chapter-organizer/tools/GoogleSheetsScheduleImport/OccurrenceEventMatcher.cs

using Core.Entities;
using Core.Models;
using FuzzySharp;

namespace GoogleSheetsScheduleImport;

/// <summary>
/// Maps a sheet cell title to the closest event definition (fuzzy) plus MS/HS for section headers.
/// </summary>
public static class OccurrenceEventMatcher
{
    private const int MinTokenScore = 62;

    public static bool TryMatch(
        string occurrenceName,
        IReadOnlyList<EventDefinition> events,
        out EventDefinition? matched,
        out SchoolLevel? level)
    {
        matched = null;
        level = null;
        if (string.IsNullOrWhiteSpace(occurrenceName) || events.Count == 0)
            return false;

        var normalized = TextNormalization.ForEmitLine(occurrenceName);
        var (remainder, prefixLevel) = SchoolLevelPrefixParser.StripLeadingSchoolPrefix(normalized);

        // Section headers require "Event Name - MS|HS". Titles without a clear school prefix stay in General Schedule.
        if (!prefixLevel.HasValue)
            return false;

        var best = FindBest(remainder, events);
        if (best == null || string.IsNullOrWhiteSpace(remainder))
            return false;

        matched = best;
        level = prefixLevel;
        return true;
    }

    private static EventDefinition? FindBest(string text, IReadOnlyList<EventDefinition> events)
    {
        if (string.IsNullOrWhiteSpace(text))
            return null;

        EventDefinition? best = null;
        var bestScore = 0;
        foreach (var e in events)
        {
            if (string.IsNullOrWhiteSpace(e.Name))
                continue;

            var score = Math.Max(
                Fuzz.TokenSetRatio(text, e.Name),
                Fuzz.PartialRatio(text, e.Name));

            if (score > bestScore)
            {
                bestScore = score;
                best = e;
            }
            else if (score == bestScore && best != null && e.Name.Length > best.Name.Length)
                best = e;
        }

        if (best == null || bestScore < MinTokenScore)
            return null;

        return best;
    }
}