using System;
using System.Data;
using System.IO;
using System.Text;
using GB5Shared.Connection;
using FrameworkDAL.DTO.PDFEncrypt;
using FrameworkDAL.Query.PDFEncrypt;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.QueryExecutor;
using iText.Kernel.Pdf;
using static GB5Shared.GB5Constant.Constant;

namespace FrameworkDAL.CustomCode.PDFEncrypt
{
    public class PDFEncryptDAL : IPDFEncryptDAL
    {
        private readonly IQueryExecutor _queryExecutor;
        private readonly IApplicationConnection _IApplicationConnection;
        public PDFEncryptDAL(IQueryExecutor queryExecutor , IApplicationConnection IApplicationConnection)
        {
            _queryExecutor = queryExecutor;
            _IApplicationConnection = IApplicationConnection;
        }
        public async Task<string> EncryptPdfBase64(string Base64Pdf, LoginDTO loginDTO)
        {
            try
            {
                string query = loginDTO.DatabaseType == DBType.SQL
                    ? PDFEncryptQB.GETEMPSECRETKEY_SQL
                    : PDFEncryptQB.GETEMPSECRETKEY_PG;

                PDFEncryptDTO pdfEncryptDTO = await _queryExecutor.QuerySingleAsync<PDFEncryptDTO>(
                    loginDTO,
                    query,
                    new Dictionary<string, object>
                    {
                { "usercode", loginDTO.UserCode }
                    }
                );

                // Convert Base64 → byte[]
                byte[] inputPdfBytes = Convert.FromBase64String(Base64Pdf);
                 
                if (pdfEncryptDTO == null || string.IsNullOrWhiteSpace(pdfEncryptDTO.SecretKey))
                {
                    return Base64Pdf; // No password, open directly
                }
                
                string UserPassword =  _IApplicationConnection.Decrypt(pdfEncryptDTO.SecretKey, "GB5");

                using var inputStream = new MemoryStream(inputPdfBytes);
                using var outputStream = new MemoryStream();

                var writerProps = new WriterProperties()
                    .SetStandardEncryption(
                        Encoding.UTF8.GetBytes(UserPassword),
                        Encoding.UTF8.GetBytes(UserPassword),
                        EncryptionConstants.ALLOW_COPY,
                        EncryptionConstants.ENCRYPTION_AES_256
                    );

                using var reader = new PdfReader(inputStream);
                using var writer = new PdfWriter(outputStream, writerProps);
                using var pdfDoc = new PdfDocument(reader, writer);

                pdfDoc.Close();

                return Convert.ToBase64String(outputStream.ToArray());
            }
            catch (Exception)
            {
                throw;
            }
        }


    }
}