namespace ClaudeDo.Data.Models;

/// <summary>
/// The optional local-time window restricting when PowerUse applies
/// (<see cref="AppSettingsEntity.PowerUseWindowStart"/> / <c>End</c>, both <c>HH:mm</c>).
/// Pure on purpose — the caller supplies "now", so the window logic is testable without a clock.
/// </summary>
public static class PowerUseWindow
{
    /// <summary>Parses an <c>HH:mm</c> string; anything else (including null/blank) is null.</summary>
    public static TimeOnly? Parse(string? value)
        => TimeOnly.TryParseExact(value?.Trim(), "HH:mm", out var t) ? t : null;

    /// <summary>Round-trips a stored/typed value through <see cref="Parse"/>, so an unparseable
    /// string is stored as null instead of sitting in the column pretending to be a window.</summary>
    public static string? Normalize(string? value) => Parse(value)?.ToString("HH:mm");

    /// <summary>
    /// True when <paramref name="now"/> falls inside the window. Half-open: start is included,
    /// end is not. Either bound missing = no window at all = always true (the pre-window
    /// behaviour). A window whose end is before its start wraps over midnight.
    /// </summary>
    public static bool Contains(TimeOnly now, TimeOnly? start, TimeOnly? end)
    {
        if (start is not { } from || end is not { } to) return true;
        return from < to ? now >= from && now < to : now >= from || now < to;
    }

    /// <summary>Convenience overload for the two stored strings and a wall clock.</summary>
    public static bool IsOpen(DateTime now, string? start, string? end)
        => Contains(TimeOnly.FromDateTime(now), Parse(start), Parse(end));
}