using System;
using System.Globalization;

namespace AspClassic.Scripting;

[Serializable]
public struct SourceSpan
{
	private readonly SourceLocation _start;

	private readonly SourceLocation _end;

	public static readonly SourceSpan None = new SourceSpan(SourceLocation.None, SourceLocation.None);

	public static readonly SourceSpan Invalid = new SourceSpan(SourceLocation.Invalid, SourceLocation.Invalid);

	public SourceLocation Start => _start;

	public SourceLocation End => _end;

	public int Length => _end.Index - _start.Index;

	public bool IsValid
	{
		get
		{
			if (_start.IsValid)
			{
				return _end.IsValid;
			}
			return false;
		}
	}

	public SourceSpan(SourceLocation start, SourceLocation end)
	{
		ValidateLocations(start, end);
		_start = start;
		_end = end;
	}

	private static void ValidateLocations(SourceLocation start, SourceLocation end)
	{
		if (start.IsValid && end.IsValid)
		{
			if (start > end)
			{
				throw new ArgumentException("Start and End must be well ordered");
			}
		}
		else if (start.IsValid || end.IsValid)
		{
			throw new ArgumentException("Start and End must both be valid or both invalid");
		}
	}

	public static bool operator ==(SourceSpan left, SourceSpan right)
	{
		if (left._start == right._start)
		{
			return left._end == right._end;
		}
		return false;
	}

	public static bool operator !=(SourceSpan left, SourceSpan right)
	{
		if (!(left._start != right._start))
		{
			return left._end != right._end;
		}
		return true;
	}

	public override bool Equals(object obj)
	{
		if (!(obj is SourceSpan sourceSpan))
		{
			return false;
		}
		if (_start == sourceSpan._start)
		{
			return _end == sourceSpan._end;
		}
		return false;
	}

	public override string ToString()
	{
		SourceLocation start = _start;
		string text = start.ToString();
		SourceLocation end = _end;
		return text + " - " + end.ToString();
	}

	public override int GetHashCode()
	{
		return _start.Column ^ (_end.Column << 7) ^ (_start.Line << 14) ^ (_end.Line << 23);
	}

	internal string ToDebugString()
	{
		return string.Format(CultureInfo.CurrentCulture, "{0}-{1}", new object[2]
		{
			_start.ToDebugString(),
			_end.ToDebugString()
		});
	}
}