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

namespace Elternbeirat.Web.Features.Home;

public partial class Home
{
    [LoggerMessage(
        Level = LogLevel.Warning,
        Message = "Could not load the pages for the home page from PocketBase; showing the static title only.")]
    private static partial void LogPagesUnavailable(
        ILogger logger,
        Exception exception);

    [LoggerMessage(
        Level = LogLevel.Warning,
        Message = "Could not load events for the home page from PocketBase; the next-event card is omitted.")]
    private static partial void LogEventsUnavailable(
        ILogger logger,
        Exception exception);

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

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

    [Inject]
    private TimeProvider Time { get; set; } = null!;

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

    // Heading, intro and buttons come from the "home" page's body. Until it is loaded
    // -- and for good if PocketBase is down -- the static fallback heading stands, so
    // the start page always has a title.
    private HomeIntro _intro = HomeIntro.Fallback;

    // The hero, the tiles and the next-event card are fixed structure of the start
    // page; which dynamic blocks follow below is editorial and comes from the "home"
    // page's embed field.
    private IReadOnlyList<HomeTile> _tiles = [];
    private IReadOnlyList<string> _embed = [];
    private Event? _nextEvent;

    protected override Task OnInitializedAsync()
    {
        var token = HttpContext?.RequestAborted ?? CancellationToken.None;
        return Task.WhenAll(LoadPagesAsync(token), LoadNextEventAsync(token));
    }

    // Pages and events load side by side and fail on their own: without events the
    // page loses only the card, without pages only text and tiles. Either way the
    // start page stays a 200 rather than a 503 -- it is degraded, not broken.
    private async Task LoadPagesAsync(CancellationToken token)
    {
        try
        {
            var pages = await PocketBase.GetPagesAsync(token);
            var home = pages.FirstOrDefault(page => Page.IsHomeSlug(page.Slug));
            _intro = HomeIntro.Parse(home?.Body);
            _embed = home?.Embed ?? [];
            _tiles = HomeTile.From(pages);
        }
        catch (PocketBaseUnavailableException exception)
        {
            LogPagesUnavailable(Logger, exception);
        }
    }

    private async Task LoadNextEventAsync(CancellationToken token)
    {
        try
        {
            var events = await PocketBase.GetEventsAsync(token);
            _nextEvent = UpcomingEvents.From(events, BerlinClock.Today(Time)).FirstOrDefault();
        }
        catch (PocketBaseUnavailableException exception)
        {
            LogEventsUnavailable(Logger, exception);
        }
    }
}