/*
Copyright 2020 The Flux authors

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 main

import (
	"context"
	"os"
	"time"

	"github.com/Masterminds/semver/v3"
	"github.com/spf13/cobra"
	v1 "k8s.io/api/apps/v1"
	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
	"k8s.io/client-go/kubernetes"
	"sigs.k8s.io/controller-runtime/pkg/client"

	"github.com/fluxcd/pkg/version"

	"github.com/fluxcd/flux2/v2/internal/utils"
	"github.com/fluxcd/flux2/v2/pkg/manifestgen"
	"github.com/fluxcd/flux2/v2/pkg/manifestgen/install"
	"github.com/fluxcd/flux2/v2/pkg/status"
)

var checkCmd = &cobra.Command{
	Use:   "check",
	Short: "Check requirements and installation",
	Long: withPreviewNote(`The check command will perform a series of checks to validate that
the local environment is configured correctly and if the installed components are healthy.`),
	Example: `  # Run pre-installation checks
  flux check --pre

  # Run installation checks
  flux check`,
	RunE: runCheckCmd,
}

type checkFlags struct {
	pre             bool
	components      []string
	extraComponents []string
	pollInterval    time.Duration
}

var kubernetesConstraints = []string{
	">=1.20.6-0",
}

var checkArgs checkFlags

func init() {
	checkCmd.Flags().BoolVarP(&checkArgs.pre, "pre", "", false,
		"only run pre-installation checks")
	checkCmd.Flags().StringSliceVar(&checkArgs.components, "components", rootArgs.defaults.Components,
		"list of components, accepts comma-separated values")
	checkCmd.Flags().StringSliceVar(&checkArgs.extraComponents, "components-extra", nil,
		"list of components in addition to those supplied or defaulted, accepts comma-separated values")
	checkCmd.Flags().DurationVar(&checkArgs.pollInterval, "poll-interval", 5*time.Second,
		"how often the health checker should poll the cluster for the latest state of the resources.")
	rootCmd.AddCommand(checkCmd)
}

func runCheckCmd(cmd *cobra.Command, args []string) error {
	logger.Actionf("checking prerequisites")
	checkFailed := false

	fluxCheck()

	if !kubernetesCheck(kubernetesConstraints) {
		checkFailed = true
	}

	if checkArgs.pre {
		if checkFailed {
			os.Exit(1)
		}
		logger.Successf("prerequisites checks passed")
		return nil
	}

	logger.Actionf("checking controllers")
	if !componentsCheck() {
		checkFailed = true
	}

	logger.Actionf("checking crds")
	if !crdsCheck() {
		checkFailed = true
	}

	if checkFailed {
		logger.Failuref("check failed")
		os.Exit(1)
	}

	logger.Successf("all checks passed")
	return nil
}

func fluxCheck() {
	curSv, err := version.ParseVersion(VERSION)
	if err != nil {
		return
	}
	// Exclude development builds.
	if curSv.Prerelease() != "" {
		return
	}
	latest, err := install.GetLatestVersion()
	if err != nil {
		return
	}
	latestSv, err := version.ParseVersion(latest)
	if err != nil {
		return
	}
	if latestSv.GreaterThan(curSv) {
		logger.Failuref("flux %s <%s (new version is available, please upgrade)", curSv, latestSv)
	}
}

func kubernetesCheck(constraints []string) bool {
	cfg, err := utils.KubeConfig(kubeconfigArgs, kubeclientOptions)
	if err != nil {
		logger.Failuref("Kubernetes client initialization failed: %s", err.Error())
		return false
	}

	clientSet, err := kubernetes.NewForConfig(cfg)
	if err != nil {
		logger.Failuref("Kubernetes client initialization failed: %s", err.Error())
		return false
	}

	kv, err := clientSet.Discovery().ServerVersion()
	if err != nil {
		logger.Failuref("Kubernetes API call failed: %s", err.Error())
		return false
	}

	v, err := version.ParseVersion(kv.String())
	if err != nil {
		logger.Failuref("Kubernetes version can't be determined")
		return false
	}

	var valid bool
	var vrange string
	for _, constraint := range constraints {
		c, _ := semver.NewConstraint(constraint)
		if c.Check(v) {
			valid = true
			vrange = constraint
			break
		}
	}

	if !valid {
		logger.Failuref("Kubernetes version %s does not match %s", v.Original(), constraints[0])
		return false
	}

	logger.Successf("Kubernetes %s %s", v.String(), vrange)
	return true
}

func componentsCheck() bool {
	ctx, cancel := context.WithTimeout(context.Background(), rootArgs.timeout)
	defer cancel()

	kubeConfig, err := utils.KubeConfig(kubeconfigArgs, kubeclientOptions)
	if err != nil {
		return false
	}

	statusChecker, err := status.NewStatusChecker(kubeConfig, checkArgs.pollInterval, rootArgs.timeout, logger)
	if err != nil {
		return false
	}

	kubeClient, err := utils.KubeClient(kubeconfigArgs, kubeclientOptions)
	if err != nil {
		return false
	}

	ok := true
	selector := client.MatchingLabels{manifestgen.PartOfLabelKey: manifestgen.PartOfLabelValue}
	var list v1.DeploymentList
	ns := *kubeconfigArgs.Namespace
	if err := kubeClient.List(ctx, &list, client.InNamespace(ns), selector); err == nil {
		if len(list.Items) == 0 {
			logger.Failuref("no controllers found in the '%s' namespace with the label selector '%s=%s'",
				ns, manifestgen.PartOfLabelKey, manifestgen.PartOfLabelValue)
			return false
		}

		for _, d := range list.Items {
			if ref, err := buildComponentObjectRefs(d.Name); err == nil {
				if err := statusChecker.Assess(ref...); err != nil {
					ok = false
				}
			}
			for _, c := range d.Spec.Template.Spec.Containers {
				logger.Actionf(c.Image)
			}
		}
	}
	return ok
}

func crdsCheck() bool {
	ctx, cancel := context.WithTimeout(context.Background(), rootArgs.timeout)
	defer cancel()

	kubeClient, err := utils.KubeClient(kubeconfigArgs, kubeclientOptions)
	if err != nil {
		return false
	}

	ok := true
	selector := client.MatchingLabels{manifestgen.PartOfLabelKey: manifestgen.PartOfLabelValue}
	var list apiextensionsv1.CustomResourceDefinitionList
	if err := kubeClient.List(ctx, &list, client.InNamespace(*kubeconfigArgs.Namespace), selector); err == nil {
		if len(list.Items) == 0 {
			logger.Failuref("no crds found with the label selector '%s=%s'",
				manifestgen.PartOfLabelKey, manifestgen.PartOfLabelValue)
			return false
		}

		for _, crd := range list.Items {
			versions := crd.Status.StoredVersions
			if len(versions) > 0 {
				logger.Successf(crd.Name + "/" + versions[len(versions)-1])
			} else {
				ok = false
				logger.Failuref("no stored versions for %s", crd.Name)
			}
		}
	}
	return ok
}