package googlecompute

import (
	"errors"
	"fmt"
	"os"
	"regexp"
	"time"

	"github.com/hashicorp/packer/common"
	"github.com/hashicorp/packer/common/uuid"
	"github.com/hashicorp/packer/helper/communicator"
	"github.com/hashicorp/packer/helper/config"
	"github.com/hashicorp/packer/packer"
	"github.com/hashicorp/packer/template/interpolate"
	compute "google.golang.org/api/compute/v1"
)

var reImageFamily = regexp.MustCompile(`^[a-z]([-a-z0-9]{0,61}[a-z0-9])?$`)

// Config is the configuration structure for the GCE builder. It stores
// both the publicly settable state as well as the privately generated
// state of the config object.
type Config struct {
	common.PackerConfig `mapstructure:",squash"`
	Comm                communicator.Config `mapstructure:",squash"`
	// The JSON file containing your account
    // credentials. Not required if you run Packer on a GCE instance with a
    // service account. Instructions for creating the file or using service
    // accounts are above.
	AccountFile string `mapstructure:"account_file" required:"false"`
	// The project ID that will be used to launch
    // instances and store images.
	ProjectId   string `mapstructure:"project_id" required:"true"`
	// Full or partial URL of the guest accelerator
    // type. GPU accelerators can only be used with
    // "on_host_maintenance": "TERMINATE" option set. Example:
    // "projects/project_id/zones/europe-west1-b/acceleratorTypes/nvidia-tesla-k80"
	AcceleratorType              string                         `mapstructure:"accelerator_type" required:"false"`
	// Number of guest accelerator cards to add to
    // the launched instance.
	AcceleratorCount             int64                          `mapstructure:"accelerator_count" required:"false"`
	// The name of a pre-allocated static external IP
    // address. Note, must be the name and not the actual IP address.
	Address                      string                         `mapstructure:"address" required:"false"`
	// If true, the default service
    // account will not be used if service_account_email is not specified. Set
    // this value to true and omit service_account_email to provision a VM with
    // no service account.
	DisableDefaultServiceAccount bool                           `mapstructure:"disable_default_service_account" required:"false"`
	// The name of the disk, if unset the instance name
    // will be used.
	DiskName                     string                         `mapstructure:"disk_name" required:"false"`
	// The size of the disk in GB. This defaults to 10,
    // which is 10GB.
	DiskSizeGb                   int64                          `mapstructure:"disk_size" required:"false"`
	// Type of disk used to back your instance, like
    // pd-ssd or pd-standard. Defaults to pd-standard.
	DiskType                     string                         `mapstructure:"disk_type" required:"false"`
	// The unique name of the resulting image. Defaults to
    // "packer-{{timestamp}}".
	ImageName                    string                         `mapstructure:"image_name" required:"false"`
	// The description of the resulting image.
	ImageDescription             string                         `mapstructure:"image_description" required:"false"`
	// Image encryption key to apply to the created image. Possible values:
	ImageEncryptionKey           *compute.CustomerEncryptionKey `mapstructure:"image_encryption_key" required:"false"`
	// The name of the image family to which the
    // resulting image belongs. You can create disks by specifying an image family
    // instead of a specific image name. The image family always returns its
    // latest image that is not deprecated.
	ImageFamily                  string                         `mapstructure:"image_family" required:"false"`
	// Key/value pair labels to
    // apply to the created image.
	ImageLabels                  map[string]string              `mapstructure:"image_labels" required:"false"`
	// Licenses to apply to the created
    // image.
	ImageLicenses                []string                       `mapstructure:"image_licenses" required:"false"`
	// A name to give the launched instance. Beware
    // that this must be unique. Defaults to "packer-{{uuid}}".
	InstanceName                 string                         `mapstructure:"instance_name" required:"false"`
	// Key/value pair labels to apply to
    // the launched instance.
	Labels                       map[string]string              `mapstructure:"labels" required:"false"`
	// The machine type. Defaults to "n1-standard-1".
	MachineType                  string                         `mapstructure:"machine_type" required:"false"`
	// Metadata applied to the launched
    // instance.
	Metadata                     map[string]string              `mapstructure:"metadata" required:"false"`
	// A Minimum CPU Platform for VM Instance.
    // Availability and default CPU platforms vary across zones, based on the
    // hardware available in each GCP zone.
    // Details
	MinCpuPlatform               string                         `mapstructure:"min_cpu_platform" required:"false"`
	// The Google Compute network id or URL to use for the
    // launched instance. Defaults to "default". If the value is not a URL, it
    // will be interpolated to
    // projects/((network_project_id))/global/networks/((network)). This value
    // is not required if a subnet is specified.
	Network                      string                         `mapstructure:"network" required:"false"`
	// The project ID for the network and
    // subnetwork to use for launched instance. Defaults to project_id.
	NetworkProjectId             string                         `mapstructure:"network_project_id" required:"false"`
	// If true, the instance will not have an
    // external IP. use_internal_ip must be true if this property is true.
	OmitExternalIP               bool                           `mapstructure:"omit_external_ip" required:"false"`
	// Sets Host Maintenance Option. Valid
    // choices are MIGRATE and TERMINATE. Please see GCE Instance Scheduling
    // Options,
    // as not all machine_types support MIGRATE (i.e. machines with GPUs). If
    // preemptible is true this can only be TERMINATE. If preemptible is false,
    // it defaults to MIGRATE
	OnHostMaintenance            string                         `mapstructure:"on_host_maintenance" required:"false"`
	// If true, launch a preemptible instance.
	Preemptible                  bool                           `mapstructure:"preemptible" required:"false"`
	// The time to wait for instance state changes.
    // Defaults to "5m".
	RawStateTimeout              string                         `mapstructure:"state_timeout" required:"false"`
	// The region in which to launch the instance. Defaults to
    // the region hosting the specified zone.
	Region                       string                         `mapstructure:"region" required:"false"`
	// The service account scopes for launched
    // instance. Defaults to:
	Scopes                       []string                       `mapstructure:"scopes" required:"false"`
	// The service account to be used for
    // launched instance. Defaults to the project's default service account unless
    // disable_default_service_account is true.
	ServiceAccountEmail          string                         `mapstructure:"service_account_email" required:"false"`
	// The source image to use to create the new image
    // from. You can also specify source_image_family instead. If both
    // source_image and source_image_family are specified, source_image
    // takes precedence. Example: "debian-8-jessie-v20161027"
	SourceImage                  string                         `mapstructure:"source_image" required:"true"`
	// The source image family to use to create
    // the new image from. The image family always returns its latest image that
    // is not deprecated. Example: "debian-8".
	SourceImageFamily            string                         `mapstructure:"source_image_family" required:"true"`
	// The project ID of the project
    // containing the source image.
	SourceImageProjectId         string                         `mapstructure:"source_image_project_id" required:"false"`
	// The path to a startup script to run on the
    // VM from which the image will be made.
	StartupScriptFile            string                         `mapstructure:"startup_script_file" required:"false"`
	// The Google Compute subnetwork id or URL to use for
    // the launched instance. Only required if the network has been created with
    // custom subnetting. Note, the region of the subnetwork must match the
    // region or zone in which the VM is launched. If the value is not a URL,
    // it will be interpolated to
    // projects/((network_project_id))/regions/((region))/subnetworks/((subnetwork))
	Subnetwork                   string                         `mapstructure:"subnetwork" required:"false"`
	// Assign network tags to apply firewall rules to
    // VM instance.
	Tags                         []string                       `mapstructure:"tags" required:"false"`
	// If true, use the instance's internal IP
    // instead of its external IP during building.
	UseInternalIP                bool                           `mapstructure:"use_internal_ip" required:"false"`
	// The zone in which to launch the instance used to create
    // the image. Example: "us-central1-a"
	Zone                         string                         `mapstructure:"zone" required:"true"`

	Account            AccountFile
	stateTimeout       time.Duration
	imageAlreadyExists bool
	ctx                interpolate.Context
}

func NewConfig(raws ...interface{}) (*Config, []string, error) {
	c := new(Config)
	c.ctx.Funcs = TemplateFuncs
	err := config.Decode(c, &config.DecodeOpts{
		Interpolate:        true,
		InterpolateContext: &c.ctx,
		InterpolateFilter: &interpolate.RenderFilter{
			Exclude: []string{
				"run_command",
			},
		},
	}, raws...)
	if err != nil {
		return nil, nil, err
	}

	var errs *packer.MultiError

	// Set defaults.
	if c.Network == "" && c.Subnetwork == "" {
		c.Network = "default"
	}

	if c.NetworkProjectId == "" {
		c.NetworkProjectId = c.ProjectId
	}

	if c.DiskSizeGb == 0 {
		c.DiskSizeGb = 10
	}

	if c.DiskType == "" {
		c.DiskType = "pd-standard"
	}

	if c.ImageDescription == "" {
		c.ImageDescription = "Created by Packer"
	}

	if c.OnHostMaintenance == "MIGRATE" && c.Preemptible {
		errs = packer.MultiErrorAppend(errs,
			errors.New("on_host_maintenance must be TERMINATE when using preemptible instances."))
	}
	// Setting OnHostMaintenance Correct Defaults
	//   "MIGRATE" : Possible and default if Preemptible is false
	//   "TERMINATE": Required if Preemptible is true
	if c.Preemptible {
		c.OnHostMaintenance = "TERMINATE"
	} else {
		if c.OnHostMaintenance == "" {
			c.OnHostMaintenance = "MIGRATE"
		}
	}

	// Make sure user sets a valid value for on_host_maintenance option
	if !(c.OnHostMaintenance == "MIGRATE" || c.OnHostMaintenance == "TERMINATE") {
		errs = packer.MultiErrorAppend(errs,
			errors.New("on_host_maintenance must be one of MIGRATE or TERMINATE."))
	}

	if c.ImageName == "" {
		img, err := interpolate.Render("packer-{{timestamp}}", nil)
		if err != nil {
			errs = packer.MultiErrorAppend(errs,
				fmt.Errorf("Unable to parse image name: %s ", err))
		} else {
			c.ImageName = img
		}
	}

	if len(c.ImageFamily) > 63 {
		errs = packer.MultiErrorAppend(errs,
			errors.New("Invalid image family: Must not be longer than 63 characters"))
	}

	if c.ImageFamily != "" {
		if !reImageFamily.MatchString(c.ImageFamily) {
			errs = packer.MultiErrorAppend(errs,
				errors.New("Invalid image family: The first character must be a lowercase letter, and all following characters must be a dash, lowercase letter, or digit, except the last character, which cannot be a dash"))
		}

	}

	if c.InstanceName == "" {
		c.InstanceName = fmt.Sprintf("packer-%s", uuid.TimeOrderedUUID())
	}

	if c.DiskName == "" {
		c.DiskName = c.InstanceName
	}

	if c.MachineType == "" {
		c.MachineType = "n1-standard-1"
	}

	if c.RawStateTimeout == "" {
		c.RawStateTimeout = "5m"
	}

	if es := c.Comm.Prepare(&c.ctx); len(es) > 0 {
		errs = packer.MultiErrorAppend(errs, es...)
	}

	// Process required parameters.
	if c.ProjectId == "" {
		errs = packer.MultiErrorAppend(
			errs, errors.New("a project_id must be specified"))
	}

	if c.Scopes == nil {
		c.Scopes = []string{
			"https://www.googleapis.com/auth/userinfo.email",
			"https://www.googleapis.com/auth/compute",
			"https://www.googleapis.com/auth/devstorage.full_control",
		}
	}

	if c.SourceImage == "" && c.SourceImageFamily == "" {
		errs = packer.MultiErrorAppend(
			errs, errors.New("a source_image or source_image_family must be specified"))
	}

	if c.Zone == "" {
		errs = packer.MultiErrorAppend(
			errs, errors.New("a zone must be specified"))
	}
	if c.Region == "" && len(c.Zone) > 2 {
		// get region from Zone
		region := c.Zone[:len(c.Zone)-2]
		c.Region = region
	}

	err = c.CalcTimeout()
	if err != nil {
		errs = packer.MultiErrorAppend(errs, err)
	}

	if c.AccountFile != "" {
		if err := ProcessAccountFile(&c.Account, c.AccountFile); err != nil {
			errs = packer.MultiErrorAppend(errs, err)
		}
	}

	if c.OmitExternalIP && c.Address != "" {
		errs = packer.MultiErrorAppend(fmt.Errorf("you can not specify an external address when 'omit_external_ip' is true"))
	}

	if c.OmitExternalIP && !c.UseInternalIP {
		errs = packer.MultiErrorAppend(fmt.Errorf("'use_internal_ip' must be true if 'omit_external_ip' is true"))
	}

	if c.AcceleratorCount > 0 && len(c.AcceleratorType) == 0 {
		errs = packer.MultiErrorAppend(fmt.Errorf("'accelerator_type' must be set when 'accelerator_count' is more than 0"))
	}

	if c.AcceleratorCount > 0 && c.OnHostMaintenance != "TERMINATE" {
		errs = packer.MultiErrorAppend(fmt.Errorf("'on_host_maintenance' must be set to 'TERMINATE' when 'accelerator_count' is more than 0"))
	}

	// If DisableDefaultServiceAccount is provided, don't allow a value for ServiceAccountEmail
	if c.DisableDefaultServiceAccount && c.ServiceAccountEmail != "" {
		errs = packer.MultiErrorAppend(fmt.Errorf("you may not specify a 'service_account_email' when 'disable_default_service_account' is true"))
	}

	if c.StartupScriptFile != "" {
		if _, err := os.Stat(c.StartupScriptFile); err != nil {
			errs = packer.MultiErrorAppend(
				errs, fmt.Errorf("startup_script_file: %v", err))
		}
	}

	// Check for any errors.
	if errs != nil && len(errs.Errors) > 0 {
		return nil, nil, errs
	}

	return c, nil, nil
}

func (c *Config) CalcTimeout() error {
	stateTimeout, err := time.ParseDuration(c.RawStateTimeout)
	if err != nil {
		return fmt.Errorf("Failed parsing state_timeout: %s", err)
	}
	c.stateTimeout = stateTimeout
	return nil
}