using System.Text;
using Core.Entities;

namespace GoogleSheetsScheduleImport;

/// <summary>
/// Loads minimal <see cref="EventDefinition"/> rows from Tests-style CSV (column "Event").
/// </summary>
public static class EventDefinitionsCsvLoader
{
    public static List<EventDefinition> Load(string path)
    {
        var list = new List<EventDefinition>();
        var lines = File.ReadAllLines(path);
        if (lines.Length < 2)
            return list;

        var header = ParseCsvLine(lines[0]);
        var eventIdx = header.FindIndex(h => h.Equals("Event", StringComparison.OrdinalIgnoreCase));
        if (eventIdx < 0)
            throw new InvalidOperationException($"CSV '{path}' must contain an 'Event' column header.");

        for (var i = 1; i < lines.Length; i++)
        {
            if (string.IsNullOrWhiteSpace(lines[i]))
                continue;
            var cols = ParseCsvLine(lines[i]);
            if (eventIdx >= cols.Count)
                continue;
            var name = cols[eventIdx].Trim();
            if (string.IsNullOrWhiteSpace(name))
                continue;
            list.Add(new EventDefinition
            {
                Id = i,
                Name = name,
                ShortName = name,
                Eligibility = "",
                EventFormat = EventFormat.Team
            });
        }

        return list;
    }

    private static List<string> ParseCsvLine(string line)
    {
        var result = new List<string>();
        var cur = new StringBuilder();
        var inQuotes = false;
        for (var i = 0; i < line.Length; i++)
        {
            var ch = line[i];
            if (inQuotes)
            {
                if (ch == '"')
                {
                    if (i + 1 < line.Length && line[i + 1] == '"')
                    {
                        cur.Append('"');
                        i++;
                    }
                    else inQuotes = false;
                }
                else cur.Append(ch);
            }
            else
            {
                if (ch == '"') inQuotes = true;
                else if (ch == ',')
                {
                    result.Add(cur.ToString());
                    cur.Clear();
                }
                else cur.Append(ch);
            }
        }

        result.Add(cur.ToString());
        return result;
    }
}