using System.Diagnostics;
using Microsoft.Extensions.Hosting;
using Moonlight.Api.Helpers;

namespace Moonlight.Api.Services;

public class ApplicationService : IHostedLifecycleService
{
    public DateTimeOffset StartedAt { get; private set; }
    public string VersionName { get; private set; } = "N/A";
    public bool IsUpToDate { get; set; } = true;
    public string OperatingSystem { get; private set; } = "N/A";
    
    public Task<long> GetMemoryUsageAsync()
    {
        using var currentProcess = Process.GetCurrentProcess();
        return Task.FromResult(currentProcess.WorkingSet64);
    }
    
    public async Task<double> GetCpuUsageAsync()
    {
        using var currentProcess = Process.GetCurrentProcess();
        
        // Get initial values
        var startCpuTime = currentProcess.TotalProcessorTime;
        var startTime = DateTime.UtcNow;

        // Wait a bit to calculate the diff
        await Task.Delay(500);

        // New values
        var endCpuTime = currentProcess.TotalProcessorTime;
        var endTime = DateTime.UtcNow;

        // Calculate CPU usage
        var cpuUsedMs = (endCpuTime - startCpuTime).TotalMilliseconds;
        var totalMsPassed = (endTime - startTime).TotalMilliseconds;
        var cpuUsagePercent = (cpuUsedMs / (Environment.ProcessorCount * totalMsPassed)) * 100;

        return Math.Round(cpuUsagePercent, 2);
    }
    
    public async Task StartedAsync(CancellationToken cancellationToken)
    {
        StartedAt = DateTimeOffset.UtcNow;
        
        // TODO: Update / version check

        VersionName = "v2.1.0 (a2d4edc0e5)";
        IsUpToDate = false;

        OperatingSystem = OsHelper.GetName();
    }

    #region Unused

    public Task StartAsync(CancellationToken cancellationToken) => Task.CompletedTask;
    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
    public Task StartingAsync(CancellationToken cancellationToken) => Task.CompletedTask;
    public Task StoppedAsync(CancellationToken cancellationToken) => Task.CompletedTask;
    public Task StoppingAsync(CancellationToken cancellationToken) => Task.CompletedTask;

    #endregion
}