(n *api.Node, labels Labels) {
	for k, v := range labels {
		n.Labels[labelPrefix+k] = v
	}
}

// Add Annotations to the Node object
func (h k8sHelpers) AddAnnotations(n *api.Node, annotations Annotations) {
	for k, v := range annotations {
		n.Annotations[annotationNs+k] = v
	}
}

func (h k8sHelpers) UpdateNode(c *k8sclient.Clientset, n *api.Node) error {
	// Send the updated node to the apiserver.
	_, err := c.Core().Nodes().Update(n)
	if err != nil {
		return err
	}

	return nil
}