using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Linq;

/// <summary>
/// Class which defines blocks around the level
/// </summary>
[RequireComponent(typeof(BoxCollider))]
public class Block : MonoBehaviour
{
    #region Inspector Fields
    [SerializeField]
    [Tooltip("Offset from the top of the block from which a character should stand")]
    private Vector3 VisualOffset = Vector3.zero;

    [SerializeField]
    [Tooltip("Can this type of block be walked on")]
    private bool _isWalkable = true;
    #endregion InspectorFields

    #region ReadOnly Properties
    /// <summary>
    /// Blocks position in global space
    /// </summary>
    public Vector3 position { get { return transform.position; } }

    /// <summary>
    /// Position character should stand in global space
    /// </summary>
    public Vector3 VisualPosition { get { return position + VisualOffset + Vector3.up * 0.5f; } }
    #endregion ReadOnly Properties

    #region Public Functions

    /// <summary>
    /// Is a block valid to walk on
    /// </summary>
    /// <param name="layerMask">Layers to check for when checking for blocks above</param>
    /// <returns></returns>
    public bool isWalkable(LayerMask layerMask)
    {
        //checks if there is no block above this one and that this is tagged as walkable
        return  (_isWalkable && !isBlockAtPosition(position + Vector3.up, 1, layerMask));
    }
    #endregion Public Functions

    #region Static Functions

    /// <summary>
    /// Checks if there is a block at supplied position
    /// </summary>
    /// <param name="position">position to check at</param>
    /// <param name="Scale">Scale of block. (should be 1)</param>
    /// <param name="layerMask">Layers to check on</param>
    /// <param name="hit">Block hit</param>
    /// <returns>if a block is at position</returns>
    public static bool isBlockAtPosition(Vector3 position, float Scale, LayerMask layerMask, out Block hit)
    {
        //Turn scale into halfextent and shrink a bit so it doesn't hit bordering blocks
        Vector3 halfExtent = Vector3.one * ((Scale - 0.1f) / 2);

        //Get every collider which is at position
        Collider[] cols = Physics.OverlapBox(position, halfExtent, Quaternion.identity, layerMask);

        //Filter colliders for only GameObjects with an Block component
        Block[] blocks = cols.Where(p => p.GetComponent<Block>() != null).Select(p => p.GetComponent<Block>()).ToArray();

        //Draw cube, for visuals
        DebugExtensions.DrawCube(position, halfExtent, Color.cyan, 1, false);

        //if didn't hit anyblocks return false
        if (blocks.Length == 0)
        {
            hit = null;
            return false;
        }
        else
        {
            //else get the closest block to disered position, (in case we hit mulitple blocks)
            hit = Utility.minBy(blocks, p => Vector3.Distance(p.transform.position, position));
            return true;
        }
    }

    /// <summary>
    /// Checks if there is a block at supplied position
    /// </summary>
    /// <param name="position">position to check at</param>
    /// <param name="Scale">Scale of block. (should be 1)</param>
    /// <param name="layerMask">Layers to check on</param>
    /// <returns>if a block is at position</returns>
    public static bool isBlockAtPosition(Vector3 position, float scale, LayerMask layerMask)
    {
        //Return Overloaded function above
        Block hit;
        return (isBlockAtPosition(position, scale, layerMask, out hit));
    }

    #endregion

}