/*
Copyright 2016 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package kubeconfig

import (
	"fmt"
	"sort"

	"github.com/golang/glog"
	"k8s.io/kops/pkg/apis/kops"
	"k8s.io/kops/pkg/dns"
	"k8s.io/kops/upup/pkg/fi"
)

func BuildKubecfg(cluster *kops.Cluster, keyStore fi.Keystore, secretStore fi.SecretStore, status kops.StatusStore) (*KubeconfigBuilder, error) {
	clusterName := cluster.ObjectMeta.Name

	master := cluster.Spec.MasterPublicName
	if master == "" {
		master = "api." + clusterName
	}

	server := "https://" + master
	topology := cluster.Spec.Topology

	if dns.IsGossipHostname(master) || topology.DNS.Type == kops.DNSTypePrivate {
		ingresses, err := status.GetApiIngressStatus(cluster)
		if err != nil {
			return nil, fmt.Errorf("error getting ingress status: %v", err)
		}

		var targets []string
		for _, ingress := range ingresses {
			if ingress.Hostname != "" {
				targets = append(targets, ingress.Hostname)
			}
			if ingress.IP != "" {
				targets = append(targets, ingress.IP)
			}
		}

		sort.Strings(targets)
		if len(targets) == 0 {
			glog.Warningf("Did not find API endpoint for gossip hostname; may not be able to reach cluster")
		} else {
			if len(targets) != 1 {
				glog.Warningf("Found multiple API endpoints (%v), choosing arbitrarily", targets)
			}
			server = "https://" + targets[0]
		}
	}

	b := NewKubeconfigBuilder()

	b.Context = clusterName

	{
		cert, _, err := keyStore.FindKeypair(fi.CertificateId_CA)
		if err != nil {
			return nil, fmt.Errorf("error fetching CA keypair: %v", err)
		}
		if cert != nil {
			b.CACert, err = cert.AsBytes()
			if err != nil {
				return nil, err
			}
		} else {
			return nil, fmt.Errorf("cannot find CA certificate")
		}
	}

	{
		cert, key, err := keyStore.FindKeypair("kubecfg")
		if err != nil {
			return nil, fmt.Errorf("error fetching kubecfg keypair: %v", err)
		}
		if cert != nil {
			b.ClientCert, err = cert.AsBytes()
			if err != nil {
				return nil, err
			}
		} else {
			return nil, fmt.Errorf("cannot find kubecfg certificate")
		}
		if key != nil {
			b.ClientKey, err = key.AsBytes()
			if err != nil {
				return nil, err
			}
		} else {
			return nil, fmt.Errorf("cannot find kubecfg key")
		}
	}

	b.Server = server

	if secretStore != nil {
		secret, err := secretStore.FindSecret("kube")
		if err != nil {
			return nil, err
		}
		if secret != nil {
			b.KubeUser = "admin"
			b.KubePassword = string(secret.Data)
		}
	}

	return b, nil
}