namespace Zinnia.Tracking.Follow.Modifier.Property
{
    using UnityEngine;
    using Zinnia.Extension;
    using Zinnia.Tracking.Follow;

    /// <summary>
    /// Modifies a specific property.
    /// </summary>
    public abstract class PropertyModifier : MonoBehaviour
    {
        #region Modifier Events
        /// <summary>
        /// Emitted before the property is modified.
        /// </summary>
        [Header("Modifier Events")]
        public ObjectFollower.FollowEvent Premodified = new ObjectFollower.FollowEvent();
        /// <summary>
        /// Emitted after the property is modified.
        /// </summary>
        public ObjectFollower.FollowEvent Modified = new ObjectFollower.FollowEvent();
        #endregion

        #region Modifier Settings
        [Header("Modifier Settings")]
        [Tooltip("Determines whether the offset will be applied on the modification.")]
        [SerializeField]
        private bool applyOffset = true;
        /// <summary>
        /// Determines whether the offset will be applied on the modification.
        /// </summary>
        public bool ApplyOffset
        {
            get
            {
                return applyOffset;
            }
            set
            {
                applyOffset = value;
            }
        }
        #endregion

        /// <summary>
        /// The event data to emit before and after the property has been modified.
        /// </summary>
        protected readonly ObjectFollower.EventData eventData = new ObjectFollower.EventData();

        /// <summary>
        /// Attempts to modify the target.
        /// </summary>
        /// <param name="data">Event data that contains the required modifier properties.</param>
        public virtual void Modifiy(ObjectFollower.EventData data)
        {
            if (!this.IsValidState())
            {
                return;
            }

            Modify(data.EventSource, data.EventTarget, data.EventTargetOffset);
        }

        /// <summary>
        /// Attempts modify the target.
        /// </summary>
        /// <param name="source">The source to utilize in the modification.</param>
        /// <param name="target">The target to modify.</param>
        /// <param name="offset">The offset of the target against the source when modifying.</param>
        public virtual void Modify(GameObject source, GameObject target, GameObject offset = null)
        {
            if (!this.IsValidState() || source == null || target == null)
            {
                return;
            }

            offset = ApplyOffset ? offset : null;

            Premodified?.Invoke(eventData.Set(source, target, offset));
            DoModify(source, target, offset);
            Modified?.Invoke(eventData.Set(source, target, offset));
        }

        /// <summary>
        /// Attempts modify the target.
        /// </summary>
        /// <param name="source">The source to utilize in the modification.</param>
        /// <param name="target">The target to modify.</param>
        /// <param name="offset">The offset of the target against the source when modifying.</param>
        protected abstract void DoModify(GameObject source, GameObject target, GameObject offset = null);
    }
}