package cluster

import (
	"context"
	"net"
	"net/url"
	"strings"
	"sync"
	"time"

	"github.com/k3s-io/k3s/pkg/cli/cmds"
	"github.com/k3s-io/k3s/pkg/clientaccess"
	"github.com/k3s-io/k3s/pkg/cluster/managed"
	"github.com/k3s-io/k3s/pkg/daemons/config"
	"github.com/k3s-io/k3s/pkg/daemons/executor"
	"github.com/k3s-io/k3s/pkg/etcd"
	"github.com/k3s-io/k3s/pkg/metrics"
	"github.com/k3s-io/k3s/pkg/signals"
	"github.com/k3s-io/k3s/pkg/util"
	"github.com/k3s-io/k3s/pkg/util/errors"
	"github.com/k3s-io/kine/pkg/endpoint"
	"github.com/sirupsen/logrus"
	"k8s.io/apimachinery/pkg/util/wait"
	utilsnet "k8s.io/utils/net"
)

type Cluster struct {
	clientAccessInfo *clientaccess.Info
	config           *config.Control
	managedDB        managed.Driver
	joining          bool
	storageRunning   bool
	saveBootstrap    bool
	cnFilterFunc     func(...string) []string
}

// ListenAndServe creates the dynamic tls listener, registers http request
// handlers, and starts the supervisor API server loop.
func (c *Cluster) ListenAndServe(ctx context.Context) error {
	// Set up the dynamiclistener and http request handlers
	return c.initClusterAndHTTPS(ctx)
}

// Start handles writing/reading bootstrap data. If embedded etcd is in use,
// a secondary call to Cluster.save is made.
func (c *Cluster) Start(ctx context.Context, wg *sync.WaitGroup) error {
	// if etcd is disabled or we're using kine, perform a no-op start of etcd
	// to close the etcd ready channel. When etcd is in use, this is handled by
	// c.start() -> c.managedDB.Start() -> etcd.Start() -> executor.ETCD()
	if c.config.DisableETCD {
		return executor.ETCD(ctx, wg, nil, nil, func(ctx context.Context, _ bool) error { return c.managedDB.Test(ctx, false) })
	}

	if c.managedDB == nil {
		if err := executor.ETCD(ctx, wg, nil, nil, func(context.Context, bool) error { return nil }); err != nil {
			return err
		}
	}

	// start managed etcd database; when kine is in use this is a no-op.
	if err := c.start(ctx, wg); err != nil {
		return errors.WithMessage(err, "start managed database")
	}

	// set c.config.Datastore and c.config.Runtime.EtcdConfig with values
	// necessary to build etcd clients, and start kine listener if necessary.
	if err := c.startStorage(ctx, false); err != nil {
		return err
	}

	// if necessary, store bootstrap data to datastore. saveBootstrap is only set
	// when using kine, so this can be done before the ready channel has been closed.
	if c.saveBootstrap {
		if err := Save(ctx, c.config, false); err != nil {
			return err
		}
	}

	if c.managedDB != nil {
		go func() {
			for {
				select {
				case <-executor.ETCDReadyChan():
					// always save to managed etcd, to ensure that any file modified locally are in sync with the datastore.
					// this will fail if multiple keys exist, to prevent nodes from running with different bootstrap data.
					if err := Save(ctx, c.config, false); err != nil && !errors.Is(err, context.Canceled) {
						signals.RequestShutdown(errors.WithMessage(err, "failed to save bootstrap data"))
						return
					}

					if !c.config.EtcdDisableSnapshots {
						// do an initial reconcile of snapshots with a fast retry until it succeeds
						backoff := wait.Backoff{Duration: time.Second, Factor: 2, Steps: 5}
						backoff.DelayFunc().Until(ctx, true, false, func(ctx context.Context) (bool, error) {
							if err := c.managedDB.ReconcileSnapshotData(ctx); err != nil {
								logrus.Errorf("Failed to record snapshots for cluster: %v", err)
								return false, nil
							}
							return true, nil
						})

						// continue reconciling snapshots in the background at the configured interval.
						// the interval is jittered by 5% to avoid all nodes reconciling at the same time.
						wait.JitterUntilWithContext(ctx, func(ctx context.Context) {
							if err := c.managedDB.ReconcileSnapshotData(ctx); err != nil {
								logrus.Errorf("Failed to record snapshots for cluster: %v", err)
							}
						}, c.config.EtcdSnapshotReconcile.Duration, 0.05, false)
					}
					return
				case <-ctx.Done():
					return
				}
			}
		}()
	}

	return nil
}

// startEtcdProxy starts an etcd load-balancer proxy, for control-plane-only nodes
// without a local datastore.
func (c *Cluster) startEtcdProxy(ctx context.Context) error {
	defaultURL, err := url.Parse(c.config.JoinURL)
	if err != nil {
		return err
	}
	_, nodeIPs, err := util.GetHostnameAndIPs(cmds.AgentConfig.NodeName, cmds.AgentConfig.NodeIP.Value())
	if err != nil {
		return errors.WithMessage(err, "failed to get node name and addresses")
	}

	defaultURL.Host = net.JoinHostPort(defaultURL.Hostname(), "2379")
	etcdProxy, err := etcd.NewETCDProxy(ctx, c.config.SupervisorPort, c.config.DataDir, defaultURL.String(), utilsnet.IsIPv6(nodeIPs[0]))
	if err != nil {
		return err
	}

	// immediately update the load balancer with all etcd addresses
	// from /db/info, for a current list of etcd cluster member client URLs.
	// client URLs are a full URI, but the proxy only wants host:port
	if clientURLs, _, err := etcd.ClientURLs(ctx, c.clientAccessInfo, c.config.PrivateIP); err != nil || len(clientURLs) == 0 {
		logrus.Warnf("Failed to get etcd ClientURLs: %v", err)
	} else {
		for i, c := range clientURLs {
			u, err := url.Parse(c)
			if err != nil {
				return errors.WithMessage(err, "failed to parse etcd ClientURL")
			}
			clientURLs[i] = u.Host
		}
		etcdProxy.Update(clientURLs)
	}

	// start periodic endpoint sync goroutine
	c.setupEtcdProxy(ctx, etcdProxy)

	// remove etcd member if it exists
	if err := c.managedDB.RemoveSelf(ctx); err != nil {
		logrus.Warnf("Failed to remove this node from etcd members: %v", err)
	}

	c.config.Runtime.EtcdConfig.Endpoints = strings.Split(c.config.Datastore.Endpoint, ",")
	c.config.Runtime.EtcdConfig.TLSConfig = c.config.Datastore.BackendTLSConfig

	return nil
}

// startStorage starts the kine listener and configures the endpoints, if necessary.
// This calls into the kine endpoint code, which sets up the database client
// and unix domain socket listener if using an external database. In the case of an etcd
// backend it just returns the user-provided etcd endpoints and tls config.
func (c *Cluster) startStorage(ctx context.Context, bootstrap bool) error {
	if c.storageRunning {
		return nil
	}

	// the datastore is started multiple times when TLS is enabled.
	// ensure that storage is no longer marked as running after its context is cancelled.
	go func() {
		<-ctx.Done()
		c.storageRunning = false
	}()
	c.storageRunning = true

	if !c.config.KineTLS {
		// if TLS is not enabled for kine, storage will only be started once,
		// so go ahead and register metrics now
		c.config.Datastore.MetricsRegisterer = metrics.DefaultRegisterer
		// also set up kine peering (if enabled) without certs
		c.setupKinePeering()
	}

	if !bootstrap {
		// only register metrics after boostrapping is done, to prevent
		// multiple datastore metrics from being registered
		c.config.Datastore.MetricsRegisterer = metrics.DefaultRegisterer
		// set the tls config for the kine storage, once bootstrapped
		c.config.Datastore.ServerTLSConfig.CAFile = c.config.Runtime.ETCDServerCA
		c.config.Datastore.ServerTLSConfig.CertFile = c.config.Runtime.ServerETCDCert
		c.config.Datastore.ServerTLSConfig.KeyFile = c.config.Runtime.ServerETCDKey
		// also set up kine peering, now that we have certs to use.
		c.setupKinePeering()
	}

	// start listening on the kine socket as an etcd endpoint, or return the external etcd endpoints
	etcdConfig, err := endpoint.Listen(ctx, c.config.Datastore)
	if err != nil {
		return errors.WithMessage(err, "creating storage endpoint")
	}

	// Persist the returned etcd configuration. We decide if we're doing leader election for embedded controllers
	// based on what the kine wrapper tells us about the datastore. Single-node datastores like sqlite don't require
	// leader election, while basically all others (etcd, external database, etc) do since they allow multiple servers.
	c.config.Runtime.EtcdConfig = etcdConfig

	// after the bootstrap we need to set the args for api-server with kine in unixs or just set the
	// values if the datastoreTLS is not enabled
	if !bootstrap || !c.config.KineTLS {
		c.config.Datastore.BackendTLSConfig = etcdConfig.TLSConfig
		c.config.Datastore.Endpoint = strings.Join(etcdConfig.Endpoints, ",")
		c.config.NoLeaderElect = !etcdConfig.LeaderElect
	}

	return nil
}

func (c *Cluster) setupKinePeering() {
	if strings.HasPrefix(c.config.Datastore.Endpoint, "t4://") {
		address := c.config.BindAddressOrLoopback(true, true) + ":3380"
		c.config.Datastore.PeerConfig.AdvertiseAddress = address
		c.config.Datastore.PeerConfig.BindAddress = address
		if c.config.KineTLS {
			c.config.Datastore.BackendTLSConfig.CAFile = c.config.Runtime.ETCDPeerCA
			c.config.Datastore.BackendTLSConfig.CertFile = c.config.Runtime.PeerServerClientETCDCert
			c.config.Datastore.BackendTLSConfig.KeyFile = c.config.Runtime.PeerServerClientETCDKey
		}
	}
}

// New creates an initial cluster using the provided configuration.
func New(config *config.Control) *Cluster {
	return &Cluster{
		config: config,
	}
}
