using System.Diagnostics;
using Catalogger.Backend.Cache.InMemoryCache;
using Catalogger.Backend.Database;
using Humanizer;
using Microsoft.EntityFrameworkCore;
using Prometheus;

namespace Catalogger.Backend.Services;

public class MetricsCollectionService(
    ILogger logger,
    GuildCache guildCache,
    ChannelCache channelCache,
    UserCache userCache,
    IServiceProvider services)
{
    private readonly ILogger _logger = logger.ForContext<MetricsCollectionService>();

    public async Task CollectMetricsAsync(CancellationToken ct = default)
    {
        var timer = CataloggerMetrics.MetricsCollectionTime.NewTimer();

        await using var scope = services.CreateAsyncScope();
        await using var db = scope.ServiceProvider.GetRequiredService<DatabaseContext>();

        var messageCount = await db.Messages.CountAsync(ct);

        CataloggerMetrics.GuildsCached.Set(guildCache.Size);
        CataloggerMetrics.ChannelsCached.Set(channelCache.Size);
        CataloggerMetrics.UsersCached.Set(userCache.Size);
        CataloggerMetrics.MessagesStored.Set(messageCount);
        CataloggerMetrics.MessageRateMinute = messageCount - CataloggerMetrics.MessageRateMinute;

        var process = Process.GetCurrentProcess();
        CataloggerMetrics.ProcessPhysicalMemory.Set(process.WorkingSet64);
        CataloggerMetrics.ProcessVirtualMemory.Set(process.VirtualMemorySize64);
        CataloggerMetrics.ProcessPrivateMemory.Set(process.PrivateMemorySize64);
        CataloggerMetrics.ProcessThreads.Set(process.Threads.Count);
        CataloggerMetrics.ProcessHandles.Set(process.HandleCount);

        _logger.Information("Collected metrics in {Duration}", timer.ObserveDuration());
    }
}

public class BackgroundMetricsCollectionService(ILogger logger, MetricsCollectionService innerService) : BackgroundService
{
    private readonly ILogger _logger = logger.ForContext<BackgroundMetricsCollectionService>();
    
    protected override async Task ExecuteAsync(CancellationToken ct)
    {
        _logger.Information("Metrics are disabled, periodically collecting metrics manually");
        
        using var timer = new PeriodicTimer(1.Minutes());
        while (await timer.WaitForNextTickAsync(ct))
        {
            _logger.Debug("Collecting metrics");
            await innerService.CollectMetricsAsync(ct);
        }
    }
}