package cloudup

import (
	"encoding/base64"
	"encoding/binary"
	"fmt"
	"k8s.io/kops/upup/pkg/api"
	"math/big"
	"net"
	"sort"
	"strings"
	"text/template"
)

type TemplateFunctions struct {
	cluster *api.Cluster
	tags    map[string]struct{}
	region  string
}

func (tf *TemplateFunctions) WellKnownServiceIP(id int) (net.IP, error) {
	_, cidr, err := net.ParseCIDR(tf.cluster.Spec.ServiceClusterIPRange)
	if err != nil {
		return nil, fmt.Errorf("error parsing ServiceClusterIPRange %q: %v", tf.cluster.Spec.ServiceClusterIPRange, err)
	}

	ip4 := cidr.IP.To4()
	if ip4 != nil {
		n := binary.BigEndian.Uint32(ip4)
		n += uint32(id)
		serviceIP := make(net.IP, len(ip4))
		binary.BigEndian.PutUint32(serviceIP, n)
		return serviceIP, nil
	}

	ip6 := cidr.IP.To16()
	if ip6 != nil {
		baseIPInt := big.NewInt(0)
		baseIPInt.SetBytes(ip6)
		serviceIPInt := big.NewInt(0)
		serviceIPInt.Add(big.NewInt(int64(id)), baseIPInt)
		serviceIP := make(net.IP, len(ip6))
		serviceIPBytes := serviceIPInt.Bytes()
		for i := range serviceIPBytes {
			serviceIP[len(serviceIP)-len(serviceIPBytes)+i] = serviceIPBytes[i]
		}
		return serviceIP, nil
	}

	return nil, fmt.Errorf("Unexpected IP address type for ServiceClusterIPRange: %s", tf.cluster.Spec.ServiceClusterIPRange)
}

func (tf *TemplateFunctions) AddTo(dest template.FuncMap) {
	dest["EtcdClusterMemberTags"] = tf.EtcdClusterMemberTags
	dest["SharedVPC"] = tf.SharedVPC
	dest["WellKnownServiceIP"] = tf.WellKnownServiceIP
	dest["AdminCIDR"] = tf.AdminCIDR

	dest["Base64Encode"] = func(s string) string {
		return base64.StdEncoding.EncodeToString([]byte(s))
	}
	dest["replace"] = func(s, find, replace string) string {
		return strings.Replace(s, find, replace, -1)
	}
	dest["join"] = func(a []string, sep string) string {
		return strings.Join(a, sep)
	}

	dest["ClusterName"] = func() string {
		return tf.cluster.Name
	}

	dest["HasTag"] = func(tag string) bool {
		_, found := tf.tags[tag]
		return found
	}

	dest["IAMPrefix"] = tf.IAMPrefix
	dest["IAMServiceEC2"] = tf.IAMServiceEC2

}

func (tf *TemplateFunctions) EtcdClusterMemberTags(etcd *api.EtcdClusterSpec, m *api.EtcdMemberSpec) map[string]string {
	tags := make(map[string]string)

	var allMembers []string

	for _, m := range etcd.Members {
		allMembers = append(allMembers, m.Name)
	}

	sort.Strings(allMembers)

	// This is the configuration of the etcd cluster
	tags["k8s.io/etcd/"+etcd.Name] = m.Name + "/" + strings.Join(allMembers, ",")

	// This says "only mount on a master"
	tags["k8s.io/role/master"] = "1"

	return tags
}

// SharedVPC is a simple helper function which makes the templates for a shared VPC clearer
func (tf *TemplateFunctions) SharedVPC() bool {
	return tf.cluster.Spec.NetworkID != ""
}

// AdminCIDR returns the single CIDR that is allowed access to the admin ports of the cluster (22, 443 on master)
func (tf *TemplateFunctions) AdminCIDR() (string, error) {
	if len(tf.cluster.Spec.AdminAccess) == 0 {
		return "0.0.0.0/0", nil
	}
	if len(tf.cluster.Spec.AdminAccess) == 1 {
		return tf.cluster.Spec.AdminAccess[0], nil
	}
	return "", fmt.Errorf("Multiple AdminAccess rules are not (currently) supported")
}

// IAMServiceEC2 returns the name of the IAM service for EC2 in the current region
// it is ec2.amazonaws.com everywhere but in cn-north, where it is ec2.amazonaws.com.cn
func (tf *TemplateFunctions) IAMServiceEC2() string {
	switch tf.region {
	case "cn-north-1":
		return "ec2.amazonaws.com.cn"
	default:
		return "ec2.amazonaws.com"
	}
}

// IAMPrefix returns the prefix for AWS ARNs in the current region, for use with IAM
// it is arn:aws everywhere but in cn-north, where it is arn:aws-cn
func (tf *TemplateFunctions) IAMPrefix() string {
	switch tf.region {
	case "cn-north-1":
		return "arn:aws-cn"
	default:
		return "arn:aws"
	}
}