using System.Globalization;
using System.Net.Http.Headers;
using System.Security.Cryptography;
using System.Text;

namespace Manager.YouTube.Util;

public static class AuthenticationUtilities
{
    private const string HeaderScheme = "SAPISIDHASH";
    
    // Dave Thomas & windy for updated answer @ https://stackoverflow.com/a/32065323/9948300
    public static AuthenticationHeaderValue GetSapisidHashHeader(string datasyncId, string sapisid, string origin)
    {
        var strHash = GetSapisidHash(datasyncId, sapisid, origin);
        return new AuthenticationHeaderValue(HeaderScheme, strHash);
    }

    public static string GetSapisidHash(string datasyncId, string sapisid, string origin, string? time = null)
    {
        if (string.IsNullOrWhiteSpace(datasyncId))
        {
            throw new ArgumentNullException(nameof(datasyncId));
        }
        if (string.IsNullOrWhiteSpace(sapisid))
        {
            throw new ArgumentNullException(nameof(sapisid));
        }
        if (string.IsNullOrWhiteSpace(origin))
        {
            throw new ArgumentNullException(nameof(origin));
        }
        
        datasyncId = datasyncId.Replace("||", "");
        sapisid = Uri.UnescapeDataString(sapisid);
        if (string.IsNullOrWhiteSpace(time))
        {
            time = GetTime();
        }
        var sha1 = HashString($"{datasyncId} {time} {sapisid} {origin}");
        var completeHash = $"{time}_{sha1}_u";
        return completeHash;
    }

    private static string HashString(string stringData)
    {
        var dataBytes = Encoding.ASCII.GetBytes(stringData);
        var hashData = SHA1.HashData(dataBytes);
        return hashData.Aggregate(string.Empty, (current, item) => current + item.ToString("x2"));
    }
    
    private static string GetTime()
    {
        var st = new DateTime(1970, 1, 1);
        var t = DateTime.Now.ToUniversalTime() - st;
        var time = (t.TotalMilliseconds + 0.5).ToString(CultureInfo.InvariantCulture);
        return time[..10];
    }
}