using UtopiaCanteenSystem.Models;

namespace UtopiaCanteenSystem.Services;

/// <summary>
/// Resolves current meal session from production (MySQL meal_schedule). Caches schedules per site for 60 seconds.
/// No SQLite; scan validation uses production data only.
/// </summary>
public class DbMealSessionResolver : IMealSessionResolver
{
    private readonly IMealScheduleService _mealScheduleService;
    private readonly TimeSpan _cacheTtl = TimeSpan.FromSeconds(60);

    private readonly Dictionary<string, (List<MealSchedule> Schedules, DateTime ExpiryUtc)> _cache = new(StringComparer.OrdinalIgnoreCase);
    private readonly object _cacheLock = new();

    public DbMealSessionResolver(IMealScheduleService mealScheduleService)
    {
        _mealScheduleService = mealScheduleService;
    }


    private static MealSession MapMealNameToSession(string? mealName)
    {
        if (string.IsNullOrWhiteSpace(mealName))
            return MealSession.None;

        var name = mealName.Trim();

        return name.ToLowerInvariant() switch
        {
            "breakfast" => MealSession.Breakfast,
            "sehri" => MealSession.Breakfast,
            "lunch" => MealSession.Lunch,
            "iftari" => MealSession.Lunch,
            "tea" => MealSession.Tea,
            "dinner" => MealSession.Dinner,
            _ => MealSession.None
        };
    }


    /// <inheritdoc />
    //public MealSession GetCurrentSession(DateTime nowLocal, string siteId)
    //{
    //    var normalizedSite = (siteId ?? string.Empty).Trim();
    //    if (string.IsNullOrEmpty(normalizedSite))
    //        normalizedSite = "01";
    //    if (normalizedSite.Length == 1 && char.IsDigit(normalizedSite[0]))
    //        normalizedSite = normalizedSite.PadLeft(2, '0');

    //    var schedules = GetSchedulesForSiteCached(normalizedSite);
    //    var t = nowLocal.TimeOfDay;

    //    //foreach (var s in schedules)
    //    //{
    //    //    if (!TryParseTime(s.StartTime, out var start) || !TryParseTime(s.EndTime, out var end))
    //    //        continue;
    //    //    if (t >= start && t < end)
    //    //        return (MealSession)s.MealSession;
    //    //}
    //    foreach (var s in schedules)
    //    {
    //        if (!TryParseTime(s.StartTime, out var start) || !TryParseTime(s.EndTime, out var end))
    //            continue;

    //        if (t >= start && t < end)
    //            return MapMealNameToSession(s.MealName);
    //    }

    //    return MealSession.None;
    //}




    public ResolvedMealSession? GetCurrentSession(DateTime nowLocal, string siteId)
    {
        var normalizedSite = (siteId ?? string.Empty).Trim();
        if (string.IsNullOrEmpty(normalizedSite))
            normalizedSite = "01";
        if (normalizedSite.Length == 1 && char.IsDigit(normalizedSite[0]))
            normalizedSite = normalizedSite.PadLeft(2, '0');

        var schedules = GetSchedulesForSiteCached(normalizedSite);
        var t = nowLocal.TimeOfDay;

        foreach (var s in schedules)
        {
            if (!TryParseTime(s.StartTime, out var start) || !TryParseTime(s.EndTime, out var end))
                continue;

            if (t >= start && t < end)
            {
                return new ResolvedMealSession
                {
                    Session = MapMealNameToSession(s.MealName),
                    MealName = s.MealName ?? string.Empty,
                    SiteId = normalizedSite,
                    StartTime = s.StartTime ?? string.Empty,
                    EndTime = s.EndTime ?? string.Empty
                };
            }
        }

        return null;
    }


    private List<MealSchedule> GetSchedulesForSiteCached(string siteId)
    {
        lock (_cacheLock)
        {
            if (_cache.TryGetValue(siteId, out var entry) && DateTime.UtcNow < entry.ExpiryUtc)
                return entry.Schedules;
        }

        var list = _mealScheduleService.GetActiveSchedulesForSite(siteId).ToList();

        lock (_cacheLock)
        {
            _cache[siteId] = (list, DateTime.UtcNow.Add(_cacheTtl));
        }

        return list;
    }

    private static bool TryParseTime(string value, out TimeSpan time)
    {
        time = TimeSpan.Zero;
        if (string.IsNullOrWhiteSpace(value))
            return false;
        return TimeSpan.TryParse(value.Trim(), null, out time)
               || TimeSpan.TryParse(value.Trim().Replace(".", ":"), null, out time);
    }
}