using System;

namespace MusicMetaTagger.Core.Utility
{
	public static class LevenshteinDistance
	{
		/// <summary>
		/// Compute the distance between two strings.
		/// </summary>
		public static int Compute(string s, string t)
		{
			var n = s.Length;
			var m = t.Length;
			var d = new int[n + 1, m + 1];

			// Step 1
			if (n == 0)
			{
				return m;
			}

			if (m == 0)
			{
				return n;
			}

			// Step 2
			for (var i = 0; i <= n; d[i, 0] = i++)
			{
			}

			for (var j = 0; j <= m; d[0, j] = j++)
			{
			}

			// Step 3
			for (var i = 1; i <= n; i++)
			{
				//Step 4
				for (var j = 1; j <= m; j++)
				{
					// Step 5
					var cost = (t[j - 1] == s[i - 1]) ? 0 : 1;

					// Step 6
					d[i, j] = Math.Min(
						Math.Min(d[i - 1, j] + 1, d[i, j - 1] + 1),
						d[i - 1, j - 1] + cost);
				}
			}
			// Step 7
			return d[n, m];
		}
	}
}
