package main

import (
	"context"
	"flag"
	"fmt"
	"net/http"
	"os"
	"strconv"
	"time"

	"github.com/aws/aws-sdk-go-v2/config"
	crossplaneeksv1alpha1 "github.com/crossplane-contrib/provider-aws/apis/eks/manualv1alpha1"
	gkecontainerv1beta1 "github.com/crossplane-contrib/provider-gcp/apis/container/v1beta1"
	"github.com/pingcap/errors"
	"github.com/pingcap/log"
	_ "k8s.io/client-go/plugin/pkg/client/auth" // Import all Kubernetes client auth plugins (e.g. Azure, GCP, OIDC, etc.)
	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"
	"sigs.k8s.io/controller-runtime/pkg/manager"
	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"

	"github.com/tidbcloud/observability/agent-control-server/controllers/kubernetesagent"
	"github.com/tidbcloud/observability/agent-control-server/controllers/o11yk8sagent"
	"github.com/tidbcloud/observability/agent-control-server/controllers/o11ytidbagent"
	"github.com/tidbcloud/observability/agent-control-server/controllers/sharedpoolagent"
	"github.com/tidbcloud/observability/agent-control-server/controllers/tidbgroupagent"
	"github.com/tidbcloud/observability/agent-control-server/pkg/cloud/alicloud"
	"github.com/tidbcloud/observability/agent-control-server/pkg/cloud/aws"
	"github.com/tidbcloud/observability/agent-control-server/pkg/cloud/gcp"
	pkgconfig "github.com/tidbcloud/observability/agent-control-server/pkg/config"
	"github.com/tidbcloud/observability/agent-control-server/pkg/consts"
	"github.com/tidbcloud/observability/agent-control-server/pkg/loader"
	"github.com/tidbcloud/observability/agent-control-server/pkg/metrics"
	"github.com/tidbcloud/observability/agent-control-server/pkg/o11y"
	"github.com/tidbcloud/observability/agent-control-server/pkg/podautoscaler"
	"github.com/tidbcloud/observability/agent-control-server/pkg/reconciler"
	"github.com/tidbcloud/observability/agent-control-server/pkg/server"
)

var (
	gitHash   string
	gitBranch string
	buildTime string
)

const (
	envConcurrentReconciles     = "CONCURRENT_RECONCILES"
	defaultConcurrentReconciles = 1
	defaultLeaderElectionID     = "4b090982.observability.pingcap.com"
)

type Option struct {
	ServerAddr              string
	ProbeAddr               string
	EnableLeaderElection    bool
	LeaderElectionID        string
	WatchNamespace          string
	RootConfigPath          string
	AgentConfigTemplatesDir string
}

func main() {
	var opt Option
	flag.StringVar(&opt.ServerAddr, "server-bind-address", ":8082", "The address the server endpoint binds to.")
	flag.StringVar(&opt.ProbeAddr, "health-probe-bind-address", ":8081", "The address the probe endpoint binds to.")
	flag.BoolVar(&opt.EnableLeaderElection, "leader-elect", false, "Enable leader election for controller manager. Enabling this will ensure there is only one active controller manager.")
	flag.StringVar(&opt.LeaderElectionID, "leader-election-id", "", "The leader election identity. Defaults to the production identity when leader election is enabled.")
	flag.StringVar(&opt.WatchNamespace, "watch-namespace", "", "Limit agent reconciliation and API queries to one namespace. Empty watches all namespaces.")
	flag.StringVar(&opt.RootConfigPath, "root-config", "", "The path to the root config.")
	flag.StringVar(&opt.AgentConfigTemplatesDir, "agent-config-templates-dir", "", "The path to the agent config templates dir.")
	flag.Parse()

	concurrentReconciles := getEnvInt(envConcurrentReconciles, defaultConcurrentReconciles)

	loader.MustInitLogger()
	log.Info(fmt.Sprintf("controller option: %+v", opt))
	log.Info(fmt.Sprintf("concurrent reconciles: %d", concurrentReconciles))

	ctr := NewController(opt, concurrentReconciles)
	if err := ctr.Start(); err != nil {
		log.Fatal(fmt.Sprintf("failed to start controller: %v", err))
	}

	// blocks until the context is cancelled
	ctr.Stop()
}

type Controller struct {
	ctx    context.Context
	cancel context.CancelFunc

	opt Option
	mgr manager.Manager
	svc *server.Server

	config               pkgconfig.RootConfig
	templates            pkgconfig.Templates
	pas                  *podautoscaler.PodAutoScaler
	concurrentReconciles int
}

func NewController(opt Option, concurrentReconciles int) *Controller {
	ctx, cancel := context.WithCancel(context.Background())
	return &Controller{
		ctx:                  ctx,
		cancel:               cancel,
		opt:                  opt,
		concurrentReconciles: concurrentReconciles,
	}
}

func (c *Controller) loadConfigs() error {
	var err error
	c.config, err = pkgconfig.LoadRootConfig(c.opt.RootConfigPath)
	if err != nil {
		return errors.Wrap(err, "load root config failed")
	}

	c.templates, err = pkgconfig.LoadAgentConfigTemplates(c.opt.AgentConfigTemplatesDir)
	if err != nil {
		return errors.Wrap(err, "load agent config templates failed")
	}
	return nil
}

func (c *Controller) setupManager() error {
	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), c.opt.managerOptions())
	if err != nil {
		return errors.Wrap(err, "create controller manager failed")
	}

	switch c.config.O11yConfig.Vendor {
	case consts.VendorTypeAWS:
		err = mgr.GetFieldIndexer().IndexField(context.Background(), &crossplaneeksv1alpha1.NodeGroup{}, ".spec.forProvider.clusterName", func(rawObj client.Object) []string {
			ng := rawObj.(*crossplaneeksv1alpha1.NodeGroup)
			if ng.Spec.ForProvider.ClusterName == "" {
				return nil
			}
			return []string{ng.Spec.ForProvider.ClusterName}
		})
		if err != nil {
			log.Error(fmt.Sprintf("create index for crossplane NodeGroup spec.forProvider.clusterName failed: %v", err))
		}
	case consts.VendorTypeGCP:
		err = mgr.GetFieldIndexer().IndexField(context.Background(), &gkecontainerv1beta1.NodePool{}, ".spec.forProvider.clusterRef.name", func(rawObj client.Object) []string {
			np := rawObj.(*gkecontainerv1beta1.NodePool)
			if np.Spec.ForProvider.ClusterRef != nil && np.Spec.ForProvider.ClusterRef.Name != "" {
				return []string{np.Spec.ForProvider.ClusterRef.Name}
			}
			return nil
		})
		if err != nil {
			log.Error(fmt.Sprintf("create index for gke NodePool spec.forProvider.clusterRef.name failed: %v", err))
		}
	}

	c.mgr = mgr
	return nil
}

func (opt Option) managerOptions() ctrl.Options {
	cacheOptions := cache.Options{ByObject: make(map[client.Object]cache.ByObject)}
	if opt.WatchNamespace != "" {
		cacheOptions.DefaultNamespaces = map[string]cache.Config{
			opt.WatchNamespace: {},
		}
	}

	leaderElectionID := ""
	if opt.EnableLeaderElection {
		leaderElectionID = opt.LeaderElectionID
		if leaderElectionID == "" {
			leaderElectionID = defaultLeaderElectionID
		}
	}

	return ctrl.Options{
		Scheme:                 loader.ProviderScheme(),
		Metrics:                metricsserver.Options{BindAddress: "0"},
		HealthProbeBindAddress: opt.ProbeAddr,
		LeaderElection:         opt.EnableLeaderElection,
		LeaderElectionID:       leaderElectionID,
		Cache:                  cacheOptions,
	}
}

func (c *Controller) installAgent(concurrentReconciles int) error {
	cfg, err := config.LoadDefaultConfig(context.Background())
	if err != nil {
		return err
	}

	awsCli := aws.NewClientSet(cfg)
	var gcpCli gcp.Client
	if c.config.O11yConfig.Vendor == consts.VendorTypeGCP {
		if gcpCli, err = gcp.NewClientSet(); err != nil {
			return errors.Wrap(err, "create gcp client failed")
		}
	}

	o11yApi := o11y.NewO11yInfraAPIClientV2(c.config.O11yConfig)
	r := reconciler.Reconciler{
		Client:                  c.mgr.GetClient(),
		Scheme:                  c.mgr.GetScheme(),
		EventRecorder:           c.mgr.GetEventRecorderFor("o11y-controller"),
		Config:                  &c.config,
		Templates:               c.templates,
		AWS:                     awsCli,
		GCP:                     gcpCli,
		AliCloud:                alicloud.NewClientSet(),
		O11yAPI:                 *o11yApi,
		MaxConcurrentReconciles: concurrentReconciles,
	}

	if err = (&o11yk8sagent.AgentReconciler{Reconciler: r}).SetupWithManager(c.mgr); err != nil {
		return errors.Wrap(err, "create O11yK8sAgent controller failed")
	}
	if err = (&o11ytidbagent.AgentReconciler{Reconciler: r}).SetupWithManager(c.mgr); err != nil {
		return errors.Wrap(err, "create O11yTiDBAgent controller failed")
	}
	if err = (&kubernetesagent.AgentReconciler{Reconciler: r}).SetupWithManager(c.mgr); err != nil {
		return errors.Wrap(err, "create KubernetesAgent controller failed")
	}
	if err = (&sharedpoolagent.AgentReconciler{Reconciler: r}).SetupWithManager(c.mgr); err != nil {
		return errors.Wrap(err, "create SharedPoolAgent controller failed")
	}
	if err = (&tidbgroupagent.AgentReconciler{Reconciler: r}).SetupWithManager(c.mgr); err != nil {
		return errors.Wrap(err, "create TiDBGroupAgent controller failed")
	}

	return nil
}

func (c *Controller) listenAndServe() {
	c.svc = server.New(c.opt.ServerAddr, c.mgr.GetClient(), &c.config, c.opt.WatchNamespace)
	if err := c.svc.Start(); err != nil {
		if !errors.ErrorEqual(err, http.ErrServerClosed) {
			log.Fatal(fmt.Sprintf("start monitor http server failed: %v", err))
		}
	}
}

func (c *Controller) runPodAutoScaler() {
	ticker := time.NewTicker(time.Minute)
	defer ticker.Stop()

	for {
		select {
		case <-ticker.C:
			if err := c.pas.Run(context.Background()); err != nil {
				log.Error(fmt.Sprintf("run pod auto scaler failed: %v", err))
			}
		case <-c.ctx.Done():
			return
		}
	}
}

func (c *Controller) updateMetrics() {
	metrics.SetBuildInfo(buildTime, gitHash, gitBranch)

	ticker := time.NewTicker(time.Minute)
	defer ticker.Stop()

	for {
		select {
		case <-ticker.C:
			if err := metrics.RecordAgentStatus(c.mgr.GetClient()); err != nil {
				log.Error(fmt.Sprintf("update agent metrics failed: %v", err))
			}
			if err := metrics.RecordVPCEndpointStatus(c.mgr.GetClient()); err != nil {
				log.Error(fmt.Sprintf("update vpcendpoint metrics failed: %v", err))
			}

			switch c.config.Mode {
			case pkgconfig.ModeServerless:
				// Skip nodegroup metrics in serverless mode.
			default:
				if err := metrics.RecordNodeGroupDesiredCount(c.mgr.GetClient(), c.config.O11yConfig.Vendor); err != nil {
					log.Error(fmt.Sprintf("update nodegroup desired count metrics failed: %v", err))
				}
			}

		case <-c.ctx.Done():
			return
		}
	}
}

func (c *Controller) Start() error {
	setupFuncs := []func() error{
		c.loadConfigs,
		c.setupManager,
		func() error { return c.installAgent(c.concurrentReconciles) },
	}
	for _, setupFunc := range setupFuncs {
		if err := setupFunc(); err != nil {
			return err
		}
	}

	go c.listenAndServe()
	go c.updateMetrics()

	if c.config.AutoScaler.Enabled {
		c.pas = podautoscaler.New(c.mgr.GetClient(), c.config)
		go c.runPodAutoScaler()
	}

	if err := c.mgr.AddHealthzCheck("healthz", healthz.Ping); err != nil {
		return errors.Wrap(err, "add healthz check failed")
	}
	if err := c.mgr.AddReadyzCheck("readyz", healthz.Ping); err != nil {
		return errors.Wrap(err, "add readyz check failed")
	}
	return c.mgr.Start(ctrl.SetupSignalHandler())
}

func (c *Controller) Stop() {
	c.cancel()
	_ = c.svc.Shutdown(context.Background())

	if c.config.AutoScaler.Enabled {
		c.pas.Clean()
	}
}

func getEnvInt(key string, defaultValue int) int {
	if val := os.Getenv(key); val != "" {
		if intVal, err := strconv.Atoi(val); err == nil && intVal > 0 {
			return intVal
		}
	}
	return defaultValue
}