package arm

import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"math/big"
	"regexp"
	"strings"
	"time"

	"github.com/Azure/azure-sdk-for-go/services/compute/mgmt/2018-04-01/compute"
	"github.com/Azure/go-autorest/autorest/azure"
	"github.com/Azure/go-autorest/autorest/to"
	"github.com/masterzen/winrm"

	"github.com/hashicorp/packer/builder/azure/common/constants"
	"github.com/hashicorp/packer/builder/azure/pkcs12"
	"github.com/hashicorp/packer/common"
	commonhelper "github.com/hashicorp/packer/helper/common"
	"github.com/hashicorp/packer/helper/communicator"
	"github.com/hashicorp/packer/helper/config"
	"github.com/hashicorp/packer/packer"
	"github.com/hashicorp/packer/template/interpolate"

	"golang.org/x/crypto/ssh"
)

const (
	DefaultCloudEnvironmentName              = "Public"
	DefaultImageVersion                      = "latest"
	DefaultUserName                          = "packer"
	DefaultPrivateVirtualNetworkWithPublicIp = false
	DefaultVMSize                            = "Standard_A1"
)

const (
	// https://docs.microsoft.com/en-us/azure/architecture/best-practices/naming-conventions#naming-rules-and-restrictions
	// Regular expressions in Go are not expressive enough, such that the regular expression returned by Azure
	// can be used (no backtracking).
	//
	//  -> ^[^_\W][\w-._]{0,79}(?<![-.])$
	//
	// This is not an exhaustive match, but it should be extremely close.
	validResourceGroupNameRe = "^[^_\\W][\\w-._\\(\\)]{0,89}$"
	validManagedDiskName     = "^[^_\\W][\\w-._)]{0,79}$"
)

var (
	reCaptureContainerName = regexp.MustCompile("^[a-z0-9][a-z0-9\\-]{2,62}$")
	reCaptureNamePrefix    = regexp.MustCompile("^[A-Za-z0-9][A-Za-z0-9_\\-\\.]{0,23}$")
	reManagedDiskName      = regexp.MustCompile(validManagedDiskName)
	reResourceGroupName    = regexp.MustCompile(validResourceGroupNameRe)
)

type PlanInformation struct {
	PlanName          string `mapstructure:"plan_name"`
	PlanProduct       string `mapstructure:"plan_product"`
	PlanPublisher     string `mapstructure:"plan_publisher"`
	PlanPromotionCode string `mapstructure:"plan_promotion_code"`
}

type Config struct {
	common.PackerConfig `mapstructure:",squash"`

	// Authentication via OAUTH
	ClientID       string `mapstructure:"client_id"`
	ClientSecret   string `mapstructure:"client_secret"`
	ObjectID       string `mapstructure:"object_id"`
	TenantID       string `mapstructure:"tenant_id"`
	SubscriptionID string `mapstructure:"subscription_id"`

	// Capture
	CaptureNamePrefix    string `mapstructure:"capture_name_prefix"`
	CaptureContainerName string `mapstructure:"capture_container_name"`

	// Compute
	ImagePublisher string `mapstructure:"image_publisher"`
	ImageOffer     string `mapstructure:"image_offer"`
	ImageSku       string `mapstructure:"image_sku"`
	ImageVersion   string `mapstructure:"image_version"`
	ImageUrl       string `mapstructure:"image_url"`

	CustomManagedImageResourceGroupName string `mapstructure:"custom_managed_image_resource_group_name"`
	CustomManagedImageName              string `mapstructure:"custom_managed_image_name"`
	customManagedImageID                string

	Location string `mapstructure:"location"`
	VMSize   string `mapstructure:"vm_size"`

	ManagedImageResourceGroupName  string `mapstructure:"managed_image_resource_group_name"`
	ManagedImageName               string `mapstructure:"managed_image_name"`
	ManagedImageStorageAccountType string `mapstructure:"managed_image_storage_account_type"`
	managedImageStorageAccountType compute.StorageAccountTypes
	manageImageLocation            string

	// Deployment
	AzureTags                         map[string]*string `mapstructure:"azure_tags"`
	ResourceGroupName                 string             `mapstructure:"resource_group_name"`
	StorageAccount                    string             `mapstructure:"storage_account"`
	TempComputeName                   string             `mapstructure:"temp_compute_name"`
	TempResourceGroupName             string             `mapstructure:"temp_resource_group_name"`
	BuildResourceGroupName            string             `mapstructure:"build_resource_group_name"`
	storageAccountBlobEndpoint        string
	CloudEnvironmentName              string `mapstructure:"cloud_environment_name"`
	cloudEnvironment                  *azure.Environment
	PrivateVirtualNetworkWithPublicIp bool   `mapstructure:"private_virtual_network_with_public_ip"`
	VirtualNetworkName                string `mapstructure:"virtual_network_name"`
	VirtualNetworkSubnetName          string `mapstructure:"virtual_network_subnet_name"`
	VirtualNetworkResourceGroupName   string `mapstructure:"virtual_network_resource_group_name"`
	CustomDataFile                    string `mapstructure:"custom_data_file"`
	customData                        string
	PlanInfo                          PlanInformation `mapstructure:"plan_info"`

	// OS
	OSType       string `mapstructure:"os_type"`
	OSDiskSizeGB int32  `mapstructure:"os_disk_size_gb"`

	// Additional Disks
	AdditionalDiskSize []int32 `mapstructure:"disk_additional_size"`

	// Runtime Values
	UserName               string
	Password               string
	tmpAdminPassword       string
	tmpCertificatePassword string
	tmpResourceGroupName   string
	tmpComputeName         string
	tmpNicName             string
	tmpPublicIPAddressName string
	tmpDeploymentName      string
	tmpKeyVaultName        string
	tmpOSDiskName          string
	tmpSubnetName          string
	tmpVirtualNetworkName  string
	tmpWinRMCertificateUrl string

	useDeviceLogin bool

	// Authentication with the VM via SSH
	sshAuthorizedKey string

	// Authentication with the VM via WinRM
	winrmCertificate string

	Comm communicator.Config `mapstructure:",squash"`
	ctx  interpolate.Context

	//Cleanup
	AsyncResourceGroupDelete bool `mapstructure:"async_resourcegroup_delete"`
}

type keyVaultCertificate struct {
	Data     string `json:"data"`
	DataType string `json:"dataType"`
	Password string `json:"password,omitempty"`
}

func (c *Config) toVMID() string {
	var resourceGroupName string
	if c.tmpResourceGroupName != "" {
		resourceGroupName = c.tmpResourceGroupName
	} else {
		resourceGroupName = c.BuildResourceGroupName
	}
	return fmt.Sprintf("/subscriptions/%s/resourceGroups/%s/providers/Microsoft.Compute/virtualMachines/%s", c.SubscriptionID, resourceGroupName, c.tmpComputeName)
}

func (c *Config) isManagedImage() bool {
	return c.ManagedImageName != ""
}

func (c *Config) toVirtualMachineCaptureParameters() *compute.VirtualMachineCaptureParameters {
	return &compute.VirtualMachineCaptureParameters{
		DestinationContainerName: &c.CaptureContainerName,
		VhdPrefix:                &c.CaptureNamePrefix,
		OverwriteVhds:            to.BoolPtr(false),
	}
}

func (c *Config) toImageParameters() *compute.Image {
	return &compute.Image{
		ImageProperties: &compute.ImageProperties{
			SourceVirtualMachine: &compute.SubResource{
				ID: to.StringPtr(c.toVMID()),
			},
		},
		Location: to.StringPtr(c.Location),
		Tags:     c.AzureTags,
	}
}

func (c *Config) createCertificate() (string, error) {
	privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		err = fmt.Errorf("Failed to Generate Private Key: %s", err)
		return "", err
	}

	host := fmt.Sprintf("%s.cloudapp.net", c.tmpComputeName)
	notBefore := time.Now()
	notAfter := notBefore.Add(24 * time.Hour)

	serialNumber, err := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
	if err != nil {
		err = fmt.Errorf("Failed to Generate Serial Number: %v", err)
		return "", err
	}

	template := x509.Certificate{
		SerialNumber: serialNumber,
		Issuer: pkix.Name{
			CommonName: host,
		},
		Subject: pkix.Name{
			CommonName: host,
		},
		NotBefore: notBefore,
		NotAfter:  notAfter,

		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
		BasicConstraintsValid: true,
	}

	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &privateKey.PublicKey, privateKey)
	if err != nil {
		err = fmt.Errorf("Failed to Create Certificate: %s", err)
		return "", err
	}

	pfxBytes, err := pkcs12.Encode(derBytes, privateKey, c.tmpCertificatePassword)
	if err != nil {
		err = fmt.Errorf("Failed to encode certificate as PFX: %s", err)
		return "", err
	}

	keyVaultDescription := keyVaultCertificate{
		Data:     base64.StdEncoding.EncodeToString(pfxBytes),
		DataType: "pfx",
		Password: c.tmpCertificatePassword,
	}

	bytes, err := json.Marshal(keyVaultDescription)
	if err != nil {
		err = fmt.Errorf("Failed to marshal key vault description: %s", err)
		return "", err
	}

	return base64.StdEncoding.EncodeToString(bytes), nil
}

func newConfig(raws ...interface{}) (*Config, []string, error) {
	var c Config
	c.ctx.Funcs = TemplateFuncs
	err := config.Decode(&c, &config.DecodeOpts{
		Interpolate:        true,
		InterpolateContext: &c.ctx,
	}, raws...)

	if err != nil {
		return nil, nil, err
	}

	provideDefaultValues(&c)
	setRuntimeValues(&c)
	setUserNamePassword(&c)
	err = setCloudEnvironment(&c)
	if err != nil {
		return nil, nil, err
	}

	err = setCustomData(&c)
	if err != nil {
		return nil, nil, err
	}

	// NOTE: if the user did not specify a communicator, then default to both
	// SSH and WinRM.  This is for backwards compatibility because the code did
	// not specifically force the user to set a communicator.
	if c.Comm.Type == "" || strings.EqualFold(c.Comm.Type, "ssh") {
		err = setSshValues(&c)
		if err != nil {
			return nil, nil, err
		}
	}

	if c.Comm.Type == "" || strings.EqualFold(c.Comm.Type, "winrm") {
		err = setWinRMCertificate(&c)
		if err != nil {
			return nil, nil, err
		}
	}

	var errs *packer.MultiError
	errs = packer.MultiErrorAppend(errs, c.Comm.Prepare(&c.ctx)...)

	assertRequiredParametersSet(&c, errs)
	assertTagProperties(&c, errs)
	if errs != nil && len(errs.Errors) > 0 {
		return nil, nil, errs
	}

	return &c, nil, nil
}

func setSshValues(c *Config) error {
	if c.Comm.SSHTimeout == 0 {
		c.Comm.SSHTimeout = 20 * time.Minute
	}

	if c.Comm.SSHPrivateKeyFile != "" {
		privateKeyBytes, err := ioutil.ReadFile(c.Comm.SSHPrivateKeyFile)
		if err != nil {
			return err
		}
		signer, err := ssh.ParsePrivateKey(privateKeyBytes)
		if err != nil {
			return err
		}

		publicKey := signer.PublicKey()
		c.sshAuthorizedKey = fmt.Sprintf("%s %s packer Azure Deployment%s",
			publicKey.Type(),
			base64.StdEncoding.EncodeToString(publicKey.Marshal()),
			time.Now().Format(time.RFC3339))
		c.Comm.SSHPrivateKey = privateKeyBytes

	} else {
		sshKeyPair, err := NewOpenSshKeyPair()
		if err != nil {
			return err
		}

		c.sshAuthorizedKey = sshKeyPair.AuthorizedKey()
		c.Comm.SSHPrivateKey = sshKeyPair.PrivateKey()
	}

	return nil
}

func setWinRMCertificate(c *Config) error {
	c.Comm.WinRMTransportDecorator =
		func() winrm.Transporter {
			return &winrm.ClientNTLM{}
		}

	cert, err := c.createCertificate()
	c.winrmCertificate = cert

	return err
}

func setRuntimeValues(c *Config) {
	var tempName = NewTempName()

	c.tmpAdminPassword = tempName.AdminPassword
	// store so that we can access this later during provisioning
	commonhelper.SetSharedState("winrm_password", c.tmpAdminPassword, c.PackerConfig.PackerBuildName)
	packer.LogSecretFilter.Set(c.tmpAdminPassword)

	c.tmpCertificatePassword = tempName.CertificatePassword
	if c.TempComputeName == "" {
		c.tmpComputeName = tempName.ComputeName
	} else {
		c.tmpComputeName = c.TempComputeName
	}
	c.tmpDeploymentName = tempName.DeploymentName
	// Only set tmpResourceGroupName if no name has been specified
	if c.TempResourceGroupName == "" && c.BuildResourceGroupName == "" {
		c.tmpResourceGroupName = tempName.ResourceGroupName
	} else if c.TempResourceGroupName != "" && c.BuildResourceGroupName == "" {
		c.tmpResourceGroupName = c.TempResourceGroupName
	}
	c.tmpNicName = tempName.NicName
	c.tmpPublicIPAddressName = tempName.PublicIPAddressName
	c.tmpOSDiskName = tempName.OSDiskName
	c.tmpSubnetName = tempName.SubnetName
	c.tmpVirtualNetworkName = tempName.VirtualNetworkName
	c.tmpKeyVaultName = tempName.KeyVaultName
}

func setUserNamePassword(c *Config) {
	if c.Comm.SSHUsername == "" {
		c.Comm.SSHUsername = DefaultUserName
	}

	c.UserName = c.Comm.SSHUsername

	if c.Comm.SSHPassword != "" {
		c.Password = c.Comm.SSHPassword
	} else {
		c.Password = c.tmpAdminPassword
	}
}

func setCloudEnvironment(c *Config) error {
	lookup := map[string]string{
		"CHINA":           "AzureChinaCloud",
		"CHINACLOUD":      "AzureChinaCloud",
		"AZURECHINACLOUD": "AzureChinaCloud",

		"GERMAN":           "AzureGermanCloud",
		"GERMANCLOUD":      "AzureGermanCloud",
		"AZUREGERMANCLOUD": "AzureGermanCloud",

		"GERMANY":           "AzureGermanCloud",
		"GERMANYCLOUD":      "AzureGermanCloud",
		"AZUREGERMANYCLOUD": "AzureGermanCloud",

		"PUBLIC":           "AzurePublicCloud",
		"PUBLICCLOUD":      "AzurePublicCloud",
		"AZUREPUBLICCLOUD": "AzurePublicCloud",

		"USGOVERNMENT":           "AzureUSGovernmentCloud",
		"USGOVERNMENTCLOUD":      "AzureUSGovernmentCloud",
		"AZUREUSGOVERNMENTCLOUD": "AzureUSGovernmentCloud",
	}

	name := strings.ToUpper(c.CloudEnvironmentName)
	envName, ok := lookup[name]
	if !ok {
		return fmt.Errorf("There is no cloud environment matching the name '%s'!", c.CloudEnvironmentName)
	}

	env, err := azure.EnvironmentFromName(envName)
	c.cloudEnvironment = &env
	return err
}

func setCustomData(c *Config) error {
	if c.CustomDataFile == "" {
		return nil
	}

	b, err := ioutil.ReadFile(c.CustomDataFile)
	if err != nil {
		return err
	}

	c.customData = base64.StdEncoding.EncodeToString(b)
	return nil
}

func provideDefaultValues(c *Config) {
	if c.VMSize == "" {
		c.VMSize = DefaultVMSize
	}

	if c.ManagedImageStorageAccountType == "" {
		c.managedImageStorageAccountType = compute.StorageAccountTypesStandardLRS
	}

	if c.ImagePublisher != "" && c.ImageVersion == "" {
		c.ImageVersion = DefaultImageVersion
	}

	if c.CloudEnvironmentName == "" {
		c.CloudEnvironmentName = DefaultCloudEnvironmentName
	}
}

func assertTagProperties(c *Config, errs *packer.MultiError) {
	if len(c.AzureTags) > 15 {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("a max of 15 tags are supported, but %d were provided", len(c.AzureTags)))
	}

	for k, v := range c.AzureTags {
		if len(k) > 512 {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("the tag name %q exceeds (%d) the 512 character limit", k, len(k)))
		}
		if len(*v) > 256 {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("the tag name %q exceeds (%d) the 256 character limit", *v, len(*v)))
		}
	}
}

func assertRequiredParametersSet(c *Config, errs *packer.MultiError) {
	/////////////////////////////////////////////
	// Authentication via OAUTH

	// Check if device login is being asked for, and is allowed.
	//
	// Device login is enabled if the user only defines SubscriptionID and not
	// ClientID, ClientSecret, and TenantID.
	//
	// Device login is not enabled for Windows because the WinRM certificate is
	// readable by the ObjectID of the App.  There may be another way to handle
	// this case, but I am not currently aware of it - send feedback.
	isUseDeviceLogin := func(c *Config) bool {

		return c.SubscriptionID != "" &&
			c.ClientID == "" &&
			c.ClientSecret == "" &&
			c.TenantID == ""
	}

	if isUseDeviceLogin(c) {
		c.useDeviceLogin = true
	} else {
		if c.ClientID == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A client_id must be specified"))
		}

		if c.ClientSecret == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A client_secret must be specified"))
		}

		if c.SubscriptionID == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A subscription_id must be specified"))
		}
	}

	/////////////////////////////////////////////
	// Capture
	if c.CaptureContainerName == "" && c.ManagedImageName == "" {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("A capture_container_name or managed_image_name must be specified"))
	}

	if c.CaptureNamePrefix == "" && c.ManagedImageResourceGroupName == "" {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("A capture_name_prefix or managed_image_resource_group_name must be specified"))
	}

	if (c.CaptureNamePrefix != "" || c.CaptureContainerName != "") && (c.ManagedImageResourceGroupName != "" || c.ManagedImageName != "") {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("Either a VHD or a managed image can be built, but not both. Please specify either capture_container_name and capture_name_prefix or managed_image_resource_group_name and managed_image_name."))
	}

	if c.CaptureContainerName != "" {
		if !reCaptureContainerName.MatchString(c.CaptureContainerName) {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A capture_container_name must satisfy the regular expression %q.", reCaptureContainerName.String()))
		}

		if strings.HasSuffix(c.CaptureContainerName, "-") {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A capture_container_name must not end with a hyphen, e.g. '-'."))
		}

		if strings.Contains(c.CaptureContainerName, "--") {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A capture_container_name must not contain consecutive hyphens, e.g. '--'."))
		}

		if c.CaptureNamePrefix == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A capture_name_prefix must be specified"))
		}

		if !reCaptureNamePrefix.MatchString(c.CaptureNamePrefix) {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A capture_name_prefix must satisfy the regular expression %q.", reCaptureNamePrefix.String()))
		}

		if strings.HasSuffix(c.CaptureNamePrefix, "-") || strings.HasSuffix(c.CaptureNamePrefix, ".") {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A capture_name_prefix must not end with a hyphen or period."))
		}
	}

	if c.TempResourceGroupName != "" && c.BuildResourceGroupName != "" {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("The settings temp_resource_group_name and build_resource_group_name cannot both be defined.  Please define one or neither."))
	}

	/////////////////////////////////////////////
	// Compute
	toInt := func(b bool) int {
		if b {
			return 1
		} else {
			return 0
		}
	}

	isImageUrl := c.ImageUrl != ""
	isCustomManagedImage := c.CustomManagedImageName != "" || c.CustomManagedImageResourceGroupName != ""
	isPlatformImage := c.ImagePublisher != "" || c.ImageOffer != "" || c.ImageSku != ""

	countSourceInputs := toInt(isImageUrl) + toInt(isCustomManagedImage) + toInt(isPlatformImage)

	if countSourceInputs > 1 {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("Specify either a VHD (image_url), Image Reference (image_publisher, image_offer, image_sku) or a Managed Disk (custom_managed_disk_image_name, custom_managed_disk_resource_group_name"))
	}

	if isImageUrl && c.ManagedImageResourceGroupName != "" {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("A managed image must be created from a managed image, it cannot be created from a VHD."))
	}

	if c.ImageUrl == "" && c.CustomManagedImageName == "" {
		if c.ImagePublisher == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("An image_publisher must be specified"))
		}
		if c.ImageOffer == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("An image_offer must be specified"))
		}
		if c.ImageSku == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("An image_sku must be specified"))
		}
	} else if c.ImageUrl == "" && c.ImagePublisher == "" {
		if c.CustomManagedImageResourceGroupName == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("An custom_managed_image_resource_group_name must be specified"))
		}
		if c.CustomManagedImageName == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A custom_managed_image_name must be specified"))
		}
		if c.ManagedImageResourceGroupName == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("An managed_image_resource_group_name must be specified"))
		}
		if c.ManagedImageName == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("An managed_image_name must be specified"))
		}
	} else {
		if c.ImagePublisher != "" || c.ImageOffer != "" || c.ImageSku != "" || c.ImageVersion != "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("An image_url must not be specified if image_publisher, image_offer, image_sku, or image_version is specified"))
		}
	}

	/////////////////////////////////////////////
	// Deployment
	xor := func(a, b bool) bool {
		return (a || b) && !(a && b)
	}

	if !xor((c.StorageAccount != "" || c.ResourceGroupName != ""), (c.ManagedImageName != "" || c.ManagedImageResourceGroupName != "")) {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("Specify either a VHD (storage_account and resource_group_name) or Managed Image (managed_image_resource_group_name and managed_image_name) output"))
	}

	if !xor(c.Location != "", c.BuildResourceGroupName != "") {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("Specify either a location to create the resource group in or an existing build_resource_group_name, but not both."))
	}

	if c.ManagedImageName == "" && c.ManagedImageResourceGroupName == "" {
		if c.StorageAccount == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A storage_account must be specified"))
		}
		if c.ResourceGroupName == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("A resource_group_name must be specified"))
		}
	}

	if c.TempResourceGroupName != "" {
		if ok, err := assertResourceGroupName(c.TempResourceGroupName, "temp_resource_group_name"); !ok {
			errs = packer.MultiErrorAppend(errs, err)
		}
	}

	if c.BuildResourceGroupName != "" {
		if ok, err := assertResourceGroupName(c.BuildResourceGroupName, "build_resource_group_name"); !ok {
			errs = packer.MultiErrorAppend(errs, err)
		}
	}

	if c.ManagedImageResourceGroupName != "" {
		if ok, err := assertResourceGroupName(c.ManagedImageResourceGroupName, "managed_image_resource_group_name"); !ok {
			errs = packer.MultiErrorAppend(errs, err)
		}
	}

	if c.ManagedImageName != "" {
		if ok, err := assertManagedImageName(c.ManagedImageName, "managed_image_name"); !ok {
			errs = packer.MultiErrorAppend(errs, err)
		}
	}

	if c.VirtualNetworkName == "" && c.VirtualNetworkResourceGroupName != "" {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("If virtual_network_resource_group_name is specified, so must virtual_network_name"))
	}
	if c.VirtualNetworkName == "" && c.VirtualNetworkSubnetName != "" {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("If virtual_network_subnet_name is specified, so must virtual_network_name"))
	}

	/////////////////////////////////////////////
	// Plan Info
	if c.PlanInfo.PlanName != "" || c.PlanInfo.PlanProduct != "" || c.PlanInfo.PlanPublisher != "" || c.PlanInfo.PlanPromotionCode != "" {
		if c.PlanInfo.PlanName == "" || c.PlanInfo.PlanProduct == "" || c.PlanInfo.PlanPublisher == "" {
			errs = packer.MultiErrorAppend(errs, fmt.Errorf("if either plan_name, plan_product, plan_publisher, or plan_promotion_code are defined then plan_name, plan_product, and plan_publisher must be defined"))
		} else {
			if c.AzureTags == nil {
				c.AzureTags = make(map[string]*string)
			}

			c.AzureTags["PlanInfo"] = &c.PlanInfo.PlanName
			c.AzureTags["PlanProduct"] = &c.PlanInfo.PlanProduct
			c.AzureTags["PlanPublisher"] = &c.PlanInfo.PlanPublisher
			c.AzureTags["PlanPromotionCode"] = &c.PlanInfo.PlanPromotionCode
		}
	}

	/////////////////////////////////////////////
	// OS
	if strings.EqualFold(c.OSType, constants.Target_Linux) {
		c.OSType = constants.Target_Linux
	} else if strings.EqualFold(c.OSType, constants.Target_Windows) {
		c.OSType = constants.Target_Windows
	} else if c.OSType == "" {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("An os_type must be specified"))
	} else {
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("The os_type %q is invalid", c.OSType))
	}

	switch c.ManagedImageStorageAccountType {
	case "", string(compute.StorageAccountTypesStandardLRS):
		c.managedImageStorageAccountType = compute.StorageAccountTypesStandardLRS
	case string(compute.StorageAccountTypesPremiumLRS):
		c.managedImageStorageAccountType = compute.StorageAccountTypesPremiumLRS
	default:
		errs = packer.MultiErrorAppend(errs, fmt.Errorf("The managed_image_storage_account_type %q is invalid", c.ManagedImageStorageAccountType))
	}
}

func assertManagedImageName(name, setting string) (bool, error) {
	if !isValidAzureName(reManagedDiskName, name) {
		return false, fmt.Errorf("The setting %s must match the regular expression %q, and not end with a '-' or '.'.", setting, validManagedDiskName)
	}
	return true, nil
}

func assertResourceGroupName(rgn, setting string) (bool, error) {
	if !isValidAzureName(reResourceGroupName, rgn) {
		return false, fmt.Errorf("The setting %s must match the regular expression %q, and not end with a '-' or '.'.", setting, validResourceGroupNameRe)
	}
	return true, nil
}

func isValidAzureName(re *regexp.Regexp, rgn string) bool {
	return re.Match([]byte(rgn)) &&
		!strings.HasSuffix(rgn, ".") &&
		!strings.HasSuffix(rgn, "-")
}