namespace NubLang.Diagnostics;

public readonly struct SourceSpan
{
    private readonly int _startIndex;
    private readonly int _endIndex;

    public static SourceSpan Merge(params IEnumerable<SourceSpan> spans)
    {
        var spanArray = spans as SourceSpan[] ?? spans.ToArray();
        if (spanArray.Length == 0)
        {
            return new SourceSpan(string.Empty, string.Empty, 0, 0, 0, 0, 0, 0);
        }

        var first = spanArray.MinBy(x => x._startIndex);
        var last = spanArray.MaxBy(x => x._endIndex);

        return new SourceSpan(first.SourcePath, first.Source, first._startIndex, last._endIndex, first.StartLine, last.EndLine, first.StartColumn, last.EndColumn);
    }

    public SourceSpan(string sourcePath, string source, int startIndex, int endIndex, int startLine, int startColumn, int endLine, int endColumn)
    {
        _startIndex = startIndex;
        _endIndex = endIndex;
        SourcePath = sourcePath;
        Source = source;
        StartLine = startLine;
        StartColumn = startColumn;
        EndLine = endLine;
        EndColumn = endColumn;
    }

    public int StartLine { get; }
    public int StartColumn { get; }
    public int EndLine { get; }
    public int EndColumn { get; }

    public string SourcePath { get; }
    public string Source { get; }

    public override string ToString()
    {
        if (StartLine == EndLine && StartColumn == EndColumn)
        {
            return $"{SourcePath}:{StartColumn}:{StartColumn}";
        }

        if (StartLine == EndLine)
        {
            return $"{SourcePath}:{StartLine}:{StartColumn}-{EndColumn}";
        }

        return $"{SourcePath}:{StartLine}:{StartColumn}-{EndLine}:{EndColumn}";
    }
}