Toolkit2/Toolkit.UI.Controls.Avalonia/QrCode/Encoding/DataEncodation/InputRecognition/InputRecognise.cs

using System;
using System.Collections.Generic;

namespace Gma.QrCodeNet.Encoding.DataEncodation.InputRecognition;

public static class InputRecognise
{
	public static RecognitionStruct Recognise(string content)
	{
		string encodingName = EightBitByteRecognision(content, 0, content.Length);
		return new RecognitionStruct(encodingName);
	}

	private static string EightBitByteRecognision(string content, int startPos, int contentLength)
	{
		if(string.IsNullOrEmpty(content))
            throw new ArgumentNullException(nameof(content));

		var eciSets = new ECISet(ECISet.AppendOption.NameToValue);

		Dictionary<string, int>? eciSet = eciSets.GetECITable();

        if(eciSet == null)
            return string.Empty;

		// we will not check for utf8 encoding.
		eciSet.Remove(QRCodeConstantVariable.UTF8Encoding);
		eciSet.Remove(QRCodeConstantVariable.DefaultEncoding);

		int scanPos = startPos;

		// default encoding as priority
		scanPos = ModeEncodeCheck.TryEncodeEightBitByte(content, QRCodeConstantVariable.DefaultEncoding, scanPos, contentLength);
		if (scanPos == -1)
		{
			return QRCodeConstantVariable.DefaultEncoding;
		}

		foreach (KeyValuePair<string, int> kvp in eciSet)
		{
			scanPos = ModeEncodeCheck.TryEncodeEightBitByte(content, kvp.Key, scanPos, contentLength);
			if (scanPos == -1)
			{
				return kvp.Key;
			}
		}

		if (scanPos == -1)
		{
			throw new ArgumentException("foreach Loop check give wrong result.");
		}
		else
		{
			return QRCodeConstantVariable.UTF8Encoding;
		}
	}
}