package cmd

import (
	"fmt"
	"io"
	"os"
	"time"

	"github.com/linkerd/linkerd2/pkg/healthcheck"
	"github.com/spf13/cobra"
)

const (
	retryStatus = "[retry]"
	failStatus  = "[FAIL]"
)

type checkOptions struct {
	versionOverride string
	preInstallOnly  bool
	dataPlaneOnly   bool
	wait            time.Duration
	namespace       string
	singleNamespace bool
}

func newCheckOptions() *checkOptions {
	return &checkOptions{
		versionOverride: "",
		preInstallOnly:  false,
		dataPlaneOnly:   false,
		wait:            300 * time.Second,
		namespace:       "",
		singleNamespace: false,
	}
}

func newCmdCheck() *cobra.Command {
	options := newCheckOptions()

	cmd := &cobra.Command{
		Use:   "check",
		Short: "Check the Linkerd installation for potential problems",
		Long: `Check the Linkerd installation for potential problems.

The check command will perform a series of checks to validate that the linkerd
CLI and control plane are configured correctly. If the command encounters a
failure it will print additional information about the failure and exit with a
non-zero exit code.`,
		Example: `  # Check that the Linkerd control plane is up and running
  linkerd check

  # Check that the Linkerd control plane can be installed in the "test" namespace
  linkerd check --pre --linkerd-namespace test

  # Check that the Linkerd data plane proxies in the "app" namespace are up and running
  linkerd check --proxy --namespace app`,
		Args: cobra.NoArgs,
		Run: func(cmd *cobra.Command, args []string) {
			configureAndRunChecks(options)
		},
	}

	cmd.Args = cobra.NoArgs
	cmd.PersistentFlags().StringVar(&options.versionOverride, "expected-version", options.versionOverride, "Overrides the version used when checking if Linkerd is running the latest version (mostly for testing)")
	cmd.PersistentFlags().BoolVar(&options.preInstallOnly, "pre", options.preInstallOnly, "Only run pre-installation checks, to determine if the control plane can be installed")
	cmd.PersistentFlags().BoolVar(&options.dataPlaneOnly, "proxy", options.dataPlaneOnly, "Only run data-plane checks, to determine if the data plane is healthy")
	cmd.PersistentFlags().DurationVar(&options.wait, "wait", options.wait, "Retry and wait for some checks to succeed if they don't pass the first time")
	cmd.PersistentFlags().StringVarP(&options.namespace, "namespace", "n", options.namespace, "Namespace to use for --proxy checks (default: all namespaces)")
	cmd.PersistentFlags().BoolVar(&options.singleNamespace, "single-namespace", options.singleNamespace, "When running pre-installation checks (--pre), only check the permissions required to operate the control plane in a single namespace")

	return cmd
}

func configureAndRunChecks(options *checkOptions) {
	checks := []healthcheck.Checks{healthcheck.KubernetesAPIChecks}

	if options.preInstallOnly {
		checks = append(checks, healthcheck.LinkerdPreInstallChecks)
	} else if options.dataPlaneOnly {
		checks = append(checks, healthcheck.LinkerdAPIChecks)
		checks = append(checks, healthcheck.LinkerdDataPlaneChecks)
	} else {
		checks = append(checks, healthcheck.LinkerdAPIChecks)
	}

	checks = append(checks, healthcheck.LinkerdVersionChecks)

	hc := healthcheck.NewHealthChecker(checks, &healthcheck.HealthCheckOptions{
		ControlPlaneNamespace:          controlPlaneNamespace,
		DataPlaneNamespace:             options.namespace,
		KubeConfig:                     kubeconfigPath,
		KubeContext:                    kubeContext,
		APIAddr:                        apiAddr,
		VersionOverride:                options.versionOverride,
		RetryDeadline:                  time.Now().Add(options.wait),
		ShouldCheckKubeVersion:         true,
		ShouldCheckControlPlaneVersion: !(options.preInstallOnly || options.dataPlaneOnly),
		ShouldCheckDataPlaneVersion:    options.dataPlaneOnly,
		SingleNamespace:                options.singleNamespace,
	})

	success := runChecks(os.Stdout, hc)

	fmt.Println("")

	if !success {
		fmt.Printf("Status check results are %s\n", failStatus)
		os.Exit(2)
	}

	fmt.Printf("Status check results are %s\n", okStatus)
}

func runChecks(w io.Writer, hc *healthcheck.HealthChecker) bool {
	prettyPrintResults := func(result *healthcheck.CheckResult) {
		checkLabel := fmt.Sprintf("%s: %s", result.Category, result.Description)

		filler := ""
		lineBreak := "\n"
		for i := 0; i < lineWidth-len(checkLabel)-len(okStatus)-len(lineBreak); i++ {
			filler = filler + "."
		}

		if result.Retry {
			fmt.Fprintf(w, "%s%s%s -- %s%s", checkLabel, filler, retryStatus, result.Err, lineBreak)
			return
		}

		if result.Err != nil {
			fmt.Fprintf(w, "%s%s%s -- %s%s", checkLabel, filler, failStatus, result.Err, lineBreak)
			return
		}

		fmt.Fprintf(w, "%s%s%s%s", checkLabel, filler, okStatus, lineBreak)
	}

	return hc.RunChecks(prettyPrintResults)
}