using System;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Gott.Extensions;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;

namespace Gott.Endpoints;

public static class BackupEndpoint
{
    public static void MapBackupEndpoint(this IEndpointRouteBuilder app)
    {
        app.MapPost("/api/backup", HandleBackup);
    }

    private static async Task HandleBackup(HttpContext ctx)
    {
        if (!ctx.IsAdmin())
        {
            ctx.Response.StatusCode = 403;
            return;
        }

        var dataDir = Path.Combine(AppContext.BaseDirectory, "data");

        if (!Directory.Exists(dataDir))
        {
            ctx.Response.StatusCode = 404;
            ctx.Response.ContentType = "application/json";
            await ctx.Response.WriteAsync("{\"error\":\"Data-Ordner nicht gefunden\"}");
            return;
        }

        var backupDir = Path.Combine(dataDir, "backup");
        Directory.CreateDirectory(backupDir);

        var timestamp = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
        var archiveName = $"gott-{timestamp}.tar.gz";
        var archivePath = Path.Combine(backupDir, archiveName);

        var entries = Directory.GetFileSystemEntries(dataDir)
            .Select(e => Path.GetFileName(e))
            .Where(e => e != "backup")
            .ToArray();

        var psi = new ProcessStartInfo
        {
            FileName = "tar",
            RedirectStandardError = true,
            UseShellExecute = false
        };
        psi.ArgumentList.Add("-czf");
        psi.ArgumentList.Add(archivePath);
        psi.ArgumentList.Add("-C");
        psi.ArgumentList.Add(dataDir);
        foreach (var entry in entries)
            psi.ArgumentList.Add(entry);

        using (var process = Process.Start(psi))
        {
            if (process == null)
            {
                ctx.Response.StatusCode = 500;
                return;
            }

            var stderr = await process.StandardError.ReadToEndAsync();
            await process.WaitForExitAsync();

            if (process.ExitCode != 0)
            {
                ctx.Response.StatusCode = 500;
                ctx.Response.ContentType = "application/json";
                await ctx.Response.WriteAsync($"{{\"error\":\"tar fehlgeschlagen: {stderr}\"}}");
                return;
            }
        }

        var bytes = await File.ReadAllBytesAsync(archivePath);
        ctx.Response.StatusCode = 200;
        ctx.Response.ContentType = "application/gzip";
        ctx.Response.Headers["Content-Disposition"] = $"attachment; filename=\"{archiveName}\"";
        await ctx.Response.Body.WriteAsync(bytes);
    }
}