using System;
using System.Reactive.Subjects;
using UnityEngine;

namespace Chernobyl.Unity.Event
{
    /// <summary>
    /// An asset that acts as a source of events.
    /// </summary>
    public interface IEventSource<out T>
    {
        /// <summary>
        /// The event to be triggered.
        /// </summary>
        IObservable<T> Observable { get; }
    }

    /// <summary>
    /// Interface for subject of events.
    /// </summary>
    public interface IEventSubject<T>
    {
        /// <summary>
        /// The subject of the events.
        /// </summary>
        ISubject<T> Subject { get; }
    }

    /// <summary>
    /// An asset that acts as a source of events.
    /// </summary>
    public abstract class BaseEventSource<T> : ScriptableObject, IEventSource<T>, IEventSubject<T>
    {
        /// <inheritdoc />
        protected BaseEventSource() : this(new Subject<T>()) {}
        /// <inheritdoc />
        protected BaseEventSource(ISubject<T> subject) => Subject = subject;

        /// <summary>
        /// The event to be triggered.
        /// </summary>
        public IObservable<T> Observable => Subject;

        /// <summary>
        /// The subject of the events.
        /// </summary>
        public ISubject<T> Subject { get; }
    }
}