using Elternbeirat.Contracts;
using Elternbeirat.PocketBase;
using Elternbeirat.Web.Shared;
using Microsoft.AspNetCore.Components;

namespace Elternbeirat.Web.Features.Events;

public partial class EventList
{
    [LoggerMessage(
        Level = LogLevel.Error,
        Message = "Could not load events from PocketBase; content source is unavailable.")]
    private static partial void LogSourceUnavailable(
        ILogger logger,
        Exception exception);

    [Inject]
    private PocketBaseClient PocketBase { get; set; } = null!;

    [Inject]
    private ILogger<EventList> Logger { get; set; } = null!;

    [CascadingParameter]
    private HttpContext? HttpContext { get; set; }

    // The "events" page record supplies the heading and intro text, so an editor
    // owns them in PocketBase like every other page, instead of them being
    // hard-coded here. Null until loaded, or when no such page exists.
    private Page? _page;

    private IReadOnlyList<Event> _upcomingEvents = [];
    private IReadOnlyList<Event> _pastEvents = [];

    // Set when the content source could not be reached or read. The markup then
    // shows a "temporarily unavailable" note instead of "no events", matching the
    // 503 this sets on the response.
    private bool _unavailable;

    // The page body rendered from Markdown to HTML, ready to emit as a MarkupString.
    private MarkupString Body => (MarkupString)Markdown.ToHtml(_page?.Body);

    protected override async Task OnInitializedAsync()
    {
        IReadOnlyList<Event> events;
        try
        {
            var token = HttpContext?.RequestAborted ?? CancellationToken.None;
            var pages = await PocketBase.GetPagesAsync(token);
            _page = pages.FirstOrDefault(
                page => string.Equals(page.Slug, "events", StringComparison.OrdinalIgnoreCase));
            events = await PocketBase.GetEventsAsync(token);
        }
        catch (PocketBaseUnavailableException exception)
        {
            // Empty sections would claim there are no events. The site works, its
            // data store is down: 503 and an honest note.
            LogSourceUnavailable(Logger, exception);
            _unavailable = true;
            SourceUnavailable.SetStatus(HttpContext);
            return;
        }

        // Split into upcoming and past by date, so an event earlier today still
        // counts as upcoming. Upcoming earliest first, past most recent first.
        var today = DateOnly.FromDateTime(DateTime.Today);
        _upcomingEvents =
        [
            .. events
                .Where(@event => DateOnly.FromDateTime(@event.Start) >= today)
                .OrderBy(@event => @event.Start)
        ];
        _pastEvents =
        [
            .. events
                .Where(@event => DateOnly.FromDateTime(@event.Start) < today)
                .OrderByDescending(@event => @event.Start)
        ];
    }
}