using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using PureCrack.Util;

namespace PureCrack.Setup;

public static class HostsManager
{
	private const string HostsPath = "C:\\Windows\\System32\\drivers\\etc\\hosts";

	private const string BackupSuffix = ".purecrack-backup";

	public static readonly string[] Domains = new string[3] { "api.purecoder.io", "api1.purecoder.io", "api2.purecoder.io" };

	public static string Path => "C:\\Windows\\System32\\drivers\\etc\\hosts";

	public static string BackupPath => "C:\\Windows\\System32\\drivers\\etc\\hosts.purecrack-backup";

	public static bool Ensure()
	{
		if (!File.Exists("C:\\Windows\\System32\\drivers\\etc\\hosts"))
		{
			throw new FileNotFoundException("C:\\Windows\\System32\\drivers\\etc\\hosts missing — Windows install looks broken");
		}
		string content = File.ReadAllText("C:\\Windows\\System32\\drivers\\etc\\hosts");
		HashSet<string> present = ScanPresent(content);
		List<string> list = Domains.Where((string d) => !present.Contains(d)).ToList();
		if (list.Count == 0)
		{
			Log.Info($"hosts: all {Domains.Length} entries already present");
			return false;
		}
		if (!File.Exists(BackupPath))
		{
			File.Copy("C:\\Windows\\System32\\drivers\\etc\\hosts", BackupPath);
			Log.Bullet("hosts: backup saved to " + BackupPath);
		}
		string text = EnsureTrailingNewline(content);
		foreach (string item in list)
		{
			text = text + "127.0.0.1 " + item + "\n";
			Log.Bullet("hosts: add 127.0.0.1 " + item);
		}
		File.WriteAllText("C:\\Windows\\System32\\drivers\\etc\\hosts", text);
		FlushDns();
		return true;
	}

	public static void Remove()
	{
		if (!File.Exists("C:\\Windows\\System32\\drivers\\etc\\hosts"))
		{
			return;
		}
		string[] array = File.ReadAllLines("C:\\Windows\\System32\\drivers\\etc\\hosts");
		List<string> list = new List<string>(array.Length);
		int num = 0;
		string[] array2 = array;
		foreach (string text in array2)
		{
			string trimmed = text.Trim();
			if (trimmed.StartsWith("#") || trimmed.Length == 0)
			{
				list.Add(text);
			}
			else if (Domains.Any((string d) => LineMapsDomainToLoopback(trimmed, d)))
			{
				num++;
			}
			else
			{
				list.Add(text);
			}
		}
		if (num > 0)
		{
			File.WriteAllText("C:\\Windows\\System32\\drivers\\etc\\hosts", string.Join("\n", list));
			Log.Ok($"hosts: removed {num} entries");
			FlushDns();
		}
	}

	public static bool IsWritable()
	{
		try
		{
			using (File.Open("C:\\Windows\\System32\\drivers\\etc\\hosts", FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite))
			{
				return true;
			}
		}
		catch (UnauthorizedAccessException)
		{
			return false;
		}
		catch (IOException)
		{
			return false;
		}
	}

	private static HashSet<string> ScanPresent(string content)
	{
		HashSet<string> hashSet = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
		string[] array = content.Split(new char[1] { '\n' });
		for (int i = 0; i < array.Length; i++)
		{
			string text = array[i].Trim();
			if (text.Length == 0 || text.StartsWith("#"))
			{
				continue;
			}
			string[] domains = Domains;
			foreach (string text2 in domains)
			{
				if (LineMapsDomainToLoopback(text, text2))
				{
					hashSet.Add(text2);
				}
			}
		}
		return hashSet;
	}

	private static bool LineMapsDomainToLoopback(string line, string domain)
	{
		string[] array = line.Split(new char[2] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);
		if (array.Length < 2)
		{
			return false;
		}
		if (!array[0].StartsWith("127."))
		{
			return false;
		}
		for (int i = 1; i < array.Length; i++)
		{
			string text = array[i];
			if (text.StartsWith("#"))
			{
				break;
			}
			if (string.Equals(text, domain, StringComparison.OrdinalIgnoreCase))
			{
				return true;
			}
		}
		return false;
	}

	private static string EnsureTrailingNewline(string content)
	{
		if (content.Length != 0 && content[content.Length - 1] != '\n')
		{
			return content + "\n";
		}
		return content;
	}

	private static void FlushDns()
	{
		try
		{
			using Process process = Process.Start(new ProcessStartInfo("ipconfig", "/flushdns")
			{
				UseShellExecute = false,
				CreateNoWindow = true,
				RedirectStandardOutput = true,
				RedirectStandardError = true
			});
			process?.WaitForExit(5000);
			Log.Bullet("hosts: dns cache flushed");
		}
		catch (Exception ex)
		{
			Log.Warn("ipconfig /flushdns failed (non-fatal): " + ex.Message);
		}
	}
}