using System.Diagnostics;
using App.Metrics;
using Catalogger.Backend.Cache;
using Catalogger.Backend.Database;
using Humanizer;
using Microsoft.EntityFrameworkCore;
using NodaTime.Extensions;

namespace Catalogger.Backend.Services;

public class MetricsCollectionService(
    ILogger logger,
    GuildCacheService guildCache,
    ChannelCacheService channelCache,
    UserCacheService userCache,
    IMetrics metrics,
    IServiceProvider services) : BackgroundService
{
    private readonly ILogger _logger = logger.ForContext<MetricsCollectionService>();

    private async Task CollectMetricsAsync()
    {
        var stopwatch = new Stopwatch();
        stopwatch.Start();

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

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

        metrics.Measure.Gauge.SetValue(CataloggerMetrics.GuildsCached, guildCache.Size);
        metrics.Measure.Gauge.SetValue(CataloggerMetrics.ChannelsCached, channelCache.Size);
        metrics.Measure.Gauge.SetValue(CataloggerMetrics.UsersCached, userCache.Size);
        metrics.Measure.Gauge.SetValue(CataloggerMetrics.MessagesStored, messageCount);

        var process = Process.GetCurrentProcess();
        metrics.Measure.Gauge.SetValue(CataloggerMetrics.ProcessPhysicalMemory, process.WorkingSet64);
        metrics.Measure.Gauge.SetValue(CataloggerMetrics.ProcessVirtualMemory, process.VirtualMemorySize64);
        metrics.Measure.Gauge.SetValue(CataloggerMetrics.ProcessPrivateMemory, process.PrivateMemorySize64);
        metrics.Measure.Gauge.SetValue(CataloggerMetrics.ProcessThreads, process.Threads.Count);
        metrics.Measure.Gauge.SetValue(CataloggerMetrics.ProcessHandles, process.HandleCount);

        stopwatch.Stop();

        metrics.Measure.Timer.Time(CataloggerMetrics.MetricsCollectionTime, stopwatch.ElapsedMilliseconds);
        _logger.Information("Collected metrics in {Duration}", stopwatch.ElapsedDuration());

        await Task.WhenAll(((IMetricsRoot)metrics).ReportRunner.RunAllAsync());
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        using var timer = new PeriodicTimer(1.Minutes());
        while (await timer.WaitForNextTickAsync(stoppingToken))
        {
            _logger.Debug("Collecting periodic metrics");
            await CollectMetricsAsync();
            _logger.Debug("Reported metrics to backend");
        }
    }
}