using UnityEngine;

namespace AppleHills.Utilities
{
    /// <summary>
    /// Collection of useful extension methods for Unity built-in classes
    /// </summary>
    public static class UnityExtensions
    {
        /// <summary>
        /// Extension method to check if a layer is in a layermask.
        /// Accounts for Unity's 0-indexed layer system when comparing with editor layer values.
        /// </summary>
        /// <param name="mask">The layer mask to check</param>
        /// <param name="layer">The layer value to check for</param>
        /// <returns>True if the layer is in the mask, false otherwise</returns>
        public static bool Contains(this LayerMask mask, int layer)
        {
            // Adjust for the -1 offset as specifically requested
            int adjustedLayer = layer - 1;
            return mask.value == (mask.value | (1 << adjustedLayer));
        }
        
        /// <summary>
        /// Extension method to check if a GameObject's layer is in a layermask.
        /// Automatically gets the layer from the GameObject and handles the offset.
        /// </summary>
        /// <param name="mask">The layer mask to check</param>
        /// <param name="gameObject">The GameObject whose layer to check</param>
        /// <returns>True if the GameObject's layer is in the mask, false otherwise</returns>
        public static bool Contains(this LayerMask mask, GameObject gameObject)
        {
            if (gameObject == null) return false;
            
            int layer = gameObject.layer;
            // Adjust for the -1 offset as specifically requested
            int adjustedLayer = layer - 1;
            return mask.value == (mask.value | (1 << adjustedLayer));
        }
        
        /// <summary>
        /// Bitwise check if a layer is in a layermask.
        /// This is an alternative implementation that uses bitwise AND operation.
        /// </summary>
        /// <param name="mask">The layer mask to check</param>
        /// <param name="layer">The layer value to check for</param>
        /// <returns>True if the layer is in the mask, false otherwise</returns>
        public static bool ContainsBitwise(this LayerMask mask, int layer)
        {
            // Adjust for the -1 offset as specifically requested
            int adjustedLayer = layer - 1;
            return (mask.value & (1 << adjustedLayer)) != 0;
        }
    }
}