package tusd

#define USE_FUNC(TYPE) func (store *StoreComposer) Use ## TYPE(x TYPE ## DataStore) { \
  store.Uses ## TYPE = x != nil; \
  store.TYPE = x; \
}

#define USE_FIELD(TYPE) Uses ## TYPE bool; \
  TYPE TYPE ## DataStore

#define USE_FROM(TYPE) if mod, ok := store.(TYPE ## DataStore); ok { \
  composer.Use ## TYPE (mod) \
}

#define USE_CAP(TYPE) str += ` TYPE: `; \
if store.Uses ## TYPE { \
  str += "✓" \
} else { \
  str += "✗" \
}

type StoreComposer struct {
  Core DataStore

  USE_FIELD(Terminater)
  USE_FIELD(Finisher)
  USE_FIELD(Locker)
  USE_FIELD(GetReader)
  USE_FIELD(Concater)
}

func NewStoreComposer() *StoreComposer {
  return &StoreComposer{}
}

func NewStoreComposerFromDataStore(store DataStore) *StoreComposer {
  composer := NewStoreComposer()
  composer.UseCore(store)

  USE_FROM(Terminater)
  USE_FROM(Finisher)
  USE_FROM(Locker)
  USE_FROM(GetReader)
  USE_FROM(Concater)

  return composer
}

func (store *StoreComposer) Capabilities() string {
  str := "Core: "

  if store.Core != nil {
    str += "✓"
  } else {
    str += "✗"
  }

  USE_CAP(Terminater)
  USE_CAP(Finisher)
  USE_CAP(Locker)
  USE_CAP(GetReader)
  USE_CAP(Concater)

  return str
}

func (store *StoreComposer) UseCore(core DataStore) {
  store.Core = core
}

USE_FUNC(Terminater)
USE_FUNC(Finisher)
USE_FUNC(Locker)
USE_FUNC(GetReader)
USE_FUNC(Concater)