namespace PLib.Domain.Videos;

/// <summary>What a label is for; the relation to videos is identical either way.</summary>
public enum LabelKind
{
    /// <summary>A free-form word used to narrow the grid down.</summary>
    Tag,

    /// <summary>A named group the user curates and browses as a whole.</summary>
    Collection,
}

/// <summary>
/// A named grouping of videos — a tag or a collection.
/// </summary>
/// <remarks>
/// Tags and collections are the same relation: a name, many videos, a video in many of them.
/// They differ only in intent, and that intent is <see cref="Kind"/>. One entity means one
/// join table, one repository and one set of rules about naming; splitting them later is a
/// rename and a migration, whereas keeping two near-identical aggregates in sync from the
/// start is a permanent tax.
/// </remarks>
public sealed class LibraryLabel
{
    private readonly List<VideoItem> _videos = [];

    /// <summary>Required by EF Core materialization; do not use from application code.</summary>
    private LibraryLabel()
    {
        Name = null!;
        NormalizedName = null!;
    }

    public LibraryLabel(string name, LabelKind kind)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(name);

        Id = Guid.CreateVersion7();
        Kind = kind;
        CreatedAt = DateTimeOffset.UtcNow;
        Name = name.Trim();
        NormalizedName = Normalize(name);
    }

    public Guid Id { get; private set; }

    public string Name { get; private set; }

    /// <summary>
    /// Upper-cased, trimmed name. Uniqueness is enforced on this rather than on
    /// <see cref="Name"/>, so "Комедия" and "комедия" cannot both exist.
    /// </summary>
    public string NormalizedName { get; private set; }

    public LabelKind Kind { get; private set; }

    public DateTimeOffset CreatedAt { get; private set; }

    public IReadOnlyCollection<VideoItem> Videos => _videos;

    public static string Normalize(string name) => name.Trim().ToUpperInvariant();

    public void Rename(string name)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(name);

        Name = name.Trim();
        NormalizedName = Normalize(name);
    }
}