boltrest/boltrest.go

package boltrest

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"strconv"
	"strings"
	"time"

	"github.com/boltdb/bolt"
)

// This is a custom library for saving/syncing data
// in a local bolt db and a remote db through a
// rest api.

// DB is a struct for accomplishing this
type DB struct {
	localFile string
	remoteURL string
	apiToken  string
	remoteMD5 string
	online    bool
	isOpen    bool
	localDB   *bolt.DB
}

// Create returns the DB object
func Create(filename string) (*DB, error) {
	var err error
	b := DB{localFile: filename}
	if err = b.Open(); err != nil {
		return nil, err
	}
	defer b.Close()
	// Go ahead and make sure it's fresh
	b.RefreshDB()
	return &b, nil
}

// Open opens the DB so things can be done
func (b *DB) Open() error {
	var err error
	if !b.isOpen {
		b.localDB, err = bolt.Open(b.localFile, 0644, nil)
		if err == nil {
			b.isOpen = true
		}
	}
	return err
}

// Close closes the DB
func (b *DB) Close() error {
	var err error
	if b.isOpen {
		err = b.localDB.Close()
		if err == nil {
			b.isOpen = false
		}
	}
	return err
}

// GetFilename returns the local file for the DB
func (b *DB) GetFilename() string {
	return b.localFile
}

// Offline sets this DB to offline mode
// That means it won't try to sync anything
func (b *DB) Offline() {
	b.online = false
}

// MkBucketPath builds all buckets in the string slice
func (b *DB) MkBucketPath(path []string) error {
	var err error
	if !b.isOpen {
		err = b.Open()
		if err != nil {
			return err
		}
		defer b.Close()
	}
	b.RefreshDB()
	err = b.localDB.Update(func(tx *bolt.Tx) error {
		var err error
		bkt := tx.Bucket([]byte(path[0]))
		if bkt == nil {
			// Create it
			bkt, err = tx.CreateBucket([]byte(path[0]))
			if err != nil {
				// error creating
				return err
			}
		}
		if len(path) > 1 {
			path = path[1:]
			for i := range path {
				nextBkt := bkt.Bucket([]byte(path[i]))
				if nextBkt == nil {
					// Create it
					nextBkt, err = bkt.CreateBucket([]byte(path[i]))
					if err != nil {
						return err
					}
				}
				bkt = nextBkt
			}
		}
		return err
	})
	return err
}

// GetValue returns the value at path
// path is a '/' separated list of tokens
// the last token is a key, all others are buckets
func (b *DB) GetValue(path []string, key string) (string, error) {
	var err error
	var ret string
	if !b.isOpen {
		err = b.Open()
		if err != nil {
			return ret, err
		}
		defer b.Close()
	}
	b.RefreshDB()
	b.localDB.View(func(tx *bolt.Tx) error {
		bkt := tx.Bucket([]byte(path[0]))
		if bkt == nil {
			return fmt.Errorf("Couldn't find bucket " + path[0])
		}
		for idx := 1; idx < len(path); idx++ {
			bkt = bkt.Bucket([]byte(path[idx]))
			if bkt == nil {
				return fmt.Errorf("Couldn't find bucket " + strings.Join(path[:idx], "/"))
			}
		}
		// newBkt should have the last bucket in the path
		ret = string(bkt.Get([]byte(key)))
		return nil
	})
	return ret, err
}

// SetValue sets the value at path to val
// path is a slice of tokens
func (b *DB) SetValue(path []string, key, val string) error {
	var err error
	if !b.isOpen {
		err = b.Open()
		if err != nil {
			return err
		}
		defer b.Close()
	}
	b.RefreshDB()
	err = b.MkBucketPath(path)
	if err != nil {
		return err
	}
	b.localDB.Update(func(tx *bolt.Tx) error {
		newBkt := tx.Bucket([]byte(path[0]))
		if newBkt == nil {
			return fmt.Errorf("Couldn't find bucket " + path[0])
		}
		for idx := 1; idx < len(path); idx++ {
			newBkt, err = newBkt.CreateBucketIfNotExists([]byte(path[idx]))
			if err != nil {
				return err
			}
		}
		// newBkt should have the last bucket in the path
		return newBkt.Put([]byte(key), []byte(val))
	})
	return err
}

// GetInt returns the value at 'path'
// path is a '/' separated list of tokens
// the last token is a key, all others are buckets
// If the value cannot be parsed as an int, error
func (b *DB) GetInt(path []string, key string) (int, error) {
	var ret int
	r, err := b.GetValue(path, key)
	if err == nil {
		ret, err = strconv.Atoi(r)
	}
	return ret, err
}

// SetInt Sets an integer value
func (b *DB) SetInt(path []string, key string, val int) error {
	return b.SetValue(path, key, strconv.Itoa(val))
}

// GetBool returns the value at 'path'
// If the value cannot be parsed as a bool, error
// We check 'true/false' and '1/0', else error
func (b *DB) GetBool(path []string, key string) (bool, error) {
	var ret bool
	r, err := b.GetValue(path, key)
	if err == nil {
		if r == "true" || r == "1" {
			ret = true
		} else if r != "false" && r != "0" {
			err = fmt.Errorf("Cannot parse as a boolean")
		}
	}
	return ret, err
}

// SetBool Sets a boolean value
func (b *DB) SetBool(path []string, key string, val bool) error {
	if val {
		return b.SetValue(path, key, "true")
	}
	return b.SetValue(path, key, "false")
}

// GetTimestamp returns the value at 'path'
// If the value cannot be parsed as a RFC3339, error
func (b *DB) GetTimestamp(path []string, key string) (time.Time, error) {
	r, err := b.GetValue(path, key)
	if err == nil {
		return time.Parse(time.RFC3339, r)
	}
	return time.Unix(0, 0), err
}

// SetTimestamp returns the value at 'path'
func (b *DB) SetTimestamp(path []string, key string, val time.Time) error {
	return b.SetValue(path, key, val.Format(time.RFC3339))
}

// GetBucketList returns a list of all sub-buckets at path
func (b *DB) GetBucketList(path []string) ([]string, error) {
	var err error
	var ret []string
	if !b.isOpen {
		err = b.Open()
		if err != nil {
			return ret, err
		}
		defer b.Close()
	}
	b.RefreshDB()
	err = b.localDB.Update(func(tx *bolt.Tx) error {
		bkt := tx.Bucket([]byte(path[0]))
		if bkt == nil {
			return fmt.Errorf("Couldn't find bucket " + path[0])
		}
		var newBkt *bolt.Bucket
		var berr error
		if len(path) > 1 {
			for idx := 1; idx < len(path); idx++ {
				newBkt = bkt.Bucket([]byte(path[idx]))
				if newBkt == nil {
					return fmt.Errorf("Couldn't find bucket " + strings.Join(path[:idx], "/"))
				}
			}
			bkt = newBkt
		}

		// newBkt should have the last bucket in the path
		berr = bkt.ForEach(func(k, v []byte) error {
			if v == nil {
				// Must be a bucket
				ret = append(ret, string(k))
			}
			return nil
		})
		return berr
	})
	return ret, err
}

// GetKeyList returns a list of all keys at path
func (b *DB) GetKeyList(path []string) ([]string, error) {
	var err error
	var ret []string
	if !b.isOpen {
		err = b.Open()
		if err != nil {
			return ret, err
		}
		defer b.Close()
	}
	b.RefreshDB()
	err = b.localDB.Update(func(tx *bolt.Tx) error {
		bkt := tx.Bucket([]byte(path[0]))
		if bkt == nil {
			return fmt.Errorf("Couldn't find bucket " + path[0])
		}
		if len(path) > 1 {
			var newBkt *bolt.Bucket
			for idx := 1; idx < len(path); idx++ {
				newBkt = bkt.Bucket([]byte(path[idx]))
				if newBkt == nil {
					return fmt.Errorf("Couldn't find bucket " + strings.Join(path[:idx], "/"))
				}
			}
			bkt = newBkt
		}
		// newBkt should have the last bucket in the path
		berr := bkt.ForEach(func(k, v []byte) error {
			if v != nil {
				// Not a bucket
				ret = append(ret, string(k))
			}
			return nil
		})
		return berr
	})
	return ret, err
}

// DeletePair deletes the pair with key at path
func (b *DB) DeletePair(path []string, key string) error {
	var err error
	if !b.isOpen {
		err = b.Open()
		if err != nil {
			return err
		}
		defer b.Close()
	}
	b.RefreshDB()
	err = b.localDB.Update(func(tx *bolt.Tx) error {
		bkt := tx.Bucket([]byte(path[0]))
		if bkt == nil {
			return fmt.Errorf("Couldn't find bucket " + path[0])
		}
		if len(path) > 1 {
			var newBkt *bolt.Bucket
			for idx := 1; idx < len(path); idx++ {
				newBkt = bkt.Bucket([]byte(path[idx]))
				if newBkt == nil {
					return fmt.Errorf("Couldn't find bucket " + strings.Join(path[:idx], "/"))
				}
			}
			bkt = newBkt
		}
		// bkt should have the last bucket in the path
		// Test to make sure that key is a pair, if so, delete it
		if tst := bkt.Bucket([]byte(key)); tst == nil {
			return bkt.Delete([]byte(key))
		}
		return nil
	})
	return err
}

// DeleteBucket deletes the bucket key at path
func (b *DB) DeleteBucket(path []string, key string) error {
	var err error
	if !b.isOpen {
		err = b.Open()
		if err != nil {
			return err
		}
		defer b.Close()
	}
	b.RefreshDB()
	err = b.localDB.Update(func(tx *bolt.Tx) error {
		bkt := tx.Bucket([]byte(path[0]))
		if bkt == nil {
			return fmt.Errorf("Couldn't find bucket " + path[0])
		}
		var newBkt *bolt.Bucket
		for idx := 1; idx < len(path); idx++ {
			newBkt = bkt.Bucket([]byte(path[idx]))
			if newBkt == nil {
				return fmt.Errorf("Couldn't find bucket " + strings.Join(path[:idx], "/"))
			}
		}
		// newBkt should have the last bucket in the path
		// Test to make sure that key is a bucket, if so, delete it
		if tst := newBkt.Bucket([]byte(key)); tst != nil {
			return newBkt.Delete([]byte(key))
		}
		return nil
	})
	return err
}

// RefreshDB makes sure that the DB is fresh with the server version
func (b *DB) RefreshDB() error {
	var err error
	if !b.isOpen {
		err = b.Open()
		if err != nil {
			return err
		}
		defer b.Close()
	}
	if b.online {
		// TODO: Compare latest change here with lates on server
		// Then sync, if needed
	}
	return err
}

type setURLResponse struct {
	dbMD5 string
}

// SetDBURL sets the DB's remote URL
func (b *DB) SetDBURL(url string) (bool, string) {
	resp, err := http.Get(url)
	if err != nil {
		return false, ""
	}
	defer resp.Body.Close()
	body, err := ioutil.ReadAll(resp.Body)
	sur := setURLResponse{}
	json.Unmarshal(body, sur)
	return true, sur.dbMD5
}