using System;
using System.IO;
using System.IO.Compression;
using System.Net;
using System.Security.Cryptography;

internal static class EngineBootstrap
{
    internal const string Url = "https://github.com/godotengine/godot-builds/releases/download/4.5-stable/Godot_v4.5-stable_win64.exe.zip";
    internal const string Hash = "e8ef4867466bb01a2b762c4ec404f54266b40a5cbba0efa95e3ab325cd7d349b5dc11259e1c1525195080dc82294ff28044f7ac4acad833e4b054b4257e9aa1a";
    internal static void Verify(string archive)
    {
        using (var stream = File.OpenRead(archive))
        using (var sha = SHA512.Create())
            if (BitConverter.ToString(sha.ComputeHash(stream)).Replace("-", "").ToLowerInvariant() != Hash)
                throw new InvalidDataException("Godot-Prüfsumme stimmt nicht. Bitte erneut versuchen.");
    }
    internal static void Install(string root, Action<string> status, string offlineArchive)
    {
        string engine = Path.Combine(root, "tools", "godot");
        if (File.Exists(Path.Combine(engine, "Godot_v4.5-stable_win64.exe")) && File.Exists(Path.Combine(engine, "Godot_v4.5-stable_win64_console.exe"))) return;
        Directory.CreateDirectory(engine);
        string archive = Path.Combine(engine, "download-" + Guid.NewGuid().ToString("N") + ".zip");
        try
        {
            if (offlineArchive == null)
            {
                string besideSetup = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Godot_v4.5-stable_win64.exe.zip");
                if (File.Exists(besideSetup)) offlineArchive = besideSetup;
            }
            if (offlineArchive != null) File.Copy(offlineArchive, archive);
            else
            {
                ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
                using (var client = new TimedClient())
                {
                    client.Headers[HttpRequestHeader.UserAgent] = "BLOCKLINE-Setup/1.0";
                    status("Godot 4.5 wird heruntergeladen …");
                    try { client.DownloadFile(Url, archive); }
                    catch (WebException ex) { throw new IOException("Godot konnte nicht geladen werden. Internet/Firewall prüfen oder Godot_v4.5-stable_win64.exe.zip von der offiziellen Godot-Seite neben die Setup-Datei legen. " + ex.Message, ex); }
                }
            }
            status("Prüfsumme prüfen und Engine entpacken …");
            Verify(archive);
            using (var zip = ZipFile.OpenRead(archive))
                foreach (string name in new[] { "Godot_v4.5-stable_win64.exe", "Godot_v4.5-stable_win64_console.exe" })
                {
                    var entry = zip.GetEntry(name);
                    if (entry == null) throw new InvalidDataException("Engine-Datei fehlt: " + name);
                    string temp = Path.Combine(engine, name + ".part");
                    entry.ExtractToFile(temp, true);
                    string target = Path.Combine(engine, name);
                    if (File.Exists(target)) File.Delete(target);
                    File.Move(temp, target);
                }
        }
        finally { if (File.Exists(archive)) File.Delete(archive); }
    }
    private sealed class TimedClient : WebClient
    {
        protected override WebRequest GetWebRequest(Uri uri)
        {
            var request = (HttpWebRequest)base.GetWebRequest(uri);
            request.Timeout = 300000;
            request.ReadWriteTimeout = 300000;
            return request;
        }
    }
}