using System.Globalization;
using PLib.Application.Library;
using PLib.Domain.Videos;
using ReactiveUI;
using RxVoid = ReactiveUI.Primitives.RxVoid;

namespace PLib.Desktop.ViewModels;

/// <summary>One tag, performer, studio or collection in a browsing tab.</summary>
public sealed class LabelSummaryViewModel
{
    public LabelSummaryViewModel(LabelSummary summary, Action<LabelSummaryViewModel> open)
    {
        ArgumentNullException.ThrowIfNull(summary);

        Id = summary.Id;
        Name = summary.Name;
        Kind = summary.Kind;
        VideoCount = summary.VideoCount;
        CountText = VideoCount.ToString(CultureInfo.CurrentCulture);

        OpenCommand = ReactiveCommand.Create(() => open(this));
    }

    public Guid Id { get; }

    public string Name { get; }

    public LabelKind Kind { get; }

    public int VideoCount { get; }

    public string CountText { get; }

    /// <summary>Narrows the video grid down to this label and switches to it.</summary>
    public ReactiveCommand<RxVoid, RxVoid> OpenCommand { get; }

    public bool Matches(string term) => Name.Contains(term, StringComparison.CurrentCultureIgnoreCase);
}

/// <summary>An order for the entity lists, and how to read it.</summary>
public sealed record EntitySortOption(string Label, Comparison<LabelSummaryViewModel> Compare)
{
    public static IReadOnlyList<EntitySortOption> All { get; } =
    [
        new("Сначала частые", (x, y) =>
        {
            var byCount = y.VideoCount.CompareTo(x.VideoCount);
            return byCount != 0 ? byCount : Name(x, y);
        }),

        new("По названию", Name),
    ];

    /// <summary>
    /// Culture-aware and case-insensitive, so Cyrillic and Latin names land where a reader
    /// expects rather than in ordinal order.
    /// </summary>
    private static int Name(LabelSummaryViewModel x, LabelSummaryViewModel y) =>
        string.Compare(x.Name, y.Name, StringComparison.CurrentCultureIgnoreCase);
}