Tesseract OCR on inbound PDF implemented in .Net, structured as an HTTP request Azure Function, uploads results to SQL Server

PDFScrape.csx

#r "iTextSharp.dll"
#r "Ghostscript.Net.dll"
#r "System.Drawing"
#r "Tesseract.dll"
#r "SqlClientHelpers.dll"
#r "iTextSharp.Licensekey.dll"
#r "System.Data"
#r "System.Configuration" 

using System;
using System.Net;
using System.Net.Http;
using iTextSharp.text.pdf;
using iTextSharp.text;
using System.IO;
using Ghostscript.NET;
using Ghostscript.NET.Rasterizer;
using System.Drawing;
using Tesseract;
using NextTech.SqlClientHelpers;
using System.Data;
using System.Text;
using System.Text.RegularExpressions;
using System.Diagnostics;


public static GhostscriptRasterizer rasterizer = new GhostscriptRasterizer();
public static GhostscriptVersionInfo gsVersion = new GhostscriptVersionInfo(@"D:\home\site\wwwroot\BlendTicketInvoicePDFScrape\bin\gsdll32.dll");
public static TesseractEngine ocr = new TesseractEngine(@"D:\home\site\wwwroot\BlendTicketInvoicePDFScrape\tessdata", "eng", EngineMode.Default);

public static int currentLineNum;
public static string[] lines;
public static TraceWriter gLog;

public const string topString = "-----top-----top-----top-----";

public static string findMatch(string pattern)
{
  Match match = null;
  while (currentLineNum < lines.Count()
    && (lines[currentLineNum] != topString || pattern == "("+topString+")") 
    && (match = Regex.Match(lines[currentLineNum], pattern)) != null 
    && !match.Success) currentLineNum++;
  var found =  (match !=null && match.Success) ? match.Groups[1].Value : null;
  if (found != null) currentLineNum++; //move to the next line to start the next search
  gLog.Info($"looking for: {pattern}, found: {found ?? "NULL"}, current line: {currentLineNum}");
  return found;
}

public static object v(string str, bool tryAsDecimal = false) {
  decimal x;
  return string.IsNullOrWhiteSpace(str) ? DBNull.Value : 
    tryAsDecimal ? (decimal.TryParse(str, out x) ? (object)x : DBNull.Value) : 
    (object)str;
}

public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, TraceWriter log)
{
  gLog = log;

  Proc.ConnectionStringDefault = System.Configuration.ConfigurationManager.ConnectionStrings["TestSQL"].ConnectionString;
  Proc.OnErrorDefault = (ex) => log.Info($"sql error: {ex}");
  Proc.OnSuccessDefault = () => log.Info($"sql Success!");

  try
  {
    log.Info($"C# HTTP trigger function processed a request. Current Folder: {System.Environment.CurrentDirectory}");

    var currentPageNum = 2;
    var skipPageCount = 3;
    int dpi = 200;

    StringBuilder pageText = new StringBuilder();
    var pageCount = 0;

    MemoryStream ghostScriptInStream;
    using (var incomingPdfStream = await req.Content.ReadAsStreamAsync())
    //using (var pdfIn = new PdfReader("LPI-Billing11-25.pdf"))
    using (var pdfIn = new PdfReader(incomingPdfStream))
    using (var pdfExtractDoc = new Document(pdfIn.GetPageSizeWithRotation(currentPageNum)))
    using (var pdfExtractStream = new MemoryStream())
    using (var pdfExtract = new PdfCopy(pdfExtractDoc, pdfExtractStream))
    //using (var pdfExtract = new PdfCopy(pdfExtractDoc, new System.IO.FileStream("out.pdf", System.IO.FileMode.Create)))
    {
      var totalPageCount = pdfIn.NumberOfPages;
      pdfExtractDoc.Open();
      while (currentPageNum < totalPageCount)
      {
        pageCount++;
        pdfIn.GetPageN(currentPageNum).Put(PdfName.ROTATE, new PdfNumber(-90));
        pdfExtract.AddPage(pdfExtract.GetImportedPage(pdfIn, currentPageNum));
        currentPageNum += skipPageCount;
        log.Info($"{pageCount} pages rotated and extracted...");
      }
      //had to load result into fresh stream, otherwise PDF structure was scrambled using the old stream for some reason
      ghostScriptInStream = new MemoryStream(pdfExtractStream.GetBuffer());
    }

    using (ghostScriptInStream)
    {
      for (int currentOcrPage = 1; currentOcrPage <= pageCount; currentOcrPage++)
      {
        rasterizer.Open(ghostScriptInStream, gsVersion, true);
        log.Info($"saving page {currentOcrPage} to BMP (\"rasterizing\")...");
        using (var img = rasterizer.GetPage(dpi, dpi, currentOcrPage))
        using (var bmp = new Bitmap(img))
        {
          log.Info($"  OCR'ing...");
          using (var ocrPage = ocr.Process(bmp)) {
            var pgTxt = ocrPage.GetText();
            log.Info(pgTxt);
            pageText.Append(topString);
            pageText.Append("\n");
            pageText.Append(pgTxt);
          }
        }

        log.Info($"{currentOcrPage} pages OCRed...");
      }
    }

    lines = pageText.ToString().Split('\n');

    log.Info($"Proc.ConnectionStringDefault: {Proc.ConnectionStringDefault}");
    using (var selectProc = new Proc("dbo.BlendTicketInvoiceItems_s"))
    using (var insertProc = new Proc("dbo.BlendTicketInvoiceItems_i"))
    {
      var sqlProcessedPageCount = 0;
      log.Info("firing select proc...");
      var sqlTable = selectProc.ExecuteDataSet().Table0();
      log.Info("debug 2");
      currentLineNum = 0;

      while (true)
      {
        sqlProcessedPageCount++;

        var top = findMatch("("+topString+")");
        if (top == null) break;
        var currentTop = currentLineNum;

        var blendTicketNumber = findMatch(@"Blend Ticket ([0-9]+)");
        if (blendTicketNumber == null) {
          log.Info($"*** couldn't find blendTicketNumber on bundle #{sqlProcessedPageCount}, bailing on to next.");
          currentLineNum--;
          continue;
        }

        currentLineNum = currentTop;

        findMatch("(Guaranteed Anal)");
        var mixRatio = lines[currentLineNum].Trim();
        var TotalPrice = findMatch(@"PRICE . ([0-9]*\.[0-9]*)");
        var TotalCost = findMatch(@"COST . ([0-9]*\.[0-9]*)");
        var TotalFreight = findMatch(@"FREIGHT . ([0-9]*\.[0-9]*)");

        currentLineNum = currentTop;

        while (!lines[currentLineNum].StartsWith("Liqlmm")) currentLineNum++;

        while (lines[currentLineNum].StartsWith("Liq"))
        {
          var groups = Regex.Match(lines[currentLineNum], @"(?<Header>[^0-9]*?) (?<ItemId>[0-9]*?) (.*?) ([^ ]*?\..*?) ([^ ]*?\..*?) (?<Cost>[^ ]*?\..*?) ").Groups;
          var itemId = groups["ItemId"]?.Value;
          var header = groups["Header"]?.Value;

          //little fix for this bad data scenario:
          //bad:  Liqlmm 14001 Hot Water Tons 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
          //good: Liqlmm I 1001 MOP 00-52 Tons 404.7300 252.8210 261.7000 151.9090 143.0300 37.5334 35.3396 60.0356 54.6542
          //      12345678
          //itemId needs to be 4001 on first line, not 14001
          if (header.Length < 8 && itemId != null) itemId = itemId.Left(-1);

          var r = sqlTable.NewRow();
          r["BlendTicketNumber"] = blendTicketNumber;
          r["MixRatio"] = v(mixRatio);
          r["ItemId"] = v(itemId);
          r["Cost"] = v(groups["Cost"]?.Value, true);
          r["TotalPrice"] = v(TotalPrice, true);
          r["TotalCost"] = v(TotalCost, true);
          r["TotalFreight"] = v(TotalFreight, true);
          sqlTable.Rows.Add(r);
          currentLineNum++;
          log.Info($"added {sqlTable.Rows.Count} sqlTable row, currentLineNum: {currentLineNum}");
        }

      }
      insertProc["@BlendTicketInvoiceItems"] = sqlTable;
      insertProc.ExecuteNonQueryAsync().Wait();

      return req.CreateResponse(HttpStatusCode.OK, $"successfully inserted rows: {sqlTable.Rows.Count}");
    }


  }
  catch (Exception ex)
  {
    return req.CreateResponse(HttpStatusCode.OK, $"Exception: {ex}");
  }

}