using System;
using System.Text.Json;
using System.Threading.Tasks;
using Godot;
using Pong.Scripts.Data;

namespace Pong.Scripts.Managers;

public partial class SettingsManager : Node
{
	private const string SettingsPath = "user://settings.json";
	public Settings SettingsData = Settings.Default;
	private static readonly JsonSerializerOptions SerializerOptions = new() { IncludeFields = true };
	public event Action SettingsChanged;

	public override async void _EnterTree()
	{
		await LoadSettings();
	}

	/// <summary>
	/// load the settings data from the filesystem.
	/// </summary>
	private async Task LoadSettings()
	{
		try
		{
			if (!FileAccess.FileExists(SettingsPath))
			{
				await SaveSettings(Settings.Default);
				return;
			}

			using var file = await OpenSettingsFile(FileAccess.ModeFlags.Read);

			SettingsData =
				await Task.Run(() => JsonSerializer.Deserialize<Settings>(file.GetAsText(), SerializerOptions));
			SettingsChanged?.Invoke();
		}
		catch (Exception e)
		{
			PrintFileError(e);
		}
	}

	/// <summary>
	/// open the settings file from the filesystem.
	/// </summary>
	/// <returns> a godot FileAccess object.</returns>
	private static async Task<FileAccess> OpenSettingsFile(FileAccess.ModeFlags flag)
	{
		return await Task.Run(() => FileAccess.Open(SettingsPath, flag));
	}

	internal async Task<bool> SaveSettings(Settings settings)
	{
		try
		{
			using var file = await OpenSettingsFile(FileAccess.ModeFlags.WriteRead);
			var json = await Task.Run(() => JsonSerializer.Serialize(settings, SerializerOptions));
			await Task.Run(() => file.StoreBuffer(json.ToUtf8Buffer()));
			SettingsData = settings;
			SettingsChanged?.Invoke();
			return true;
		}
		catch (Exception e)
		{
			PrintFileError(e);
			return false;
		}
	}

	private static void PrintFileError(Exception e)
	{
		GD.PrintErr($"a {e.GetType()} has occured while trying to load the settings file: {e}.");
		GD.PrintErr("default settings will be used.");
	}
}