package googlecompute

import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"encoding/pem"
    "os"
	"fmt"
	"code.google.com/p/go.crypto/ssh"
	"github.com/mitchellh/multistep"
	"github.com/mitchellh/packer/packer"
)

// StepCreateSSHKey represents a Packer build step that generates SSH key pairs.
type StepCreateSSHKey struct {
  key          int
  Debug        bool
  DebugKeyPath string
}

// Run executes the Packer build step that generates SSH key pairs.
func (s *StepCreateSSHKey) Run(state multistep.StateBag) multistep.StepAction {
	ui := state.Get("ui").(packer.Ui)

	ui.Say("Creating temporary SSH key for instance...")
	priv, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		err := fmt.Errorf("Error creating temporary ssh key: %s", err)
		state.Put("error", err)
		ui.Error(err.Error())
		return multistep.ActionHalt
	}

	priv_blk := pem.Block{
		Type:    "RSA PRIVATE KEY",
		Headers: nil,
		Bytes:   x509.MarshalPKCS1PrivateKey(priv),
	}

	pub, err := ssh.NewPublicKey(&priv.PublicKey)
	if err != nil {
		err := fmt.Errorf("Error creating temporary ssh key: %s", err)
		state.Put("error", err)
		ui.Error(err.Error())
		return multistep.ActionHalt
	}
    state.Put("ssh_private_key", string(pem.EncodeToMemory(&priv_blk)))
    state.Put("ssh_public_key", string(ssh.MarshalAuthorizedKey(pub)))

    if s.Debug {
      ui.Message(fmt.Sprintf("Saving key for debug purposes: %s", s.DebugKeyPath))
      f, err := os.OpenFile(s.DebugKeyPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
      if err != nil {
        state.Put("error", fmt.Errorf("Error saving debug key: %s", err))
        return multistep.ActionHalt
      }
      // Write out the key
      pem.Encode(f, &priv_blk)
      f.Close()
    }
	return multistep.ActionContinue
}

// Nothing to clean up. SSH keys are associated with a single GCE instance.
func (s *StepCreateSSHKey) Cleanup(state multistep.StateBag) {}