Matrix spiral copy - four direction

MatrixSpiralCopy.cs

using System;
using System.Collections.Generic;

class Solution
{
    public static int[] SpiralCopy(int[,] inputMatrix)
    {
      if(inputMatrix == null || inputMatrix.GetLength(0) == 0 ||  // false
        inputMatrix.GetLength(1) == 0)
      {
        return new int[0]; 
      }
      
      var rows = inputMatrix.GetLength(0); // 4
      var columns = inputMatrix.GetLength(1);// 5
      
      var visited = new int[rows, columns]; // 0 
      
      var fourDirections = new List<int[]>(); 
      
      fourDirections.Add(new int[]{ 0,  1}); /// left to right
      fourDirections.Add(new int[]{ 1,  0}); // top to bottom
      fourDirections.Add(new int[]{ 0, -1}); // right to left
      fourDirections.Add(new int[]{-1,  0}); // bottom to top
      
      var total = rows * columns;
      var index = 0; 
      
      int row = 0; 
      int col = 0; 
      int direction = 0; 
      
      var spiral = new int[total]; 
      
      while(index < total)
      {
        var current = inputMatrix[row, col]; 
        visited[row, col] = 1; 
        
        spiral[index] = current; 
        
        var nextRow = row + fourDirections[direction][0]; 
        var nextCol = col + fourDirections[direction][1]; 
        var isInRange = nextRow < 0 || nextRow >= rows || nextCol < 0 || nextCol >= columns;
        
        if( isInRange || visited[nextRow, nextCol] == 1)
        {
          direction = (direction + 1) % 4; 
        }
        
        // next iteration 
        row = row + fourDirections[direction][0]; 
        col = col + fourDirections[direction][1]; 
        
        index++; 
      }
      
      return spiral; 
    }

    static void Main(string[] args)
    {

    }
}
/*
mark visited 

define four directions array - 
  left to right 
  top to bottom 
  right to left
  down to up   0 - 3
  
Define the check when to change direction 

1  2 3 4 5 -> out of bound -
        change direction -> top to bottom
        ...
  
   7 8 9 10 - change the direction, visited array, 10 is visited
 
   direction = (direction + 1) % 4 // map to 0 - 3, automatically 
  
time complexity O(n * m )   , n - rows, m - columns 

space O(n * m)
  
 write one loop 
 */