organize essential APIs into platform, workflow and pkg folders (#337)

Add more logic to the way code is organized.

	/pkg -- library code not directly connected to micromdm
	/mdm -- packages meant for the services devices interract with. The MDM protocol.
	/dep -- DEP API and related packages.
	/platform -- Core APIs the server provides. Commands API, Devices API, queue, pubsub etc.
	/workflow -- Packages/API that build on top of platform. Today that's the webhook package.
		     Depending on what ends up here, the workflow folder might become its own repository.

platform/queue/queue.go

@@ -0,0 +1,246 @@
+// Package queue implements a boldDB backed queue for MDM Commands.
+package queue
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/boltdb/bolt"
+	"github.com/groob/plist"
+	"github.com/pkg/errors"
+
+	"github.com/micromdm/mdm"
+	"github.com/micromdm/micromdm/platform/command"
+	"github.com/micromdm/micromdm/platform/pubsub"
+)
+
+const (
+	DeviceCommandBucket = "mdm.DeviceCommands"
+
+	CommandQueuedTopic = "mdm.CommandQueued"
+)
+
+type Store struct {
+	*bolt.DB
+}
+
+func (db *Store) Next(ctx context.Context, resp mdm.Response) (*Command, error) {
+	udid := resp.UDID
+	if resp.UserID != nil {
+		// use the user id for user level commands
+		udid = *resp.UserID
+	}
+	dc, err := db.DeviceCommand(udid)
+	if err != nil {
+		if isNotFound(err) {
+			return nil, nil
+		}
+		return nil, errors.Wrapf(err, "get device command from queue, udid: %s", resp.UDID)
+	}
+
+	var cmd *Command
+	switch resp.Status {
+	case "NotNow":
+		// We will try this command later when the device is not
+		// responding with NotNow
+		x, a := cut(dc.Commands, resp.CommandUUID)
+		dc.Commands = a
+		if x == nil {
+			break
+		}
+		dc.NotNow = append(dc.NotNow, *x)
+
+	case "Acknowledged":
+		// move to completed, send next
+		x, a := cut(dc.Commands, resp.CommandUUID)
+		dc.Commands = a
+		if x == nil {
+			break
+		}
+		dc.Completed = append(dc.Completed, *x)
+	case "Error":
+		// move to failed, send next
+		x, a := cut(dc.Commands, resp.CommandUUID)
+		dc.Commands = a
+		if x == nil { // must've already bin ackd
+			break
+		}
+		dc.Failed = append(dc.Failed, *x)
+
+	case "CommandFormatError":
+		// move to failed
+		x, a := cut(dc.Commands, resp.CommandUUID)
+		dc.Commands = a
+		if x == nil {
+			break
+		}
+		dc.Failed = append(dc.Failed, *x)
+
+	case "Idle":
+		// will send next command below
+
+	default:
+		return nil, fmt.Errorf("unknown response status: %s", resp.Status)
+	}
+
+	// pop the first command from the queue and add it to the end.
+	// If the regular queue is empty, send a command that got
+	// refused with NotNow before.
+	cmd, dc.Commands = popFirst(dc.Commands)
+	if cmd != nil {
+		dc.Commands = append(dc.Commands, *cmd)
+	} else if resp.Status != "NotNow" {
+		cmd, dc.NotNow = popFirst(dc.NotNow)
+		if cmd != nil {
+			dc.Commands = append(dc.Commands, *cmd)
+		}
+	}
+
+	if err := db.Save(dc); err != nil {
+		return nil, err
+	}
+
+	return cmd, nil
+}
+
+func popFirst(all []Command) (*Command, []Command) {
+	if len(all) == 0 {
+		return nil, all
+	}
+	first := all[0]
+	all = append(all[:0], all[1:]...)
+	return &first, all
+}
+
+func cut(all []Command, uuid string) (*Command, []Command) {
+	for i, cmd := range all {
+		if cmd.UUID == uuid {
+			all = append(all[:i], all[i+1:]...)
+			return &cmd, all
+		}
+	}
+	return nil, all
+}
+
+func NewQueue(db *bolt.DB, pubsub pubsub.PublishSubscriber) (*Store, error) {
+	err := db.Update(func(tx *bolt.Tx) error {
+		_, err := tx.CreateBucketIfNotExists([]byte(DeviceCommandBucket))
+		return err
+	})
+	if err != nil {
+		return nil, errors.Wrapf(err, "creating %s bucket", DeviceCommandBucket)
+	}
+	datastore := &Store{DB: db}
+	if err := datastore.pollCommands(pubsub); err != nil {
+		return nil, err
+	}
+	return datastore, nil
+}
+
+func (db *Store) Save(cmd *DeviceCommand) error {
+	tx, err := db.DB.Begin(true)
+	if err != nil {
+		return errors.Wrap(err, "begin transaction")
+	}
+	bkt := tx.Bucket([]byte(DeviceCommandBucket))
+	if bkt == nil {
+		return fmt.Errorf("bucket %q not found!", DeviceCommandBucket)
+	}
+	devproto, err := MarshalDeviceCommand(cmd)
+	if err != nil {
+		return errors.Wrap(err, "marshalling DeviceCommand")
+	}
+	key := []byte(cmd.DeviceUDID)
+	if err := bkt.Put(key, devproto); err != nil {
+		return errors.Wrap(err, "put DeviceCommand to boltdb")
+	}
+	return tx.Commit()
+}
+
+func (db *Store) DeviceCommand(udid string) (*DeviceCommand, error) {
+	var dev DeviceCommand
+	err := db.View(func(tx *bolt.Tx) error {
+		b := tx.Bucket([]byte(DeviceCommandBucket))
+		v := b.Get([]byte(udid))
+		if v == nil {
+			return &notFound{"DeviceCommand", fmt.Sprintf("udid %s", udid)}
+		}
+		return UnmarshalDeviceCommand(v, &dev)
+	})
+	if err != nil {
+		return nil, err
+	}
+	return &dev, nil
+}
+
+type notFound struct {
+	ResourceType string
+	Message      string
+}
+
+func (e *notFound) Error() string {
+	return fmt.Sprintf("not found: %s %s", e.ResourceType, e.Message)
+}
+
+func (db *Store) pollCommands(pubsub pubsub.PublishSubscriber) error {
+	commandEvents, err := pubsub.Subscribe(context.TODO(), "command-queue", command.CommandTopic)
+	if err != nil {
+		return errors.Wrapf(err,
+			"subscribing push to %s topic", command.CommandTopic)
+	}
+	go func() {
+		for {
+			select {
+			case event := <-commandEvents:
+				var ev command.Event
+				if err := command.UnmarshalEvent(event.Message, &ev); err != nil {
+					fmt.Println(err)
+					continue
+				}
+
+				cmd := new(DeviceCommand)
+				cmd.DeviceUDID = ev.DeviceUDID
+				byUDID, err := db.DeviceCommand(ev.DeviceUDID)
+				if err == nil && byUDID != nil {
+					cmd = byUDID
+				}
+				newPayload, err := plist.Marshal(&ev.Payload)
+				if err != nil {
+					fmt.Println(err)
+					continue
+				}
+				newCmd := Command{
+					UUID:    ev.Payload.CommandUUID,
+					Payload: newPayload,
+				}
+				cmd.Commands = append(cmd.Commands, newCmd)
+				if err := db.Save(cmd); err != nil {
+					fmt.Println(err)
+					continue
+				}
+				fmt.Printf("queued event for device: %s\n", ev.DeviceUDID)
+
+				cq := new(QueueCommandQueued)
+				cq.DeviceUDID = ev.DeviceUDID
+				cq.CommandUUID = ev.Payload.CommandUUID
+
+				msgBytes, err := MarshalQueuedCommand(cq)
+				if err != nil {
+					fmt.Println(err)
+					continue
+				}
+
+				pubsub.Publish(context.TODO(), CommandQueuedTopic, msgBytes)
+			}
+		}
+	}()
+
+	return nil
+}
+
+func isNotFound(err error) bool {
+	if _, ok := err.(*notFound); ok {
+		return true
+	}
+	return false
+}