DD.WellWorkover.Cloud/AsbCloudInfrastructure/Services/DrillingProgram/Convert/ConvertToPdf.cs

using iTextSharp.text;
using iTextSharp.text.pdf;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using CliWrap;
using System.Threading.Tasks;

namespace AsbCloudInfrastructure.Services.DrillingProgram.Convert
{
    internal class ConvertToPdf
    {
        private readonly string[] fileExtension = { ".xlsx", ".xls", ".ods", ".odt", ".doc", ".docx", ".pdf" };

        public static void DoMergedAsync(IEnumerable<string> inputFiles, string outFile)
        {
            using (FileStream stream = new FileStream(outFile, FileMode.Create))
            using (Document doc = new Document())
            using (PdfCopy pdf = new PdfCopy(doc, stream))
            {
                doc.Open();
                PdfReader reader = null;
                PdfImportedPage page = null;
                inputFiles.ToList().ForEach(file =>
                {
                    reader = new PdfReader(file);
                    for (int i = 0; i < reader.NumberOfPages; i++)
                    {
                        page = pdf.GetImportedPage(reader, i + 1);
                        pdf.AddPage(page);
                    }
                    pdf.FreeReader(reader);
                    reader.Close();                    
                    File.Delete(file);
                });
            }
        }

        private async Task StartConvertProcessAsync(string inputFileName, string outFileName)
        {
            var result = Cli.Wrap("/usr/bin/soffice")
                .WithArguments($"--headless --convert-to pdf {inputFileName} --outdir {outFileName}");
            await result.ExecuteAsync();
        }

        public async Task GetConverteAndMergedFileAsync(IEnumerable<string> filesNames, string resultPath)
        {
            var filteredFilesNames = filesNames
                .Distinct()
                .Where(f => fileExtension.Any(fe => f.ToLower().EndsWith(fe)))
                .ToList();
            var listFileNames = filteredFilesNames
                .ToList()
                .Select(o => new {
                    inputFile = o,
                    convertedFile = Path.ChangeExtension(o, ".pdf")
                });
            foreach (var fileName in listFileNames)
            {
                if (!fileName.inputFile.ToLower().EndsWith(".pdf"))
                    await StartConvertProcessAsync(fileName.inputFile, fileName.convertedFile);
            }
            DoMergedAsync(listFileNames.Select(c => c.convertedFile), resultPath);
        }
    }
}