using Foundation;

namespace Blahblah.Library.Network;

class NSMultipartFormData
{
    public const string DefaultMimeType = "application/octet-stream";

    public NSMutableData Data => boundaryData;

    readonly string boundary;
    readonly NSMutableData boundaryData;

    public string ContentType => $"{NetworkHelper.ContentFormData}; boundary={boundary}";

    public NSMultipartFormData()
    {
        var data = new byte[12];
        for (var i = 0; i < 12; i++)
        {
            data[i] = (byte)(Random.Shared.Next(0x30, 0x3a));
        }
        var id = Convert.ToBase64String(data);
        boundary = $"----WebKitFormBoundary{id}";
        boundaryData = new NSMutableData();
    }

    public void AddTextField(string name, string value)
    {
        // Content-Type: text/plain; charset=ISO-8859-1
        // Content-Transfer-Encoding: 8bit

        var field = $"--{boundary}\r\n" +
            $"Content-Disposition: form-data; name=\"{name}\"\r\n\r\n" +
            $"{value}\r\n";
        boundaryData.AppendData(NSData.FromString(field, NSStringEncoding.UTF8));
    }

    public void AddDataField(string name, Stream data, string? fileName = null, string mimeType = DefaultMimeType)
    {
        if (fileName == null)
        {
            fileName = "";
        }
        else if (!string.IsNullOrEmpty(fileName))
        {
            fileName = $"; filename=\"{fileName}\"";
        }
        var field = $"--{boundary}\r\n" +
            $"Content-Disposition: form-data; name=\"{name}\"{fileName}\r\n" +
            $"Content-Type: {mimeType}\r\n\r\n";
        boundaryData.AppendData(NSData.FromString(field, NSStringEncoding.UTF8));

        var stream = NSData.FromStream(data);
        if (stream != null)
        {
            boundaryData.AppendData(stream);
        }
        boundaryData.AppendData(NSData.FromString("\r\n"));
    }

    public void AddEnd()
    {
        boundaryData.AppendData(NSData.FromString($"--{boundary}--"));
    }
}