package certs

import (
	"net"
	"time"
)

// Certificates is the set of certificates required to run our Kubernetes
// production.
type Certificates struct {
	CAs CAs

	ProdviderIntermediateCA *Certificate

	Global  Global
	PerNode map[string]PerNode
}

type ensurer interface {
	Ensure() error
}

// Ensure checks that all the Kubernetes production certificates and keys are
// present on disk, generating them as necessary.
//
// If the user has not decrypted cluster/secrets, an error will be returned.
// However, deeper sync checks are not currently performed.
func (c *Certificates) Ensure() error {
	sub := []ensurer{
		&c.CAs,
		c.ProdviderIntermediateCA,
		&c.Global,
	}
	for _, pn := range c.PerNode {
		sub = append(sub, &pn)
	}
	for _, s := range sub {
		if err := s.Ensure(); err != nil {
			return err
		}
	}
	return nil
}

// CAs are the root certificate authorities we use.
type CAs struct {
	// EtcdPeer is used by etcd member nodes to authenticate peers.
	EtcdPeer *Certificate
	// Etcd is used by etcd membrer nodes to authenticate clients (ie.
	// kube-apiservers).
	Etcd *Certificate
	// Kube is the main Kubernetes 'identity' CA, used to identify components
	// and users.
	Kube *Certificate
	// KubeFront is the proxy/aggregation CA used by external apiservices to
	// authenticate incoming apiserver connections.
	KubeFront *Certificate
	// Admitomatic is the CA used by the admitomatic webhook to authenticate
	// incoming apiserver connections.
	Admitomatic *Certificate
}

func (c *CAs) Ensure() error {
	sub := []ensurer{
		c.EtcdPeer,
		c.Etcd,
		c.Kube,
		c.KubeFront,
		c.Admitomatic,
	}
	for _, s := range sub {
		if err := s.Ensure(); err != nil {
			return err
		}
	}
	return nil
}

// Global are all the non-per-node certificates we use.
type Global struct {
	// EtcdKube is used by kubernetes apiservers to authenticate to etcd
	// members.
	EtcdKube *Certificate

	// KubeApiserver is used by kubernetes apiservers to authenticate to other
	// kubernetes components/users.
	KubeApiserver *Certificate
	// KubeControllerManager is used by kubernetes controller managers to
	// authenticate to the kubernetes apiservers.
	KubeControllerManager *Certificate
	// KubeScheduler is used by the kubernetes schedulers to authenticate to
	// the kubernetes apiservers.
	KubeScheduler *Certificate

	// KubefrontApiserver is used by the kubernetes apiserver to authenticate
	// to external apiservices.
	KubefrontApiserver *Certificate

	// AdmitomaticWebhook is used by the admitomatic webhook to authenticate to
	// the Kubernetes apiservers.
	AdmitomaticWebhook *Certificate
}

func (g *Global) Ensure() error {
	sub := []ensurer{
		g.EtcdKube,
		g.KubeApiserver,
		g.KubeControllerManager,
		g.KubeScheduler,
		g.KubefrontApiserver,
		g.AdmitomaticWebhook,
	}
	for _, s := range sub {
		if err := s.Ensure(); err != nil {
			return err
		}
	}
	return nil
}

func (c *Certificates) MakeKubeEmergencyCreds(root, breadcrumb string) *Certificate {
	return &Certificate{
		name:     "emergency",
		duration: 7 * 24 * time.Hour,
		root:     root,
		kind:     kindClient,
		cn:       "admin",
		san:      []string{"admin", breadcrumb},
		o:        "system:masters",
		issuer:   c.CAs.Kube,
	}
}

// Per node are all the per-node certificates we use.
type PerNode struct {
	// EtcdPeer is used by etcd members to authenticate to other etcd members.
	EtcdPeer *Certificate
	// EtcdClient is used by etcd members to authenticate to their clients.
	EtcdClient *Certificate

	// Kubelet is used by kubelets to authenticate to other kubernetes
	// components.
	Kubelet *Certificate
}

func (p *PerNode) Ensure() error {
	sub := []ensurer{
		p.EtcdPeer,
		p.EtcdClient,
		p.Kubelet,
	}
	for _, s := range sub {
		if err := s.Ensure(); err != nil {
			return err
		}
	}
	return nil
}

func mkCA(root, name, cn string) *Certificate {
	return &Certificate{
		name: name,
		root: root,
		kind: kindCA,
		cn:   cn,
	}
}

// Prepare builds our Certificates structure at a given location on the
// filesystem, for the given nodes.
//
// Calling Ensure() on the returned Certificates will actually engage
// generation logic. Before that, no disk accesses are performed.
func Prepare(root string, fqdns []string) Certificates {
	certs := Certificates{
		CAs: CAs{
			EtcdPeer:    mkCA(root, "ca-etcdpeer", "etcd peer ca"),
			Etcd:        mkCA(root, "ca-etcd", "etcd ca"),
			Kube:        mkCA(root, "ca-kube", "kubernetes main CA"),
			KubeFront:   mkCA(root, "ca-kubefront", "kubernetes frontend CA"),
			Admitomatic: mkCA(root, "ca-admitomatic", "admitomatic webhook CA"),
		},
		PerNode: make(map[string]PerNode),
	}

	certs.ProdviderIntermediateCA = &Certificate{
		name:   "ca-kube-prodvider",
		root:   root,
		kind:   kindProdvider,
		cn:     "kubernetes prodvider intermediate",
		issuer: certs.CAs.Kube,
	}
	certs.Global = Global{
		EtcdKube: &Certificate{
			name:   "etcd-kube",
			root:   root,
			kind:   kindClient,
			cn:     "kube etcd client certificate",
			san:    []string{"kube"},
			issuer: certs.CAs.Etcd,
		},
		KubeApiserver: &Certificate{
			name: "kube-apiserver",
			root: root,
			kind: kindClientServer,
			cn:   "k0.hswaw.net",
			san: []string{
				"k0.hswaw.net",
				"kubernetes.default.svc.k0.hswaw.net",
			},
			ips: []net.IP{
				{10, 10, 12, 1},
			},
			issuer: certs.CAs.Kube,
		},
		KubeControllerManager: &Certificate{
			name:   "kube-controllermanager",
			root:   root,
			kind:   kindClientServer,
			cn:     "system:kube-controller-manager",
			san:    []string{"system:kube-controller-manager"},
			o:      "system:kube-controller-manager",
			issuer: certs.CAs.Kube,
		},
		KubeScheduler: &Certificate{
			name:   "kube-scheduler",
			root:   root,
			kind:   kindClientServer,
			cn:     "system:kube-scheduler",
			san:    []string{"system:kube-scheduler"},
			o:      "system:kube-scheduler",
			issuer: certs.CAs.Kube,
		},
		KubefrontApiserver: &Certificate{
			name:   "kubefront-apiserver",
			root:   root,
			kind:   kindClientServer,
			cn:     "Kubernetes Frontend",
			san:    []string{"apiserver"},
			issuer: certs.CAs.KubeFront,
		},
		AdmitomaticWebhook: &Certificate{
			name:   "admitomatic-webhook",
			root:   root,
			kind:   kindServer,
			cn:     "Admitomatic Webhook",
			san:    []string{"admitomatic.admitomatic.svc"},
			issuer: certs.CAs.Admitomatic,
		},
	}
	for _, fqdn := range fqdns {
		certs.PerNode[fqdn] = PerNode{
			EtcdPeer: &Certificate{
				name:   "etcdpeer-" + fqdn,
				root:   root,
				kind:   kindClientServer,
				cn:     "node etcd peer certificate",
				san:    []string{fqdn},
				issuer: certs.CAs.EtcdPeer,
			},
			EtcdClient: &Certificate{
				name: "etcd-" + fqdn,
				root: root,
				// etcd seems to need client too, as it's connecting to itself
				// for... some reason?
				// https://github.com/etcd-io/etcd/issues/9785
				kind:   kindClientServer,
				cn:     "node etcd server certificate",
				san:    []string{fqdn},
				issuer: certs.CAs.Etcd,
			},
			Kubelet: &Certificate{
				name: "kube-kubelet-" + fqdn,
				root: root,
				kind: kindClientServer,
				cn:   "system:node:" + fqdn,
				o:    "system:nodes",
				san: []string{
					"system:node:" + fqdn,
					fqdn,
				},
				issuer: certs.CAs.Kube,
			},
		}
	}

	return certs
}