boltrest/boltrest.go

package boltrest

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

	"github.com/boltdb/bolt"
)

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

// Custom BoltRest DB keys:
//	__BR_LastUpdate: <RFC3339 Timestamp>

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

// Open returns the DB object
func Open(filename string) (*DB, error) {
	var err error
	b := DB{localFile: filename}
	b.localDB, err = bolt.Open(filename, 0644, nil)
	if err != nil {
		return nil, err
	}
	return &b, nil
}

// 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
	// TODO: Make sure local db is fresh (or offline)

	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])
		}
		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
		ret = string(newBkt.Get([]byte(key)))
		return nil
	})
	return ret, err
}

// SetValue sets the value at path to val
// path is a '/' separated list of tokens
// the last token is a key, all others are buckets
func (b *DB) SetValue(path []string, key, val string) error {
	var err error
	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))
}

type setURLResponse struct {
	dbMD5 string
}

// SetURL sets the DB's remote URL
func (b *DB) SetURL(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
}