using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Application.Abstractions.YouTube;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;
using SharedKernel;

namespace Application.Features.Admin.Channel.YouTubePubSub.GetHealth;

internal sealed class Handler(
    IAppDbContext db,
    IYouTubePubSubService pubSubService,
    IYouTubeLiveChatService liveChatService,
    IYouTubeLiveStateStore liveStateStore,
    IOptions<AppSettings> settings
) : IQueryHandler<Query, Response>
{
    public async Task<Response> Handle(Query request, CancellationToken ct)
    {
        var cfg = await db.Config.AsNoTracking().FirstOrDefaultAsync(ct);
        var apiKey = cfg?.External?.YouTubeApiKeyEnc;
        var hmac = settings.Value.YouTube.HmacSecret;

        var subscribedIds = (await pubSubService.GetSubscribedChannelIdsAsync(ct)).ToHashSet();
        var lastPolled = await pubSubService.GetAllLastPolledAtAsync(ct);
        var leaseExpiries = await pubSubService.GetAllLeaseExpiriesAsync(ct);
        var lastProcessed = await pubSubService.GetAllLastProcessedVideoIdsAsync(ct);
        var liveChannels = await liveStateStore.GetAllLiveAsync();

        var channels = await db.Channel.AsNoTracking()
            .Where(c => c.YouTubeChannelID != null && c.YouTubeChannelID != "")
            .OrderByDescending(c => c.IsActive)
            .ThenBy(c => c.Name)
            .Select(c => new
            {
                c.YouTubeChannelID,
                c.Name,
                c.Handle,
                c.IsActive
            })
            .ToListAsync(ct);

        var items = channels.Select(c =>
        {
            var ytId = c.YouTubeChannelID!;
            return new ChannelHealthItem(
                ytId,
                c.Name,
                c.Handle,
                c.IsActive,
                subscribedIds.Contains(ytId),
                lastPolled.TryGetValue(ytId, out var lp) ? lp : null,
                leaseExpiries.TryGetValue(ytId, out var le) ? le : null,
                lastProcessed.TryGetValue(ytId, out var vid) ? vid : null
            );
        }).ToList();

        return new Response(
            ApiKeyConfigured: !string.IsNullOrEmpty(apiKey),
            ApiKeyMaskedTail: MaskTail(apiKey),
            HmacSecretConfigured: !string.IsNullOrEmpty(hmac),
            HmacSecretMaskedTail: MaskTail(hmac),
            CallbackUrl: settings.Value.YouTube.CallbackUrl,
            FeedPollingIntervalMinutes: settings.Value.YouTube.FeedPollingIntervalMinutes > 0
                ? settings.Value.YouTube.FeedPollingIntervalMinutes
                : 3,
            ActiveLiveChatCollectors: liveChatService.GetActiveChatIds().Count,
            ActiveLiveVideosCount: liveChannels.Count,
            SubscribedChannelsCount: subscribedIds.Count,
            ActiveInternalChannelsCount: channels.Count(c => c.IsActive),
            Channels: items
        );
    }

    // 키 앞뒤 노출 방지 — 마지막 4글자만 표시
    private static string? MaskTail(string? value)
    {
        if (string.IsNullOrEmpty(value))
        {
            return null;
        }

        return value.Length <= 4
            ? new string('*', value.Length)
            : $"****{value[^4..]}";
    }
}