using SharpExifTool;
using System.Security.Cryptography;
namespace Shadow.Tools;

public static class MetadataExtractor
{
	private readonly static ExifTool exifTool = new();
	private readonly static GeneralUseHelpers guhf = new();
	public async static Task<Dictionary<string, string>> ExtractAsync(string fullPath)
	{
		// Get all relevant metadata
		Dictionary<string, string> fileMetadata = new(await
			exifTool.ExtractAllMetadataAsync(fullPath));

		// Add in a MD5 hint
		string md5sum = await GetFileMD5Async(fullPath);
		fileMetadata?.Add("_shadow:fileHash", md5sum);

		return fileMetadata ?? [];
	}

	/// <summary>
	/// Compute MD5 checksum of a file
	/// </summary>
	/// <param name="fullPath">Input file absolute path</param>
	/// <returns>MD5 hexstring</returns>
	public static async Task<string> GetFileMD5Async(string fullPath)
	{
		string fallbackValue = String.Empty;
		
		try
		{
			if (File.Exists(fullPath))
				using (MD5 md5 = MD5.Create())
				{
					using (FileStream stream = File.OpenRead(fullPath))
					{
						byte[] hashBytes = await md5.ComputeHashAsync(stream);
						string hashString = Convert.ToHexStringLower(hashBytes);
						return hashString;
					}
				}
			else return fallbackValue;
		}
		catch
		{
			return fallbackValue;
		}
	}

	/// <summary>
	/// Compute MD5 checksum of a string
	/// </summary>
	/// <param name="input">Input string for the MD5 hash</param>
	/// <returns>MD5 hexstring</returns>
	public static string GetStringMD5(string input)
	{
		// https://stackoverflow.com/a/24031467
		byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(input);
		byte[] hashBytes = MD5.HashData(inputBytes);
		string hashString = Convert.ToHexStringLower(hashBytes);

		return hashString;
	}


}