using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Newtonsoft.Json;
using ResourceMonitorService.Configuration;
using ResourceMonitorService.Models;
using ResourceMonitorService.Services;
using System.Diagnostics;

namespace ResourceMonitorService
{
    public class Worker : BackgroundService
    {
        private readonly ILogger<Worker> _logger;
        private readonly IHostApplicationLifetime _lifetime;
        private readonly ISystemInfoService _systemInfoService;
        private readonly IResourceMonitorService _resourceMonitorService;
        private readonly IGameDetectionService _gameDetectionService;
        private readonly IAlertService _alertService;
        private readonly ApiSettings _apiSettings;
        private readonly MonitoringSettings _monitoringSettings;

        public Worker(
            ILogger<Worker> logger,
            IHostApplicationLifetime lifetime,
            ISystemInfoService systemInfoService,
            IResourceMonitorService resourceMonitorService,
            IGameDetectionService gameDetectionService,
            IAlertService alertService,
            IOptions<ApiSettings> apiSettings,
            IOptions<MonitoringSettings> monitoringSettings)
        {
            _logger = logger;
            _lifetime = lifetime;
            _systemInfoService = systemInfoService;
            _resourceMonitorService = resourceMonitorService;
            _gameDetectionService = gameDetectionService;
            _alertService = alertService;
            _apiSettings = apiSettings.Value;
            _monitoringSettings = monitoringSettings.Value;
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            _logger.LogInformation("Resource Monitor Service starting...");

            var builder = WebApplication.CreateBuilder();
            
            // Configure CORS
            builder.Services.AddCors(options =>
            {
                options.AddPolicy("AllowedOrigins", policy =>
                    policy.WithOrigins(_apiSettings.AllowedOrigins.ToArray())
                          .AllowAnyHeader()
                          .AllowAnyMethod());
            });

            builder.Services.AddControllers().AddNewtonsoftJson();

            var app = builder.Build();

            // API Key middleware (if enabled)
            if (_apiSettings.RequireApiKey)
            {
                app.Use(async (context, next) =>
                {
                    if (!context.Request.Headers.TryGetValue("X-API-KEY", out var extractedApiKey) || 
                        extractedApiKey != _apiSettings.ApiKey)
                    {
                        context.Response.StatusCode = StatusCodes.Status401Unauthorized;
                        await context.Response.WriteAsync("Unauthorized: Invalid API Key");
                        return;
                    }
                    await next();
                });
            }

            app.UseCors("AllowedOrigins");

            // Enhanced API endpoints
            ConfigureApiEndpoints(app);

            // Start background monitoring
            _ = Task.Run(async () => await BackgroundMonitoringLoop(stoppingToken), stoppingToken);

            // Start the web application
            _ = app.RunAsync(stoppingToken);

            await Task.Delay(Timeout.Infinite, stoppingToken);
        }

        private void ConfigureApiEndpoints(WebApplication app)
        {
            var basePath = _apiSettings.BasePath;

            // System information endpoints
            app.MapGet($"{basePath}/system-info", async () => 
                Results.Ok(await _systemInfoService.GetSystemInfoAsync()));

            // Resource usage endpoints
            app.MapGet($"{basePath}/resource-usage", async () => 
                Results.Ok(await _resourceMonitorService.GetResourceUsageAsync()));

            app.MapGet($"{basePath}/cpu-usage", async () => 
                Results.Ok(await _resourceMonitorService.GetCpuUsageAsync()));

            app.MapGet($"{basePath}/memory-usage", async () => 
                Results.Ok(await _resourceMonitorService.GetMemoryUsageAsync()));

            app.MapGet($"{basePath}/gpu-usage", async () => 
                Results.Ok(await _resourceMonitorService.GetGpuUsageAsync()));

            app.MapGet($"{basePath}/disk-usage", async () => 
                Results.Ok(await _resourceMonitorService.GetDiskUsageAsync()));

            app.MapGet($"{basePath}/network-usage", async () => 
                Results.Ok(await _resourceMonitorService.GetNetworkUsageAsync()));

            app.MapGet($"{basePath}/top-processes", async (int count = 10) => 
                Results.Ok(await _resourceMonitorService.GetTopProcessesAsync(count)));

            // Game detection endpoints
            app.MapGet($"{basePath}/current-game", async () => 
                Results.Ok(await _gameDetectionService.GetCurrentlyRunningGameAsync()));

            app.MapGet($"{basePath}/all-games", async () => 
                Results.Ok(await _gameDetectionService.GetAllDetectedGamesAsync()));

            app.MapGet($"{basePath}/fullscreen-status", async () => 
                Results.Ok(new { IsFullscreen = await _gameDetectionService.IsGameRunningFullscreenAsync() }));

            // Alert endpoints
            app.MapGet($"{basePath}/alerts/active", async () => 
                Results.Ok(await _alertService.GetActiveAlertsAsync()));

            app.MapGet($"{basePath}/alerts/history", async (int count = 100) => 
                Results.Ok(await _alertService.GetAlertHistoryAsync(count)));

            app.MapPost($"{basePath}/alerts/{{alertId}}/resolve", async (string alertId) =>
            {
                await _alertService.ResolveAlertAsync(alertId);
                return Results.Ok(new { Message = "Alert resolved successfully" });
            });

            app.MapGet($"{basePath}/alerts/enabled", async () => 
                Results.Ok(new { Enabled = await _alertService.IsAlertingEnabledAsync() }));

            // Process management endpoints (enhanced)
            app.MapPost($"{basePath}/process/kill", async (HttpContext context) =>
            {
                try
                {
                    var body = await new StreamReader(context.Request.Body).ReadToEndAsync();
                    var request = JsonConvert.DeserializeObject<dynamic>(body);
                    
                    int processId = request?.ProcessId ?? 0;
                    bool force = request?.Force ?? false;

                    if (processId <= 0)
                    {
                        return Results.BadRequest("Invalid process ID");
                    }

                    var processes = Process.GetProcesses().Where(p => p.Id == processId).ToArray();

                    if (processes.Length == 0)
                    {
                        return Results.NotFound($"No process found with ID {processId}");
                    }

                    var process = processes[0];
                    var processName = process.ProcessName;

                    if (force)
                    {
                        process.Kill(true); // Force kill entire process tree
                    }
                    else
                    {
                        process.CloseMainWindow(); // Try graceful close first
                        
                        // Wait a bit for graceful close
                        await Task.Delay(3000);
                        
                        if (!process.HasExited)
                        {
                            process.Kill();
                        }
                    }

                    _logger.LogWarning("Process {ProcessName} (ID: {ProcessId}) was terminated", processName, processId);
                    return Results.Ok(new { Message = $"Process {processName} (ID: {processId}) has been terminated." });
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, "Error terminating process");
                    return Results.Problem(ex.Message);
                }
            });

            // Enhanced shutdown/restart endpoints
            app.MapPost($"{basePath}/system/shutdown", async (HttpContext context) =>
            {
                try
                {
                    var body = await new StreamReader(context.Request.Body).ReadToEndAsync();
                    var request = JsonConvert.DeserializeObject<dynamic>(body);

                    string action = request?.Action?.ToString()?.ToLower() ?? "shutdown";
                    int delaySeconds = request?.DelaySeconds ?? 0;
                    string message = request?.Message?.ToString() ?? "System shutdown initiated by Resource Monitor";

                    if (action != "shutdown" && action != "restart" && action != "cancel")
                    {
                        return Results.BadRequest("Invalid action. Use 'shutdown', 'restart', or 'cancel'.");
                    }

                    if (action == "cancel")
                    {
                        var cancelProcess = new ProcessStartInfo
                        {
                            FileName = "shutdown",
                            Arguments = "/a",
                            CreateNoWindow = true,
                            UseShellExecute = false
                        };
                        Process.Start(cancelProcess);
                        
                        _logger.LogWarning("System shutdown cancelled");
                        return Results.Ok(new { Message = "Shutdown cancelled." });
                    }

                    if (delaySeconds < 0)
                    {
                        return Results.BadRequest("Delay must be a non-negative integer.");
                    }

                    string shutdownCommand = action == "shutdown" 
                        ? $"/s /f /t {delaySeconds} /c \"{message}\""
                        : $"/r /f /t {delaySeconds} /c \"{message}\"";

                    var processStartInfo = new ProcessStartInfo
                    {
                        FileName = "shutdown",
                        Arguments = shutdownCommand,
                        CreateNoWindow = true,
                        UseShellExecute = false
                    };

                    Process.Start(processStartInfo);

                    _logger.LogWarning("System {Action} initiated with {Delay} seconds delay", action, delaySeconds);
                    return Results.Ok(new { 
                        Message = $"{action.ToUpper()} command executed with a delay of {delaySeconds} seconds.",
                        Action = action,
                        DelaySeconds = delaySeconds,
                        Timestamp = DateTime.Now
                    });
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, "Error executing system command");
                    return Results.Problem(ex.Message);
                }
            });

            // VM-specific endpoints for Unraid
            app.MapGet($"{basePath}/vm/info", async () =>
            {
                var systemInfo = await _systemInfoService.GetSystemInfoAsync();
                return Results.Ok(new
                {
                    IsVirtualMachine = systemInfo.IsVirtualMachine,
                    HypervisorVendor = systemInfo.HypervisorVendor,
                    Uptime = systemInfo.Uptime,
                    BootTime = systemInfo.BootTime,
                    MachineName = systemInfo.MachineName,
                    Domain = systemInfo.Domain
                });
            });

            // Performance history endpoint (simple in-memory storage)
            app.MapGet($"{basePath}/performance/history", async (int minutes = 60) =>
            {
                // This would ideally be stored in a database or time-series database
                // For now, return current snapshot with timestamp
                var usage = await _resourceMonitorService.GetResourceUsageAsync();
                return Results.Ok(new { 
                    Current = usage,
                    Message = "Historical data not implemented yet - showing current values"
                });
            });

            // Health check endpoint
            app.MapGet($"{basePath}/health", async () =>
            {
                var systemInfo = await _systemInfoService.GetSystemInfoAsync();
                var alerts = await _alertService.GetActiveAlertsAsync();
                
                return Results.Ok(new
                {
                    Status = "Healthy",
                    Timestamp = DateTime.Now,
                    Uptime = systemInfo.Uptime,
                    ActiveAlerts = alerts.Count,
                    MonitoringEnabled = new
                    {
                        GPU = _monitoringSettings.EnableGpuMonitoring,
                        Disk = _monitoringSettings.EnableDiskMonitoring,
                        Network = _monitoringSettings.EnableNetworkMonitoring,
                        Temperature = _monitoringSettings.EnableTemperatureMonitoring,
                        Processes = _monitoringSettings.EnableProcessMonitoring,
                        Games = _monitoringSettings.EnableGameDetection,
                        Alerts = _monitoringSettings.EnableAlerts
                    }
                });
            });

            // Service control endpoints
            app.MapPost($"{basePath}/service/stop", () =>
            {
                _logger.LogWarning("Service stop requested via API");
                _lifetime.StopApplication();
                return Results.Ok(new { Message = "Stopping the service..." });
            });

            // Root endpoint
            app.MapGet("/", () => Results.Ok(new
            {
                Service = "Resource Monitor Service",
                Version = "2.0.0",
                Status = "Running",
                Timestamp = DateTime.Now,
                ApiBasePath = _apiSettings.BasePath,
                Documentation = $"{_apiSettings.BasePath}/health"
            }));

            _logger.LogInformation("API endpoints configured. Base path: {BasePath}", _apiSettings.BasePath);
        }

        private async Task BackgroundMonitoringLoop(CancellationToken cancellationToken)
        {
            _logger.LogInformation("Background monitoring started");

            while (!cancellationToken.IsCancellationRequested)
            {
                try
                {
                    // Get current resource usage
                    var resourceUsage = await _resourceMonitorService.GetResourceUsageAsync();

                    // Add current game info if game detection is enabled
                    if (_monitoringSettings.EnableGameDetection)
                    {
                        resourceUsage.RunningGame = await _gameDetectionService.GetCurrentlyRunningGameAsync();
                    }

                    // Check for alerts
                    if (_monitoringSettings.EnableAlerts)
                    {
                        await _alertService.CheckAndGenerateAlertsAsync(resourceUsage);
                    }

                    // Log performance metrics occasionally
                    if (DateTime.Now.Second % 30 == 0) // Every 30 seconds
                    {
                        _logger.LogDebug("Performance: CPU: {CpuUsage:F1}%, Memory: {MemoryUsage:F1}%, GPU: {GpuUsage}%", 
                            resourceUsage.CPU.Usage, 
                            resourceUsage.Memory.UsagePercentage,
                            resourceUsage.GPU.Usage);
                    }
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, "Error in background monitoring loop");
                }

                await Task.Delay(_monitoringSettings.UpdateIntervalMs, cancellationToken);
            }

            _logger.LogInformation("Background monitoring stopped");
        }
    }
}