using System.Text.RegularExpressions;

namespace StellaOps.ElkSharp;

public sealed record ElkSharpSourceProfile
{
    public required string SourceName { get; init; }
    public int LineCount { get; init; }
    public int CharacterCount { get; init; }
    public int FunctionCount { get; init; }
    public int DefineClassCount { get; init; }
    public int CreateForClassCount { get; init; }
    public int InternConstantCount { get; init; }
    public int LayoutCommandCount { get; init; }
    public int RegisterAlgorithmCount { get; init; }
}

public static partial class ElkSharpSourceAnalyzer
{
    [GeneratedRegex(@"(?m)^\s*function\s+[A-Za-z0-9_$]+\s*\(", RegexOptions.CultureInvariant)]
    private static partial Regex FunctionRegex();

    [GeneratedRegex(@"defineClass\(", RegexOptions.CultureInvariant)]
    private static partial Regex DefineClassRegex();

    [GeneratedRegex(@"createForClass\(", RegexOptions.CultureInvariant)]
    private static partial Regex CreateForClassRegex();

    [GeneratedRegex(@"\$intern_", RegexOptions.CultureInvariant)]
    private static partial Regex InternConstantRegex();

    [GeneratedRegex(@"cmd:\s*'layout'|layout_[0-9]+\(", RegexOptions.CultureInvariant)]
    private static partial Regex LayoutCommandRegex();

    [GeneratedRegex(@"registerLayoutAlgorithms\(", RegexOptions.CultureInvariant)]
    private static partial Regex RegisterAlgorithmRegex();

    public static ElkSharpSourceProfile Analyze(string sourceName, string sourceText)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(sourceName);
        ArgumentNullException.ThrowIfNull(sourceText);

        return new ElkSharpSourceProfile
        {
            SourceName = sourceName,
            LineCount = CountLines(sourceText),
            CharacterCount = sourceText.Length,
            FunctionCount = FunctionRegex().Matches(sourceText).Count,
            DefineClassCount = DefineClassRegex().Matches(sourceText).Count,
            CreateForClassCount = CreateForClassRegex().Matches(sourceText).Count,
            InternConstantCount = InternConstantRegex().Matches(sourceText).Count,
            LayoutCommandCount = LayoutCommandRegex().Matches(sourceText).Count,
            RegisterAlgorithmCount = RegisterAlgorithmRegex().Matches(sourceText).Count,
        };
    }

    public static async Task<ElkSharpSourceProfile> AnalyzeFileAsync(
        string path,
        CancellationToken cancellationToken = default)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(path);

        var sourceText = await File.ReadAllTextAsync(path, cancellationToken);
        return Analyze(Path.GetFileName(path), sourceText);
    }

    private static int CountLines(string text)
    {
        if (text.Length == 0)
        {
            return 0;
        }

        var lines = 1;
        foreach (var character in text)
        {
            if (character == '\n')
            {
                ++lines;
            }
        }

        return lines;
    }
}