using MathGame.ViewModels;

using System;
using System.Threading;

using CommunityToolkit.Mvvm.ComponentModel;
using System.Threading.Tasks;
using MathGame.Services;
using System.Collections.Generic;
using System.IO;

namespace SplashScreen.ViewModels;

public partial class SplashViewModel : ViewModelBase
{
    [ObservableProperty]
    private string _startupMessage = "Starting Application. . .Please Wait. . .";

    [ObservableProperty]
    private double _progress = 0;

    private CancellationTokenSource _cts = new CancellationTokenSource();
    public CancellationToken cancellationToken => _cts.Token;

    public void Cancel()
    {
        _cts.Cancel();
    }

    /* Loading Screen Control Flow
     *
     * - Check for application config.json file, required file for application, call function to create if not exists
     * - Check for application database file, required file for application, call function to create if not exists
     * - If neither of those files exists, launch create new user screen (handled in MainWindowViewModel).
     *
     */

    public async Task<bool> LoadApplication()
    {
        var timer = new FunctionTimer();
        double elapsedTime = 0;

        int sleep = 500;

        try
        {
            // Give the application's system a moment to catch up
            StartupMessage = "Starting Application. . .Please Wait. . .";
            await Task.Delay(sleep, cancellationToken);

            StartupMessage = "Checking For Application Config File. . .Please Wait. . .";
            timer.Start();

            bool configExists = await FileCheckService.FileExistsAsync("config.json");

            if (!configExists)
            {
                var configResults = JsonService.CheckConfig();

                if (!configResults.IsSuccess)
                {
                    timer.Stop();
                    StartupMessage = $"Error: {configResults.Message}";
                    await Task.Delay(sleep, cancellationToken);
                    Environment.Exit(0);
                    return false;
                }
            }

            StartupMessage = "Application Config File Found. . .Please Wait. . .";
            timer.Stop();
            elapsedTime = timer.GetElapsedTimeInSeconds();
            UpdateProgress(elapsedTime);
            timer.Clear();

            StartupMessage = "Checking For Application Database. . .Please Wait. . .";
            timer.Start();

            bool databaseExists = await FileCheckService.FileExistsAsync("main.db");

            if (!databaseExists)
            {
                var dbResults = Database.CreateDatabase();

                if (!dbResults.IsSuccess)
                {
                    timer.Stop();
                    StartupMessage = $"Error: {dbResults.Message}";
                    await Task.Delay(500, cancellationToken);
                    Environment.Exit(0);
                    return false;
                }
            }

            StartupMessage = "Application Database Found. . .Please Wait. . .";
            timer.Stop();
            elapsedTime = timer.GetElapsedTimeInSeconds();
            UpdateProgress(elapsedTime);
            timer.Clear();
            return true;
        }
        catch (TaskCanceledException)
        {
            Environment.Exit(0);
            return false;
        }
    }

    private void UpdateProgress(double progress)
    {
        Progress = Math.Min(progress, 1.0);
    }
}