package cmd

import (
	"bytes"
	"fmt"
	"io"
	"os"
	"path"
	"time"

	"github.com/linkerd/linkerd2/pkg/charts"
	partials "github.com/linkerd/linkerd2/pkg/charts/static"
	"github.com/linkerd/linkerd2/pkg/flags"
	"github.com/linkerd/linkerd2/pkg/healthcheck"
	"github.com/linkerd/linkerd2/pkg/k8s"
	"github.com/linkerd/linkerd2/viz/static"
	"github.com/spf13/cobra"
	"helm.sh/helm/v3/pkg/chart/loader"
	"helm.sh/helm/v3/pkg/chartutil"
	"helm.sh/helm/v3/pkg/cli/values"
	"helm.sh/helm/v3/pkg/engine"
)

var (
	templatesVIz = []string{
		"templates/namespace.yaml",
		"templates/grafana-rbac.yaml",
		"templates/prometheus-rbac.yaml",
		"templates/tap-rbac.yaml",
		"templates/web-rbac.yaml",
		"templates/psp.yaml",
		"templates/grafana.yaml",
		"templates/prometheus.yaml",
		"templates/tap.yaml",
		"templates/web.yaml",
	}
)

func newCmdInstall() *cobra.Command {
	var skipChecks bool
	var ha bool
	var wait time.Duration
	var options values.Options

	cmd := &cobra.Command{
		Use:   "install [flags]",
		Args:  cobra.NoArgs,
		Short: "Output Kubernetes resources to install linkerd-viz extension",
		Long:  `Output Kubernetes resources to install linkerd-viz extension.`,
		Example: `  # Default install.
  linkerd viz install | kubectl apply -f -
 
The installation can be configured by using the --set, --values, --set-string and --set-file flags.
A full list of configurable values can be found at https://www.github.com/linkerd/linkerd2/tree/main/viz/charts/linkerd-viz/README.md
  `,
		RunE: func(cmd *cobra.Command, args []string) error {
			if !skipChecks {
				// Ensure there is a Linkerd installation.
				kubeAPI, err := k8s.NewAPI(kubeconfigPath, kubeContext, impersonate, impersonateGroup, 0)
				if err != nil {
					return err
				}

				exists, err := healthcheck.CheckIfLinkerdExists(cmd.Context(), kubeAPI, controlPlaneNamespace)
				if err != nil {
					return fmt.Errorf("could not check for Linkerd existence: %s", err)
				}

				if !exists {
					return fmt.Errorf("could not find a Linkerd installation")
				}

				// Wait for the proxy-injector to be up and running
				checkInjectorRunningOrRetryOrExit(wait)
			}

			return install(os.Stdout, options, ha)
		},
	}

	cmd.Flags().BoolVar(
		&skipChecks, "skip-checks", false,
		`Skip checks for namespace existence`,
	)

	cmd.Flags().BoolVar(
		&ha, "ha", false,
		`Install Viz Extension in High Availability mode.`,
	)
	cmd.Flags().DurationVar(
		&wait, "wait", 300*time.Second,
		"Wait for core control-plane components to be available")

	flags.AddValueOptionsFlags(cmd.Flags(), &options)

	return cmd
}

func install(w io.Writer, options values.Options, ha bool) error {

	// Create values override
	valuesOverrides, err := options.MergeValues(nil)
	if err != nil {
		return err
	}

	if ha {
		valuesOverrides, err = charts.OverrideFromFile(valuesOverrides, static.Templates, vizChartName, "values-ha.yaml")
		if err != nil {
			return err
		}
	}

	// TODO: Add any validation logic here

	return render(w, valuesOverrides)
}

func render(w io.Writer, valuesOverrides map[string]interface{}) error {

	files := []*loader.BufferedFile{
		{Name: chartutil.ChartfileName},
		{Name: chartutil.ValuesfileName},
	}

	for _, template := range templatesVIz {
		files = append(files,
			&loader.BufferedFile{Name: template},
		)
	}

	var partialFiles []*loader.BufferedFile
	for _, template := range charts.L5dPartials {
		partialFiles = append(partialFiles,
			&loader.BufferedFile{Name: template},
		)
	}

	// Load all Viz chart files into buffer
	if err := charts.FilesReader(static.Templates, vizChartName+"/", files); err != nil {
		return err
	}

	// Load all partial chart files into buffer
	if err := charts.FilesReader(partials.Templates, "", partialFiles); err != nil {
		return err
	}

	// Create a Chart obj from the files
	chart, err := loader.LoadFiles(append(files, partialFiles...))
	if err != nil {
		return err
	}

	vals, err := chartutil.CoalesceValues(chart, valuesOverrides)
	if err != nil {
		return err
	}

	vals, err = charts.InsertVersionValues(vals)
	if err != nil {
		return err
	}

	// Attach the final values into the `Values` field for rendering to work
	renderedTemplates, err := engine.Render(chart, map[string]interface{}{"Values": vals})
	if err != nil {
		return err
	}

	// Merge templates and inject
	var buf bytes.Buffer
	for _, tmpl := range chart.Templates {
		t := path.Join(chart.Metadata.Name, tmpl.Name)
		if _, err := buf.WriteString(renderedTemplates[t]); err != nil {
			return err
		}
	}

	_, err = w.Write(buf.Bytes())
	return err
}

func checkInjectorRunningOrRetryOrExit(retryDeadline time.Duration) {
	checks := []healthcheck.CategoryID{
		healthcheck.KubernetesAPIChecks,
		healthcheck.LinkerdControlPlaneExistenceChecks,
		healthcheck.LinkerdAPIChecks,
	}

	hc := healthcheck.NewHealthChecker(checks, &healthcheck.Options{
		ControlPlaneNamespace: controlPlaneNamespace,
		KubeConfig:            kubeconfigPath,
		KubeContext:           kubeContext,
		Impersonate:           impersonate,
		ImpersonateGroup:      impersonateGroup,
		APIAddr:               apiAddr,
		RetryDeadline:         time.Now().Add(retryDeadline),
	})

	hc.RunChecks(exitOnError)
}

func exitOnError(result *healthcheck.CheckResult) {
	if result.Retry {
		fmt.Fprintln(os.Stderr, "Waiting for core control plane to become available")
		return
	}

	if result.Err != nil && !result.Warning {
		var msg string
		switch result.Category {
		case healthcheck.KubernetesAPIChecks:
			msg = "Cannot connect to Kubernetes"
		case healthcheck.LinkerdControlPlaneExistenceChecks:
			msg = "Cannot find Linkerd"
		case healthcheck.LinkerdAPIChecks:
			msg = "Cannot connect to Linkerd"
		}
		fmt.Fprintf(os.Stderr, "%s: %s\n", msg, result.Err)

		checkCmd := "linkerd check"
		if controlPlaneNamespace != defaultLinkerdNamespace {
			checkCmd += fmt.Sprintf(" --linkerd-namespace %s", controlPlaneNamespace)
		}
		fmt.Fprintf(os.Stderr, "Validate the install with: %s\n", checkCmd)

		os.Exit(1)
	}
}