//---------------------------------------------------------------------------------------
// Copyright (c) 2001-2020 by PDFTron Systems Inc. All Rights Reserved.
// Consult legal.txt regarding legal and license information.
//---------------------------------------------------------------------------------------

#include <PDF/PDFNet.h>
#include <PDF/PDFDoc.h>
#include <PDF/ElementWriter.h>
#include <Common/Matrix2D.h>
#include <PDF/ElementReader.h>
#include <PDF/ElementBuilder.h>
#include <SDF/Obj.h>
#include <set>
#include <iostream>

using namespace pdftron;
using namespace std;
using namespace SDF;
using namespace PDF;
using namespace Common;


//---------------------------------------------------------------------------------------
// The sample code shows how to edit the page display list and how to modify graphics state 
// attributes on existing Elements. In particular the sample program strips all images from 
// the page, changes path fill color to red, and changes text fill color to blue. 
//---------------------------------------------------------------------------------------

// XObjects are guaranteed to have unique object numbers 
typedef set<pdftron::UInt32> XObjSet;


static void ProcessElements(ElementReader& reader, ElementWriter& writer, XObjSet& visited)
{
	Element element;
	while (element = reader.Next()) // Read page contents
	{
		switch (element.GetType())
		{
		case Element::e_text_begin:
		case Element::e_text_end:
			break;
		case Element::e_text:
		{
			Matrix2D ctm = element.GetCTM();
			GState gs = element.GetGState();
			double fontSize = gs.GetFontSize();
			Font font = gs.GetFont();
			double hscale = gs.GetHorizontalScale() / 100.0;
			Matrix2D textMtx = element.GetTextMatrix();
			Matrix2D posMtx = Matrix2D(1, 0, 0, 1, 0, 0);
			Matrix2D fontMtx = Matrix2D(fontSize * hscale, 0, 0, fontSize, 0, 0);
			double unitsPerEm = font.GetUnitsPerEm();
			Matrix2D unitsPerEmMtx = Matrix2D(1.0 / unitsPerEm, 0, 0, -1.0 / unitsPerEm, 0, 0);
			fontMtx = fontMtx * unitsPerEmMtx;
			for (CharIterator citr = element.GetCharIterator(); citr.HasNext(); citr.Next())
			{
				CharData charData = citr.Current();
				posMtx.m_h = charData.x;
				posMtx.m_v = charData.y;
				Matrix2D pathMtx = ctm * textMtx * posMtx * fontMtx;
				PathData pathData = font.GetGlyphPath(charData.char_code, true);
				if (pathData.GetOperators().size() > 0 && pathData.GetPoints().size() > 0)
				{
					vector<double> points = pathData.GetPoints();
					for (int i = 0; i < points.size(); i += 2)
					{
						double x = points[i];
						double y = points[i + 1];
						Point translatedPoint = pathMtx.Mult(Point(x, y));
						points[i] = translatedPoint.x;
						points[i + 1] = translatedPoint.y;
					}
					pathData.SetPoints(points);
					ElementBuilder builder;
					Element pathElement = builder.CreatePath(pathData.GetPoints(), pathData.GetOperators());
					pathElement.SetPathFill(true);
					pathElement.SetPathStroke(false);
					pathElement.GetGState().SetFillColorSpace(ColorSpace::CreateDeviceGray());
					pathElement.GetGState().SetFillColor(ColorPt(0.5, 0.0, 0.0));
					writer.WritePlacedElement(pathElement);
				}
			}
			break;
		}
		case Element::e_form:
		{
			writer.WriteElement(element); // write Form XObject reference to current stream

			Obj form_obj = element.GetXObject();
			if (visited.find(form_obj.GetObjNum()) == visited.end()) // if this XObject has not been processed
			{
				// recursively process the Form XObject
				visited.insert(form_obj.GetObjNum());
				ElementWriter new_writer;
				reader.FormBegin();
				new_writer.Begin(form_obj);

				reader.ClearChangeList();
				new_writer.SetDefaultGState(reader);

				ProcessElements(reader, new_writer, visited);
				new_writer.End();
				reader.End();
			}
			break;
		}
		default:
			writer.WriteElement(element);
		}
	}
}

int main(int argc, char* argv[])
{
	int ret = 0;
	PDFNet::Initialize();

	// Relative path to the folder containing test files.
	string input_path = "../../TestFiles/";
	string output_path = "../../TestFiles/Output/";
	string input_filename = "newsletter.pdf";
	string output_filename = "newsletter_edited.pdf";

	try
	{
		cout << "Opening the input file..." << endl;
		PDFDoc doc(input_path + input_filename);
		doc.InitSecurityHandler();

		ElementWriter writer;
		ElementReader reader;
		XObjSet visited;

		// Process each page in the document
		for (PageIterator itr = doc.GetPageIterator();itr.HasNext();itr.Next())
		{
			try {
				Page page = itr.Current();
				visited.insert(page.GetSDFObj().GetObjNum());

				reader.Begin(page);
				writer.Begin(page, ElementWriter::e_replacement, false, true, page.GetResourceDict());
				ProcessElements(reader, writer, visited);
				writer.End();
				reader.End();
			}
			catch (Common::Exception& e)
			{
				cout << e << endl;
			}
		}

		// Save modified document
		doc.Save(output_path + output_filename, SDFDoc::e_remove_unused, 0);
		cout << "Done. Result saved in " << output_filename << "..." << endl;
	}
	catch (std::exception& e)
	{
		cout << e.what() << endl;
		ret = 1;
	}
	catch (...)
	{
		cout << "Unknown Exception" << endl;
		ret = 1;
	}
	PDFNet::Terminate();
	return ret;
}