/*
Copyright 2018 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 serviceaccount

import (
	"time"

	apiserverserviceaccount "k8s.io/apiserver/pkg/authentication/serviceaccount"
	"k8s.io/kubernetes/pkg/apis/core"

	"gopkg.in/square/go-jose.v2/jwt"
)

// time.Now stubbed out to allow testing
var now = time.Now

type privateClaims struct {
	Kubernetes kubernetes `json:"kubernetes.io,omitempty"`
}

type kubernetes struct {
	Namespace string `json:"namespace,omitempty"`
	Svcacct   ref    `json:"serviceaccount,omitempty"`
	Pod       *ref   `json:"pod,omitempty"`
	Secret    *ref   `json:"secret,omitempty"`
}

type ref struct {
	Name string `json:"name,omitempty"`
	UID  string `json:"uid,omitempty"`
}

func Claims(sa core.ServiceAccount, pod *core.Pod, secret *core.Secret, expirationSeconds int64, audience []string) (*jwt.Claims, interface{}) {
	now := now()
	sc := &jwt.Claims{
		Subject:   apiserverserviceaccount.MakeUsername(sa.Namespace, sa.Name),
		Audience:  jwt.Audience(audience),
		IssuedAt:  jwt.NewNumericDate(now),
		NotBefore: jwt.NewNumericDate(now),
		Expiry:    jwt.NewNumericDate(now.Add(time.Duration(expirationSeconds) * time.Second)),
	}
	pc := &privateClaims{
		Kubernetes: kubernetes{
			Namespace: sa.Namespace,
			Svcacct: ref{
				Name: sa.Name,
				UID:  string(sa.UID),
			},
		},
	}
	switch {
	case pod != nil:
		pc.Kubernetes.Pod = &ref{
			Name: pod.Name,
			UID:  string(pod.UID),
		}
	case secret != nil:
		pc.Kubernetes.Secret = &ref{
			Name: secret.Name,
			UID:  string(secret.UID),
		}
	}
	return sc, pc
}