af83/edwig

package uuid

import (
    "fmt"
    "sync"

    "bitbucket.org/enroute-mobi/ara/config"
    "github.com/satori/uuid"
)

type UUIDGenerator interface {
    NewUUID() string
}

var defaultUUIDGenerator = NewRealUUIDGenerator()

func DefaultUUIDGenerator() UUIDGenerator {
    return defaultUUIDGenerator
}

func SetDefaultUUIDGenerator(generator UUIDGenerator) {
    defaultUUIDGenerator = generator
}

func NewRealUUIDGenerator() UUIDGenerator {
    return &realUUIDGenerator{}
}

type realUUIDGenerator struct{}

func (generator *realUUIDGenerator) NewUUID() string {
    return uuid.NewV4().String()
}

func NewFakeUUIDGenerator() *FakeUUIDGenerator {
    return &FakeUUIDGenerator{realFormat: config.Config.FakeUUIDRealFormat}
}

type FakeUUIDGenerator struct {
    mutex      sync.Mutex
    counter    int
    lastUUID   string
    realFormat bool
}

const fakeRealFormat = "6ba7b814-9dad-11d1-%04x-00c04fd430c8"
const fakeLegacyFormat = "6ba7b814-9dad-11d1-%x-00c04fd430c8"

func (generator *FakeUUIDGenerator) Format() string {
    if generator.realFormat {
        return fakeRealFormat
    } else {
        return fakeLegacyFormat
    }
}

func (generator *FakeUUIDGenerator) NextUUID() string {
    return fmt.Sprintf(generator.Format(), generator.counter)
}

func (generator *FakeUUIDGenerator) NewUUID() string {
    generator.mutex.Lock()
    defer generator.mutex.Unlock()

    uuid := generator.NextUUID()

    generator.lastUUID = uuid
    generator.counter = (generator.counter + 1) % 0xffff

    return uuid
}

func (generator *FakeUUIDGenerator) LastUUID() string {
    return generator.lastUUID
}

type UUIDConsumer struct {
    uuidGenerator UUIDGenerator
}

func NewUUIDConsumer(g UUIDGenerator) UUIDConsumer {
    return UUIDConsumer{uuidGenerator: g}
}

type UUIDInterface interface {
    SetUUIDGenerator(uuidGenerator UUIDGenerator)
    UUIDGenerator() UUIDGenerator
    NewUUID() string
}

func (consumer *UUIDConsumer) SetUUIDGenerator(uuidGenerator UUIDGenerator) {
    consumer.uuidGenerator = uuidGenerator
}

func (consumer *UUIDConsumer) UUIDGenerator() UUIDGenerator {
    if consumer.uuidGenerator == nil {
        consumer.uuidGenerator = DefaultUUIDGenerator()
    }
    return consumer.uuidGenerator
}

func (consumer *UUIDConsumer) NewUUID() string {
    return consumer.UUIDGenerator().NewUUID()
}