/*
 * Copyright (c) 2017-present Robert Jaros
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package pl.treksoft.kvision.state

import kotlin.properties.Delegates

/**
 * The observable value class.
 * @param value the initial value
 */
class ObservableValue<T>(value: T) : ObservableState<T> {
    private val observers = mutableListOf<(T) -> Unit>()

    /**
     * The observed variable.
     */
    var value: T by Delegates.observable(value) { _, _, new ->
        observers.forEach { it(new) }
    }

    override fun getState(): T {
        return value
    }

    override fun subscribe(observer: (T) -> Unit): () -> Unit {
        observers += observer
        observer(value)
        return {
            observers -= observer
        }
    }
}