using Microsoft.VisualBasic.CompilerServices;

namespace AspClassic.Parser;

/// <summary>
/// Stores source code line and column information.
/// </summary>
public struct Location
{
	private readonly int _Index;

	private readonly int _Line;

	private readonly int _Column;

	/// <summary>
	/// The index in the stream (0-based).
	/// </summary>
	public int Index => _Index;

	/// <summary>
	/// The physical line number (1-based).
	/// </summary>
	public int Line => _Line;

	/// <summary>
	/// The physical column number (1-based).
	/// </summary>
	public int Column => _Column;

	/// <summary>
	/// Whether the location is a valid location.
	/// </summary>
	public bool IsValid => Line != 0 && Column != 0;

	/// <summary>
	/// Constructs a new Location for a particular source location.
	/// </summary>
	/// <param name="index">The index in the stream (0-based).</param>
	/// <param name="line">The physical line number (1-based).</param>
	/// <param name="column">The physical column number (1-based).</param>
	public Location(int index, int line, int column)
	{
		this = default(Location);
		_Index = index;
		_Line = line;
		_Column = column;
	}

	/// <summary>
	/// Compares two specified Location values to see if they are equal.
	/// </summary>
	/// <param name="left">One location to compare.</param>
	/// <param name="right">The other location to compare.</param>
	/// <returns>True if the locations are the same, False otherwise.</returns>
	public static bool operator ==(Location left, Location right)
	{
		return left.Index == right.Index;
	}

	/// <summary>
	/// Compares two specified Location values to see if they are not equal.
	/// </summary>
	/// <param name="left">One location to compare.</param>
	/// <param name="right">The other location to compare.</param>
	/// <returns>True if the locations are not the same, False otherwise.</returns>
	public static bool operator !=(Location left, Location right)
	{
		return left.Index != right.Index;
	}

	/// <summary>
	/// Compares two specified Location values to see if one is before the other.
	/// </summary>
	/// <param name="left">One location to compare.</param>
	/// <param name="right">The other location to compare.</param>
	/// <returns>True if the first location is before the other location, False otherwise.</returns>
	public static bool operator <(Location left, Location right)
	{
		return left.Index < right.Index;
	}

	/// <summary>
	/// Compares two specified Location values to see if one is after the other.
	/// </summary>
	/// <param name="left">One location to compare.</param>
	/// <param name="right">The other location to compare.</param>
	/// <returns>True if the first location is after the other location, False otherwise.</returns>
	public static bool operator >(Location left, Location right)
	{
		return left.Index > right.Index;
	}

	/// <summary>
	/// Compares two specified Location values to see if one is before or the same as the other.
	/// </summary>
	/// <param name="left">One location to compare.</param>
	/// <param name="right">The other location to compare.</param>
	/// <returns>True if the first location is before or the same as the other location, False otherwise.</returns>
	public static bool operator <=(Location left, Location right)
	{
		return left.Index <= right.Index;
	}

	/// <summary>
	/// Compares two specified Location values to see if one is after or the same as the other.
	/// </summary>
	/// <param name="left">One location to compare.</param>
	/// <param name="right">The other location to compare.</param>
	/// <returns>True if the first location is after or the same as the other location, False otherwise.</returns>
	public static bool operator >=(Location left, Location right)
	{
		return left.Index >= right.Index;
	}

	/// <summary>
	/// Compares two specified Location values.
	/// </summary>
	/// <param name="left">One location to compare.</param>
	/// <param name="right">The other location to compare.</param>
	/// <returns>0 if the locations are equal, -1 if the left one is less than the right one, 1 otherwise.</returns>
	public static int Compare(Location left, Location right)
	{
		if (left == right)
		{
			return 0;
		}
		if (left < right)
		{
			return -1;
		}
		return 1;
	}

	public override string ToString()
	{
		return "(" + Conversions.ToString(Column) + "," + Conversions.ToString(Line) + ")";
	}

	public override bool Equals(object obj)
	{
		if (obj is Location)
		{
			return this == (Location)obj;
		}
		return false;
	}

	public override int GetHashCode()
	{
		return checked((int)(Index & 0xFFFFFFFFu));
	}
}