using AsbCloudApp.Data;
using AsbCloudApp.Services;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace AsbCloudInfrastructure.Services
{
    public class DrillingProgramApacheService : IDrillingProgramApacheService
    {
        private readonly IFileService fileService;
        private readonly IWellService wellService;
        private const int idFileCategoryDrillingProgramItems = 13;
        private const int idFileCategoryDrillingProgram = 14;

        public DrillingProgramApacheService(IFileService fileService, IWellService wellService)
        {
            this.fileService = fileService;
            this.wellService = wellService;
        }

        public async Task<FileInfoDto> GetAsync(int idWell, CancellationToken token = default)
        {
            var filesInfos = await fileService.GetInfosByCategoryAsync(idWell, idFileCategoryDrillingProgramItems, token)
                .ConfigureAwait(false);

            var well = await wellService.GetAsync(idWell, token)
                .ConfigureAwait(false);

            var resultFileName = $"Программа бурения {well.Cluster} {well.Caption}.xlsx";

            var matchFiles = await fileService.GetInfosByCategoryAsync(idWell, idFileCategoryDrillingProgram, token)
                .ConfigureAwait(false);

            if (matchFiles is not null && matchFiles.Any())
            {
                matchFiles = matchFiles.OrderByDescending(f => f.UploadDate);
                var matchFilesIterator = matchFiles.GetEnumerator();
                matchFilesIterator.MoveNext();
                var matchFile = matchFilesIterator.Current;
                while (matchFilesIterator.MoveNext())
                    await fileService.DeletedAsync(matchFilesIterator.Current.Id, token)
                        .ConfigureAwait(false);

                if (filesInfos.All(f => f.UploadDate <= matchFile.UploadDate))
                    return matchFile;
                else
                    await fileService.DeletedAsync(matchFile.Id, token)
                        .ConfigureAwait(false);
            }

            var fileNames = filesInfos
                .Where(f => f.Name != resultFileName)
                .Select(f => fileService.GetUrl(f));

            var stream = new MemoryStream(1024 * 1024);
            UniteExcelFiles(fileNames, stream);
            var buffer = stream.ToArray();
            var fileStream = new MemoryStream(buffer);
            return await fileService.SaveAsync(idWell, null, idFileCategoryDrillingProgram, resultFileName, fileStream, token)
                .ConfigureAwait(false);
        }

        private static void UniteExcelFiles(IEnumerable<string> excelFilesNames, Stream stream)
        {
            IWorkbook product = new XSSFWorkbook();

            foreach (var excelFileName in excelFilesNames)
            {
                IWorkbook book = new XSSFWorkbook(new FileStream(excelFileName, FileMode.Open));

                for (int i = 0; i < book.NumberOfSheets; i++)
                {
                    ISheet sheet = book.GetSheetAt(i);
                    try
                    {
                        sheet.CopyTo(product, sheet.SheetName, true, true);
                    }
                    catch
                    {
                        //what can't be done - can't be done. ignore it.
                    }
                }
            }
            product.Write(stream);
        }
    }
}