package app

import (
	"context"
	"flag"
	"fmt"
	"os"

	"github.com/go-logr/logr"
	"github.com/spf13/cobra"
	"github.com/spf13/pflag"
	"go.uber.org/zap"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/fields"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/cache"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/healthz"
	zapopt "sigs.k8s.io/controller-runtime/pkg/log/zap"
	"sigs.k8s.io/controller-runtime/pkg/manager"

	"github.com/tidbcloud/shared-provider/cmd/throttler/app/config"
	"github.com/tidbcloud/shared-provider/cmd/throttler/app/options"
	"github.com/tidbcloud/shared-provider/pkg/scheme"
	"github.com/tidbcloud/shared-provider/pkg/throttler"
	"github.com/tidbcloud/shared-provider/pkg/version"
)

// NewCommand returns app command.
func NewCommand() *cobra.Command {
	setupLog := ctrl.Log.WithName("setup")

	opts := options.New()
	lvl := zap.NewAtomicLevelAt(zap.FatalLevel)
	zapOpts := zapopt.Options{
		Development:     true,
		StacktraceLevel: &lvl,
	}

	cmd := &cobra.Command{
		Use:  "throttler",
		Long: "throttler will try to throttle bandwidth for specified pod",
		Run: func(cmd *cobra.Command, args []string) {
			fmt.Printf("%v\n", version.Get())
			ctrl.SetLogger(zapopt.New(zapopt.UseFlagOptions(&zapOpts)))
			printFlags(setupLog, cmd.Flags())

			cfg, err := opts.Config()
			if err != nil {
				setupLog.Error(err, "can't parse options to config")
				os.Exit(-1)
			}

			setupLog.Info("begin to start throttler")
			if err := Run(cfg); err != nil {
				setupLog.Error(err, "run throttler failed")
				os.Exit(-1)
			}
		},
	}
	opts.AddFlags(cmd.Flags())
	zapOpts.BindFlags(flag.CommandLine)

	cmd.AddCommand(NewVersionCmd())

	return cmd
}

// NewVersionCmd return cmd reports version.
func NewVersionCmd() *cobra.Command {
	cmd := &cobra.Command{
		Use:  "version",
		Long: "throttler version",
		Run: func(cmd *cobra.Command, args []string) {
			fmt.Printf("%v\n", version.Get())
		},
	}

	return cmd
}

// Run runs the operator.
func Run(cfg *config.Config) error {
	mgr, err := manager.New(cfg.Kubeconfig, manager.Options{
		Scheme:                 scheme.Scheme,
		MetricsBindAddress:     cfg.MetricsBindAddress,
		Port:                   cfg.WebhookPort,
		HealthProbeBindAddress: cfg.HealthProbeBindAddress,
		LeaderElection:         false,
		NewCache: cache.BuilderWithOptions(cache.Options{
			SelectorsByObject: cache.SelectorsByObject{
				&corev1.Pod{}: {
					Field: fields.SelectorFromSet(
						fields.Set{
							"spec.nodeName": cfg.NodeName,
						},
					),
				},
			},
		}),
	})
	if err != nil {
		return fmt.Errorf("unable to start throttler: %w", err)
	}

	if err := mgr.GetFieldIndexer().IndexField(
		context.TODO(),
		&corev1.Pod{},
		"spec.nodeName",
		func(obj client.Object) []string {
			pod := obj.(*corev1.Pod)
			return []string{pod.Spec.NodeName}
		},
	); err != nil {
		return fmt.Errorf("unable to add index for pod spec.nodeName: %w", err)
	}

	if err = (&throttler.Reconciler{}).SetupWithManager(mgr); err != nil {
		return fmt.Errorf("unable to create throttler controller: %w", err)
	}

	if err := mgr.AddHealthzCheck("healthz", healthz.Ping); err != nil {
		return fmt.Errorf("unable to set up health check: %w", err)
	}
	if err := mgr.AddReadyzCheck("readyz", healthz.Ping); err != nil {
		return fmt.Errorf("unable to set up ready check: %w", err)
	}

	if err := mgr.Start(ctrl.SetupSignalHandler()); err != nil {
		return fmt.Errorf("problem running manager: %w", err)
	}

	return nil
}

func printFlags(logger logr.Logger, fs *pflag.FlagSet) {
	fs.VisitAll(func(f *pflag.Flag) {
		logger.Info("FLAG", f.Name, f.Value)
	})
}