namespace AssetRipper.VersionUtilities;

public readonly partial struct UnityVersion
{
	/// <summary>
	/// A maximizing function for Unity versions
	/// </summary>
	/// <param name="left">A Unity version</param>
	/// <param name="right">A Unity version</param>
	/// <returns>The larger Unity version</returns>
	public static UnityVersion Max(UnityVersion left, UnityVersion right)
	{
		return left > right ? left : right;
	}

	/// <summary>
	/// A minimizing function for Unity versions
	/// </summary>
	/// <param name="left">A Unity version</param>
	/// <param name="right">A Unity version</param>
	/// <returns>The smaller Unity version</returns>
	public static UnityVersion Min(UnityVersion left, UnityVersion right)
	{
		return left < right ? left : right;
	}

	/// <summary>
	/// A distance function for measuring version proximity
	/// </summary>
	/// <remarks>
	/// The returned value is ordinal and should not be saved anywhere.
	/// It's only for runtime comparisons, such as finding the closest version in a list.
	/// </remarks>
	/// <param name="left">A Unity version</param>
	/// <param name="right">A Unity version</param>
	/// <returns>
	/// An ordinal number representing the distance between 2 versions. 
	/// A value of zero means they're equal.
	/// </returns>
	public static ulong Distance(UnityVersion left, UnityVersion right)
	{
		return left.m_data < right.m_data 
			? right.m_data - left.m_data 
			: left.m_data - right.m_data;
	}

	/// <summary>
	/// Get the closest Unity version in an array of versions using <see cref="Distance(UnityVersion, UnityVersion)"/>
	/// </summary>
	/// <param name="versions">The Unity version array</param>
	/// <returns>The closest Unity version</returns>
	/// <exception cref="ArgumentNullException">The array is null</exception>
	/// <exception cref="ArgumentException">The array is empty</exception>
	public UnityVersion GetClosestVersion(UnityVersion[] versions)
	{
		if (versions is null)
		{
			throw new ArgumentNullException(nameof(versions));
		}

		if (versions.Length == 0)
		{
			throw new ArgumentException("Length cannot be zero", nameof(versions));
		}

		UnityVersion result = versions[0];
		ulong currentDistance = Distance(this, result);
		for(int i = 1; i < versions.Length; i++)
		{
			ulong newDistance = Distance(this, versions[i]);
			if (newDistance < currentDistance)
			{
				currentDistance = newDistance;
				result = versions[i];
			}
		}

		return result;
	}
}