A generic class that holds a value with its loading status.

Resource.kt

/**
 * A generic class that holds a value with its loading status.
 * @param <T>
 */
// ImmutableClass
class Resource<T> private constructor(
        val status: Status,
        val data: T? = null,
        val throwable: Throwable? = null,
        val id: Long = 0
) {
    companion object {
        fun <T> success(data: T): Resource<T> = Resource(Status.SUCCESS, data = data)
        fun <T> error(throwable: Throwable): Resource<T> = Resource(Status.ERROR, throwable = throwable)
        fun <T> loading(): Resource<T> = Resource(Status.LOADING)
        fun <T> loading(id: Long): Resource<T> = Resource(Status.LOADING, id = id)
    }

    var hasBeenHandled = false
        private set // Allow external read but not write

    fun getContentIfNotHandled(): Resource<T>? {
        return if (hasBeenHandled) {
            null
        } else {
            hasBeenHandled = true
            this
        }
    }

    fun peekContent(): Resource<T> = this

    override fun toString(): String {
        return "Resource(status=$status, data=$data, throwable=$throwable, hasBeenHandled=$hasBeenHandled)"
    }
}