using Microsoft.AspNetCore.Components;
using Microsoft.JSInterop;

namespace AyCode.Blazor.Components.Components.CardViews;

/// <summary>
/// Generic card view component that displays items in a responsive CSS Grid layout
/// with optional pagination and scroll-to-item support.
/// </summary>
/// <typeparam name="TItem">The type of data item displayed in each card.</typeparam>
public partial class MgCardView<TItem> : ComponentBase
{
    [Inject] private IJSRuntime JSRuntime { get; set; } = null!;

    /// <summary>
    /// The collection of items to display as cards.
    /// </summary>
    [Parameter, EditorRequired]
    public IReadOnlyList<TItem> Data { get; set; } = [];

    /// <summary>
    /// Template for rendering each card's content.
    /// </summary>
    [Parameter, EditorRequired]
    public RenderFragment<TItem> CardTemplate { get; set; } = null!;

    /// <summary>
    /// Fired when a card is clicked/tapped.
    /// </summary>
    [Parameter]
    public EventCallback<TItem> OnCardClick { get; set; }

    /// <summary>
    /// Number of columns on extra-small screens (below 576px). Default: 1.
    /// </summary>
    [Parameter]
    public int ColumnCountXs { get; set; } = 1;

    /// <summary>
    /// Number of columns on small screens (576–768px). Default: 2.
    /// </summary>
    [Parameter]
    public int ColumnCountSm { get; set; } = 2;

    /// <summary>
    /// Number of columns on medium+ screens (769px+). Default: 3.
    /// </summary>
    [Parameter]
    public int ColumnCountLg { get; set; } = 3;

    /// <summary>
    /// Whether to show the pager below the cards. Default: false.
    /// </summary>
    [Parameter]
    public bool ShowPager { get; set; }

    /// <summary>
    /// Number of items per page when paging is enabled. Default: 12.
    /// </summary>
    [Parameter]
    public int PageSize { get; set; } = 12;

    /// <summary>
    /// Additional CSS class for the card view container.
    /// </summary>
    [Parameter]
    public string? CssClass { get; set; }

    /// <summary>
    /// Additional CSS class applied to each individual card wrapper.
    /// </summary>
    [Parameter]
    public string? CardCssClass { get; set; }

    /// <summary>
    /// Height of the card view container (e.g., "500px", "70vh"). When set, the component uses its own scroll area.
    /// </summary>
    [Parameter]
    public string? Height { get; set; }

    /// <summary>
    /// Whether to show the filter panel above the cards. Default: false.
    /// </summary>
    [Parameter]
    public bool ShowFilterPanel { get; set; }

    /// <summary>
    /// Custom content for the filter panel. Rendered above the card grid when ShowFilterPanel is true.
    /// </summary>
    [Parameter]
    public RenderFragment? FilterPanel { get; set; }

    /// <summary>
    /// Item to scroll into view after render. Set to null to disable.
    /// </summary>
    [Parameter]
    public TItem? ScrollToItem { get; set; }

    /// <summary>
    /// Key selector for identifying items (e.g., item => item.Id). Required when ScrollToItem is used.
    /// </summary>
    [Parameter]
    public Func<TItem, object>? ItemKeySelector { get; set; }

    private int _activePageIndex;
    private object? _lastScrolledKey;

    private string? ContainerStyle => Height is not null ? $"height: {Height};" : null;

    private IReadOnlyList<TItem> PagedItems
    {
        get
        {
            if (!ShowPager)
                return Data;

            return Data
                .Skip(_activePageIndex * PageSize)
                .Take(PageSize)
                .ToList();
        }
    }

    private async Task OnCardClickInternal(TItem item)
    {
        if (OnCardClick.HasDelegate)
            await OnCardClick.InvokeAsync(item);
    }

    private void OnActivePageIndexChanged(int newPageIndex)
    {
        _activePageIndex = newPageIndex;
    }

    /// <summary>
    /// Generates a stable DOM element id for a card item using the key selector.
    /// </summary>
    private string? GetCardElementId(TItem item)
    {
        return ItemKeySelector is null ? null : $"mg-card-{ItemKeySelector(item)}";
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (ScrollToItem is not null && ItemKeySelector is not null)
        {
            var key = ItemKeySelector(ScrollToItem);
            if (!Equals(key, _lastScrolledKey))
            {
                _lastScrolledKey = key;
                var elementId = $"mg-card-{key}";
                try
                {
                    await JSRuntime.InvokeVoidAsync("MgCardView.scrollToElement", elementId);
                }
                catch (JSException)
                {
                    // JS might not be loaded yet
                }
            }
        }
    }
}