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

namespace Moonlight.Api.Services;

public class ApplicationService : IHostedService
{
    private readonly VersionService VersionService;
    private readonly ILogger<ApplicationService> Logger;

    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 ApplicationService(VersionService versionService, ILogger<ApplicationService> logger)
    {
        VersionService = versionService;
        Logger = logger;
    }

    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 StartAsync(CancellationToken cancellationToken)
    {
        StartedAt = DateTimeOffset.UtcNow;
        
        OperatingSystem = OsHelper.GetName();

        try
        {
            var currentVersion = await VersionService.GetInstanceVersionAsync();
            var latestVersion = await VersionService.GetLatestVersionAsync();

            VersionName = currentVersion.Identifier;
            IsUpToDate = latestVersion == null || currentVersion.Identifier == latestVersion.Identifier;
            
            Logger.LogInformation("Running Moonlight Panel {version} on {operatingSystem}", VersionName, OperatingSystem);

            if (!IsUpToDate)
                Logger.LogWarning("Your instance is not up-to-date");

            if (currentVersion.IsDevelopment)
                Logger.LogWarning("Your instance is running a development version");

            if (currentVersion.IsPreRelease)
                Logger.LogWarning("Your instance is running a pre-release version");
        }
        catch (Exception e)
        {
            Logger.LogError(e, "An unhandled exception occurred while fetching version details");
        }
    }

    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
}