ResourceProvider.kt

/**
 * Provides resources without context.
 * should be initial when [Application.onCreate]
 */
@SuppressLint("StaticFieldLeak")
class ResourceProvider(

        private var resources: Resources

) : AppResource {

    fun application(): Application = APPLICATION!!

    override fun resources(): Resources = resources

    override fun getString(stringRes: Int): String = resources.getString(stringRes)

    override fun getColor(@ColorRes colorRes: Int): Int = ContextCompat.getColor(APPLICATION!!, colorRes)

    override fun getDrawable(@DrawableRes drawableRes: Int): Drawable = ContextCompat.getDrawable(APPLICATION!!, drawableRes)!!

    companion object {

        private var APPLICATION: Application? = null
        private var INSTANCE: ResourceProvider? = null
        private var RESOURCES: Resources? = null

        @JvmStatic
        fun init(application: Application) {
            APPLICATION = application
            RESOURCES = application.resources
        }

        @JvmStatic
        fun getInstance(): ResourceProvider {
            return INSTANCE ?: ResourceProvider(

                    resources = RESOURCES!!

            ).apply { INSTANCE = this }
        }

        @VisibleForTesting
        fun destroyInstance() {
            INSTANCE = null
        }
    }
}